study crushing snd flexural strength of fiber reinforced concrete ...

International Journal of Advanced Engineering Technology E-ISSN 0976-3945

IJAET/Vol.II/ Issue I/January-March 2011/299-305

Research Article

STUDY CRUSHING SND FLEXURAL STRENGTH OF

FIBER REINFORCED CONCRETE CONTAINING HIGH

VOLUME FLY ASH Indrajit Patel

1, C D Modhera

2

Address for Correspondence 1Research Scholar, Applied Mech. Department, SVNIT, Surat, Gujarat

2Professor and Supervisor, Applied Mech. Department, SVNIT, Surat, Gujarat

E Mail: [email protected]

ABSTRACT.

Concrete is the most consumed material after water on the earth for infrastructure & construction

industries, a commendable contribution can be made by optimizing the use of cement and natural

resources in concrete manufacturing. High volume Fly Ash concrete is one of the major developments

since last three decades leading to utilization of Fly Ash in a bulk quantity and thereby reducing cement

consumption and ultimately reducing emulsion of CO2 in order of one ton per a ton of Cement. The past

research has been given due consideration for application of HVFA in different sectors like mass

concrete, foundation, transportation etc. But the limitations of HVFA like early slower strength

development, ductility, poor performance towards expansion and contraction, flexural property,

impact and abrasion resistance have made its use limited. Introduction of structural/non structural

fiber with HVFA concrete application can overcome these problems and use of HVFA can be

increased in developing nation like India for sustainability.

KEY WORDS: Fly Ash, Polyester fibre, Compressive Strength, Flexural Strength.

INTRODUCTION

With aim to improve engineering and

durability properties of conventional High

Volume Fly Ash (HVFA) concrete

experimental work has been carried out as

part of PhD study. Though HVFA

concrete has development history of more

than four decades the use has not been

significant and notable due to many reason

including slower early strength

development, resistance to bending,

impact and abrasion for its application on

wide base. The replacement of Portland

cement in context of Indian Standard is of

order 35% by mass of cementing material.

Even the blended cement contains 25% of

fly ash. This will not address the issue of

green concrete and sustainability of

concrete technology to the desired extent.

Inclusion of 50% or more fly ash to

normal concrete forms HVFA concrete for

low to high strength and high performance

concrete with or without adding micro

sized material like silica fume or micro

quartz.

The present work includes mix design for

M25, M30, M35 and M40 grade HVFA

concrete with different percentage of class

F fly ash 50%, 55% and 60%. To improve

the engineering properties viz.

compressive, flexural, impact strength and

abrasion resistance 12mm triangular

shaped polyester fibre is use at rate of

0.25% by the mass of cementitious

material. The test results for compressive

strength at 3,7,28 and 56 days for plain

HVFA concrete for all grade with and

without meets codal requirement. The use

of polyester fibres has increased the

compressive strength to order of 12 to 15

%. Flexural strength using center point

loading also meets the required parameters

and fibre reinforced HVFA shows 16 to

23% increase compared to plain HVFA

concrete at 28 and 56 days. There is

notable increase in ductility of HVFA

concrete which is the need of days for

design & construction of earthquake

resistant structures.

MATERIALS

Cement & Fly Ash: 53 grade Ordinary

Portland cement conforming to BIS

12269-1999 was used. Class F fly ash

from Wanakbori Thermal Power station,



Gujarat conforming to BIS 3812-2003 was

used in the present study. Test results are

shown in Table [1] & Scanning Electron

Microscopic view for fly ash is shown fig.

[1]

Admixtures: High range water reducing

admixtures for fibre reinforced HVFA

samples Poly carboxylate based super

plasticizer was used.

Aggregates: Crushed stones of 20mm

down and 10mm down were used as

coarse aggregate. Local river sand was

used as fine aggregate in the concrete

mixtures. Samples ere tested as per BIS-

2386 and results were confirmed with IS-

383

Fiber: 12mm size triangular-Trilobal

shaped polyester fibre confirming to type

III fibres under ASTM C: 1116 were used

as a supplementary reinforcing material to

enhance the mechanical properties of

hardened concrete. The test results and

microscopic view is presented in Table [2]

& fig. [2] respectively.

