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5.0 DISCUSSION OF EXPERIMENTAL RESULTS
5.1 MIX PROPORTIONS OF OPC CONCRETE
The experimental investigation adopted IS-code (IS-10262-1982)
and Erntroy & Shack lock method of mix design procedure for
designing M20 and M50 grade concrete. The mix proportions of OPC
concrete of M20 grade are given in table 4.2.3. The ratio of the
quantities obtained were cement: Fine aggregate: Coarse aggregate =
1: 1.92: 2.64 with w/c = 0.55. The mix proportions of OPC concrete of
M50 grade are given in table 4.2.4. The ratio of the quantities obtained
were cement: Fine aggregate: Coarse aggregate = 1: 0.96: 3.64 with
w/c = 0.33.
5.2 WORKABILITY OF OPCC, MKC, SFRC & SFRC – MK
MIXES OF M20 AND M50 GRADES
(i) The workability of OPCC, SFRC, and MKC & SFRC-MK mixes of
M20 and M50 grade in terms of compacting factor, vee-bee time and
slump are given in tables 4.3.1 to 4.3.2 respectively. The variation of
workability in terms of compacting factor, Vee-bee time and slump for
MKC, SFRC, and SFRC-MK are given in figures 1.0 to 6.0.
(ii) The super plasticizer content in OPCC, MKC, SFRC, SFRC-MK
mixes is taken as 1% of the weight of binding material to improve the
workability and to prevent balling of fibres.
(iii) The workability in terms of compacting factor of OPCC and MKC
of M20 grade is found to be 0.976, 0.930 and 0.892, 0.862 for M50
266
grade respectively. The workability of MKC is less than the OPCC
because of high fineness of Metakaolin.
(iv) The workability of SFRC, SFRC-MK in terms of compacting
factor is decreasing from 0.910 to 0.890 with increasing fibre content
from 0.50% to 1.50%. The workability of SFRC-MK is less than SFRC
due to high fineness of Metakaolin.
5.3 COMPRESSIVE STRENGTH OF OPCC, MKC, SFRC &
SFRC – MK MIXES OF M20 AND M50 GRADES
5.3.1 Experimental results
Compressive strength of OPCC, MKC, SFRC & SFRC-MK mixes of
M20 grade with fibres of aspect ratio 60 and 80.
Compressive strength of OPCC, SFRC, MKC and SFRC-MK are
given in tables 4.4.1.1 to 4.4.1.4 respectively. From these tables it is
observed that:
(i) The compressive strength of OPC concrete at 7, 14 & 28 days is
found to be 19.96MPa, 24.66MPa and 30.69MPa. The corresponding
values for MKC are 21.27MPa, 29.55MPa and 32.86MPa respectively.
(ii) The experimental compressive strength of OPCC i.e. 30.69MPa
at 28 days is greater than the mean strength.
Due to addition of Metakaolin to the concrete, the compressive
strength at 7 days is increased from 19.96 to 21.27MPa, 24.66 to
29.55MPa at 14 days and 30.69 to 32.86MPa at 28 days. The
compressive strength of MKC is increased by 6.56% at 7 days, 19.83%
267
at 14 days and 7.07% at 28 days for M20 grade when compared with
its OPC concrete.
The compressive strength of SFRC is 1.70% to 6.61% more than that
of OPC concrete at 7 days, 2.63% to 7.54% at 14 days and 3.16% to
9.02% at 28 days depending on the value of fibre factor F. This is due
to the addition of crimped steel fibres from 0.50% to 1.50%.
(iii) The compressive strength of SFRC-MK at 7 days is 10.21% to
16.0% more than that of OPC concrete and 3.38% to 8.80% more than
MKC depending on the value of fibre factor F. This is due to the
addition of crimped steel fibres from 0.50% to 1.50% and due to the
high pozzolanic reactivity of Metakaolin.
(iv) The compressive strength of SFRC-MK at 14 days is 22.84% to
34.26% more than that of OPC concrete and 2.50% to 12.0% more
than MKC depending on the value of fibre factor F. This is due to the
addition of crimped steel fibres from 0.50% to 1.50% and high
pozzolanic reactivity of Metakaolin.
The compressive strength of SFRC-MK at 28 days is 11.51% to
18.90% more than that of OPC concrete and 4.20% to 11.0% more
than MKC depending on the value of fibre factor F. This is because of
high pozzolanic reactivity of Metakaolin, acceleration of hydration
reaction, micro -filling action of Metakaolin, better Pore refinement
caused due to the presence of Metakaolin, reduction in the quantity of
Ca (OH)2 and enhanced C-S-H gel formation due to the pozzolanic
reaction, decrease in the width of the interfacial zone between cement
paste and aggregate when compared to the OPC concrete and also due
268
to the addition of crimped steel fibres from 0.50% to 1.50% resulted in
improved bond between the fibres and matrix in SFRC-MK.
Compressive strength of OPCC, MKC, SFRC and SFRC-MK mixes
of M50 grade with fibres of aspect ratio 60 and 80.
Compressive strength of OPCC, SFRC and SFRC-MK are given
in tables 4.4.1.6 and 4.4.1.7 respectively. From these tables it is
observed that:
(v) The compressive strength of OPC concrete at 7, 14 & 28 days is
found to be 40.02 MPa, 49.54 MPa and 61.40 MPa. The
corresponding values for MKC are 44.08MPa, 62.42 MPa and 68.90
MPa respectively.
(vi) The experimental compressive strength of OPCC i.e. 61.40MPa
at 28 days is greater than the mean strength.
Compressive strength is increased from 40.02 to 44.08 MPa at 7 days,
49.54 to 62.42 MPa at 14 days and 61.40 to 68.90 MPa at 28 days.
The compressive strength of SFRC-MK is increased by 14.85% to
19.86% at 7 days, 29.76% to 36.68% at 14 days and 15.70% to
23.25% at 28 days when compared with its OPC concrete.
The compressive strength of SFRC is 2.88% to 8.70% more than that
of OPC concrete at 7 days, 3.54% to 10.74% at 14 days and 3.92% to
12.24% at 28 days depending on the fibre factor F. This is due to the
addition of crimped steel fibres from 0.50% to 1.50%.
(vii) The compressive strength of SFRC-MK at 7 days is 14.85% to
19.86% more than that of OPC concrete and 4.26% to 8.80% more
than MKC depending on the value of fibre factor F. The compressive
269
strength of SFRC-MK at 14 days is 29.76% to 36.68% more than that
of OPC concrete and 2.97% to 8.50% more than MKC depending on
the value of fibre factor F.
(viii) The compressive strength of SFRC-MK at 28 days is 15.70% to
23.25% more than that of OPC concrete and 3.80% to 9.80% more
than MKC depending on the value of fibre factor F.
5.3.1.1 Effect of fibre content and aspect ratio of fibres on
compressive strength of SFRC Mixes of M20 & M50 Grade
The compressive strength of SFRC at 7 days, 14 days and 28
days is increasing with fiber content and aspect ratio of fibres as
shown in tables 4.4.1.1 and 4.4.1.5. As the compressive strength is
increasing with fiber content, aspect ratio of the fibres and the bond
characteristics of fibres, these factors are incorporated into a single
parameter called as fiber factor F15.
A regression analysis performed on the test results of table
4.4.1.1 gave the following expression for the compressive strength of
SFRC of M20 grade as
σcs,predicted = 4.097(F) + σc ----------- (1)
r2 = 0.994
where
r = coefficient of correlation
σcs,predicted = predicted compressive strength of SFRC in MPa
σc = experimental compressive strength of OPCC in MPa.
F = fibre factor = Vf.AR.β.
270
From table 4.4.1.2, the average percentage error between the
experimental values and the predicted values of compressive strength
of SFRC is 0.80% from table 4.4.1.2.
Another regression analysis performed on the test results of
SFRC of M50 grade from table 4.4.1.5 gave the following expression
for the compressive strength of SFRC as:
σcs,predicted = 8.289 (F) + σc --------- (2)
r2 = 0.986
Where
r = coefficient of correlation
σcs,predicted = proposed compressive strength of SFRC in MPa.
σc = experimental compressive strength of OPCC in MPa
F = fibre factor = Vf.AR.β.
From table 4.4.1.6, the average percentage error between the
experimental values and the predicted values of compressive strength
of SFRC is 1.10% from table 4.4.1.6.
5.3.1.2 Effect of fibre content and aspect ratio of fibres on
compressive strength of SFRC - MK Mixes of M20 & M50 Grade
The compressive strength of SFRC-MK at 7,14 and 28 days is
increasing with fibre content and higher aspect ratio of fibres when
compared with MK concrete as shown in tables 4.4.1.3 and 4.4.1.7.
As the compressive strength is increasing with fibre content, aspect
ratio of fibres and the bond characteristics of fibres, these factors are
incorporated into a single parameter called as fibre factor F15.
271
A regression analysis performed on the test results of table 4.4.1.3
gave the following expression for the compressive strength of SFRC -
MK. of M20 grade as
σcsm,proposed = 3.95 (F) + σcm ---------- (3)
r2 = 0.982
Where
r = coefficient of correlation
σcsm, proposed = predicted compressive strength of SFRC-MK in MPa.
σcm = experimental compressive strength of MKC in MPa
F = fibre factor = Vf.AR.β.
From table 4.4.1.4, the average percentage error between the
experimental values and the predicted values of compressive strength
of SFRC-MK is 1.10% from table 4.4.1.4.
Another regression analysis performed on the test results of SFRC-MK
of M50 grade concrete from table 4.4.1.7 gave the following expression
for the compressive strength of SFRC-MK as:
σcsm,predicted = 7.06 (F) + σcm --------- (4)
r2 = 0.975
Where
r = coefficient of correlation
σcsm,predicted = predicted compressive strength of SFRC-MK in MPa.
σcm = experimental compressive strength of MKC in MPa
F = fibre factor = Vf.AR.β.
272
From table 4.4.1.8, the average percentage error between the
experimental values and the predicted values of compressive strength
of SFRC is 0.90% from table 4.4.1.8.
5.4 SPLITTING TENSILE STRENGTH OF OPCC, MKC,
SFRC & SFRC – MK MIXES OF M20 AND M50 GRADES
5.4.1 Experimental Results
Tables 4.4.2.1 to 4.4.2.8 gives the test results of splitting tensile
strength for the various mixes of M20 and M50 grade concrete (OPCC,
MKC, and SFRC & SFRC-MK). Figures 18.0 to 28.0 show the variation
of splitting tensile strength with fibre content and fibre factor. It is
evident from the tables 4.4.2.1 to 4.4.2.8, that the addition of crimped
steel fibres to concrete improves its splitting tensile strength. The
experimental results of the various mixes studied are given below:
Splitting tensile strength of OPCC, MKC, SFRC and SFRC-MK of
M20 grade concrete with fibres of aspect ratio 60 and 80.
Splitting tensile strength of OPCC, SFRC, MKC and SFRC-MK
are given in tables 4.4.2.1 and 4.4.2.3 respectively. From these
tables it is observed that:
(i) The splitting tensile strength of OPCC and MKC at 28 days is
found to be 2.84 MPa and 3.08 MPa.
(ii) 16.90% to 63.0% increase in splitting tensile strength of SFRC
is observed when compared with the splitting tensile strength of OPC
concrete from table 4.4.2.1.
273
(iii) 11.04% to 61.0% and 20.42% to 74.65% increase in splitting
tensile strength of SFRC-MK is observed when compared with the
splitting tensile strength of MKC and OPC concrete respectively from
table 4.4.2.3.
Splitting tensile strength of OPCC, MKC, SFRC and SFRC-MK of
M50 grade concrete with fibres of aspect ratio 60 and 80.
Splitting tensile strength of OPCC, SFRC, MKC and SFRC-MK are
given in tables 4.4.2.5 and 4.4.2.7 respectively. From these tables it
is observed that:
(i) The splitting tensile strength of OPCC and MKC at 28 days is
found to be 4.32 and 4.76 MPa.
(ii) 22.22% to 67.13% increase in splitting tensile strength of SFRC
is observed when compared with the splitting tensile strength of OPC
concrete from table 4.4.2.5.
(iii) 18.69% to 61.55% and 30.78% to 78.0% increase in splitting
tensile strength of SFRC-MK is observed when compared with the
splitting tensile strength of MKC and OPC concrete respectively from
table 4.4.2.7.
5.4.1.1 Effect of fibre content and aspect ratio of fibres on
splitting tensile strength of SFRC Mixes of M20 & M50 Grade
The splitting tensile strength of SFRC is increasing from 16.90%
to 63.0% with fibre content and aspect ratio of fibres when compared
with OPC concrete as shown in tables 4.4.2.2 and 4.4.2.6. As the
splitting tensile strength is increasing with fibre content, aspect ratio
274
of the fibres and the bond characteristics of fibres, these factors are
incorporated into a single parameter called as fibre factor F15.
A regression analysis performed on the test results of table
4.4.2.1 gave the following expression for the compressive strength of
SFRC of M20 grade as
σst,predicted = 2.097 (F) + σst ----------- (5)
r2 = 0.991
Where
r = coefficient of correlation
σst,predicted = predicted splitting tensile strength of SFRC in MPa
σst = experimental splitting tensile strength of OPCC in MPa.
F = fibre factor = Vf.AR.β.
The average percentage error between the experimental values and the
predicted values of splitting tensile strength of SFRC is 1.60% from
table 4.4.2.2.
Another regression analysis performed on the test results of SFRC of
M50 grade concrete from table 4.4.2.5 gave the following expression
for the compressive strength of SFRC as:
σst,predicted = 3.24 (F) + σst --------- (6)
r2 = 0.992
Where
r = coefficient of correlation
σst,predicted = predicted splitting tensile strength of SFRC in MPa.
σst = experimental splitting tensile strength of OPCC in MPa
F = fibre factor = Vf.AR.β.
275
From table 4.4.2.6, the average percentage error between the
experimental values and the predicted values of compressive strength
of SFRC is 1.01% from table 4.4.2.6.
5.4.1.2 Effect of fibre content and aspect ratio of fibres on
splitting tensile strength of SFRC -MK Mixes of M20 & M50 Grade
The splitting tensile strength of SFRC - MK is increasing
from11.04% to 61.04% with fibre content and higher aspect ratio of
fibres when compared with MK concrete as shown in table 4.4.2.3 and
4.4.2.7. As the splitting tensile strength is increasing with fibre
content, aspect ratio of fibres and the bond characteristics of fibres,
these factors are incorporated into a single parameter called as fibre
factor F15.
A regression analysis performed on the test results of table
4.4.2.3 gave the following expression for the compressive strength of
SFRC -MK of M20 grade as.
σstm,predicted = 2.125(F) + σstm ---------- (7)
r2 = 0.990
Where
r = coefficient of correlation
σstm,predicted = predicted splitting tensile strength of SFRC-MK in MPa.
σstm = experimental splitting tensile strength of MKC in MPa
F = fibre factor = Vf.AR.β.
From table 4.4.2.4, the average percentage error between the
experimental values and the predicted values of splitting tensile
strength of SFRC-MK is 1.10% from table 4.4.2.4.
276
Another regression analysis performed on the test results of
SFRC-MK of M50 grade concrete from table 4.4.2.7 gave the following
expression for the splitting tensile strength of SFRC-MK as:
σstm,predicted = 3.30(F) + σstm --------- (8)
r2 = 0.982
Where
r = coefficient of correlation
σstm,predicted = proposed splitting tensile strength of SFRC-MK in MPa.
σstm = experimental splitting tensile strength of MKC in MPa
F = fibre factor = Vf.AR.β.
From table 4.4.2.8, the average percentage error between the
experimental values and the predicted values of splitting tensile
strength of SFRC-MK is 2.60% from table 4.4.2.8.
5.5 MODULUS OF RUPTURE OF OPCC, MKC, SFRC &
SFRC – MK MIXES OF M20 AND M50 GRADES
5.5.1 Experimental Results
Tables 4.4.3.1 to 4.4.3.8 gives the test results of modulus of rupture
of OPCC, MKC, SFRC and SFRC-MK mixes of M20 and M50 grade
concretes. Figures 29.0 to 38.0 show the variation of modulus of
rupture with fibre content and fibre factor. It is evident from tables
4.4.3.1 to 4.4.3.8, that the addition of fibres to concrete improves its
modulus of rupture. The experimental results of the modulus of
rupture of the various mixes studied are given below:
277
Modulus of rupture of OPCC, MKC, SFRC & SFRC-MK of M20
grade concrete
(i) The modulus of rupture of OPC and MK concretes are found to
be 4.03 MPa and 4.26 MPa respectively.
(ii) 18.12% to 66.74% increase in modulus of rupture of SFRC is
observed when compared with the modulus of rupture of OPC
concrete from table 4.4.3.1. The average of value of the ratio of
modulus of rupture to splitting tensile strength of SFRC mix is found
to be 1.90 and that of modulus of rupture to compressive strength is
found to be 0.183 from table 4.4.3.1.
(iii) 14.32% to 61.97% and 20.84% to 71.22% increase in modulus
of rupture of SFRC-MK is observed when compared with the modulus
of rupture of MKC and OPC concrete respectively. The average value of
the modulus of rupture to splitting tensile strength of SFRC-MK mix is
found to be 1.92 and that of modulus of rupture to compressive
strength was found to be 0.178 from table 4.4.3.3.
Modulus of rupture of OPCC, MKC, SFRC & SFRC-MK of M50
grade concrete:
(i) The modulus of rupture of OPC and MK concretes are found to
be 5.42 MPa and 5.87 MPa respectively.
(ii) 19.56% to 68.82% increase in modulus of rupture of SFRC is
observed when compared with the modulus of rupture of OPC
concrete from table 4.4.3.5. The average value of the ratio of modulus
of rupture to splitting tensile strength of SFRC mix was found to be
278
1.43 and that of modulus of rupture to compressive strength was
found to be 0.126 from table 4.4.3.5.
(iii) 16.0% to 44.20% and 25.65% to 81.20% increase in modulus of
rupture of SFRC-MK is observed when compared with the modulus of
rupture of MKC and OPC concrete respectively from table 4.4.3.7. The
average value of the modulus of rupture to splitting tensile strength of
SFRC-MK mix was found to be 1.51 and that of modulus of rupture to
compressive strength was found to be 0.119 from table 4.4.3.7.
5.5.1.1 Effect of fibre content and aspect ratio of fibres on
modulus of rupture of SFRC Mixes of M20 & M50 grade
The modulus of rupture of SFRC of M20 and M50 grade
concrete mixes is increasing with fibre content for concrete mixes with
aspect ratio of 60 & 80 when compared with OPC concrete as shown
in tables 4.4.3.1 and 4.4.3.5. As the modulus of rupture is increasing
with fibre content, aspect ratio of the fibre and the bond
characteristics of fibres, these factors are incorporated into a single
parameter called as fibre factor F15.
