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INVESTIGATION OF MECHANICAL PROPERTIES OF

NO AGGREGATE CONCRETE INCORPORATING NON-METALLIC FIBERS

by CHETAN VAIJNATH MANE

(140918016)

Under the Guidance ofUnder guidance of

 Dr. GOPINATHA NAYAKAssociate professor, Department of Civil Engineering, MIT, Manipal

&LAXMAN KUDVA

Assistant professor, Department of Civil Engineering, MIT, Manipal

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CONTENT INTRODUCTION LITERATURE REVIEW OBJECTIVE OF PRESENT STUDY METHODOLOGY RESULTS AND DISCUSSIONS REFERENCE

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INTRODUCTION Present scenario:

Scarcity of coarse aggregate and fine aggregate are felt by mega and metro cities in India.184.14 Tonnes of fly ash is generated in India which leads to thousands of acres of land as landfills for fly ash.About 40-50% of fly ash is utilized.

Concrete: In concrete technology concrete can be defined as pourable mix of

cement, water, sand, and aggregate that hardens into a super-strong building material, were sand and aggregates are the essential ingredients in concrete.

No Aggregate Concrete (NAC):No Aggregate Concrete is a concrete in which coarse aggregate and fine aggregate have been totally replaced by fly ash.

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FLY ASH IN CONCRETE Fly ash is generally used as replacement to

cement, as an admixture in concrete. Silica and Alumina in fly ash react with the

free lime available in concrete to form calcium silicate hydrate and calcium aluminate hydrate gel.

This gel helps to fill the pores and provides extra cementing material in concrete.

The advantages of fly ash when used in concrete is improves workability, reduced permeability, increased ultimate strength, reduced bleeding, and reduced heat of hydration.

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FEATURES OF NO-AGGREGATE CONCRETE Moderate water is required for curing, as the cast product is

porous-free and internal (mix) water would accomplish considerable curing needs.

The matrix of No Aggregate Concrete is as dense as ceramic with negligible porosity, Thus the durability is expected to be over 1000+ years .

The strength of NAC ranges at 40-80 MPa, by two to four fold of conventional concrete.

By no presence of coarse aggregate, NAC emerges devoid of transition zone nullifying the negative features of performance.

The density of this concrete is around 1800 kg/m3 as against 2400 kg/m3 for conventional concrete .

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INNOVATION

INSWAREB :- Institute for Solid Waste Research and Ecological Balance

DEVELOPED BY:- Dr. Bhanumathidas and

N. Kalidas

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LITERATURE REVIEW Kolli.Ramujee (2013) investigated strength properties of

concrete incorporating polypropylene fibers , where they found that compressive strength and splitting tensile strength were increased proportionately with the increase in volume ratios of polypropylene fibers with reference to the controlled mix without fibers, The samples with fibers content of 1.5 % showed optimum results in comparison with other samples in this study.

S. M. Kinayekar et al. (2014) studied effect of addition of carbon fibers on mechanical properties of high strength concrete. In this study, cement content in the HSC mix is replaced with fixed percentages of fly ash (10%) and carbon fiber are added in volume fraction (0 to 0.60%) the carbon fiber is used in varying length 10 mm, 20 mm, and 30 mm with 0%, 0.10%, 0.20%, 0.30%, 0.40%, 0.50% and 0.60% in volume fraction. It was observed that compressive strength and split tensile strength increases with fiber length.

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CONTINUED…. Vahid Afroughsabet et al. (2015) investigated the effect

of the addition of steel and polypropylene fibers on the mechanical and some durability properties of high-strength concrete (HSC).hybrid fiber-reinforced concretes show that substitution of steel fiber with PP fiber results in a lower mechanical strength, where Increase in the fiber content of both polypropylene and steel fiber-reinforced concretes results in enhancements in mechanical properties of the concrete.

Dr. Gopinatha Nayak et al. (2015) studied the compressive strength, flexural strength and split tensile strength of NAC. Two types of steel fibers were used with aspect ratio of 50 and 37.5 with volume fraction of 1.5% by volume. It was observed that increase of aspect ratio of steel fibers led’s to decrease of compressive strength, were additions of steel fibers slightly increase the flexural strength and split tensile strength of NAC.

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OBJECTIVE OF PRESENT STUDY

To test the strength characteristics of control NAC (without synthetic fibers) and SCC.