TABLE 1: CHMICAL AND PHYSICAL PROPERTIES OF FLY ASH

Sr.

No Properties

Result

obtained

in %

Requirement as IS 3812-Part-1-

2003

Siliceous

Pulverize

Fuel Ash

Calcareous

Pulverized

Fuel Ash

1 Silicon dioxide (Sio2) plus aluminium oxide

( Al2O3), plus Iron Oxide ( Fe2O3), Percent by

mass min.

95 70 50

2 Silicon dioxide ( SiO2), Percent by mass, min 62 35 25

3 *Reactive silica in percent by mass, min -- 20 20

4 Magnesium oxide ( MgO), percent by mass, max 0.50 5.0 5.0

5 Total Sulphur as sulphur trioxide (SO3). Percent

by mass, max 0.30 3.0 3.0

6 Available alkalis as sodium oxide (Na2O) in

percent by mass, Max 0.90 1.5 1.5

7 Total chlorides in percent by mass Max 00.035 0.05 0.05

8 Loss on ignition, in percent by mass ,Max 1.20 5.0 5.0

9 Calcium Oxide 22.15 -- --

10 Moisture content 01.30 -- --

Sr. No. Properties Test Results

1 Fineness - Specific Surface in m2/kg 395

2 Lime Reactivity, N/mm2 2.50

3 Compressive Strength, N/mm2 79.00

4 Drying Shrinkage 0.21

5 Soundness, 0.33

Figure 1 : SEM VIEW OF FLY ASH



TABLE 2: POLYESTER FIBRE

Figure 2: SEM VIEW OF POLYSTER FIBRE

EXPERIMENTAL SET UP

Final design mix was prepared for all the

designated mix as shown table [3]. Latter in

second stage with the same proportion 0.25%

of polyester fibre was added. For each

batching of the sample and design mix the

slump values were measured after 60 min

retention period using standard slump cone

and results were confirmed as per BIS: 456-

2000. For compression strength standard

150mm cube were casted to measure strength

at 3, 7, 28 and 56 days. Sample were casted

and tested as per BIS 516 Comparative study

was made for strength development for

different dose of flyash as well as with

inclusion of 12mm triangular shaped polyester

fibre content i.e. 0.25 . Flexural strength was

measured at the age of 14, 28 and 56 days for

all samples using central point load over span

of 400mm, for specimen size

100x100x500mm and span 400mm. Test

procedure was carried out as per BIS-516.On

the basis of test results obtained from the trial

mixes, final concrete mixes were cast with

minimum cement content fulfilling the

strength requirements.