A regression analysis performed on the test results of table
4.4.3.1 gave the following expression for the modulus of rupture of
SFRC of M20 grade as
σr,predicted = 2.93 (F) + σr ----------- (9)
r2 = 0.997
where
r = coefficient of correlation
σrf,predicted = predicted modulus of rupture of SFRC in MPa
279
σrf = experimental modulus of rupture of OPCC in MPa.
F = fibre factor = Vf.AR.β.
The average percentage error between the experimental values
and the predicted values of modulus of rupture of SFRC is negligible
from table 4.4.3.2.
Another regression analysis performed on the test results of
SFRC of M50 grade concrete from table 4.4.3.5 gave the following
expression for the modulus of rupture of SFRC as:
σr,predicted = 4.35(F) + σr --------- (6)
r2 = 0.990
Where
r = coefficient of correlation
σr,predicted = predicted modulus of rupture of SFRC in MPa.
σr = experimental modulus of rupture of OPCC in MPa
F = fibre factor = Vf.AR.β.
From table 4.4.3.6, the average percentage error between the
experimental values and the predicted values of compressive strength
of SFRC is 1.29% from table 4.4.3.6.
5.5.1.2 Effect of fibre content and aspect ratio of fibres on
modulus of rupture of SFRC -MK Mixes of M20 & M50 Grade
The modulus of rupture of SFRC - MK is increasing with fibre
content and higher aspect ratio of fibres when compared with MK
concrete as shown in table 4.4.3.3 and 4.4.3.7. As the modulus of
rupture is increasing with fibre content, aspect ratio of fibres and the
280
bond characteristics of fibres, these factors are incorporated into a
single parameter called as fibre factor F15.
A regression analysis performed on the test results of table
4.4.3.3 gave the following expression for the modulus of rupture of
SFRC -MK of M20 grade as
σrm,predicted = 3.127(F) + σrm ---------- (10)
r2 = 0.992
Where
r = coefficient of correlation
σrm,predicted = predicted modulus of rupture of SFRC-MK in MPa.
σrm = experimental modulus of rupture of MKC in MPa
F = fibre factor = Vf.AR.β.
From table 4.4.3.4, the average percentage error between the
experimental values and the predicted values of modulus of rupture of
SFRC-MK is 0.3% from table 4.4.3.4.
Another regression analysis performed on the test results of
SFRC-MK of M50 grade concrete from table 4.4.3.7 gave the following
expression for the modulus of rupture of SFRC-MK as:
σrm,predicted = 4.478(F) + σrm --------- (11)
r2 = 0.991
Where
r = coefficient of correlation
σrm,predicted = predicted modulus of rupture of SFRC-MK in MPa.
σrm = experimental modulus of rupture of MKC in MPa
F = fibre factor = Vf.AR.β.
281
From table 4.4.3.8, the average percentage error between the
experimental values and the predicted values of modulus of rupture of
SFRC-MK is 0.10% from table 4.4.3.8.
5.6 MODULUS OF ELASTICITY OF OPCC, MKC, SFRC &
SFRC – MK MIXES OF M20 AND M50 GRADES
5.6.1 Experimental Results:
Tables 4.4.4.1 to 4.4.4.8 gives the test result of modulus of
elasticity for the various mixes of OPC, MKC, SFRC & SFRC-MK of
M20 and M50 grade concrete. Figures 39.0 to 48.0 show the variation
of modulus of elasticity with fibre content and fibre factor F. It is
evident from tables 4.4.4.1 to 4.4.4.8, that the addition of crimped
steel fibres to concrete improves its modulus of elasticity. The
experimental results of modulus of elasticity of the various mixes
studied are given below:
Modulus of Elasticity of OPCC, MKC, SFRC & SFRC-MK of M20
grade concrete:
(i) The modulus of elasticity of OPC and MK concretes are found to
be 24.26 GPa and 25.43 GPa respectively.
(ii) 3.22% to 12.11% increase in modulus of elasticity of SFRC is
observed when compared with the modulus of elasticity of OPC
concrete from table 4.4.4.1.
(iii) 3.58% to 9.71% and 8.57% to 15.0% increase in modulus of
elasticity of SFRC-MK is observed when compared with the modulus
of elasticity of MKC and OPC concrete respectively from table 4.4.4.3.
282
Modulus of elasticity of OPCC, MKC, SFRC & SFRC-MK of M50
grade concrete:
(i) The modulus of elasticity of OPC and MK concretes are found to
be 33.88 GPa and 36.32 GPa respectively.
(ii) 4.78% to 13.16% increase in modulus of elasticity of SFRC is
observed when compared with the modulus of elasticity of OPC
concrete from table 4.4.4.5.
(iii) 4.76%% to 10.90% and 12.30% to 18.90% increase in modulus
of elasticity of SFRC-MK when compared with the modulus of
elasticity of MKC and OPC concrete respectively from table 4.4.4.7.
5.6.1.1 Effect of fibre content and aspect ratio of fibres on
modulus of elasticity of SFRC Mixes of M20 & M50 grade
The modulus of elasticity of SFRC of M20 and M50 grade
concrete mixes is increasing with fibre content for concrete mixes with
aspect ratio of 60 & 80 when compared with OPC concrete as shown
in tables 4.4.4.1 and 4.4.4.5. As the modulus of elasticity is
increasing with fibre content, aspect ratio of the fibre and the bond
characteristics of fibres, these factors are incorporated into a single
parameter called as fibre factor F15.
A regression analysis performed on the test results of table
4.4.4.1 gave the following expression for the modulus of elasticity of
SFRC of M20 grade as
Epredicted = 3.204 (F) + E ----------- (12)
r2 = 0.990
Where
283
r = coefficient of correlation
Epredicted = predicted modulus of elasticity of SFRC in GPa
E= experimental modulus of elasticity of OPCC in GPa.
F = fibre factor = Vf.AR.β.
The average percentage error between the experimental values
and the predicted values of modulus of elasticity of SFRC is 0.40%
from table 4.4.4.2.
Another regression analysis performed on the test results of
SFRC of M50 grade concrete from table 4.4.4.5 gave the following
expression for the modulus of elasticity of SFRC as:
Epredicted = 4.69 (F) + E --------- (13)
r2 = 0.972
Where
r = coefficient of correlation
Epredicted = predicted modulus of elasticity of SFRC in GPA.
E= experimental modulus of elasticity of OPCC in GPa
F = fibre factor = Vf.AR.β.
From table 4.4.4.6, the average percentage error between the
experimental values and the predicted values of compressive strength
of SFRC is 1.39% from table 4.4.4.6.
5.6.1.2 Effect of fibre content and aspect ratio of fibres on
modulus of elasticity of SFRC - MK Mixes of M20 & M50 Grade
The modulus of elasticity of SFRC - MK is increasing with fibre
content and higher aspect ratio of fibres when compared with MK
concrete as shown in table 4.4.4.3 and 4.4.4.7. As the modulus of
284
elasticity is increasing with fibre content, aspect ratio of fibres and the
bond characteristics of fibres, these factors are incorporated into a
single parameter called as fibre factor F15.
A regression analysis performed on the test results of table
4.4.4.3 gave the following expression for the modulus of elasticity of
SFRC -MK. Of M20 grade as
Esm,predicted =2.68(F) + Em ---------- (14)
r2 = 0.983
Where
r = coefficient of correlation
Esm,predicted = predicted modulus of elasticity of SFRC-MK in GPa.
Em = experimental modulus of elasticity of MKC in GPa
F = fibre factor = Vf.AR.β.
From table 4.4.4.4, the average percentage error between the
experimental values and the predicted values of modulus of elasticity
of SFRC-MK is 0.80% from table 4.4.4.4.
Another regression analysis performed on the test results of
SFRC-MK of M50 grade concrete from table 4.4.4.7 gave the following
expression for the modulus of elasticity of SFRC-MK as:
Esm,predicted = 4.51(F) + Em --------- (14)
r2 = 0.993
Where
r = coefficient of correlation
Esm,predicted = predicted modulus of elasticity of SFRC-MK in GPa.
Em = experimental modulus of elasticity of MKC in GPa
285
F = fibre factor = Vf.AR.β.
From table 4.4.4.8, the average percentage error between the
experimental values and the predicted values of modulus of elasticity
of SFRC-MK is 1.20% from table 4.4.4.8.
5.7 IMPACT RESISTANCE OF OPCC, MKC, SFRC &
SFRC – MK MIXES OF M20 AND M50 GRADES
5.7.1 Experimental Results:
Tables 4.4.5.1 to 4.4.5.8 gives the test results of impact
resistance to first crack and up to failure for the various mixes of M20
and M50 grade. Tables 4.4.5.1 to 4.4.5.8 give the comparison of
experimental test results with the predicted values using the proposed
equations. Figures 49.0 to 58.0 show the variation of impact
resistance with fibre content and fibre factor for OPCC, MKC, SFRC &
SFRC-MK mixes.
It is evident from tables 4.4.5.1 to 4.4.5.8 the addition of fibres
to concrete improves its impact resistance. The experimental results of
the impact resistance of various mixes studied are given below:
The impact resistance of OPCC, MKC, SFRC & SFRC-MK mixes of
M20 grade concrete
The impact resistance of OPC concrete to first crack and to
failure is found to be 12 and 18 blows. The corresponding values for
MK concrete are 8 and 11 blows respectively.
The impact resistance of Metakaolin concrete is 34% and 39% less at
1st crack and at failure respectively when compared with OPC
286
concrete. The impact resistance of MK concrete is less than OPC
concrete.
(i) The increase in impact resistance of SFRC is observed as 1.75
to 6.84 times at first crack and 3.88 to 12.11 times at failure, when
compared with the impact resistance of OPC concrete as the fibre
content is increased from 0.50% to 1.50% from table 4.4.5.1.
(ii) The increase in impact resistance of SFRC-MK is observed as
5.87 to 25.37 times at first crack and 10.0 to 37.82 times at failure,
when compared with the impact resistance of MK concrete as the fibre
content is increased from 0.50% to 1.50% from table 4.4.5.3.
The impact resistance of OPCC, MKC, SFRC & SFRC-MK mixes of
M50 grade concrete
(i) The impact resistance of OPC concrete to first crack and to
failure is found to be 17 and 25 blows. The corresponding values for
MK concrete are 12 and 18 blows respectively.
(ii) The impact resistance of Metakaolin concrete is 30% and 28%
less at 1st crack and at failure respectively when compared with OPC
concrete.
(iii) The increase in impact resistance of SFRC is observed as 3.05
to 10.29 times at first crack and 6.24 to 19.40 time at failure, when
compared with the impact resistance of OPC concrete as the fibre
content is increased from 0.50% to 1.50% from table 4.4.5.5.
(iv) The increase in impact resistance of SFRC-MK is observed as
10.42 to 31.85 times at first crack and 14.33 to 47.88 times at failure,
287
when compared with the impact resistance of MK concrete as the fibre
content is increased from 0.50% to 1.50% from table 4.4.5.7.
This improvement in impact resistance is due to the increase in
ductility of SFRC with the addition of steel fibres from 0.5% to 1.50%
and due to the increased effectiveness of steel fibres in the presence of
Metakaolin caused by the improved fibre to matrix bonding.
5.7.1.1 Effect of fibre content and aspect ratio of fibres on the
impact resistance of SFRC Mixes of M20 & M50 grade
The impact resistance of SFRC of M20 and M50 grade concrete
mixes is increasing with fibre content and aspect ratio of fibres when
compared with OPC concrete as shown in table 4.4.5.1 and 4.4.5.5.
As the impact resistance is increasing with fibre content, aspect ratio
of the fibre and the bond characteristics of fibres, these factors are
incorporated into a single parameter called as fibre factor F.
A regression analysis performed on the test results of table
4.4.5.1 gave the following expression for the impact resistance of
SFRC of M20 grade as
Ipredicted = 243.26 (F) + I ----------- (15)
r2 = 0.993
Where
r = coefficient of correlation
Ipredicted = predicted impact resistance of SFRC in number of blows.
E= experimental impact resistance of OPCC in number of blows.
F = fibre factor = Vf.AR.β.
288
The average percentage error between the experimental values
and the predicted values of impact resistance of SFRC is 1.90% from
table 4.4.5.2.
Another regression analysis performed on the test results of
SFRC of M50 grade concrete from table 4.4.5.5 gave the following
expression for the impact resistance of SFRC as:
Ipredicted = 503 (F) + I --------- (16)
r2 = 0.994
Where
r = coefficient of correlation
Ipredicted = predicted impact resistance of SFRC in number of blows.
I= experimental impact resistance of OPCC in number of blows
F = fibre factor = Vf.AR.β.
From table 4.4.5.6, the average percentage error between the
experimental values and the predicted values of impact resistance of
SFRC is 4.50% from table 4.4.5.6.
5.7.1.2 Effect of fibre content and aspect ratio of fibres on impact
resistance of SFRC - MK Mixes of M20 & M50 Grade
The impact resistance of SFRC - MK is increasing with fibre
content and higher aspect ratio of fibres when compared with MK
concrete as shown in table 4.4.5.3 and 4.4.5.7. As the impact
resistance is increasing with fibre content, aspect ratio of fibres and
the bond characteristics of fibres, these factors are incorporated into a
single parameter called as fibre factor F.
289
A regression analysis performed on the test results of table
4.4.5.3 gave the following expression for the impact resistance of
SFRC - MK of M20 grade as.
Ism,predicted = 461.22 (F) + Im ---------- (17)
r2 = 0.998
Where
r = coefficient of correlation
Ism,predicted = predicted impact resistance of SFRC-MK in number of
blows.
Im = experimental impact resistance of MKC in number of blows
F = fibre factor = Vf.AR.β.
From table 4.4.5.4, the average percentage error between the
experimental values and the predicted values of impact resistance of
SFRC-MK is 0.50% from table 4.4.5.4.
Another regression analysis performed on the test results of
SFRC-MK of M50 grade concrete from table 4.4.5.7 gave the following
expression for the impact resistance of SFRC-MK as:
Ism,proposed = 956(F) + Im --------- (18)
r2 = 0.995
Where
r = coefficient of correlation
Im,predicted = predicted impact resistance of SFRC-MK in number of
blows
Im = experimental impact resistance of MKC in number of blows
F = fibre factor = Vf.AR.β.
290
From table 4.4.5.8, the average percentage error between the
experimental values and the predicted values of SFRC-MK is 3.75%
from table 4.4.5.8.
5.8 EFFECT OF ELEVATED TEMPERATURES ON
COMPRESSIVE STRENGTH, PULSE VELOCITY AND
PERCENTAGE WEIGHT LOSS OF OPCC, MKC, SFRC &
SFRC-MK MIXES OF M20 AND M50 GRADE
5.8.1 Variation of compressive strength of OPCC, MKC, SFRC &
SFRC-MK Mixes at elevated temperatures
5.8.1.1 Variation of compressive strength of OPCC, MKC, SFRC &
SFRC-MK mixes of M20 and M50 grade at room temperature
Tables 4.6.1.1 & 4.6.1.4 gives the compressive strength of OPCC
and SFRC (1.5-80) mix of M20 grade at room temperature. These
values vary from 30.69 to 34.10 MPa.
Tables 4.6.1.1 & 4.6.1.2 gives the compressive strength of OPCC
and MKC mix of M20 grade at room temperature. These values vary
from 30.69 to 32.86 MPa.
Tables 4.6.1.1 & 4.6.1.6 gives the compressive strength of OPCC
and SFRC – MK (1.5-80) mix of M20 grade at room temperature. These
values vary from 30.69 to 36.50 MPa respectively.
Tables 4.6.1.7 & 4.6.1.10 gives the compressive strength of OPCC
and SFRC (1.5-80) mix of M50 grade at room temperature. These
values vary from 61.4 to 69.04 MPa.
291
Tables 4.6.1.7 & 4.6.1.8 gives the compressive strength of OPCC
and MKC mix of M50 grade at room temperature. These values vary
from 61.4 to 68.90 MPa respectively.
Tables 4.6.1.7 & 4.6.1.12 gives the compressive strength of OPCC
and SFRC –MK (1.5-80) mix of M50 grade at room temperature. These
values vary from 61.4 to 75.68 MPa respectively.
5.8.1.2 Variation of compressive strength of OPCC, MKC, SFRC &
SFRC-MK concrete mixes of M20 and M50 grade at 2000C.
Tables 4.6.1.1 & 4.6.1.4 gives the compressive strength of OPCC
and SFRC (1.5-80) mix of M20 grade after exposing the specimens to
2000C for duration of 12 Hrs. These values vary from 30.69 to 28.08
MPa for OPCC and 34.10 to 28.17 MPa for SFRC (1.5-80) respectively.
Tables 4.6.1.1 & 4.6.1.2 gives the compressive strength of OPCC
and MKC mix of M20 grade after exposure of the specimens to 2000C
for duration of 12 Hrs. These values vary from 30.69 to 28.08 MPa for
OPCC and 32.86 to 31.10 MPa for MKC respectively.
Tables 4.6.1.1 & 4.6.1.6 gives the compressive strength of OPCC
and SFRC-MK (1.5-80) mix of M20 grade after exposing the specimens
to 2000C for duration of 12 Hrs. These values vary from 30.69 to
28.08 MPa for OPCC and 36.50 to 30.28MPa for SFRC -MK (1.5-80)
respectively.
Tables 4.6.1.7 & 4.6.1.10 gives the compressive strength of OPCC
and SFRC (1.5-80) mix of M50 grade at 2000C after exposing the
specimens for duration of 12 Hrs. These values vary from 61.4 to
292
51.33MPa for OPCC and 69.04 to 48.88 MPa for SFRC (1.5-80)
respectively.
Tables 4.6.1.7 & 4.6.1.8 gives the compressive strength of OPCC
and MKC mix of M50 grade at 2000C after exposing the specimens for
duration of 12 Hrs. These values vary from 61.4 to 51.33 MPa for
OPCC and 68.90 to 57.88 MPa for MKC respectively.
Tables 4.6.1.7 & 4.6.1.12 gives the compressive strength of OPCC
and SFRC-MK (1.5-80) mix of M50 grade at 2000C after exposing the
specimens for duration of 12 Hrs. These values vary from 61.4 to
51.33 MPa for OPCC and 75.68 to 54.57 MPa for SFRC-MK (1.5-80)
respectively.
5.8.1.3 Variation of compressive strength of OPCC, MKC, SFRC &
SFRC-MK mixes of M20 and M50 grade after cooling to room
temperature.
Tables 4.6.1.1 & 4.6.1.4 gives the compressive strength of OPCC
and SFRC (1.5-80) mix of M20 grade when cooled to room
temperature from 2000C for duration of 24 Hrs. The compressive
strength varies from 28.08 to 31.95 MPa for OPCC and from 28.17 to
32.90 MPa for SFRC (1.5-80) respectively.
Table 4.6.1.2 gives the compressive strength of MKC of M20
grade when cooled to room temperature from 2000C for duration of 24
Hrs. The compressive strength varies from 31.10 to 36.32 MPa
respectively.