To test the strength characteristics of NAC with synthetic fibers.

To compare and evaluate the strength characteristics of NAC with fibers with control NAC and SCC.

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METHODOLOGYMaterials Used And Their Properties: Cement used was Ordinary Portland Cement 43 grade with a

specific gravity of 3.15. Coarse aggregates used to prepare control concrete SCC has

maximum size of 20mm and specific gravity 2.54. Fine aggregates used to prepare SCC has maximum size of

4.75 mm and specific gravity 2.77 The two types of admixtures were used in the present study.

Conplast SP 430 (FOSROC) was used in case of self compacting concrete, while special super plasticizer was used in all types of NAC mixes.

Fly ash used was obtained from Raichur Thermal Power station (RTPS) located in Karnataka, India. According to IS:3812-2000 it is classified as class F fly ash. Specific gravity is measured as 2.064. Strength activity index with Portland cement is 75.94.

Gypsum used was first grade gypsum manufactured in Tamil Nadu with a specific gravity of 2.32.

0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.20

50

100

150

200

250

300

350

400

Dosage (%)

Tim

e (s

ec)

Fig. 1 Optimum dosage of admixture (Conplast SP430)

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CONTINUED… Portable water was used in all mixes. Salts and other

organic impurities were absent.

In the present study two types of fibers are used i.e. carbon fiber and polypropylene fiber.

Carbon fibers used for the study are collected from a fiber JARLARK CARBON located in Gujarat as 6-10 mm chopped with relative density of 1.85.

Polypropylene fibers, which was obtained from Pune DOLPHIN FLOATS are used for all the mixes with 12mm length and 0.91 relative density. Mixes are made with different volume fraction. Since dry mixing procedure is followed no additional dispersion agents are used.

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Polypropylene fibersCarbon Fibers

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PREPARATION OF CONCRETE MIXES AND TEST SPECIMENS Total, eight No-Aggregate concrete Mixes and one Self-

compacting concrete were prepared. One No-aggregate concrete without fibers was prepared to study

the strength properties of No-aggregate concrete. Four mixes of polypropylene fiber with volume fractions of 0.2,

0.4, 0.6, 0.8 percentage and three mixes of carbon fibers with volume fractions of 0.2, 0.4, and 0.6 percentage (replacement was done with fly ash) are used to study the strength properties of synthetic fiber in No- aggregate concrete.

Self compacting concrete and NAC is used as control mix. Mix proportion of NAC

Cement: Fly Ash = 1:4Gypsum = 2% of Fly ashAdmixture = 0.4% Summation of cement and fly ashWater = 16-18% of Summation of cement and fly ash

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CONTINUED… Self-compacting concrete mix is prepared as per

EFNARC guidelines. After trial and error process final SCC mix is fixed based on compressive strength and fresh concrete properties.

Fig. 2 Pan mixer and Mechanical Mixer

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Mixture Cement Fly Ash Coarse Aggregate

Fine Aggregate Gypsum

Poly-propylene

Fiber

Carbon Fiber Water

Admix-

ture

kg/m³ kg/m³ kg/m³ kg/m³ kg/m³ kg/m³ kg/m³ lit/m³ kg/m³

SCC 360 240  700  763   - - - 195 7.5

NAC 315.5 1262 - - 25.24 - - 252.4 6.31

NAC-PP-0.2 315.5 1260.19 - - 25.24 1.81(0.2%)  - 252.4 6.31

NAC-PP-0.4 315.5 1258.36 - - 25.24 3.64(0.4%) - 252.4 6.31

NAC-PP-0.6 315.5 1256.54 - - 25.24 5.46(0.6%) - 252.4 6.31

NAC-PP-0.8 315.5 1254.72 - - 25.24 7.28(0.8%) - 252.4 6.31

NAC-CF-0.2 315.5 1258.4 - - 25.24 - 3.6(0.2%) 252.4 6.31NAC-CF-0.4 315.5 1254.8 - - 25.24 - 7.2(0.4%) 252.4 6.31

NAC-CF-0.6 315.5 1251.2 - - 25.24 - 10.8(0.6%) 252.4 6.31

Table 1 Mix Compositions of concrete per cubic meter

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FRESH AND HARDENED PROPERTIES OF SCC

TestSlump flow

(mm)

T50

(sec)

V

funnel

(sec)

T5

(sec)