Particular Test Result/Observation

Application Concrete

Indian Roads Congress Accredited

Material Polypropylene

Denier (Approximate) 11.7

Shape(Cross-section) Triangular –Trilobal

Cut Length 12.1 mm

Diameter 30-35u

Specific Gravity 0.91

Packing Type Pouch

Dispersion Excellent

Melt Point 160-165 0

Elastic Modulus, psi (ACI) 500-700

pH 7.3 ± 0.5 @ 10%

Colour Colourless & White

Solubility in Water Not Soluble in Water

Water Absorption (% by Wt.) Nil

Alkaline Resistance Conforms to Test Procedure laid by ICBO AC 32

UV Stability Higher UV Resistance



Table 3: HVFA DESIGN MIX

M25 GRADE SAMLE C FA C=FA W SP W/C+

FA

S CA

<20MM

CA

<10M

SLUMP

MM

DENSITY

KG/M3

A10 195 195 390 120 2.40 0.30 642 761 441 90 2394.4

A20 202 248 450 125 3.6 0.28 600 853 379 75 2410.6

A30 180 270 450 140 3.6 0.31 591 839 373 110 2396.6

M30 GRADE SAMPLE C FA C=FA W SP W/C+

FA

S CA

<20MM

CA

<10M

SLUMP

MM

DENSITY

KG/M3

B10 225 225 450 130 3.4 0.29 554 757 432 95 2326.4

B20* 225 275 500 130 4.0 0.26 585 850 351 90 2417.0

B30 200 300 500 145 4.00 0.30 568 825 341 100 2383.0

M35 GRADE

SAMPLE C FA C=FA W SP W/C+

FA

S CA

<20MM

CA

<10M

SLUMP

MM

DENSITY

KG/M3

C10 250 250 500 140.0 4.0 0.28 554 757 432 100 2387.0

C20 247 303 550 138.0 3.8 0.26 526 848 336 95 2370.0

C30 220 330 550 137.5 3.8 0.25 514 826 327 110 2358.3

M40 GRADE SAMPLE C FA C=FA W SP W/C+

FA

S CA

<20MM

CA

<10M

SLUMP

MM

DENSITY

KG/M3

D10 280 280 560 150 4.0 0.27 501 761 415 110 2392.6

D20 270 330 600 160.0 4.0 0.27 486 800 367 95 2437.0

D30 240 360 600 144.0 4.20 0.35 471 839 319 110 2377.2 A: M25, B=M30,C=M35,D=M40 1= 50 2=55 3=60 % flyash 0= no fibre 1=0.25 % fibre

Action of Fly Ash Incorporating Matrix and Chain Mechanism



RESULTS AND DISCUSSION

The batching for all the designed mix and

inclusion of varied flyash as well as polyester

fibres have made as per the standard

procedure. Slump for all the batches were

measured after 60 min. retention period and

comparative study for different mix meets

desired value ranging from 85 mm to 115 mm

as desired for RMC standards. W/C ratio is of

order 0.25% to 0.40% within limits specified

under guide lines of HVFA and BIS. Slump

measurement and comparative study is

presented in Table [4] & Fig [3].Compressive

strength measurement for all the mix with 0.0

and 0.25% fibre dose was measured 3, 7, 28,

56 days as shown in Table [5]. Comparison of

compressive strength according to variation in

fibre content 0.0 and 0.25% at end of 28 days

for all mix is shown graphically in figure [4]

28 days flexural strength comparative study is

shown study in fig. [5]