Table 4.6.1.6 gives the compressive strength of SFRC-MK (1.5-80)
of M20 grade when cooled to room temperature from 2000C for
293
duration of 24 Hrs. The compressive strength varies from 30.28 to
38.22 MPa respectively.
Tables 4.6.1.7 & 4.6.1.10 gives the compressive strength of OPCC
and SFRC (1.5-80) of M50 grade when cooled to room temperature
from 2000C for duration of 24 Hrs. These values vary from 51.33 to
64.60 MPa for OPCC and 48.88 to 52.26 MPa for SFRC (1.5-80)
respectively.
Tables 4.6.1.8 give the compressive strength of MKC of M50
grade after cooling the specimens to room temperature from 2000C for
duration of 24 Hrs. The compressive strength varies from 57.88 to
74.62 MPa respectively.
Table 4.6.1.12 gives the compressive strength of SFRC-MK (1.5-
80) mix of M50 grade after cooling to room temperature from 2000C
for duration of 24 Hrs. The compressive strength varies from 54.18 to
65.45 MPa respectively.
5.8.1.4 Variation of compressive strength of OPCC, MKC, SFRC &
SFRC-MK mixes of M20 and M50 grade after cooling to room
temperature from 2000C and compared with normal strength.
Tables 4.6.1.1 & 4.6.1.4 gives the compressive strength of OPCC
and SFRC (1.5-80) mix of M20 grade and gives the comparison of
strength after cooling to room temperature to the normal strength.
These values vary from 30.69 to 31.95 MPa for OPCC and 34.10 to
32.90 MPa for SFRC (1.5-80) respectively.
Tables 4.6.1.1 & 4.6.1.2 gives the compressive strength of OPCC
and MKC mix of M20 grade and gives the comparison of strength after
294
cooling to room temperature to normal strength. These values vary
from 30.69 to 31.95 MPa for OPCC and 32.86 to 36.32 MPa for MKC
mix respectively.
Tables 4.6.1.1 & 4.6.1.6 gives the compressive strength of OPCC
and SFRC-MK (1.5-80) mix of M20 grade and gives the comparison of
strength after cooling to room temperature to normal strength. These
values vary from 30.69 to 31.95MPa for OPCC and 36.50 to 38.22
MPa for SFRC-MK (1.5-80) mix respectively.
Tables 4.6.1.7 & 4.6.1.10 gives the compressive strength of
OPCC and SFRC (1.5-80) mix of M50 grade and gives the comparison
of strength after cooling to room temperature to normal strength.
These values vary from 61.4 to 64.60 MPa for OPCC and 69.04 to
52.26 MPa for SFRC (1.5-80) respectively.
Tables 4.6.1.7 & 4.6.1.8 gives the compressive strength of OPCC
and MKC of M50 grade and gives the comparison of strength after
cooling to room temperature to normal strength. These values vary
from 61.4 to 64.60 MPa for OPCC and 68.90 to 74.62 MPa for MKC
mix respectively.
Tables 4.6.1.7 & 4.6.1.12 gives the compressive strength of
OPCC and SFRC-MK (1.5-80) of M50 grade and gives the comparison
of strength after cooling to room temperature to normal strength.
These values vary from 61.4 to 64.60 MPa for OPCC and 75.68 to
65.45 MPa for SFRC-MK (1.5-80) respectively.
295
5.8.1.5 Variation of compressive strength of OPCC, MKC, and
SFRC & SFRC-MK mixes of M20 and M50 grade at 4000C.
Tables 4.6.1.1 & 4.6.1.4 gives the compressive strength of OPCC
and SFRC (1.5-80) mix of M20 grade after exposing the specimens to
4000C for duration of 12 Hrs. Theses values vary from 30.69 to 24.92
MPa for OPCC and 34.10 to 22.30 MPa for SFRC (1.5-80) mix
respectively.
Tables 4.6.1.1 & 4.6.1.2 gives the compressive strength of OPCC
and MKC mix of M20 grade after exposure of the specimens to 4000C
for duration of 12 Hrs. These values vary from 30.69 to 24.92 MPa for
OPCC and 32.86 to 27.60 MPa for MKC mix respectively.
Tables 4.6.1.1 & 4.6.1.6 gives the compressive strength of OPCC
and SFRC-MK (AR-80) mix of M20 grade after exposure of the
specimens to 4000C for duration of 12 Hrs. These values vary from
30.69 to 24.92 MPa for OPCC and 36.50 to 25.22 MPa for SFRC-MK
mix respectively.
Tables 4.6.1.7 & 4.6.1.10 gives the compressive strength of OPCC
and SFRC (1.5-80) of M50 grade after exposure of the specimens to
4000C for duration of 12 Hrs. These values vary from 61.4 to 42.24
MPa for OPCC and 69.04 to 37.56 MPa for SFRC (1.5-80) mix
respectively.
Tables 4.6.1.7 & 4.6.1.8 gives the compressive strength of OPCC
and MKC mix of M50 grade after exposure of the specimens to 4000C
for duration of 12 Hrs. These values vary from 61.4 to 42.24 MPa for
OPCC and 68.90 to 50.30 MPa for MKC mix respectively.
296
Tables 4.6.1.7 & 4.6.1.12 gives the compressive strength of OPCC
and SFRC-MK (1.5-80) mix of M50 grade after exposure of the
specimens to 4000C for duration of 12 Hrs. These values vary from
61.4 to 42.24 MPa for OPCC and 75.68 to 46.60 MPa for SFRC-MK
(1.5-80) mix respectively.
5.8.1.6 Variation of compressive strength of OPCC, MKC, SFRC
& SFRC-MK mixes of M20 and M50 grade after cooling to room
temperature from 4000C.
Tables 4.6.1.1 & 4.6.1.4 gives the compressive strength of OPCC
and SFRC (1.5-80) mix of M20 grade after cooling to room
temperature from 4000C for duration of 24 Hrs. The compressive
strength varies from 24.92 to 27.18 MPa for OPCC and 22.42 to 25.09
MPa for SFRC (1.5-80) mix respectively.
Tables 4.6.1.1 & 4.6.1.2 gives the compressive strength of OPCC
and MKC mix of M20 grade after cooling to room temperature from
4000C for duration of 24 Hrs. The compressive strength varies from
24.92 to 27.18 MPa for OPCC and 27.60 to 30.73 MPa for MKC
respectively.
Tables 4.6.1.1 & 4.6.1.6 gives the compressive strength of OPCC
and SFRC-MK (1.5-80) mix of M20 grade after cooling to room
temperature from 4000C for duration of 24 Hrs. The compressive
strength varies from 24.92 to 27.18 MPa for OPCC and 25.22 to 29.67
MPa for SFRC-MK (1.5-80) respectively.
Tables 4.6.1.7 & 4.6.1.10 gives the compressive strength of OPCC
and SFRC (1.5-80) of M50 grade after cooling to room temperature
297
from 4000C for duration of 24 Hrs. The compressive strength varies
from 42.24 to 48.50 MPa for OPCC and 37.56 to 42.14 MPa for
SFRC (1.5-80) mix respectively.
Tables 4.6.1.7 & 4.6.1.8 gives the compressive strength of OPCC
and MKC mix of M50 grade after cooling to room temperature from
4000C for duration of 24 Hrs. The compressive strength varies from
42.24 to 48.50 MPa for OPCC and 50.30 to 60.25 MPa for MKC mix
respectively.
Tables 4.6.1.7 & 4.6.1.12 gives the compressive strength of OPCC
and SFRC-MK (1.5-80) mix of M50 grade after cooling to room
temperature from 4000C for duration of 24 Hrs. The compressive
strength varies from 42.24 to 48.50 MPa for OPCC and 46.60 to 54.0
MPa for SFRC-MK (1.5-80) respectively.
5.8.1.7 Variation of compressive strength of OPCC, MKC, SFRC
& SFRC-MK mixes of M20 & M50 grade at 6000C.
Tables 4.6.1.1 & 4.6.1.4 gives the compressive strength of OPCC
and SFRC (1.5-80) mix of M20 grade concrete after exposing the
specimens to 6000C for duration of 12 Hrs. These values vary from
30.69 to 20.65 MPa for OPCC and 34.10 to 13.32 MPa for SFRC (1.5-
80) respectively.
Tables 4.6.1.1 & 4.6.1.2 gives the compressive strength of OPCC
and MKC mix of M20 grade after exposing the specimens to 6000C for
duration of 12 Hrs. These values vary from 30.69 to 20.65 MPa for
OPCC and 32.86 to 20.53 MPa for MKC respectively.
298
Tables 4.6.1.1 & 4.6.1.6 gives the compressive strength of OPCC
and SFRC-MK (1.5-80) mix of M20 grade after exposing the specimens
to 6000C for duration of 12 Hrs. These values vary from 30.69 to
20.65 MPa for OPCC and 36.50 to 14.52 MPa for SFRC-MK (1.5-80)
respectively.
Tables 4.6.1.7 & 4.6.1.10 gives the compressive strength of OPCC
and SFRC (1.5-80) mix of M50 grade after exposing the specimens to
6000C for duration of 12 Hrs. These values vary from 61.4 to 29.40
MPa for OPCC and 69.04 to 21.40 MPa for SFRC (1.5-80) mix
respectively.
Tables 4.6.1.7 & 4.6.1.8 gives the compressive strength of OPCC
and MKC mix of M50 grade after exposing the specimens to 6000C for
duration of 12 Hrs. These values vary from 61.4 to 29.40 MPa for
OPCC and 68.9 to 27.96 MPa for MKC mix respectively.
Tables 4.6.1.7 & 4.6.1.12 gives the compressive strength of OPCC
and SFRC-MK (1.5-80) mix of M50 grade after exposing the specimens
to 6000C for duration of 12 Hrs. These values vary from 61.4 to 29.40
MPa for OPCC and 75.68 to 18.31 MPa for SFRC-MK (1.5-80)
respectively.
5.8.1.8 Variation of compressive strength of OPCC, MKC, SFRC
& SFRC-MK mixes of M20 and M50 grade after cooling to room
temperature from 6000C.
Tables 4.6.1.1 & 4.6.1.4 gives the compressive strength of OPCC
and SFRC (1.5-80) of M20 grade after cooling to room temperature
from 6000C for duration of 24 Hrs. The compressive strength is varied
299
from 20.65 to 22.77 MPa for OPCC and 13.32 to 17.11MPa for SFRC
(1.5-80) mix respectively.
Tables 4.6.1.1 & 4.6.1.2 gives the compressive strength of OPCC
and MKC mix of M20 grade after cooling to room temperature from
6000C for duration of 24 Hrs. The compressive strength is varied from
20.65 to 22.77 MPa for OPCC and 20.53 to 21.95 MPa for MKC mix
respectively.
Tables 4.6.1.1 & 4.6.1.6 gives the compressive strength of OPCC
and SFRC-MK (1.5-80) of M20 grade after cooling to room temperature
from 6000C for duration of 24 Hrs. The compressive strength varies
from 20.65 to 22.77 MPa for OPCC and 14.52 to 16.13 MPa for SFRC-
MK (1.5-80) mix respectively.
Tables 4.6.1.7 & 4.6.1.10 gives the compressive strength of OPCC
and SFRC (1.5-80) mix of M50 grade after cooling to room
temperature from 6000C for duration of 24Hrs. The compressive
strength varies from 29.40 to 35.24 MPa for OPCC and 21.40 to 26.23
MPa for SFRC (1.5-80) mix respectively.
Tables 4.6.1.7 & 4.6.1.8 gives the compressive strength of OPCC
and MKC mix of M50 grade after cooling the specimens to room
temperature from 6000C for duration of 24Hrs. These values vary
from 29.40 to 35.24 MPa for OPCC and 27.96 to 33.07 MPa for MK
concrete mix respectively.
Tables 4.6.1.7 & 4.6.1.12 gives the compressive strength of OPCC
and SFRC-MK (1.5-80) of M50 grade after cooling to room temperature
from 6000C for duration of 24 Hrs. These values vary from 29.40 to
300
35.24 MPa for OPCC and 18.31 to 21.94 MPa for SFRC-MK (1.5-80)
mix respectively.
5.8.1.9 Variation of compressive strength of OPCC, MKC, SFRC
& SFRC-MK mixes of M20 and M50 grade after cooling to room
temperature from 6000C and compared with normal strength.
Tables 4.6.1.1 & 4.6.1.4 gives the compressive strength of OPCC
and SFRC (1.5-80) mix of M20 grade and gives the comparison of
strength after cooling to room temperature to the normal strength.
These values vary from 30.69 to 22.77 MPa for OPCC and 34.10 to
17.11 MPa for SFRC (1.5-80) respectively.
Tables 4.6.1.1 & 4.6.1.2 gives the compressive strength of OPCC
and MKC mix of M20 grade and gives the comparison of strength after
cooling to room temperature to the normal strength. These values
vary from 30.69 to 22.77 MPa for OPCC and 32.86 to 21.95 MPa for
MKC respectively.
Tables 4.6.1.1 & 4.6.1.6 gives the compressive strength of OPCC
and SFRC-MK (1.5-80) mix of M20 grade and gives the comparison of
strength after cooling to room temperature to the normal strength.
These values vary from 30.69 to 22.77 MPa for OPCC and 36.50 to
16.13 MPa for SFRC-MK (1.5-80) respectively.
Tables 4.6.1.7 & 4.6.1.10 gives the compressive strength of OPCC
and SFRC (1.5-80) mix of M50 grade and gives the comparison of
strength after cooling to room temperature to the normal strength.
These values vary from 61.4 to 35.24 MPa for OPCC and 69.04 to
26.23MPa for SFRC (AR-80) respectively.
301
Tables 4.6.1.7 & 4.6.1.8 gives the compressive strength of OPCC
& MKC mix of M50 grade and gives the comparison of strength after
cooling to room temperature to the normal strength. These values
vary from 61.4 to 35.24 MPa for OPCC and 68.90 to 33.07 MPa for
MKC respectively.
Tables 4.6.1.7 & 4.6.1.12 gives the compressive strength of OPCC
and SFRC-MK (1.5-80) mix of M50 grade and gives the comparison of
strength after cooling to room temperature to the normal strength.
These values vary from 61.4 to 35.24 MPa for OPCC and 75.68 to
21.94 MPa for SFRC-MK (1.5-80) respectively.
5.8.1.10 Percentage increase/decrease in compressive strength
of OPCC, MKC, SFRC & SFRC-MK mixes of M20 and M50 grade at
2000C, 4000C & 6000C when compared with normal strength
Table 4.6.1.13 gives the percentage decrease in compressive
strength of OPCC mix of M20 grade at 2000C, 4000C and 6000C in
comparison with normal strength. These values are found as -8.70%
at 2000C, -18.80% at 4000C and -32.70% at 6000C respectively.
Table 4.6.1.13 gives the percentage decrease in compressive
strength of MKC of M20 grade at 2000C, 4000C and 6000C in
comparison with normal strength. These values vary from -5.30% at
2000C, -16.0% at 4000C and -37.50% at 6000C respectively.
Table 4.6.1.13 gives the percentage decrease in compressive
strength of SFRC (1.5-80) mix of M20 grade at 2000C, 4000C and
6000C in comparison with normal strength. These values are found
302
as -18.50% at 2000C, -34.60% at 4000C and -56.60% at 6000C
respectively.
Table 4.6.1.13 gives the percentage decrease in compressive
strength of SFRC-MK (1.5-80) mix of M20 grade at 2000C, 4000C and
6000C in comparison with normal strength. These values are found
as -17.0% at 2000C, -30.50% at 4000C and -60.20% at 6000C
respectively.
Table 4.6.1.14 gives the percentage decrease in compressive
strength of OPCC mix of M50 grade at 2000C, 4000C and 6000C in
comparison with normal strength. These values are found as -16.40%
at 2000C, -31.2% at 4000C and -52.19% at 6000C respectively.
Table 4.6.1.14 gives the percentage decrease in compressive
strength of MKC mix of M50 grade at 2000C, 4000C and 6000C in
comparison with normal strength. These values are found as -15.60%
at 2000C, -26.90% at 4000C and -59.40% at 6000C respectively.
Table 4.6.1.14 gives the percentage decrease in compressive
strength of SFRC (1.5-80) mix of M50 grade at 2000C, 4000C and
6000C in comparison with normal strength. These values are found
as -34.79% at 2000C, -45.60% at 4000C and -69.0% at 6000C
respectively.
Table 4.6.1.14 gives the percentage decrease in compressive
strength of SFRC-MK (1.5-80) mix of M50 grade at 2000C, 4000C and
6000C in comparison with normal strength. These values are found
as -28.40% at 2000C, -38.46% at 4000C and -75.80% at 6000C
respectively.
303
Beyond 4000C, the percentage decrease in compressive strength
of M50 grade OPCC mix is high when compared with OPCC mix of
M20 grade64. The reason may be due to high brittleness and dense
micro structure of high grade concrete.
The percentage decrease in compressive strength of MKC beyond
4000C is higher than OPCC. The cause may be due to the buildup of
vapour pressure by dense pore structure of the MKC.
At 6000C, the loss in strength of MKC is higher than the loss in
strength of OPCC72. The reason is due to the decomposition of
Ca(OH)2 at temperature above 4000C, and also may be due to
differential thermal expansion of aggregate.
5.8.2 Percentage increase in compressive strength of OPCC, MKC,
SFRC & SFRC-MK mixes of M20 and M50 grade after cooling to
room temperature
5.8.2.1 Percentage increase in compressive strength of OPCC,
MKC, SFRC & SFRC-MK mixes of M20 and M50 grade after
cooling to room temperature from 2000C
Table 4.6.1.14 gives the percentage increase in compressive
strength of OPCC mixes of M20 and M50 grade after cooling from
2000C. These values vary from 13.0% to 25.0%. These variations are
shown in fig 74.0 and 76.0
Table 4.6.1.14 gives the percentage increase in compressive
strength of MKC mixes of M20 and M50 grade after cooling from
2000C. These values vary from 17.0% to 28.0 %. These variations are
shown in fig 74.0 and 76.0.
304
Table 4.6.1.14 gives the percentage increase in compressive
strength of SFRC (1.5-80) mixes of M20 and M50 grade after cooling
from 2000C. These values vary from 17.0% to 16.0%. These variations
are shown in fig 74.0 and 76.0.
Table 4.6.1.14 gives the percentage increase in compressive
strength of SFRC-MK (1.5-80) mixes of M20 and M50 grade after
cooling from 2000C. These values vary from 26.0% to 19.0%.
These variations are shown in fig 74.0 and 76.0.
5.8.2.2. Percentage increase in compressive strength of OPCC,
MKC, SFRC & SFRC-MK mixes of M20 and M50 grade after
cooling to room temperature from 4000C.
Table 4.6.1.14 gives the percentage increase in compressive
strength of OPCC mixes of M20 and M50 grade after cooling from
4000C. These values vary from 9.0% to 14.0%. These variations are
shown in fig 74.0 and 76.0
Table 4.6.1.14 gives the percentage increase in compressive
strength of MKC mixes of M20 and M50 grade after cooling from
4000C. These values vary from 11.0% to 19.0 %. These variations are
shown in fig 74.0 and 76.0.