L-Box

test

(Ratio)

U-

Box

test

(mm)

7-day

strength

(MPa)

28-day

strength

(MPa)

90-day

strength

(MPa)

Result 710 4.96 10.27 15.38 1.01 26 34.12 46.55 50.20

Table 2 Fresh and hardened concrete properties of SCC

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HARDENED CONCRETE TESTS

Parameters Age of Testing

Compression Test 7 days 28 days 90 days

Flexural Test 28 days 90 days

Split tensile Test 28 days 90 days

Pull out Test 56 days

Load Vs Deflection

Behavior 28 days

Table 3 Test schedule for hardened concrete

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COMPRESSIVE STRENGTH TEST

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FLEXURAL STRENGTH TEST Flexural strength was determined referring IS: 516-1959 Beam Size: 100mm x 100mm x 500mm, average 2 beams was considered Universal Testing machine was used Two point loading method was adopted

Flexural strength (MPa), (fb)=

When a is greater than 13.3 cm for a 10.0 cm specimen.

Flexural strength (MPa), (fb)=

When a is less than 13.3 cm but greater than 11.0 cm for a 10.0 cm specimen. Where, b = measured width in cm of the specimen. d = measured depth in cm of the specimen at the point of failure. l = length in cm of the span on which the specimen was supported.P = maximum load in kg applied to the specimen.

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SPLIT TENSILE STRENGTH TEST Split tensile strength was determined referring IS: 5816-

1999 Cylinder size: 150mm ø x 300mm, average of two cylinders

was considered Test performed : Universal Testing Machine

Split tensile strength (MPa)=

where, P = load applied to the specimen in Newton. d = diameter of the specimen (cylinder) in

mml = length of the specimen (cylinder) in mm

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PULL OUT TEST Bond strength was determined referring IS: 2770-

1967 (part-1) Thermo mechanically treated bars of 10 mm was

used as reinforcement The length of bar was taken as 750mm and the

embedded length was taken as 90mm, average of 2 cubes were considered

bond strength (MPa) τ = Where, P = the ultimate load at specimen fails.

l = the embedded length of the reinforcing bar (100 mm for cubes).d = the reinforcing bar diameter (10 mm)

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LOAD VS DEFLECTION BEHAVIOUR OF RCC BEAM RCC beams were tested in a loading frame

for flexural behavior after curing for 28 days referring IS: 516-1959.

The beams were placed in loading frame and two point loading method is adopted.

To measure vertical deflection a dial gauge was placed at the mid span of the beam.

Loading is continued till failure of beam.

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RESULTS AND DISCUSSIONS

Compression Test

7 28 9030

35

40

45

50

55

Com

pres

sive

Stre

ngth

(MPa

)

Fig. 3 Compressive strength of NAC, SCC and NAC with polypropylene fibers at different curing period

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CONTINUED…

7 28 9020

25

30

35

40

45

50

55

60C

ompr

essi

ve S

tren

gth

(MPa

)

Fig. 3 Compressive strength of NAC, SCC and NAC with Carbon Fiber at different curing period

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(a) (b)

(c) (d)Fig. 4 Failure pattern of (a) NAC, (b) SCC, (c) NAC with PPF,

(d) NAC with CF

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FLEXURAL TEST

28 902

3

4

5

6

7

8Fl

exur

al S

tren

gth

(MPa

)

Fig. 5 Flexural strength of NAC, SCC, NAC with PPF mixes at different curing period

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CONTINUED…

28 902

3

4

5

6

7

8

Flex

ural

Str

engt

h (M

Pa)

Fig. 6 Flexural strength of NAC, SCC, NAC with CF mixes at different curing period

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SPLIT TENSILE STRENGTH TEST

28 902

3

4

5Sp

lit te

nsile

stre

ngth

(MPa

)

Fig. 7 Split tensile strength of NAC, SCC, NAC with PPF mixes at different curing period

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CONTINUED…

28 901

2

3

4

5Sp

lit t

ensi

le st

reng

th (M

Pa)

Fig. 8 Splitting tensile strength of NAC, SCC, NAC with CF mixes at different curing period