Table 4: SLUMP MESUREMENT

MIX

Fly Ash 50% 55 % 60%

Fibre 0.00% 0.25% 0.50% 0.00% 0.25% 0.50% 0.00% 0.25% 0.50%

w/c S w/c S w/c S w/c S w/c S w/c S w/c S w/c S w/c S

M25 .30 90 .40 95 .44 110 .28 90 .32 90 .32 95 .31 90 .42 110 .35 115

M30 .29 95 .34 90 .44 115 .28 100 .30 85 .32 90 .30 100 .36 90 .32 105

M35 .28 100 .34 90 .34 95 .26 100 .28 80 .28 85 .25 110 .30 85 .32 100

M40 .27 110 .30 85 .39 100 .26 110 .28 80 .28 85 .35 110 .28 80 .30 95

Fig 3: SLUMP COMPARRISION



Table 5: COMPRESSIVE STRENGTH N/MM2

Mix Days/

Fiber

50% flyash 55% flyash 60%flyash

0.0 0.25 0.0 0.25 0.0 0.25

25

3 15.30 16.05 16.20 17.29 18.56 19.48

7 19.40 20.66 24.81 26.80 29.96 32.13

28 35.33 39.74 37.48 42.35 35.61 39.52

56 40.625 46.100 41.800 46.805 38.99 44.16

30

3 16.65 17.73 19.67 20.75 19.91 21.20

7 23.30 25.16 25.42 27.45 30.28 32.47

28 36.45 43.74 37.72 41.86 39.16 43.27

56 40.64 46.33 42.055 47.735 43.66 49.23

35

3 21.18 22.35 22.94 24.31 24.44 25.87

7 25.37 27.27 28.84 31.09 28.65 31.08

28 40.22 46.25 41.10 44.59 42.90 47.83

56 44.443 50.310 45.825 51.55 47.51 53.45

40

3 21.93 23.24 29.39 31.08 29.39 31.37

7 29.06 32.50 33.65 36.45 31.83 34.61

28 48.23 55.93 49.16 55.30 49.48 55.66

56 53.775 59.425 53.830 60.695 53.20 61.30

Table 6: FLEXURAL STRENGTH IN N/MM2

Mix Days/

Fiber

50% flyash 55% flyash 60%flyash

0.00 0.25 0.0 0.25 0.0 0.25

25

14 3.96 4.93 4.05 4.91 3.92 4.67

28 4.76 6.14 5.21 6.43 4.85 5.77

56 5.84 6.70 6.12 7.05 5.61 6.35

30

14 4.20 5.57 4.33 5.94 4.42 5.22

28 5.63 7.01 6.25 8.01 5.56 6.44

56 6.62 7.77 7.20 8.14 6.40 7.17

35

14 4.53 5.60 4.71 5.87 4.46 5.45

28 6.16 7.43 6.27 7.50 5.86 6.57

56 6.65 8.04 7.90 8.17 6.33 7.30

40

14 4.76 5.88 4.83 6.24 4.72 5.80

28 6.25 7.47 6.63 7.90 6.02 7.01

56 7.10 7.44 8.40 7.05 7.53

Figure 4: 28 DAYS COMPRESSIVE STRENGTH



Figure 5: 28 DAYS FLEXURAL STRENGTH

CONCLUSION

• Inclusion of fibre at the rate of 0.25% by

mass of the cementitious material does not

have much effect on the w/c ratio and 60

min. slump values as well.

• For higher proportion of cementing

material in higher concrete grade the

dosage of plasticizer was increased to

1.00% to achieve desired slump and

workability.

• Increase in compressive strength at 7 days

age for all mix with fibre varies between

7.00 to 9.50%,this will address to slower

strength gaining problem in case of plain

HVFA concrete.

• Increase in 28 days compressive strength

as compared to plain HVFA concrete is of

the order 9.75 to 15 %

• All sample shows required flexural

strength at 14, 28 and 56 days age.

Increase in strength between 14 to 28 days

is of order 22 to 30% and 28 to 56 days is

7.50 to 13.5%.

• 55% cement replacement shows optimum

gain of compressive and flexural strength

for all grade of plain and fibre reinforced

HVFA concrete.

REFERENCES 1. Bouzoubaa,N.,Fournier,B.,Malhotra,V.M.,

and D.M.Golden,”Mechanical Properties

and Durability of Concrete Made with

HVFA Blended Cements Produced in a

Cement Plant”;CANMET Report MTL

2001-23 (J) ,October 2001, Natural

Resources Canada , Ottawa, Canada.

2. Desai, J.P., “Construction and

Performance of High Volume Fly Ash

Concrete Roads in India, ACI SP-221,

V.M.Malhotra, ed, 2004,pp.589-603.

3. Malhotra, V.M., “Making Concrete

Greener with Fly Ash”; Concrete

International, V.21, No.5, May 1999,

pp.61-66.

4. Malhotra, V.M., “CANMET

Investigations Dealing with High-Volume

Fly Ash Concrete”; CANMET

Publication: Advance in Concrete

Technology, MSL 92-6, 1992, pp. 433-

470.

5. Mehta P.K.and V.M.Malhotra, “High

Performance, High Volume Fly Ash

Concrete “, February 2002, pp.15-32,

pp.34-36, pp. 37-42 , pp.43-49, pp.66-69.

6. Mehta, P.K.,”Concrete Technology for

Sustainable Development”, Concrete

International, V.21, No.11, Nov.1999.

7. M.S.Shetty, “Concrete Technology

Theory and Practice “ , Pub. S. Chand ,

2006, Pp.27-296, pp. 421-428.

8. Naik, Tarun et al, “Mechanical Properties

and Durability of Concrete Pavements

Containing High Volumes of Fly Ash;

ACI SP-212, June 2003, V.M.Malhotra

ed., pp.319-340.

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