Table 4.6.1.14 gives the percentage increase in compressive
strength of SFRC (1.5-80) mixes of M20 and M50 grade after cooling
from 4000C. These values vary from 13.0% to 12.0%.
Table 4.6.1.14 gives the percentage increase in compressive
strength of SFRC-MK (1.5-80) mixes of M20 and M50 grade after
cooling from 4000C. These values vary from 17.0% to 17.0%.
305
These variations are shown in fig 74.0 and 76.0.
5.8.2.3. Percentage increase in compressive strength of OPCC,
MKC, SFRC & SFRC-MK mixes of M20 and M50 grade after
cooling to room temperature from 6000C
Table 4.6.1.14 gives the percentage increase in compressive
strength of OPCC mixes of M20 and M50 grade after cooling from
6000C. These values vary from 10.0% to 20.0%.
These variations are shown in fig 74.0 and 76.0
Table 4.6.1.14 gives the percentage increase in compressive
strength of MKC mixes of M20 and M50 grade after cooling from
6000C. These values vary from 7.0% to 18.0 %.
These variations are shown in fig 74.0 and 76.0.
Table 4.6.1.14 gives the percentage increase in compressive
strength of SFRC (1.5-80) mixes of M20 and M50 grade after cooling
from 6000C. These values vary from 15.0% to 22.0%.
These variations are shown in fig 74.0 and 76.0.
Table 4.6.1.14 gives the percentage increase in compressive
strength of SFRC-MK (1.5-80) mixes of M20 and M50 grade after
cooling from 6000C. These values vary from 11.0% to 19.0%.
These variations are shown in fig 74.0 and 76.0.
One of the reasons for increase in compressive strength of the
above mixes on cooling may be due to the re-absorption of moisture
from atmosphere which may lead to extra hydration and form extra C
– S – H gel and also may be due to the presence of steel fibres 60, 64.
306
5.8.3 Variation of pulse velocity of OPCC, MKC, SFRC & SFRC-
MK mixes of M20 and M50 grade
5.8.3.1 Variation of pulse velocity of OPCC, MKC, SFRC & SFRC-
MK mixes of M20 and M50 grade concrete at room temperature:
Tables 4.6.2.1 and 4.6.2.2 gives the pulse velocity of OPCC mixes
of M20 and M50 grade at room temperature. These values vary from
4325 to 4477 m/s.
Tables 4.6.2.1 and 4.6.2.2 gives the pulse velocity of MKC mixes
of M20 and M50 grade at room temperature. These values vary from
4333 to 4492 m/s.
Tables 4.6.2.1 and 4.6.2.2 gives the pulse velocity of SFRC (AR-
80) mixes of M20 and M50 grade at room temperature. These values
vary from 4329 to 4485 m/s.
Tables 4.6.2.1 and 4.6.2.2 gives the pulse velocity of SFRC-MK
(AR-80) mixes of M20 and M50 grade at room temperature. These
values vary from 4342 to 4497 m/s.
The variation of pulse velocity of OPCC, MKC, SFRC & SFRC-
MK mixes of M20 and M50 grade concrete at room temperature are
shown in fig.79.0.
5.8.3.2 Variation of pulse velocity of OPCC, MKC, SFRC & SFRC-
MK mixes of M20 and M50 grade at 2000C.
Tables 4.6.2.1 and 4.6.2.2 gives the pulse velocity of OPCC
mixes of M20 and M50 grade after exposing the specimens to 2000C
for duration of 12 Hrs. These values vary from 3927 to 3989 m/s
respectively.
307
Tables 4.6.2.1 and 4.6.2.2 gives the pulse velocity of MKC mixes
of M20 and M50 grade after exposing the specimens to 2000C for
duration of 12 Hrs. These values vary from 3930 to 3993 m/s
respectively.
Tables 4.6.2.1 and 4.6.2.2 gives the pulse velocity of SFRC (AR-
80) mixes of M20 and M50 grade after exposing the specimens to
2000C for duration of 12 Hrs. These values vary from 3929 to 3992
m/s respectively.
Tables 4.6.2.1 and 4.6.2.2 gives the pulse velocity of SFRC-MK
(AR-80) mixes of M20 and M50 grade after exposing the specimens to
2000C for duration of 12 Hrs. These values vary from 3934 to 3996
m/s respectively.
The variation of pulse velocity of OPCC, MKC, SFRC & SFRC-
MK mixes of M20 and M50 grade concrete at 2000C are shown in
fig.79.0.
5.8.3.3 Variation of pulse velocity of OPCC, MKC, SFRC & SFRC-
MK mixes of M20 and M50 grade at 4000C.
Tables 4.6.2.1 and 4.6.2.2 gives the pulse velocity of OPCC mixes
of M20 and M50 grade after exposing the specimens to 4000C for
duration of 12 Hrs. These values vary from 3335 to 3398 m/s
respectively.
Tables 4.6.2.1 and 4.6.2.2 gives the pulse velocity of MKC mixes
of M20 and M50 grade after exposing the specimens to 4000C for
duration of 12 Hrs. These values vary from 3347 to 3410 m/s
respectively.
308
Tables 4.6.2.1 and 4.6.2.2 gives the pulse velocity of SFRC (AR-
80) mixes of M20 and M50 grade after exposing the specimens to
4000C for duration of 12 Hrs. These values vary from 3341 to 3401
m/s respectively.
Tables 4.6.2.1 and 4.6.2.2 gives the pulse velocity of SFRC-MK
(AR-80) mixes of M20 and M50 grade after exposing the specimens to
4000C for duration of 12 Hrs. These values vary from 3356 to 3412
m/s respectively.
The variation of pulse velocity of OPCC, MKC, SFRC & SFRC-MK
mixes of M20 and M50 grade concrete at 4000C are shown in fig.79.0.
5.8.3.4 Variation of pulse velocity of OPCC, MKC, SFRC & SFRC-
MK mixes of M20 and M50 grade at 6000C.
Tables 4.6.2.1 and 4.6.2.2 gives the pulse velocity of OPCC mixes
of M20 and M50 grade after exposing the specimens to 6000C for
duration of 12 Hrs. These values vary from 2571 to 2767 m/s
respectively.
Tables 4.6.2.1 and 4.6.2.2 gives the pulse velocity of MKC mixes
of M20 and M50 grade after exposing the specimens to 6000C for
duration of 12 Hrs. These values vary from 2587 to 2780 m/s
respectively.
Tables 4.6.2.1 and 4.6.2.2 gives the pulse velocity of SFRC (AR-
80) mixes of M20 and M50 grade after exposing the specimens to
6000C for duration of 12 Hrs. These values vary from 2575 to 2771
m/s respectively.
309
Tables 4.6.2.1 and 4.6.2.2 gives the pulse velocity of SFRC-MK
(AR-80) mixes of M20 and M50 grade after exposing the specimens to
6000C for duration of 12 Hrs. These values vary from 2605 to 2778
m/s respectively.
The variation of pulse velocity of OPCC, MKC, SFRC & SFRC-
MK mixes of M20 and M50 grade concrete at 6000C are shown in
fig.79.0.
The reason for reduction in pulse velocity is due to the improved
density of MKC and SFRC-MK mixes.
5.8.4. Percentage weight loss of OPCC, MKC, SFRC & SFRC-MK
mixes of M20 and M50 grade
5.8.4.1. Percentage weight loss of OPCC, MKC, SFRC & SFRC-MK
mixes of M20 and M50 grade at 2000C
Tables 4.6.3.1 and 4.6.3.2 gives the percentage weight loss of
OPCC mixes of M20 and M50 grade after exposing the specimens to
2000C for duration of 12 Hrs. These values vary from 4.02 to 6.21%
respectively.
Tables 4.6.3.1 and 4.6.3.2 gives the percentage weight loss of
MKC mixes of M20 and M50 grade after exposing the specimens to
2000C for duration of 12 Hrs. These values vary from 2.90 to 3.18%
respectively.
Tables 4.6.3.1 and 4.6.3.2 gives the percentage weight loss of
SFRC (AR-80) mixes of M20 and M50 grade after exposing the
specimens to 2000C for duration of 12 Hrs. These values vary from
6.41 to 9.98% respectively.
310
Tables 4.6.3.1 and 4.6.3.2 gives the percentage weight loss of
SFRC-MK (AR-80) mixes of M20 and M50 grade after exposing the
specimens to 2000C for duration of 12 Hrs. These values vary from
4.76 to 6.67% respectively.
The variation in percentage weight loss for OPCC, MKC, SFRC &
SFRC-MK mixes of M20 and M50 grade at 2000C are given in fig 77.0.
5.8.4.2 Percentage weight loss of OPCC, MKC, SFRC & SFRC-MK
mixes of M20 and M50 grade at 4000C
Tables 4.6.3.1 and 4.6.3.2 gives the percentage weight loss of
OPCC mixes of M20 and M50 grade after exposing the specimens to
4000C for duration of 12 Hrs. These values vary from 4.60 to 7.76%
respectively.
Tables 4.6.3.1 and 4.6.3.2 gives the percentage weight loss of
MKC mixes of M20 and M50 grade after exposing the specimens to
4000C for duration of 12 Hrs. These values vary from 3.16 to 3.93%
respectively.
Tables 4.6.3.1 and 4.6.3.2 gives the percentage weight loss of
SFRC (AR-80) mixes of M20 and M50 grade after exposing the
specimens to 4000C for duration of 12 Hrs. These values vary from
7.31 to 12.55% respectively.
Tables 4.6.3.1 and 4.6.3.2 gives the percentage weight loss of
SFRC-MK (AR-80) mixes of M20 and M50 grade after exposing the
specimens to 4000C for duration of 12 Hrs. These values vary from
5.30 to 8.25% respectively.
311
The variation in percentage weight loss for OPCC, MKC, SFRC &
SFRC-MK mixes of M20 and M50 grade at 4000C are given in fig 77.0.
5.8.4.3 Percentage weight loss of OPCC, MKC, SFRC & SFRC-MK
mixes of M20 and M50 grade at 6000C
Tables 4.6.3.1 and 4.6.3.2 gives the percentage weight loss of
OPCC mixes of M20 and M50 grade after exposing the specimens to
6000C for duration of 12 Hrs. These values vary from 5.36 to 9.49%
respectively.
Tables 4.6.3.1 and 4.6.3.2 gives the percentage weight loss of
MKC mixes of M20 and M50 grade after exposing the specimens to
6000C for duration of 12 Hrs. These values vary from 3.68 to 4.75%
respectively.
Tables 4.6.3.1 and 4.6.3.2 gives the percentage weight loss of
SFRC (AR-80) mixes of M20 and M50 grade after exposing the
specimens to 6000C for duration of 12 Hrs. These values vary from
8.32 to 15.09% respectively.
Tables 4.6.3.1 and 4.6.3.2 gives the percentage weight loss of
SFRC-MK (AR-80) mixes of M20 and M50 grade after exposing the
specimens to 6000C for duration of 12 Hrs. These values vary from
6.04 to 9.96% respectively.
The variation in percentage weight loss for OPCC, MKC, SFRC &
SFRC-MK mixes of M20 and M50 grade at 6000C are given in fig 77.0.
When the heating temperature is under 2000C, the weight loss
is completely caused by the quick evaporation of capillary water, and
the concrete undergoes a physical process. For a temperature
312
between 2000C and 4000C, the weight loss is mainly caused by the
gradual evaporation of gel water, and the concrete undergoes a mixed
physio-chemical process. For a temperature over 4000C, the weight
loss is mainly caused by the evaporation of chemically bound water
(dehydration) and decomposition, so the concrete undergoes higher
weight loss.
5.9 EFFECT OF THERMAL CYCLES ON OPCC, MKC,
SFRC & SFRC-MK MIXES OF M20 AND M50 GRADE
5.9.1 Effect on compressive strength of OPCC, MKC, SFRC &
SFRC-MK mixes subjected to different thermal cycles at 500C and
1000C.
5.9.1.1 Compressive strength of OPCC, MKC, SFRC and SFRC-MK
mixes of M20 and M50 grade at zero thermal cycles.
Table 4.5.1 gives the comparative study on compressive
strength of OPCC, MKC, SFRC and SFRC-MK mixes investigated at
zero thermal cycles. These values vary from 30.69 MPa for OPCC of
M20 grade and 61.4 MPa for OPCC of M50 grade, 32.86 MPa for MKC
of M20 grade and 68.90 MPa for MKC of M50 grade, 34.10 MPa for
SFRC (1.5-80) mix of M20 grade, 69.04 MPa for SFRC(1.5-80) mix of
M50 grade, 36.50 MPa for SFRC-MK(1.5-80) mix of M20 grade and
75.68 MPa for SFRC-MK(1.5-80) mix of M50 grade respectively.
5.9.1.2 Compressive strength of OPCC, MKC, SFRC and SFRC-MK
mixes of M20 and M50 grade at 28 thermal cycles.
Tables 4.5.1 to 4.5.4 gives a comparative study on compressive
strength of OPC concrete mixes investigated at 28 thermal cycles at
313
500C and 1000C. These values vary from 30.69 to 26.80 MPa for
OPCC of M20 grade and 61.4 to 55.99 MPa for OPCC of M50 grade at
500C, 30.69 to 24.35 MPa for OPCC of M20 grade and 61.4 to 52.66
MPa for OPCC of M50 grade at 1000C respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on compressive
strength of MK concrete mixes investigated at 28 thermal cycles at
500C and 1000C. These values vary from 32.86 to 34.93 MPa for MKC
of M20 grade and 68.9 to 75.56 MPa for MKC of M50 grade at 500C,
32.86 to 35.80 MPa for MKC of M20 grade and 68.9 to 77.77 MPa for
MKC of M50 grade at 1000C respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on compressive
strength of SFRC mixes investigated at 28 thermal cycles at 500C and
1000C. These values vary from 34.10 to 30.88 MPa for SFRC (1.5-60)
of M20 grade and 69.04 to 65.89 MPa for SFRC (1.5-60) of M50 grade
at 500C, 34.10 to 28.20 MPa for SFRC (1.5-60) of M20 grade and
69.04 to 62.60 MPa for SFRC (1.5-60) of M50 grade at 1000C
respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on compressive
strength of SFRC-MK mixes investigated at 28 thermal cycles at 500C
and 1000C. These values vary from 36.50 to 33.88 MPa for SFRC-
MK(1.5-60) mix of M20 grade and 75.68 to 74.10 MPa for SFRC-
MK(1.5-60) mix of M50 grade at 500C, 36.50 to 31.68 MPa for SFRC-
MK(1.5-60) mix of M20 grade and 75.68 to 72.26 MPa for SFRC-
MK(1.5-60) mix of M50 grade at 1000C respectively.
314
5.9.1.3 Compressive strength of OPCC, MKC, SFRC and SFRC-MK
of M20 and M50 grade at 90 thermal cycles.
Tables 4.5.1 to 4.5.4 gives a comparative study on compressive
strength of OPC concrete mixes investigated at 90 thermal cycles at
500C and 1000C. These values vary from 30.69 to 25.18 MPa for
OPCC of M20 grade and 61.4 to 53.26 MPa for OPCC of M50 grade at
500C, 30.69 to 21.15 MPa for OPCC of M20 grade and 61.4 to 46.72
MPa for OPCC of M50 grade at 1000C respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on compressive
strength of MK concrete mixes investigated at 90 thermal cycles at
500C and 1000C. These values vary from 32.86 to 35.96 MPa for MKC
of M20 grade and 68.9 to 77.74 MPa for MKC of M50 grade at 500C,
32.86 to 36.62 MPa for MKC of M20 grade and 68.9 to 80.06 MPa for
MKC of M50 grade at 1000C respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on compressive
strength of SFRC mixes investigated at 90 thermal cycles at 500C and
1000C. These values vary from 34.10 to 29.05 MPa for SFRC (1.5-60)
of M20 grade and 69.04 to 62.70 MPa for SFRC (1.5-60) of M50 grade
at 500C, 34.10 to 24.53 MPa for SFRC (1.5-60) of M20 grade and
69.04 to 55.58 MPa for SFRC (1.5-60) of M50 grade at 1000C
respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on compressive
strength of SFRC-MK mixes investigated at 90 thermal cycles at 500C
and 1000C. These values vary from 36.50 to 31.72 MPa for SFRC-MK
(1.5-60) of M20 grade and 75.68 to 71.14 MPa for SFRC-MK (1.5-60)
315
of M50 grade at 500C, 36.50 to 27.64 MPa for SFRC-MK(1.5-60) of
M20 grade and 75.68 to 64.26 MPa for SFRC-MK(1.5-60) mix of M50
grade at 1000C respectively.
5.9.1.4 Compressive strength of OPCC, MKC, SFRC and SFRC-MK
concrete of M20 and M50 grade at 180 thermal cycles.
Tables 4.5.1 to 4.5.4 gives a comparative study on compressive
strength of OPC concrete mixes investigated at 180 thermal cycles at
500C and 1000C. These values vary from 30.69 to 24.54 MPa for
OPCC of M20 grade and 61.4 to 51.29 MPa for OPCC of M50 grade at
500C, 30.69 to 18.95 MPa for OPCC of M20 grade and 61.4 to 42.72
MPa for OPCC of M50 grade at 1000C respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on compressive
strength of MK concrete mixes investigated at 180 thermal cycles at
500C and 1000C. These values vary from 32.86 to 36.60 MPa for MKC
of M20 grade and 68.9 to 79.18 MPa for MKC of M50 grade at 500C,
32.86 to 37.33 MPa for MKC of M20 grade and 68.9 to 81.89 MPa for
MKC of M50 grade at 1000C respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on compressive
strength of SFRC mixes investigated at 180 thermal cycles at 500C
and 1000C. These values vary from 34.10 to 28.20 MPa for
SFRC(1.5-60) of M20 grade and 69.04 to 60.35 MPa for SFRC(1.5-60)
of M50 grade at 500C, 34.10 to 22.01 MPa for SFRC(1.5-60) of M20
grade and 69.04 to 50.88 MPa for SFRC(1.5-60) of M50 grade at
1000C respectively.
316
Tables 4.5.1 to 4.5.4 gives a comparative study on compressive
strength of SFRC-MK mixes investigated at 180 thermal cycles at 500C
and 1000C. These values vary from 36.50 to 31.05 MPa for SFRC-
MK(1.5-60) of M20 grade and 75.68 to 67.94 MPa for SFRC-MK(1.5-
60) of M50 grade at 500C, 36.50 to 24.86 MPa for SFRC-MK(1.5-60)
of M20 grade and 75.68 to 58.92 MPa for SFRC-MK(1.5-60) mix of
M50 grade at 1000C respectively.
5.9.2 Effect on splitting tensile strength of OPCC, MKC, SFRC &
SFRC-MK mixes subjected to different thermal cycles at 500C and
1000C.
5.9.2.1 Splitting tensile strength of OPCC, MKC, SFRC and SFRC-
MK mixes of M20 and M50 grade at zero thermal cycles.