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COMPRESSION-TENSION RATIO

Mixes

Compression Test (fc) MPa

Flexural Test (ff) MPa

Split Tensile Test (fst) MPa ff/fc fst/fc

28 days 90 days

28 days

90 days

28 days

90 days

28 days

90 days

28 days

90 days

NAC 41.20 51.99 2.79 5.29 2.85 2.89 0.07 0.10 0.07 0.06SCC 46.55 50.20 4.31 7.64 2.54 3.82 0.09 0.15 0.05 0.08

NACPPF-0.2 43.21 49.06 5.39 5.90 2.85 2.91 0.12 0.12 0.07 0.06NACPPF-0.4 45.40 47.81 5.53 6.58 2.13 2.81 0.12 0.14 0.05 0.06NACPPF-0.6 45.33 52.30 4.29 6.90 2.69 3.36 0.09 0.13 0.06 0.06NACPPF-0.8 46.19 51.56 4.27 6.47 4.07 4.28 0.09 0.13 0.09 0.08NACCF-0.2 39.20 48.55 4.16 6.59 1.80 3.16 0.11 0.14 0.05 0.07NACCF-0.4 43.90 49.03 2.18 5.84 2.00 3.13 0.05 0.12 0.05 0.06NACCF-0.6 43.50 53.45 2.76 5.84 3.44 4.13 0.06 0.11 0.08 0.08

Table 4 Effect of fibers on tensile-compressive strength relation in NAC, SCC, NACPPF and NACCF at the age of

28 and 90 days

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PULL OUT TEST:

560

1

2

3

4

5

6

3.39

5.18

4.29

2.05

4.62

2.48

NAC SCCNACPPF-0.2NACPPF-0.4NACPPF-0.6NACPPF-0.8

Curing Age (days)

Bon

d St

reng

th (M

Pa)

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CONTINUED…

560

1

2

3

4

5

6

3.39

5.18 5.174.39 4.55

NAC SCCNACCF-0.2NACCF-0.4NACCF-0.6

Curing Age (days)

Bon

d St

reng

th (M

Pa)

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LOAD VS DEFLECTION BEHAVIOUR OF RCC BEAMS

Mixes Division deflection (mm)

Load @50 division (MPa)

Ultimate load (kN)

NAC 50 8.32 32 63SCC 50 21.55 33 33

NACPPF-0.2 50 7.6 34 63NACPPF-0.4 50 7.2 34 67NACPPF-0.6 50 7.65 31 64NACPPF-0.8 50 5.86 34 72NACCF-0.2 50 7.21 32 72NACCF-0.4 50 7.9 33 67NACCF-0.6 50 5.68 35 75

Table 5 Load Vs deflection behaviour of RCC beams

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CONCLUSION The increase in compressive strength is credited

to high dense matrix of NAC as transition zone is completely avoided in NAC. Due to the elimination of aggregates, the mix is less likely to develop micro crack which enhance compressive strength. Incorporation of fibers has managed to increase the compressive strength by a small amount, which is clearly because of restraining the crack propagation in the matrix.

Incorporation of polypropylene fibers into NAC mixes controls the spalling behavior of NAC during failure, whereas addition of carbon fiber reduces brittle nature of NAC which prevents the catastrophic failure.

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CONTINUED… Incorporating polypropylene fiber to NAC in 0.4% volume fraction

and carbon fiber to NAC in 0.2% volume fraction efficiently increase the flexural behaviour of NAC.

Addition of 0.8% and 0.6% volume fraction of polypropylene and carbon fibers respectively improves the split tensile strength of NAC. This is due to the ability of fibers to restrain the extension of cracks, reduce the extent of stress concentration at the tip of cracks, and delay the growth rate of cracks.

Tensile strength of polypropylene fiber is around 800 MPa and that of carbon fiber is around 2500 MPa. The addition of carbon fiber to NAC improves the interfacial force, which strengthens the bond between the reinforcing bar and the NAC, which leads to increase in bond strength. This phenomenon can also be the prime reason for showing better results in ultimate load carrying capacity of RCC beams of NACCF specimen compared to NACPP specimen. This fact is also helped by carbon fibers’ high density, stiffness, and highest tensile strength among all other fibers.

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CONTINUED… As per the current demand of construction

industry, new types of concrete are to be developed. In this approach NAC with polypropylene fiber and carbon fiber will be a good substitute, which will promise better behavior compared to control concretes.