Tables 4.5.1 to 4.5.4 gives the comparative study on
splitting tensile strength of OPCC, MKC, SFRC and SFRC-MK concrete
mixes investigated at zero thermal cycles. These values vary from 2.84
MPa for OPCC of M20 grade and 4.32 MPa for OPCC of M50 grade,
3.08 MPa for MKC of M20 grade and 4.76 MPa for MKC of M50 grade,
4.68 MPa for SFRC (1.5-60) mix of M20 grade, 7.22 MPa for SFRC
(1.5-60) mix of M50 grade, 4.96 MPa for SFRC-MK (1.5-60) mix of M20
grade and 7.69 MPa for SFRC-MK (1.5-60) mix of M50 grade
respectively.
5.9.2.2 Splitting tensile strength of OPCC, MKC, SFRC &
SFRC-MK of M20 and M50 grade at 28 thermal cycles.
Tables 4.5.1 to 4.5.4 gives a comparative study on splitting
tensile strength of OPC concrete mixes investigated at 28 thermal
317
cycles at 500C and 1000C. These values vary from 2.84 to 2.42 MPa
for OPCC of M20 grade and 4.32 to 3.86MPa for OPCC of M50 grade
at 500C, 2.84 to 2.18MPa for OPCC of M20 grade and 4.32 to 3.61
MPa for OPCC of M50 grade at 1000C respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on splitting
tensile strength of MK concrete mixes investigated at 28 thermal
cycles at 500C and 1000C. These values vary from 3.08 to 3.20 MPa
for MKC of M20 grade and 4.76 to 5.28 MPa for MKC of M50 grade at
500C, 3.08 to 3.26 MPa for MKC of M20 grade and 4.76 to 5.41 MPa
for MKC of M50 grade at 1000C respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on splitting
tensile strength of SFRC mixes investigated at 28 thermal cycles at
500C and 1000C. These values vary from 4.68 to 4.18 MPa for
SFRC(1.5-60) of M20 grade and 7.22 to 6.85 MPa for SFRC(1.5-60)
of M50 grade at 500C, 4.68 to 3.75 MPa for SFRC(1.5-60) of M20
grade and 7.22 to 6.36 MPa for SFRC(1.5-60) of M50 grade at 1000C
respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on splitting
tensile strength of SFRC-MK mixes investigated at 28 thermal cycles
at 500C and 1000C. These values vary from 4.96 to 4.56 MPa for
SFRC-MK(1.5-60) of M20 grade and 7.69 to 7.52 MPa for SFRC-
MK(1.5-60) of M50 grade at 500C, 4.96 to 4.16 MPa for SFRC-
MK(1.5-60) of M20 grade and 7.69 to 7.18MPa for SFRC-MK(1.5-60)
mix of M50 grade at 1000C respectively.
318
5.9.2.3 Splitting tensile strength of OPCC, MKC, SFRC &
SFRC-MK of M20 and M50 grade at 90 thermal cycles.
Tables 4.5.1 to 4.5.4 gives a comparative study on splitting
tensile strength of OPC concrete mixes investigated at 90 thermal
cycles at 500C and 1000C. These values vary from 2.84 to 2.22 MPa
for OPCC of M20 grade and 4.32 to 3.59 MPa for OPCC of M50 grade
at 500C, 2.84 to 1.99 MPa for OPCC of M20 grade and 4.32 to 3.28
MPa for OPCC of M50 grade at 1000C respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on splitting
tensile strength of MK concrete mixes investigated at 90 thermal
cycles at 500C and 1000C. These values vary from 3.08 to 3.27 MPa
for MKC of M20 grade and 4.76 to 5.43 MPa for MKC of M50 grade at
500C, 3.08 to 3.32 MPa for MKC of M20 grade and 4.76 to 5.69 MPa
for MKC of M50 grade at 1000C respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on splitting
tensile strength of SFRC mixes investigated at 90 thermal cycles at
500C and 1000C. These values vary from 4.68 to 3.85 MPa for
SFRC(1.5-60) of M20 grade and 7.22 to 6.40 MPa for SFRC(1.5-60)
of M50 grade at 500C, 4.68 to 3.45 MPa for SFRC(1.5-60) of M20
grade and 7.22 to 5.77 MPa for SFRC(1.5-60) of M50 grade at 1000C
respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on compressive
strength of SFRC-MK mixes investigated at 90 thermal cycles at 500C
and 1000C. These values vary from 4.96 to 4.20 MPa for SFRC-
MK(1.5-60) of M20 grade and 7.69 to 7.06 MPa for SFRC-MK(1.5-60)
319
of M50 grade at 500C, 4.96 to 3.86 MPa for SFRC-MK(1.5-60) of M20
grade and 7.69 to 6.53 MPa for SFRC-MK(1.5-60) mix of M50 grade
at 1000C respectively.
5.9.2.4 Splitting tensile strength of OPCC, MKC, SFRC & SFRC-
MK of M20 and M50 grade at 180 thermal cycles.
Tables 4.5.1 to 4.5.4 gives a comparative study on splitting
tensile strength of OPC concrete mixes investigated at 180 thermal
cycles at 500C and 1000C. These values vary from 2.84 to 2.09 MPa
for OPCC of M20 grade and 4.32 to 3.41 MPa for OPCC of M50 grade
at 500C, 2.84 to 1.86 MPa for OPCC of M20 grade and 4.32 to 3.08
MPa for OPCC of M50 grade at 1000C respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on splitting
tensile strength of MK concrete mixes investigated at 180 thermal
cycles at 500C and 1000C. These values vary from 3.08 to 3.32 MPa
for MKC of M20 grade and 4.76 to 5.53 MPa for MKC of M50 grade at
500C, 3.08 to 3.37 MPa for MKC of M20 grade and 4.76 to 5.88MPa
for MKC of M50 grade at 1000C respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on splitting tensile
strength of SFRC mixes investigated at 180 thermal cycles at 500C
and 1000C. These values vary from 4.68 to 3.19 MPa for SFRC(1.5-
60) of M20 grade and 7.22 to 6.09 MPa for SFRC(1.5-60) of M50
grade at 500C, 4.68 to 3.19 MPa for SFRC(1.5-60) of M20 grade and
7.22 to 5.44 MPa for SFRC(1.5-60) of M50 grade at 1000C
respectively.
320
Tables 4.5.1 to 4.5.4 gives a comparative study on compressive
strength of SFRC-MK mixes investigated at 180 thermal cycles at 500C
and 1000C. These values vary from 4.96 to 3.97 MPa for SFRC-MK
(AR-80) of M20 grade and 7.69 to 6.74 MPa for SFRC-MK (1.5-60) of
M50 grade at 500C, 4.96 to 3.52MPa for SFRC-MK(1.5-60) of M20
grade and 7.69 to 6.12 MPa for SFRC-MK(1.5-60) mix of M50 grade
at 1000C respectively.
5.9.3 Effect on modulus of rupture of OPCC, MKC, SFRC & SFRC-
MK mixes subjected to different thermal cycles at 500C and
1000C.
5.9.3.1 Modulus of rupture of OPCC, MKC, SFRC & SFRC-MK
concrete of M20 and M50 grade at zero thermal cycles.
Tables 4.5.1 to 4.5.4 gives the comparative study on modulus of
rupture of OPCC, MKC, SFRC and SFRC-MK mixes investigated at
zero thermal cycles. These values vary from 4.03 MPa for OPCC of
M20 grade and 5.42 MPa for OPCC of M50 grade, 4.26 MPa for MKC
of M20 grade and 5.87 MPa for MKC of M50 grade, 6.72 MPa for SFRC
mix of M20 grade, 9.15 MPa for SFRC mix of M50 grade, 6.90 MPa for
SFRC-MK mix of M20 grade and 9.82 MPa for SFRC-MK mix of M50
grade respectively.
5.9.3.2 Modulus of Rupture of OPCC, MKC, SFRC & SFRC-MK of
M20 and M50 grade at 28 thermal cycles.
Tables 4.5.1 to 4.5.4 gives a comparative study on modulus of
rupture of OPC concrete mixes investigated at 28 thermal cycles at
500C and 1000C. These values vary from 4.03 to 3.32 MPa for OPCC
321
of M20 grade and 5.42 to 4.70 MPa for OPCC of M50 grade at 500C,
4.03 to 3.04 MPa for OPCC of M20 grade and 5.42 to 4.43 MPa for
OPCC of M50 grade at 1000C respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on modulus of
rupture of MK concrete mixes investigated at 28 thermal cycles at
500C and 1000C. These values vary from 4.26 to 4.43 MPa for MKC of
M20 grade and 5.87 to 6.42 MPa for MKC of M50 grade at 500C, 4.26
to 4.55 MPa for MKC of M20 grade and 5.87 to 6.63 MPa for MKC of
M50 grade at 1000C respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on modulus of
rupture of SFRC mixes investigated at 28 thermal cycles at 500C and
1000C. These values vary from 6.72 to 5.97 MPa for SFRC(1.5-60) of
M20 grade and 9.15 to 8.66 MPa for SFRC(1.5-60) of M50 grade at
500C, 6.72 to 5.43MPa for SFRC(1.5-60) of M20 grade and 9.15 to
8.09 MPa for SFRC (1.5-60) of M50 grade at 1000C respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on modulus of
rupture of SFRC-MK mixes investigated at 28 thermal cycles at 500C
and 1000C. These values vary from 6.90 to 6.33 MPa for SFRC-
MK(1.5-60) of M20 grade and 9.82 to 9.60 MPa for SFRC-MK(1.5-60)
of M50 grade at 500C, 6.90 to 5.79 MPa for SFRC-MK(1.5-60) of M20
grade and 9.82 to 9.04 MPa for SFRC-MK(1.5-60) mix of M50 grade
at 1000C respectively.
5.9.3.3 Modulus of Rupture of OPCC, MKC, SFRC & SFRC-MK of
M20 and M50 grade at 90 thermal cycles.
322
Tables 4.5.1 to 4.5.4 gives a comparative study on modulus of
rupture of OPC concrete mixes investigated at 90 thermal cycles at
500C and 1000C. These values vary from 4.03 to 3.04 MPa for OPCC
of M20 grade and 5.42 to 4.33 MPa for OPCC of M50 grade at 500C,
4.03 to 2.75 MPa for OPCC of M20 grade and 5.42 to 3.94 MPa for
OPCC of M50 grade at 1000C respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on modulus of
rupture of MK concrete mixes investigated at 90 thermal cycles at
500C and 1000C. These values vary from 4.26 to 4.55 MPa for MKC of
M20 grade and 5.87 to 6.61 MPa for MKC of M50 grade at 500C, 4.26
to 4.65 MPa for MKC of M20 grade and 5.87 to 6.92 MPa for MKC of
M50 grade at 1000C respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on modulus of
rupture of SFRC mixes investigated at 90 thermal cycles at 500C and
1000C. These values vary from 6.72 to 5.46 MPa for SFRC(1.5-60) of
M20 grade and 9.15 to 7.94 MPa for SFRC(1.5-60) of M50 grade at
500C, 6.72 to 4.94 MPa for SFRC(1.5-60) of M20 grade and 9.15 to
7.24 MPa for SFRC(1.5-60) of M50 grade at 1000C respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on modulus of
rupture of SFRC-MK mixes investigated at 90 thermal cycles at 500C
and 1000C. These values vary from 6.90 to 5.36 MPa for SFRC-
MK(1.5-60) of M20 grade and 9.82 to 8.20 MPa for SFRC-MK (1.5-60)
of M50 grade at 500C, 6.90 to 4.92 MPa for SFRC-MK(1.5-60) of M20
grade and 9.82 to 7.54 MPa for SFRC-MK(1.5-60) mix of M50 grade
at 1000C respectively.
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5.9.3.4 Modulus of Rupture of OPCC, MKC, SFRC & SFRC-MK of
M20 and M50 grade at 180 thermal cycles.
Tables 4.5.1 to 4.5.4 gives a comparative study on modulus of
rupture of OPC concrete mixes investigated at 180 thermal cycles at
500C and 1000C. These values vary from 4.03 to 2.83 MPa for OPCC
of M20 grade and 5.42 to 4.05 MPa for OPCC of M50 grade at 500C,
4.03 to 2.51 MPa for OPCC of M20 grade and 5.42 to 3.62 MPa for
OPCC of M50 grade at 1000C respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on modulus of
rupture of MK concrete mixes investigated at 180 thermal cycles at
500C and 1000C. These values vary from 4.26 to 4.61 MPa for MKC of
M20 grade and 5.87 to 6.71 MPa for MKC of M50 grade at 500C, 4.26
to 4.74 MPa for MKC of M20 grade and 5.87 to 7.08 MPa for MKC of
M50 grade at 1000C respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on modulus of
rupture of SFRC mixes investigated at 180 thermal cycles at 500C and
1000C. These values vary from 6.72 to 5.06 MPa for SFRC(1.5-60) of
M20 grade and 9.15 to 7.36 MPa for SFRC(1.5-60) of M50 grade at
500C, 6.72 to 4.54MPa for SFRC(1.5-60) of M20 grade and 9.15 to
6.71 MPa for SFRC(1.5-60) of M50 grade at 1000C respectively.
Tables 4.5.1 to 4.5.4 gives a comparative study on modulus of
rupture of SFRC-MK mixes investigated at 180 thermal cycles at 500C
and 1000C. These values vary from 6.90 to 5.36 MPa for SFRC-
MK(1.5-60) of M20 grade and 9.82 to 8.20 MPa for SFRC-MK(1.5-60)
of M50 grade at 500C, 6.90 to 4.92MPa for SFRC-MK(1.5-60) of M20
324
grade and 9.82 to 7.54MPa for SFRC-MK(1.5-60) mix of M50 grade at
1000C respectively.
5.9.4 Variation of the compressive strength of OPCC, MKC, SFRC
& SFRC-MK mixes of M20 and M50 grade compared with zero
thermal cycles:
Tables 4.5.1 to 4.5.4 gives the decrease in the compressive
strength of OPCC of M20 and M50 grade in comparison with zero
thermal cycles at 500C and 1000C. These values vary from 30.69 to
26.80 MPa, 30.69 to 25.18 MPa, and 30.69 to 24.54 MPa for OPCC
mix of M20 grade at 500C for 28, 90 and 180 thermal cycles
respectively. 30.69 to 24.35 MPa, 30.69 to 21.15 MPa, and 30.69 to
18.95 MPa for OPCC mix of M20 grade at 1000C for 28, 90 & 180
thermal cycles respectively. 61.4 to 55.99 MPa, 61.4 to 53.26 MPa
and 61.4 to 51.29 MPa for OPCC mix of M50 grade at 500C at 28, 90
& 180 thermal cycles respectively. 61.4 to 52.66 MPa, 61.4 to 46.72
MPa and 61.4 MPa to 42.72 MPa for OPCC mix of M50 grade at 1000C
for 28, 90 & 180 thermal cycles respectively.
Tables 4.5.1 to 4.5.4 gives the decrease in compressive strength
of MKC in comparison with zero thermal cycles at 500C and 1000C.
These values vary from 32.86 to 34.93 MPa, 32.87 to 35.96 MPa and
32.87 to 36.60 MPa for MKC mix of M20 grade at 500C, 32.86 to 35.80
MPa, 32.87 to 36.62 MPa and 32.87 to 37.33 MPa for MKC mix of
M20 grade at 1000C for 28, 90 & 180 thermal cycles respectively.
68.90 to 75.56 MPa, 68.90 to 77.74 MPa and 68.90 to 79.18 MPa for
MKC mix of M50 grade at 500C, 68.90 MPa to 77.77 , 68.90 to 80.06
325
MPa and 68.90 to 81.89 MPa for MKC mix of M50 grade at 1000C for
28, 90 and 180 thermal cycles respectively.
Tables 4.5.1 to 4.5.4 gives the decrease in compressive strength
of SFRC mixes in comparison with zero thermal cycles at 500C and
1000C. These values vary from 34.10 to 30.88 MPa, 34.10 to 29.05
MPa and 34.10 to 28.20 MPa for SFRC(1.5-60) mix of M20 grade at
500C, 34.10 to 28.20 MPa, 34.10 to 24.53 MPa and 34.10 to 22.01
MPa for SFRC(1.5-60) mix of M20 grade at 1000C for 28, 90 & 180
thermal cycles respectively. 69.04 to 65.89 MPa, 69.04 to 62.70 MPa
and 69.04 to 60.35 MPa for SFRC(1.5-60) mix of M50 grade at 500C,
69.04 to 62.60 MPa, 69.04 to 55.58 MPa and 69.04 to 50.88 MPa for
SFRC(1.5-80) mix of M50 grade at 1000C for 28, 90 and 180 thermal
cycles respectively.
Tables 4.5.1 to 4.5.4 gives the decrease in compressive strength
of SFRC-MK mixes in comparison with zero thermal cycles at 500C
and 1000C. These values vary from 36.50 to 33.88 MPa, 36.50 to
31.72 MPa and 36.50 to 31.05 MPa for SFRC-MK (1.5-60) mix of M20
grade at 500C, 36.50 to 31.68 MPa, 36.28 to 27.64 MPa and 36.28 to
24.86 MPa for SFRC-MK (1.5-60) mix of M20 grade at 1000C for 28,
90 & 180 thermal cycles respectively. 75.68 to 74.10 MPa, 75.68 to
71.14 MPa and 75.68 to 67.94 MPa for SFRC-MK(1.5-60) mix of M50
grade at 500C, 75.68 to 72.26 MPa, 75.68 to 64.26 MPa and 75.68
to 58.92 MPa for SFRC-MK(1.5-60) mix of M50 grade at 1000C for
28, 90 and 180 thermal cycles respectively.
326
5.9.5 Variation of the splitting tensile strength of OPCC, MKC and
SFRC & SFRC-MK mixes of M20 and M50 grade when compared
with zero thermal cycles
Tables 4.5.1 to 4.5.4 gives the decrease in the splitting tensile
strength of OPCC of M20 and M50 grade in comparison with zero
thermal cycles at 500C and 1000C. These values vary from 2.84 to
2.42 MPa, 2.84 to 2.22MPa, and 2.84 to 2.09 MPa for OPCC mix of
M20 grade at 500C, 2.84 to 2.18 MPa, 2.84 to 1.99 MPa, and 2.84 to
1.84 MPa for OPCC mix of M20 grade at 1000C for 28, 90 & 180
thermal cycles respectively. 4.32 to 3.86 MPa, 4.32 to 3.59 MPa and
4.32 to 3.41 MPa for OPCC mix of M50 grade at 500C, 4.32 to
3.61MPa, 4.32 to 3.28 and 4.32 to 3.08 MPa for OPCC mix of M50
grade at 1000C for 28,90 & 180 thermal cycles respectively.
Tables 4.5.1 to 4.5.4 give the decrease in splitting tensile
strength of MKC in comparison with zero thermal cycles at 500C and
1000C. These values vary from 3.08 to 3.20 MPa, 3.08 to 3.27 MPa
and 3.08 to 3.32 MPa for MKC mix of M20 grade at 500C, 3.08 to 3.26
MPa, 3.08 to 3.32MPa and 3.08 to 3.37 MPa for MKC mix of M20
grade at 1000C for 28, 90 & 180 thermal cycles respectively. 4.76 to
5.28 MPa, 4.76 to 5.43 MPa and 4.56 to 5.30 MPa for MKC mix of
M50 grade at 500C, 4.76 to 5.41 MPa, 4.76 to 5.69 MPa and 4.76 to
5.88MPa for MKC mix of M50 grade at 1000C for 28, 90 and 180
thermal cycles respectively.
Tables 4.5.1 to 4.5.4 gives the decrease in splitting tensile
strength of SFRC mixes in comparison with zero thermal cycles at
327
500C and 1000C. These values vary from 4.68 to 4.18 MPa, 4.68 to
3.85 MPa and 4.68 to 3.61MPa for SFRC(1.5-60) mix of M20 grade at
500C, 4.68 to 3.75 MPa, 4.68 to 3.45 MPa and 4.68 to 3.19 MPa for
SFRC(1.5-60) mix of M20 grade at 1000C for 28, 90 & 180 thermal
cycles respectively. 7.22 to 6.85 MPa, 7.22 to 6.40 MPa and 7.22 to
6.09 MPa for SFRC(1.5-60) mix of M50 grade at 500C, 7.22 to 6.36
MPa, 7.22 to 5.77 MPa and 7.22 to 5.44 MPa for SFRC(1.5-60) mix of
M50 grade at 1000C for 28, 90 and 180 thermal cycles respectively.
Tables 4.5.1 to 4.5.4 give the decrease in splitting tensile
strength of SFRC-MK in comparison with zero thermal cycles at 500C
and 1000C. These values vary from 4.96 to 4.56MPa, 4.96 to 4.20
MPa and 4.96 to 3.97MPa for SFRC-MK(1.5-60) mix of M20 grade at
500C, 4.96 to 4.16 MPa, 4.96 to 3.86 MPa and 4.96 to 3.52MPa for
SFRC-MK(1.5-60) mix of M20 grade at 1000C for 28, 90 & 180
thermal cycles respectively. 7.69 to 7.52 MPa, 7.69 to 7.06 MPa and
7.69 to 6.74 MPa for SFRC-MK(1.5-60) mix of M50 grade at 500C,
7.69 to 7.18MPa, 7.69 to 6.53MPa and 7.69 to 6.12 MPa for SFRC-
MK(1.5-60) mix of M50 grade at 1000C for 28, 90 and 180 thermal
cycles respectively.
5.9.6 Variation of the modulus of rupture of OPCC, MKC, SFRC &
SFRC-MK mixes of M20 and M50 grade compared with zero
thermal cycles:
Tables 4.5.1 to 4.5.4 gives the decrease in the modulus of
rupture of OPCC of M20 and M50 grade in comparison with zero
thermal cycles at 500C and 1000C. These values vary from 4.03 to
328
3.32 MPa, 4.03 MPa to 3.04 MPa, and 4.03 to 2.83 MPa for OPCC mix
of M20 grade at 500C, 4.03 to 3.03 MPa, 4.03 to 2.75 MPa, and 4.03
to 2.51 MPa for OPCC mix of M20 grade at 1000C for 28, 90 & 180
thermal cycles respectively. 5.42 to 4.70 MPa, 5.42 to 4.33 MPa and
5.42 to 4.05 MPa for OPCC mix of M50 grade at 500C, 5.42 to 4.42
MPa, 5.42 to 3.94 MPa and 5.42 to 3.62 MPa for OPCC mix of M50
grade at 1000C for 28,90 & 180 thermal cycles respectively.
Tables 4.5.1 to 4.5.4 gives the decrease in modulus of rupture of
MKC in comparison with zero thermal cycles at 500C and 1000C.
These values vary from 4.26 to 4.43 MPa, 4.26 to 4.55 MPa and 4.26
to 4.61 MPa for MKC mix of M20 grade at 500C, 4.26 to 4.55 MPa,
4.26 to 4.65 MPa and 4.26 to 4.74 MPa for MKC mix of M20 grade at
1000C for 28, 90 & 180 thermal cycles respectively. 5.87 to 6.42
MPa, 5.87 to 6.61 MPa and 5.87 to 6.72 MPa for MKC mix of M50
grade at 500C, 5.87 to 6.63 MPa, 5.87 to 6.92 MPa and 5.87 to 7.08
MPa for MKC mix of M50 grade at 1000C for 28, 90 and 180 thermal
cycles respectively.
Tables 4.5.1 to 4.5.4 gives the decrease in modulus of rupture of
SFRC mixes in comparison with zero thermal cycles at 500C and
1000C. These values vary from 6.72 to 5.97 MPa, 6.72 to 5.46 MPa
and 6.72 to 5.06 MPa for SFRC (1.5-60) mix of M20 grade at 500C,
6.72 to 5.43MPa, 6.72 to 4.94 MPa and 6.72 to 4.54 MPa for SFRC
(1.5-60) mix of M20 grade at 1000C for 28, 90 & 180 thermal cycles
respectively. 9.15 to 8.66 MPa, 9.15 to 7.94 MPa and 9.15 to 7.36
MPa for SFRC(1.5-60) mix of M50 grade at 500C, 9.15 to 8.09 MPa,
329
9.15 to 7.24 MPa and 9.15 to 6.71 MPa for SFRC(1.5-60) mix of M50
grade at 1000C for 28, 90 and 180 thermal cycles respectively.
Tables 4.5.1 to 4.5.4 gives the decrease in modulus of rupture of
SFRC-MK mixes in comparison with zero thermal cycles at 500C and
1000C. These values vary from 6.90 to 6.33 MPa , 6.90 to 5.80 MPa
and 6.90 to 5.36 MPa for SFRC-MK(1.5-60) mix of M20 grade at
500C, 6.90 to 5.72 MPa , 6.90 to 5.37 MPa and 6.90 to 4.92 MPa
for SFRC-MK(1.5-60) mix of M20 grade at 1000C for 28, 90 & 180
thermal cycles respectively. 9.82 to 9.60 MPa, 9.82 to 8.85 MPa
and 9.82 to 8.20 MPa for SFRC-MK(1.5-60) mix of M50 grade at
500C, 9.82 to 9.04 MPa, 9.82 to 8.05 MPa and 9.82 to 7.54
MPa for SFRC-MK(1.5-80) mix of M50 grade at 1000C for 28, 90
and 180 thermal cycles respectively.
Thermal cycling imposes a mechanical alternating loading on
the aggregate, cement paste and bond shell. This can result in the
gradual loosening of the aggregate from the surrounding matrix and
the development of cracks leads to the decrease in strength. The
percentage decrease in compressive strength of OPCC and SFRC
mixes of M50 grade is less when compared to the respective mixes of
M20 grade. The reason may be due to lower w/c ratio of M50 grade
mixes when compared to M20 grade mixes. It is clear that, when the
air in the pores has been partially displaced by water (or) moisture,
the concrete would have greater conductivity.
The percentage increase in the strength of MK concrete was due
to the dehydration of C-S-H gel bond forms, leaving some amount of
330
Ca (OH)2 free. The free lime will be engaged by the SiO2 available in the
Metakaolin and forms a strong C-S-H bond, which is responsible for
higher strength.
5.9.7 Percentage increase/decrease in compressive strength of
OPCC, MKC, SFRC & SFRC-MK mixes of M20 and M50 grade at
different thermal cycles when compared with zero thermal cycles:
Tables 4.5.5 and 4.5.6 gives the percentage decrease in
compressive strength of OPCC mix of M20 grade in comparison with
zero thermal cycles at 500C and 1000C. These values vary from -
12.66% to -20.04% at 500C and -20.64% to -38.26% at 1000C for 28,
90 &180 thermal cycles respectively.
Tables 4.5.5 and 4.5.6 gives the percentage increase in
compressive strength of MKC mix of M20 grade in comparison with
zero thermal cycles at 500C and 1000C. These values vary from 6.26%
to 11.36% at 500C and 8.92% to 13.58% at 1000C for 28, 90 &180
thermal cycles respectively.
Tables 4.5.5 and 4.5.6 gives the percentage decrease in
compressive strength of SFRC (1.5-60) mix of M20 grade in
comparison with zero thermal cycles at 500C and 1000C. These values
vary from -10.38% to -18.66% at 500C and -18.76% to -36.58% at
1000C for 28, 90 &180 thermal cycles respectively.
Tables 4.5.5 and 4.5.6 gives the percentage decrease in
compressive strength of SFRC-MK (1.5-60) mix of M20 grade in
comparison with zero thermal cycles at 500C and 1000C. These values
331
vary from -8.10% to -16.24% at 500C and -14.67% to -33.38% at
1000C for 28, 90 &180 thermal cycles respectively.
Tables 4.5.5 and 4.5.6 gives the percentage decrease in
compressive strength of OPCC mix of M50 grade in comparison with
zero thermal cycles at 500C and 1000C. These values vary from -8.8%
to -16.46% at 500C and -14.23% to -30.42% at 1000C for 28, 90 &180
thermal cycles respectively.
Tables 4.5.5 and 4.5.6 gives the percentage increase in
compressive strength of MKC mix of M50 grade in comparison with
zero thermal cycles at 500C and 1000C. These values vary from 9.68%
to 14.92% at 500C and 12.88% to 18.86% at 1000C for 28, 90 &180
thermal cycles respectively.
Tables 4.5.5 and 4.5.6 gives the percentage decrease in
compressive strength of SFRC (1.5-60) mix of M50 grade in
comparison with zero thermal cycles at 500C and 1000C. These values
vary from -5.92% to -14.0% at 500C and -11.27% to -27.74% at 1000C
for 28, 90 &180 thermal cycles respectively.
Tables 4.5.5 and 4.5.6 gives the percentage decrease in
compressive strength of SFRC-MK (1.5-60) mix of M50 grade in
comparison with zero thermal cycles at 500C and 1000C. These values
vary from -2.54% to -11.86% at 500C and -5.47% to -23.08% at
1000C for 28, 90 &180 thermal cycles respectively.
5.9.8 Percentage increase/decrease in splitting tensile strength
of OPCC, MKC, SFRC & SFRC-MK mixes of M20 and M50 grade at
different thermal cycles when compared with zero thermal cycles:
332
Tables 4.5.5 and 4.5.6 gives the percentage decrease in splitting
tensile strength of OPCC mix of M20 grade in comparison with zero
thermal cycles at 500C and 1000C. These values vary from -14.57% to
-26.20% at 500C and -23.14% to -35.08% at 1000C for 28, 90 &180
thermal cycles respectively.
Tables 4.5.5 and 4.5.6 gives the percentage increase in splitting
tensile strength of MKC mix of M20 grade in comparison with zero
thermal cycles at 500C and 1000C. These values vary from 4.12% to
7.94% at 500C and 6.08% to 9.4% at 1000C for 28, 90 &180 thermal
cycles respectively.
Tables 4.5.5 and 4.5.6 gives the percentage decrease in splitting
tensile strength of SFRC (1.5-80) mix of M20 grade in comparison with
zero thermal cycles at 500C and 1000C. These values vary from -
11.53% to -23.70% at 500C and -20.86% to -32.58% at 1000C for 28,
90 &180 thermal cycles respectively.
Tables 4.5.5 and 4.5.6 gives the percentage decrease in splitting
tensile strength of SFRC-MK (1.5-60) mix of M20 grade in comparison
with zero thermal cycles at 500C and 1000C. These values vary from -
9.06% to -21.10% at 500C and -17.24% to -30.26% at 1000C for 28,
90 &180 thermal cycles respectively.
Tables 4.5.5 and 4.5.6 gives the percentage decrease in splitting
tensile strength of OPCC mix of M50 grade in comparison with zero
thermal cycles at 500C and 1000C. These values vary from -10.64% to
-21.0% at 500C and -16.38% to -28.72% at 1000C for 28, 90 &180
thermal cycles respectively.
333
Tables 4.5.5 and 4.5.6 gives the percentage increase in splitting
tensile strength of MKC mix of M50 grade in comparison with zero
thermal cycles at 500C and 1000C. These values vary from 10.80% to
16.22% at 500C and 13.74% to 23.49% at 1000C for 28, 90 &180
thermal cycles respectively.
Tables 4.5.5 and 4.5.6 gives the percentage decrease in splitting
tensile strength of SFRC (1.5-60) mix of M50 grade in comparison with
zero thermal cycles at 500C and 1000C. These values vary from -
6.46% to -17.12% at 500C and -13.12% to -25.86% at 1000C for 28,
90 &180 thermal cycles respectively.
Tables 4.5.5 and 4.5.6 gives the percentage decrease in splitting
tensile strength of SFRC-MK (1.5-60) mix of M50 grade in comparison
with zero thermal cycles at 500C and 1000C. These values vary from -
5.04% to -15.60% at 500C and -11.90% to -24.70% at 1000C for 28,
90 &180 thermal cycles respectively.
5.9.9 Percentage increase/decrease in modulus of rupture of
OPCC, MKC, SFRC & SFRC-MK mixes of M20 and M50 grade at
different thermal cycles when compared with zero thermal cycles
Tables 4.5.5 and 4.5.6 gives the percentage decrease in
modulus of rupture of OPCC mix of M20 grade in comparison with
zero thermal cycles at 500C and 1000C. These values vary from -
17.66% to -29.72% at 500C and -24.72% to -37.60% at 1000C for 28,
90 &180 thermal cycles respectively.
Tables 4.5.5 and 4.5.6 gives the percentage increase in modulus
of rupture of MKC mix of M20 grade in comparison with zero thermal
334
cycles at 500C and 1000C. These values vary from 4.18% to 8.33% at
500C and 6.72% to 11.08% at 1000C for 28, 90 &180 thermal cycles
respectively.
Tables 4.5.5 and 4.5.6 gives the percentage decrease in
modulus of rupture of SFRC (1.5-60) mix of M20 grade in comparison
with zero thermal cycles at 500C and 1000C. These values vary from -
12.3% to -25.88% at 500C and -20.47% to -33.76% at 1000C for 28,
90 &180 thermal cycles respectively.
Tables 4.5.5 and 4.5.6 gives the percentage decrease in
modulus of rupture of SFRC-MK (1.5-60) mix of M20 grade in
comparison with zero thermal cycles at 500C and 1000C. These values
vary from -8.62% to -22.92% at 500C and -17.10% to -30.24% at
1000C for 28, 90 &180 thermal cycles respectively.
Tables 4.5.5 and 4.5.6 gives the percentage decrease in
modulus of rupture of OPCC mix of M50 grade in comparison with
zero thermal cycles at 500C and 1000C. These values vary from -
13.28% to -25.20% at 500C and -18.40% to -33.14% at 1000C for 28,
90 &180 thermal cycles respectively.
Tables 4.5.5 and 4.5.6 gives the percentage increase in modulus
of rupture of MKC mix of M50 grade in comparison with zero thermal
cycles at 500C and 1000C. These values vary from 9.36% to 14.32% at
500C and 12.94% to 20.74% at 1000C for 28, 90 &180 thermal cycles
respectively.
Tables 4.5.5 and 4.5.6 gives the percentage decrease in
modulus of rupture of SFRC (1.5-60) mix of M50 grade in comparison
335
with zero thermal cycles at 500C and 1000C. These values vary from -
7.04% to -21.08% at 500C and -13.16% to -28.40% at 1000C for 28,
90 &180 thermal cycles respectively.
Tables 4.5.5 and 4.5.6 gives the percentage decrease in
modulus of rupture of SFRC-MK (1.5-60) mix of M50 grade in
comparison with zero thermal cycles at 500C and 1000C. These values
vary from -3.76% to -17.80% at 500C and -8.84% to -24.58% at 1000C
for 28, 90 &180 thermal cycles respectively.
5.10 DURABILITY STUDIES OF OPCC, MKC, SFRC &
SFRC-MK MIXES OF M20 AND M50 GRADE WHEN
EXPOSED TO DIFFERENT SOLUTIONS FOR 30, 60, 90 &
120 DAYS
Experimental Results
Tables 4.7.2.1 to 4.7.2.4 give the values of loss in compressive
strength due to acid attack in 5% HCL and 5% H2SO4. Tables 4.7.1.1
to 4.7.1.4 give the values of loss in weight due to acid attack in 5%
HCL and 5% H2SO4. Tables 4.7.3 to 4.7.6 gives the values of acid
durability factors for specimens immersed in 5% HCL and 5% H2SO4.
Fig. 59.0 to 62.0 gives the variation of loss in compressive
strength in 5% HCL and 5% H2SO4. Fig. 65.0 to 68.0 gives the
variation of loss in weight in 5% HCL and 5% H2SO4.
5.10.1 Studies on loss of weight of OPCC, MKC, SFRC & SFRC-MK
mixes of M20 and M50 grade mixes in different solutions
5.10.1.1 Loss of weight of specimens after immersing in 5 % HCL
Solution
336
Tables 4.7.1.1 and 4.7.1.3 gives the percentage weight loss of
OPCC mixes of M20 and M50 grade after immersing in 5 % HCL
solution. These values vary from 5.45 to 3.97 % for 30 days , 5.82 to
5.24 % for 60 days, 8.76 to 8.40 % for 90 days and 10.23 to 9.20 %
for 120 days respectively.
Tables 4.7.1.1 and 4.7.1.3 gives the percentage weight loss of
MKC mixes of M20 and M50 grade after immersing in 5 % HCL
solution. These values vary from 2.37 to 0.89 % for 30 days , 2.66 to
2.08 % for 60 days, 3.90 to 3.58 % for 90 days and 5.16 to 4.22 % for
120 days respectively.
Tables 4.7.1.1 and 4.7.1.3 gives the percentage weight loss of
SFRC (1.5-60) mix of M20 and M50 grade after immersing in 5 % HCL
solution. These values vary from 1.93 to 0.96 % for 30 days , 2.64 to
1.48 % for 60 days, 3.37 to 2.14 % for 90 days and 3.98 to 2.62 % for
120 days respectively.
Tables 4.7.1.1 and 4.7.1.3 gives the percentage weight loss of
SFRC (1.5-80) mix of M20 and M50 grade after immersing in 5 % HCL
solution. The values vary from 1.69 to 0.80 % for 30 days, 2.22 to
1.20 % for 60 days, 2.78 to 1.76 % for 90 days and 3.48 to 1.88% for
120 days respectively.
Tables 4.7.1.1 and 4.7.1.3 gives the percentage weight loss of
SFRC-MK (1.5-60) mix of M20 and M50 grade after immersing in 5 %
HCL solution. The values vary from 1.58 to 0.76 % for 30 days, 2.08
to 1.02 % for 60 days, 2.40 to 1.36 % for 90 days and 2.95 to 1.94 %
for 120 days respectively.
337
Tables 4.7.1.1 and 4.7.1.3 gives the percentage weight loss of
SFRC-MK (1.5-80) mix of M20 and M50 grade after immersing in 5 %
HCL solution. The values vary from 1.26 to 0.52 % for 30 days, 1.59
to 0.78 % for 60 days, 1.83 to 1.12 % for 90 days and 2.08 to 1.38 %
for 120 days respectively.