With the addition of fibers, performance of plain NAC is enhanced for majority of mechanical properties. It is evident that, polypropylene is the better choice out of two because of its much lesser cost. For highest volume fraction i.e. 0.6%, polypropylene fiber cost around Rs. 1400/m3, whereas for same volume fraction of carbon fiber cost around Rs. 23760/m3.

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LIMITATIONS Quality of ingredients of NAC is a primary factor. The

performance of NAC is purely dependent on the quality of fly ash that is selected. Maximum compressive strength that was observed was 52.30 MPa for NACCF against 51.99 MPa for plain NAC which is not very much satisfactory considering the previous research.

Slight variations in moisture content in the fly ash, relative humidity of the atmosphere and time of casting seriously affects the mixing duration. Non-uniformity was observed in the consistency of the final mix because of this.

Flexural test results were inconsistent. NACPPF-0.6% gave the best flexure result whereas NACPPF-0.8% was the highest in splitting tension result for 90 day curing period.

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FUTURE SCOPE Micro structural analysis can be carried out

to further investigate the matrix structure for the same mixes.

Flexural strength comparison can be carried out for higher volume fraction of polypropylene fibers and different types of synthetic fibers, even hybridization of fibers may be used for this purpose.

Shrinkage properties can be studied as the NAC is devoid of aggregate.

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REFERENCES A. D. Pofale and S. V. Deo, “Comparative Long Term Study of Concrete Mix Design

Procedure for Fine Aggregate Replacement with Fly Ash by Minimum Voids Method and Maximum Density Method,” KSCE J. Civ. Eng., vol. 14, no. 5, pp. 759–764, 2010.

S. Major and K. Lalit, “Report On Fly Ash Generation At Coal/Lignite Based Thermal Power Stations And Its Utilization In The Country For The Year 2014-15,” pp. 1–50, 2015.

S. Yoo, G. Ryu, and J. F. Choo, “Evaluation of the effects of high-volume fly ash on the flexural behavior of reinforced concrete beams,” Constr. Build. Mater., vol. 93, pp. 1132–1144, 2015.

E. Balance, “INSWAREB Develops,” no. May, pp. 214–217, 2013. R. Siddique, “Effect of fine aggregate replacement with Class F fly ash on the abrasion

resistance of concrete,” Cem. Concr. Res., vol. 33, no. 11, pp. 1877–1881, 2003. G. Nayak, K. K. Shetty, V. Khandagale, S. S. Kumara, N. Bhanumathidas, and N. Kalidas,

“STRENGTH PROPERTIES OF NO AGGREGATE CONCRETE USING FIBERS,” pp. 2–4, 2015. V. Afroughsabet and T. Ozbakkaloglu, “Mechanical and durability properties of high-

strength concrete containing steel and polypropylene fibers,” Constr. Build. Mater., vol. 94, pp. 73–82, 2015.

A. Sofi, K. Swathy, and G. Srija, “Toughness study on fly ash based fiber reinforced concrete,” p. 1, 2013.

S. T. Kang, B. Y. Lee, J.-K. Kim, and Y. Y. Kim, “The effect of fibre distribution characteristics on the flexural strength of steel fibre-reinforced ultra high strength concrete,” Constr. Build. Mater., vol. 25, no. 5, pp. 2450–2457, 2011.

I. H. Yang, C. Joh, and B. S. Kim, “Flexural strength of ultra high strength concrete beams reinforced with steel fibers,” Procedia Eng., vol. 14, pp. 793–796, 2011.

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CONTINUED… M. Pajak and T. Ponikiewski, “Flexural behavior of self-

compacting concrete reinforced with different types of steel fibers,” Constr. Build. Mater., vol. 47, pp. 397–408, 2013.

J. Bayasi, Z. & Zeng, “Properties of Polypropylene Fiber Reinforced Concrete.,” ACI Mater. J., vol. 90, no. 6, pp. 605–610., 1993.

S. M. Kinayekar and K. Kulkarni, “The Effect of Addition of Carbon Fibers on Mechanical Properties of High Strength Concrete,” vol. 3, no. 1, pp. 8777–8784, 2014.

M. S. S. K, “Strength and Behaviour of High Volume Fly Ash Concrete,” vol. 3, no. 5, pp. 12416–12424, 2014.

R. S. Atea, “Flexural Behavior of self Compacting Concrete Beams Strengthened with Carbon Fiber Reinforced Polymer Sheets,” vol. 3, no. 1, pp. 714–722, 2015.

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