The percentage weight loss of M20 and M50 grades of OPCC,
MKC, SFRC and SFRC-MK mixes after immersing in 5% HCL solution
increases corresponding to the time of exposure. The percentage
weight loss of all mixes of M50 grade is less when compared to the
mixes of M20 grade. The reason may be due to lower w/c ratio.
5.10.1.2 Loss of weight of specimens after immersing in 5%
H2SO4 Solution
Tables 4.7.1.2 and 4.7.1.4 gives the percentage weight loss of
OPCC mixes of M20 and M50 grade after immersing in 5 % H2SO4
solution. The values vary from 9.22 to 2.96 % for 30 days , 16.32 to
9.32 % for 60 days, 24.86 to 17.74 % for 90 days and 33.2 to 26.38 %
for 120 days respectively.
Tables 4.7.1.2 and 4.7.1.4 gives the percentage weight loss of
MKC mixes of M20 and M50 grade after immersing in 5 % H2SO4
solution. The values vary from 5.36 to 1.62 % for 30 days , 11.58 to
3.69 % for 60 days, 16.43 to 6.37 % for 90 days and 23.69 to 9.88 %
for 120 days respectively.
Tables 4.7.1.2 and 4.7.1.4 gives the percentage weight loss of
SFRC (1.5-60) mix of M20 and M50 grade after immersing in 5 %
H2SO4 solution. The values vary from 5.67 to 2.14 % for 30 days,
338
11.78 to 6.92 % for 60 days, 17.14 to 11.24 % for 90 days and 21.22
to 14.54 % for 120 days respectively.
Tables 4.7.1.2 and 4.7.1.4 gives the percentage weight loss of
SFRC (1.5-80) mix of M20 and M50 grade after immersing in 5%
H2SO4 solution. The values vary from 4.86 to 1.38 % for 30 days,
10.52 to 6.26 % for 60 days, 15.26 to 10.18 % for 90 days and 19.82
to 13.76% for 120 days respectively.
Tables 4.7.1.2 and 4.7.1.4 gives the percentage weight loss of
SFRC-MK (1.5-60) mix of M20 and M50 grade after immersing in 5%
H2SO4 solution. The values vary from 4.22 to 1.52 % for 30 days, 9.56
to 4.86 % for 60 days, 12.16 to 5.36 % for 90 days and 14.06 to 7.02%
for 120 days respectively.
Tables 4.7.1.2 and 4.7.1.4 gives the percentage weight loss of
SFRC-MK (1.5-80) mix of M20 and M50 grade after immersing in 5%
H2SO4 solution. The values vary from 3.20 to 0.93 % for 30 days, 7.04
to 3.60 % for 60 days, 9.48 to 4.32 % for 90 days and 11.34 to 5.90 %
for 120 days respectively.
The percentage weight loss of M20 and M50 grades of OPCC,
MKC, SFRC & SFRC-MK mixes after immersing in 5% H2SO4 solution
increases corresponding to the time of exposure.
The loss in weight in MKC, SFRC & SFRC-MK is decreasing due to the
replacement of cement with 10% Metakaolin, addition of steel fibres of
1.5% of single aspect ratio 60 or 80 with and without Metakaolin.
339
This is due to the reduced permeability of MK concrete, better pore
refinement due to MK and due to the addition of crimped steel fibres
to OPC and MK concretes.
The loss in weight due to acid attack is increasing with age of
exposure in 5% HCL and 5% H2SO4.
The loss in weight in 5% H2SO4 is higher than in 5% HCL.
5.10.2 Studies on loss of compressive strength of OPCC, MKC,
SFRC & SFRC-MK mixes of M20 and M50 grade in different
solutions
5.10.2.1. Loss of compressive strength of specimens after
immersing in 5% HCL solution
Tables 4.7.2.1 and 4.7.2.3 gives the percentage loss of
compressive strength of OPCC mixes of M20 and M50 grade after
immersing in 5 % HCL solution. The values vary from 9.46 to 5.73 %
for 30 days , 16.28 to 9.62 % for 60 days, 20.94 to 14.26 % for 90
days and 26.96 to 18.53 % for 120 days respectively.
Tables 4.7.2.1 and 4.7.2.3 gives the percentage loss of
compressive strength of MKC mixes of M20 and M50 grade after
immersing in 5 % HCL solution. The values vary from 7.68 to 2.15 %
for 30 days , 13.15 to 2.78 % for 60 days, 17.72 to 6.9 % for 90 days
and 23.61 to 10.57 % for 120 days respectively.
Tables 4.7.2.1 and 4.7.2.3 gives the percentage loss of
compressive strength of SFRC (1.5-60) mix of M20 and M50 grade
after immersing in 5 % HCL solution. The values vary from 7.58 to
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1.79 % for 30 days , 12.58 to 2.64 % for 60 days, 17.25 to 6.66 % for
90 days and 22.47 to 10.03 % for 120 days respectively.
Tables 4.7.2.1 and 4.7.2.3 gives the percentage loss of
compressive strength of SFRC (1.5-80) mix of M20 and M50 grade
after immersing in 5 % HCL solution. The values vary from 6.95 to
1.07 % for 30 days , 12.04 to 1.94 % for 60 days, 16.3 to 5.84 % for
90 days and 22.05 to 9.19% for 120 days respectively.
Tables 4.7.2.1 and 4.7.2.3 gives the percentage loss of
compressive strength of SFRC-MK (1.5-60) mix of M20 and M50 grade
after immersing in 5 % HCL solution. The values vary from 6.45 to
0.83 % for 30 days , 11.22 to 1.32 % for 60 days, 13.84 to 4.30 % for
90 days and 19.16 to 6.33 % for 120 days respectively.
Tables 4.7.2.1 and 4.7.2.3 gives the percentage loss of
compressive strength of SFRC-MK (1.5-80) mix of M20 and M50 grade
after immersing in 5 % HCL solution. The values vary from 5.89 to
0.36 % for 30 days , 10.68 to 0.76 % for 60 days, 13.21 to 3.56 % for
90 days and 17.52 to 5.59 % for 120 days respectively.
The percentage loss of compressive strength of OPCC, MKC,
SFRC & SFRC-MK mixes of M20 and M50 grades after immersing in 5
% HCL solution increases corresponding to the time of exposure.
5.10.2.2. Loss of compressive strength of specimens after
immersing in 5% H2SO4 solution
Tables 4.7.2.2 and 4.7.2.4 gives the percentage loss of
compressive strength of OPCC mixes of M20 and M50 grade after
immersing in 5 % H2SO4 solution. The values vary from 34.84 to
341
17.87 % for 30 days, 38.20 to 20.43 % for 60 days, 40.68 to 22.28 %
for 90 days and 42.72 to 24.16 % for 120 days respectively.
Tables 4.7.2.2 and 4.7.2.4 gives the percentage loss of
compressive strength of MKC mixes of M20 and M50 grade after
immersing in 5 % H2SO4 solution. The values vary from 30.76 to 9.69
% for 30 days, 33.92 to 11.97 % for 60 days, 36.14 to 12.66 % for 90
days and 38.06 to 17.30 % for 120 days respectively.
Tables 4.7.2.2 and 4.7.2.4 gives the percentage loss of
compressive strength of SFRC (AR-60) mix of M20 and M50 grade
after immersing in 5 % H2SO4 solution. The values vary from 32.39 to
10.13% for 30 days, 36.05 to 13.05 % for 60 days, 39.56 to 14.68 %
for 90 days and 41.98 to 17.72 % for 120 days respectively.
Tables 4.7.2.2 and 4.7.2.4 gives the percentage loss of
compressive strength of SFRC (1.5-80) mix of M20 and M50 grade
after immersing in 5 % H2SO4 solution. The values vary from 30.78 to
8.20 % for 30 days, 35.10 to 10.87 % for 60 days, 37.82 to 12.98 %
for 90 days and 41.0 to 15.06% for 120 days respectively.
Tables 4.7.2.2 and 4.7.2.4 gives the percentage loss of
compressive strength of SFRC-MK (1.5-60) mix of M20 and M50 grade
after immersing in 5 % H2SO4 solution. The values vary from 26.23 to
4.82 % for 30 days, 27.78 to 5.49 % for 60 days, 30.54 to 7.20 % for
90 days and 32.78 to 9.38 % for 120 days respectively.
Tables 4.7.2.2 and 4.7.2.4 gives the percentage loss of
compressive strength of SFRC-MK (1.5-80) mix of M20 and M50 grade
after immersing in 5% H2SO4 solution. The values vary from 24.86 to
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3.39 % for 30 days, 25.45 to 4.23 % for 60 days, 29.26 to 5.34 % for
90 days and 31.06 to 6.72 % for 120 days respectifvely.
The percentage loss of compressive strength of OPCC, MKC,
SFRC & SFRC-MK mixes of M20 and M50 grades after immersing in
5% H2SO4 solution increases corresponding to the time of exposure.
The loss in compressive strength in MKC, SFRC & SFRC-MK
mixes is decreasing due to the replacement of cement with 10%
Metakaolin, addition of steel fibres of 1.5% of single aspect ratio 60 or
80 with and without mineral admixtures. Also due to the reduced
permeability and better pore refinement of MK.
The strength loss in 5% H2SO4 is higher than in 5% HCL.
The strength loss is increasing with age of exposure from 30 to 120
days in 5% HCL and 5% H2SO4.
Sulphuric acid involves the dissolution and leaching of dissolved
constituents of hardened cement from the concrete leading to loss in
its compressive strength. Deterioration of concrete may involve the
removal of material from the surface by a dissolution mechanism
which leads to deterioration of concrete. But the partial replacement
of cement with Metakaolin and addition of crimped steel fibres has
increased the resistance of OPC Concrete to acid attack.
5.10.3 The resistance to loss of compressive strength of MKC,
SFRC & SFRC-MK mixes of M20 and M50 grade in comparison
with OPCC mixes when immersed in different solutions
As seen in comparison, the durability of OPCC is increased due
to the presence of Metakaolin and steel fibres.
343
5.10.3.1 The resistance to loss of compressive strength of MKC,
SFRC & SFRC-MK mixes of M20 and M50 grade in comparison
with OPCC mixes when immersed in HCL solution
Table 4.7.2.5 gives the percentage increase in resistance to the
loss of compressive strength of MKC mixes of M20 and M50 grade
after immersing in 5 % HCL solution in comparison with OPCC mixes.
These values vary from 1.78 to 3.58 % for 30 days, 3.13 to 6.84% for
60 days, 3.22 to 7.36% for 90 days and 2.68 to 7.98% for 120 days
respectively.
Table 4.7.2.5 gives the percentage increase in resistance to the
loss of compressive strength of SFRC (1.5-60) mix of M20 and M50
grade after immersing in 5 % HCL solution in comparison with OPCC
mixes. These values vary from 1.88 to 3.94 % for 30 days, 3.70 to 6.98
% for 60 days, 3.69 to 7.60% for 90 days and 3.67 to 8.50 % for 120
days respectively.
Table 4.7.2.5 gives the percentage increase in resistance to the
loss of compressive strength of SFRC (1.5-80) mix of M20 and M50
grade after immersing in 5 % HCL solution in comparison with OPCC
mixes. These values vary from 2.51 to 4.66 % for 30 days, 4.24 to 7.68
% for 60 days, 4.65 to 8.42% for 90 days and 4.16 to 9.34 % for 120
days respectively.
Table 4.7.2.5 gives the percentage increase in resistance to the
loss of compressive strength of SFRC-MK (1.5-60) mix of M20 and
M50 grade after immersing in 5 % HCL solution in comparison with
OPCC mixes. These values vary from 3.01 to 4.90 % for 30 days, 5.06
344
to 8.30 % for 60 days, 7.10 to 9.96 % for 90 days and 6.80 to 12.20 %
for 120 days respectively.
Table 4.7.2.5 gives the percentage increase in resistance to the
loss of compressive strength of SFRC-MK (AR-80) mix of M20 and M50
grade after immersing in 5 % HCL solution in comparison with OPCC
mixes. These values vary from 3.57 to 5.38 % for 30 days, 5.60 to 8.86
% for 60 days, 7.73 to 10.70 % for 90 days and 9.44 to 13.01 % for
120 days respectively.
5.10.3.2 The resistance to loss of compressive strength of MKC,
SFRC & SFRC-MK mixes of M20 and M50 grade in comparison
with OPCC mixes when immersed in H2SO4 solution
Table 4.7.2.5 gives the percentage increase in resistance to the
loss of compressive strength of MKC mixes of M20 and M50 grade
after immersing in 5 % H2SO4 solution in comparison with OPCC
mixes. These values vary from 4.08 to 8.18 % for 30 days, 4.28 to 8.46
% for 60 days, 4.54 to 9.62 % for 90 days and 4.66 to 6.86 % for 120
days respectively.
Table 4.7.2.5 gives the percentage increase in resistance to the
loss of compressive strength of SFRC (1.5-60) mix of M20 and M50
grade after immersing in 5 % H2SO4 solution in comparison with
OPCC mixes. These values vary from 2.45 to 7.74 % for 30 days, 2.15
to 7.38 % for 60 days, 1.12 to 7.60 % for 90 days and 0.74 to 6.44 %
for 120 days respectively.
Table 4.7.2.5 gives the percentage increase in resistance to the
loss of compressive strength of SFRC (1.5-80) mix of M20 and M50
345
grade after immersing in 5 % H2SO4 solution in comparison with
OPCC mixes. These values vary from 4.06 to 9.67 % for 30 days, 3.10
to 9.56 % for 60 days, 2.86 to 9.30% for 90 days and 1.72 to 9.10 %
for 120 days respectively.
Table 4.7.2.5 gives the percentage increase in resistance to the
loss of compressive strength of SFRC-MK (AR-60) mix of M20 and M50
grade after immersing in 5% H2SO4 solution in comparison with OPCC
mixes. These values vary from 8.61 to 13.05 % for 30 days, 10.42 to
14.94 % for 60 days, 10.14 to 15.08 % for 90 days and 9.94 to 14.78
% for 120 days respectively.
Table 4.7.2.5 gives the percentage increase in resistance to the
loss of compressive strength of SFRC-MK (AR-80) mix of M20 and M50
grade after immersing in 5 % H2SO4 solution in comparison with
OPCC mixes. These values vary from 9.98 to 14.48 % for 30 days,
12.75 to 16.20 % for 60 days, 11.42 to 16.94 % for 90 days and 11.66
to 17.44 % for 120 days respectively.
5.10.4 Studies on durability factors of OPCC, MKC, SFRC & SFRC-
MK mixes of M20 and M50 grade when exposed to different
solutions
5.10.4.1. Durability factors of specimens after immersing in 5 %
HCL solution
Table 4.7.5 gives the durability factors of OPCC mixes of M20
and M50 grades after immersing in 5 % HCL solution. These values
vary from 22.63 to 23.57 for 30 days, 41.85 to 45.18 for 60 days,
346
59.28 to 64.3 for 90 days and 73.08 to 81.46 for 120 days
respectively.
Table 4.7.5 gives the durability factors of MKC mixes of M20
and M50 grades after immersing in 5 % HCL solution. These values
vary from 23.08 to 24.46 for 30 days, 43.42 to 48.60 for 60 days,
61.72 to 69.82 for 90 days and 76.38 to 89.43 for 120 days
respectively.
Table 4.7.5 gives the durability factors of SFRC (1.5-60) mix of
M20 and M50 grades after immersing in 5 % HCL solution. These
values vary from 23.10 to 24.55 for 30 days, 43.71 to 48.67 for 60
days, 62.05 to 70.0 for 90 days and 77.51 to 89.97 for 120 days
respectively.
Table 4.7.5 gives the durability factors of SFRC (1.5-80) mix of
M20 and M50 grades after immersing in 5 % HCL solution. These
values vary from 23.26 to 24.73 for 30 days, 43.97 to 49.02 for 60
days, 62.76 to 70.61 for 90 days and 77.95 to 90.80 for 120 days
respectively.
Table 4.7.5 gives the durability factors of SFRC-MK (1.5-60) mix
of M20 and M50 grades after immersing in 5 % HCL solution. These
values vary from 23.38 to 24.79 for 30 days, 44.38 to 49.33 for 60
days, 64.62 to 71.78 for 90 days and 80.85 to 93.67 for 120 days
respectively.
Table 4.7.5 gives the durability factors of SFRC-MK (1.5-80) mix
of M20 and M50 grades after immersing in 5 % HCL solution. These
values vary from 23.52 to 24.90 for 30 days, 44.66 to 49.57 for 60
347
days, 65.09 to 72.31 for 90 days and 82.46 to 94.47 for 120 days
respectively.
5.10.4.2. Durability factors of specimens after immersing in 5 %
H2SO4 solution
Table 4.7.5 gives the durability factors of OPCC mixes of M20
and M50 grades after immersing in 5 % H2SO4 solution. These values
vary from 16.28 to 20.53 for 30 days, 30.88 to 39.80 for 60 days,
44.50 to 58.29 for 90 days and 57.21 to 75.83 for 120 days
respectively.
Table 4.7.5 gives the durability factors of MKC mixes of M20
and M50 grades after immersing in 5 % H2SO4 solution. These values
vary from 17.30 to 22.57 for 30 days, 33.03 to 44.0 for 60 days, 47.88
to 65.42 for 90 days and 61.93 to 82.58 for 120 days respectively.
Table 4.7.5 gives the durability factors of SFRC (1.5-60) mix of
M20 and M50 grades after immersing in 5 % H2SO4 solution. These
values vary from 16.90 to 22.46 for 30 days, 31.98 to 43.47 for 60
days, 45.32 to 63.99 for 90 days and 58.02 to 82.27 for 120 days
respectively.
Table 4.7.5 gives the durability factors of SFRC (1.5-80) mix of
M20 and M50 grades after immersing in 5 % H2SO4 solution. These
values vary from 17.30 to 22.95 for 30 days, 32.44 to 44.56 for 60
days, 46.62 to 65.25 for 90 days and 59.0 to 84.94 for 120 days
respectively.
Table 4.7.5 gives the durability factors of SFRC-MK (1.5-60) mix
of M20 and M50 grades after immersing in 5 % H2SO4 solution. These
348
values vary from 18.44 to 23.79 for 30 days, 36.11 to 47.25 for 60
days, 52.08 to 69.59 for 90 days and 67.21 to 90.62 for 120 days
respectively.
Table 4.7.5 gives the durability factors of SFRC-MK (1.5-80) mix
of M20 and M50 grades after immersing in 5 % H2SO4 solution. These
values vary from 18.78 to 24.15 for 30 days, 37.27 to 47.88 for 60
days, 53.04 to 70.99 for 90 days and 68.93 to 93.27 for 120 days
respectively.
From the durability tests such as loss in compressive strength,
loss in weight and acid durability factors, it is concluded that
MK concrete is showing more resistance to 5% HCL and 5% H2SO4.
MK concrete containing fibres of aspect ratio 80 is showing more
resistance to acid attack than with fibres of aspect ratio 60.
Due to use of pozzolans like Metakaolin and steel fibres, the loss
in compressive strength and loss in weight are decreasing due to the
Reduction in permeability of MK concrete,
Better pore refinement caused by MK and
Due to the addition of crimped steel fibres.
5.10.5 Percentage increase in durability factors of MKC, SFRC &
SFRC-MK mixes of M20 & M50 grade in comparison with OPCC
mixes.
5.10.5.1 Percentage increase in durability factors of MKC, SFRC
& SFRC-MK mixes in comparison with OPCC mixes after
immersing in 5 % HCL solution.
349
The percentage increase in the durability factors of MKC mixes
after immersing in 5% HCL solution and in comparison with OPCC
mixes vary from 0.45 to 0.89% for 30days, 1.57 to 3.42% for 60days,
2.43 to 5.52% for 90 days and 3.30 to 7.97% for 120 days
respectively.
The percentage increase in the durability factors of SFRC (1.5-
60) mixes after immersing in 5% HCL solution and in comparison with
OPCC mixes vary from 0.47 to 0.99% for 30days, 1.86 to 3.49% for
60days, 2.77 to 5.70% for 90 days and 4.43 to 8.51% for 120 days
respectively.
The percentage increase in the durability factors of SFRC (1.5-
80) mixes after immersing in 5% HCL solution and in comparison with
OPCC mixes vary from 0.63 to 1.16% for 30days, 2.12 to 3.84% for
60days, 3.48 to 6.31% for 90 days and 4.87 to 9.34% for 120 days
respectively.
The percentage increase in the durability factors of SFRC-MK
(1.5-60) mixes after immersing in 5% HCL solution and in comparison
with OPCC mixes vary from 0.75 to 1.22% for 30days, 2.53 to 4.15%
for 60days, 5.34 to 7.48% for 90 days and 7.77 to 12.21% for 120
days respectively.
The percentage increase in the durability factors of SFRC-MK
(1.5-80) mixes after immersing in 5% HCL solution and in comparison
with OPCC mixes vary from 0.89 to 1.33% for 30days, 2.81 to 4.39%
for 60days, 5.80 to 8.01% for 90 days and 9.38 to 13.0% for 120 days
respectively.
350
5.10.5.2 Percentage increase in durability factors of MKC, SFRC
& SFRC-MK mixes in comparison with OPCC mixes after
immersing in 5 % H2SO4 solution.
The percentage increase in the durability factors of MKC mixes
after immersing in 5% H2SO4 solution and in comparison with OPCC
mixes vary from 1.02 to 2.05% for 30days, 2.15 to 4.21% for 60days,
3.38 to 7.13% for 90 days and 4.72 to 6.75% for 120 days
respectively.
The percentage increase in the durability factors of SFRC (1.5-
60) mixes after immersing in 5% H2SO4 solution and in comparison
with OPCC mixes vary from 0.62 to 1.93% for 30 days, 1.10 to 3.67%
for 60days, 0.82 to 5.70% for 90 days and 0.81 to 6.44% for 120 days
respectively.
The percentage increase in the durability factors of SFRC (1.5-
80) mixes after immersing in 5% H2SO4 solution and in comparison
with OPCC mixes vary from 1.02 to 2.42% for 30 days, 1.56 to 4.76%
for 60days, 2.12 to 6.96% for 90 days and 1.79 to 9.11% for 120 days
respectively.
The percentage increase in the durability factors of SFRC-MK
(1.5-60) mixes after immersing in 5% H2SO4 solution and in
comparison with OPCC mixes vary from 2.16 to 3.26% for 30days,
5.23 to 7.45% for 60days, 7.58 to 11.3% for 90 days and 10.02 to
14.79% for 120 days respectively.
The percentage increase in the durability factors of SFRC-MK
(1.5-80) mixes after immersing in 5% H2SO4 solution and in
351
comparison with OPCC mixes vary from 2.50 to 3.62% for 30days,
6.39 to 8.08% for 60days, 8.54 to 12.70% for 90 days and 11.72 to
17.44% for 120 days respectively.
5.11 FLEXURAL BEHAVIOUR OF REINFORCED OPCC,
MKC, SFRC & SFRC-MK BEAMS OF M20 AND M50
GRADE
5.11.1. Beam designations of reinforced OPCC, MKC, SFRC &
SFRC-MK beams of M20 and M50 grade.
Tables 4.8.1 to 4.8.8 gives the central deflections of M20 and
M50 grades of reinforced OPCC, MKC, SFRC & SFRC-MK beams over
the full depth. The beam designations 1 to 4 are of M20 grade
reinforced concrete beams with 0%, 0.5%, 1.0% and 1.50% of crimped
steel fibres of aspect ratio as 60. The designations 5 to 8 are of M20
grade reinforced concrete beams with 0%, 0.5%, 1.0% and 1.50% of
crimped steel fibres of aspect ratio as 80. The designations 9 to 12 are
of M50 grade reinforced concrete beams with 0%, 0.5%, 1.0% and
1.50% of crimped steel fibres of aspect ratio as 60. The designations
13 to 16 are of M50 grade reinforced concrete beams with 0%, 0.5%,
1.0% and 1.50% of crimped steel fibres of aspect ratio as 80. The
designations 17 to 20 are of M20 grade reinforced Metakaolin concrete
beams with 0%, 0.5%, 1.0% and 1.50% of crimped steel fibres of
aspect ratio as 60. The designations 21 to 24 are of M20 grade
reinforced Metakaolin concrete beams with 0%, 0.5%, 1.0% and
1.50% of crimped steel fibres of aspect ratio as 80. The designations
352
25 to 28 are of M50 grade reinforced Metakaolin concrete beams with
0%, 0.5%, 1.0% and 1.50% of crimped steel fibres of aspect ratio as
60. The designations 29 to 32 are of M50 grade reinforced Metakaolin
concrete beams with 0%, 0.5%, 1.0% and 1.50% of crimped steel
fibres of aspect ratio as 80.
5.11.2. Flexural strength of reinforced OPCC, MKC beams of M20
and M50 grade
The beam 1(M20, 0% fibre) failed at a load of 66.50 KN and the
first crack observed to be at 38.50 KN. The beam 5(M20, 0% fibre)
failed at a load of 66.50 KN and the first crack observed to be at 38.50
KN. The beam 9(M50, 0% fibre) failed at a load of 78.50 KN and the
first crack observed to be at 53.50 KN. The beam 13(M50, 0% fibre)
failed at a load of 78.50 KN and the first crack to be observed at 53.50
KN. The beam 17(M20, 10% Metakaolin, 0% fibre) failed at a load of
57.50 KN and the first crack observed to be at 31.50 KN. The beam
21(M20, 10% Metakaolin, 0% fibre) failed at a load of 57.50 KN and
the first crack to be observed at 31.50 KN. The beam 25(M50, 10%
Metakaolin, 0% fibre) failed at a load of 65.00 KN and the first crack
to be observed at 33.50 KN. The beam 29(M50, 10% Metakaolin, 0%
fibre) failed at a load of 65.00 KN and the first crack to be observed at
33.50 KN.
5.11.3 Flexural strength of reinforced SFRC, SFRC-MK beams of
M20 and M50 grade
The beam 2(M20, 0.5% fibre) failed at a load of 76.50 KN and
the first crack observed to be at 45.50 KN. The beam 6(M20, 0.5%
353
fibre) failed at a load of 78.50 KN and the first crack observed to be at
48.00 KN. The beam 10(M50, 0.5% fibre) failed at a load of 90.00 KN
and the first crack observed to be at 62.00 KN. The beam 14(M50,
0.5% fibre) failed at a load of 96.50 KN and the first crack to be
observed at 53.50 KN. The beam 18(M20, 10% Metakaolin, 0.5% fibre)
failed at a load of 82.50 KN and the first crack observed to be at 48.50
KN. The beam 22(M20, 10% Metakaolin, 0.5% fibre) failed at a load of
86.00 KN and the first crack to be observed at 50.50 KN. The beam
26(M50, 10% Metakaolin, 0.5% fibre) failed at a load of 99.50 KN and
the first crack to be observed at 65.00 KN. The beam 30(M50, 10%
Metakaolin, 0.5% fibre) failed at a load of 108.00 KN and the first
crack to be observed at 72.50 KN.
The beam 3(M20, 1.0% fibre) failed at a load of 90.50 KN and
the first crack observed to be at 54.50 KN. The beam 7(M20, 1.0%
fibre) failed at a load of 96.00 KN and the first crack observed to be at
56.50 KN. The beam 11(M50, 1.0% fibre) failed at a load of 103.50 KN
and the first crack observed to be at 71.50 KN. The beam 15(M50,
1.0% fibre) failed at a load of 112.00 KN and the first crack to be
observed at 76.00 KN. The beam 19(M20, 10% Metakaolin, 1.0% fibre)
failed at a load of 100.50 KN and the first crack observed to be at
59.00 KN. The beam 23(M20, 10% Metakaolin, 1.0% fibre) failed at a
load of 110.00 KN and the first crack to be observed at 65.00 KN. The
beam 27(M50, 10% Metakaolin, 1.0% fibre) failed at a load of 118.50
KN and the first crack to be observed at 80.50 KN. The beam 31(M50,
354
10% Metakaolin, 1.0% fibre) failed at a load of 129.00 KN and the first
crack to be observed at 89.00 KN.
The beam 4(M20, 1.5% fibre) failed at a load of 101.50 KN and
the first crack observed to be at 61.50 KN. The beam 8(M20, 1.5%
fibre) failed at a load of 106.00 KN and the first crack observed to be
at 64.50 KN. The beam 12(M50, 1.5% fibre) failed at a load of 115.00
KN and the first crack observed to be at 82.00 KN. The beam 16(M50,
1.5% fibre) failed at a load of 122.50 KN and the first crack to be
observed at 89.00 KN. The beam 20(M20, 10% Metakaolin, 1.5% fibre)
failed at a load of 114.00 KN and the first crack observed to be at
70.50 KN. The beam 24(M20, 10% Metakaolin, 1.5% fibre) failed at a
load of 122.50 KN and the first crack to be observed at 76.00 KN. The
beam 28(M50, 10% Metakaolin, 1.5% fibre) failed at a load of 133.00
KN and the first crack to be observed at 97.50 KN. The beam 32(M50,
10% Metakaolin, 1.5% fibre) failed at a load of 144.00 KN and the first
crack to be observed at 99.00 KN.
The ultimate Flexural load of the beams with 1.50% of fibres
and 10% replacement of cement by Metakaolin is more than that of
the beams without fibres. The ultimate flexural load of MK beams is
less than the OPC Concrete beams. The ultimate flexural load of steel
fibre reinforced Metakaolin beams is more than that of other beams
due to the better anchorage between the fibres and the matrix. From
the above we can observe that the ultimate flexural strength is
observed in a beam having 1.50 % crimped steel fibres.
355
5.11.4 Load Deflection characteristics of reinforced OPCC, MKC,
SFRC & SFRC-MK beams of M20 and M50 grade
Tables 4.8.1 to 4.8.8 gives experimental investigation of the
load deflection behaviour and failure characteristics of 1200 x 150 x
100 mm reinforced OPCC, MKC, SFRC & SFRC-MK beams of M20 and
M50 grade. The variation of reinforced OPCC, MKC, SFRC & SFRC-MK
beams of M20 and M50 grade are given in fig. 88.0 to 91.0.
Tables 4.8.1 to 4.8.8 give ultimate load and deflections at
maximum load for reinforced OPCC, MKC, SFRC & SFRC-MK beams
of M20 and M50 grade. By observing the behaviour of cracks it can
be seen that the load carrying capacity of steel fibre reinforced
concrete and steel fibre reinforced Metakaolin concrete beams having
1.50 % steel fibres are on higher side when compared with other
beams with 0%, 0.5%, 1.0% steel fibres. This is true almost up to the
failure even though at certain loads identical deflection is observed.
However the failure patterns of the beams are shown in
Photographs, Load vs Deflection curves for the beams over full depth
are shown in the figures.
5.11.5 Variation in load deflection characteristics of MKC, SFRC
& SFRC-MK beams over OPCC reinforced beams
The presence of Metakaolin in the conventional R.C.C beams
has caused appreciable change in the flexural behaviour leading to
higher deflections with reduced load carrying capacity. The load -
deflection characteristics of MKC beams are slightly affected. The
incorporation of 1.50% fibres with higher aspect ratio (80) in
356
reinforced Metakaolin concrete beams is advantageous in respect of
ductility. The ultimate load carrying capacity of SFRC - MK beams are
able to take more deflections with more loads. Due to the presence of
higher percentage of fibres with higher aspect ratio, the formation of
first crack and subsequent cracks has been delayed. Hence in the
present case, it may be concluded that the presence of high
percentage of fibres with higher aspect ratio along with Metakaolin
has helped in imparting ductile behaviour to OPCC and MKC beams
5.12 FLEXURAL BEHAVIOUR OF REINFORCED OPCC,
MKC, SFRC & SFRC-MK SLABS OF M20 AND M50
GRADE
5.12.1 Slab designations of reinforced OPCC, MKC, SFRC & SFRC-
MK slabs of M20 and M50 grade
Tables 4.10.1 and 4.10.2 gives the central deflections of M20
and M50 grade of reinforced OPCC, MKC, SFRC & SFRC-MK slabs.
The slab designation represents that the slabs Z1 to Z4 of reinforced
SFRC slabs of M20 grade with 0, 0.5, 1.0, and 1.5 % of crimped steel
fibres of aspect ratio 80. The slabs Z5 to Z8 represent slabs of M50
grade with 0, 0.5, 1.0, and 1.5 % of crimped steel fibres of aspect ratio
80. The slabs Z9 to Z12 represent slabs of M20 grade steel fibre
reinforced Metakaolin concrete (SFRC-MK) with 0, 0.5, 1.0, 1.5 % of
crimped steel fibres of aspect ratio 80. The slabs Z13 to Z16 represent
slabs of M50 grade steel fibre reinforced Metakaolin concrete (SFRC-
MK) with 0, 0.5, 1.0, 1.5 % of crimped steel fibres of aspect ratio 80.
357
5.12.2 Flexural strength of reinforced OPCC and MKC slabs of
M20 and M50 grade
The slab 1(M20 + 0% fibre) failed at a load of 195 KN and the
first crack observed to be at 122.5 KN. The slab 5(M50 + 0% fibre)
failed at a load of 315 KN and the first crack observed to be at 219
KN. The slab 9(M20 + 10% MK + 0% fibre) failed at a load of 167 KN
and the first crack observed to be at 97 KN. The slab 17(M50 +10%
MK + 0% fibre) failed at a load of 264 KN and the first crack observed
to be at 143 KN.
5.12.3 Flexural strength of SFRC & SFRC-MK slabs of M20 and
M50 grade
5.12.3.1 Flexural strength of SFRC & SFRC-MK slabs of M20
grade
The slab 2(M20 + 0.5% fibre) failed at a load of 211 kN and the
first crack to be observed at 139 kN. The slab 3(M20 + 1.0% fibre)
failed at a load of 231 kN and the first crack observed to be at 152 kN.
The slab 4(M20 + 1.5% fibre) failed at a load of 249 kN and the first
crack observed to be at 166 kN.
The slab 10(M20 + 10% MK + 0.5% fibre) failed at a load of 225
kN and the first crack to be observed at 151 kN. The slab 11(M20 +
10% MK + 1.0% fibre) failed at a load of 250 kN and the first crack
observed to be at 169.5 kN. The slab 12(M20 + 10% MK + 1.5% fibre)
failed at a load of 269 kN and the first crack observed to be at 187.5
kN.
358
5.12.3.2 Flexural strength of SFRC & SFRC-MK slabs of M50
grade
The slab 6(M50 + 0.5% fibre) failed at a load of 344 KN and the
first crack to be observed at 237.5 kN. The slab 7(M50 + 1.0% fibre)
failed at a load of 354 kN and the first crack observed to be at 244.5
kN. The slab 8(M50 + 1.5% fibre) failed at a load of 373 kN and the
first crack observed to be at 262.5 kN.
The slab 14(M50+ 10% MK +0.5% fibre) failed at a load of 372
KN and the first crack to be observed at 267 KN. The slab 15(M50 +
10% MK + 1.0% fibre) failed at a load of 387 KN and the first crack
observed to be at 276.5 KN. The slab 16(M50 + 10% MK + 1.5% fibre)
failed at a load of 410 KN and the first crack observed to be at 300.5
kN.
The ultimate flexural load of the slabs with 1.5% of steel fibres
and aspect ratio as 80 is more than that of slabs without steel fibres.
From the above discussions, we can observe that the ultimate flexural
strength is observed in a slab having 1.5 % crimped steel fibres .The
plate 19 and 20 gives the failure pattern of M20 and M50 grade SFRC
and SFRC-MK slabs with 0.0% to 1.5% fibres.
5.12.4 Load deflection characteristics of reinforced SFRC &
SFRC-MK slabs of M20 and M50 grade slabs
Tables 4.9.1 and 4.9.4 gives the experimental investigation for
studying the load deflection behavior of 1400 x 1200 x 100 mm
reinforced SFRC & SFRC-MK reinforced concrete slabs under 1/3 rd
359
point loading. The variation of both reinforced SFRC & SFRC-MK
concrete slabs are given in fig. 93.0 and 94.0.
Table 4.9.5 gives ultimate load and deflections at maximum load
for both reinforced SFRC and SFRC-MK concrete slabs. From the
observations, it can be seen that load carrying capacity of SFRC &
SFRC-MK slabs having 1.5% crimped steel fibres with higher aspect
ratio are on higher side when compared with other slabs having 0%,
0.5 % and 1.0 % crimped steel fibres.
5.12.5 Variation of load deflection characteristics of MKC, SFRC
& SFRC-MK slabs over reinforced OPC concrete slabs
Hence it is clear that the incorporation of high percentage of
steel fibres with higher aspect ratio in Metakaolin concrete has
improved the ductility and load carrying capacity of SFRC and SFRC –
MK slabs over OPCC slabs. The load carrying capacity of SFRC slabs
with 0.50% steel fibres and higher aspect ratio has increased to 17 %
with 1.0% to 27 % and with 1.50% to 36 % over OPCC slabs. The load
carrying capacity of SFRC - MK slabs has increased to 25 % with
0.50% steel fibres, 38 % with 1.0 % fibres and 49 % with 1.50 % fibres
of higher aspect ratio. It can be seen that the presence of 1.50% steel
fibres with higher aspect ratio in OPCC and MKC slabs is
advantageous in respect of ductility. The load carrying capacity of
SFRC - MK slabs of M20 grade increased by 36 % and of M50 grade
increased by 49% when compared to OPCC slabs of M20 and M50
grades. Due to the presence of higher percentage of steel fibres, the
formation of cracks has been delayed considerably. Hence in the
360
present study, it may be concluded that the presence of steel fibres in
OPCC and MKC slabs has helped in imparting more ductility and
better cracking behaviour. This is effective in SFRC - MK slabs due to
the better fibre - matrix bond.
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