5.0 discussion of experimental resultsshodhganga.inflibnet.ac.in/bitstream/10603/2171/15/15_chapter...

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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

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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%

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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


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

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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


than MKC depending on the value of fibre factor F. The compressive

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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


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.

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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


σcs,predicted = proposed compressive strength of SFRC in MPa.

σc = experimental compressive strength of OPCC in MPa






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.

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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


σcsm, proposed = predicted compressive strength of SFRC-MK in MPa.

σcm = experimental compressive strength of MKC in MPa




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


σcsm,predicted = predicted compressive strength of SFRC-MK in MPa.

σcm = experimental compressive strength of MKC in MPa


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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.

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(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


(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.


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

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of the fibres and the bond characteristics of fibres, these factors are

incorporated into a single parameter called as fibre factor F15.




σst,predicted = 2.097 (F) + σst ----------- (5)

r2 = 0.991

Where


σst,predicted = predicted splitting tensile strength of SFRC in MPa

σst = experimental splitting tensile strength of OPCC in MPa.


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


σst,predicted = predicted splitting tensile strength of SFRC in MPa.

σst = experimental splitting tensile strength of OPCC in MPa


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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.



SFRC -MK of M20 grade as.

σstm,predicted = 2.125(F) + σstm ---------- (7)

r2 = 0.990

Where


σstm,predicted = predicted splitting tensile strength of SFRC-MK in MPa.

σstm = experimental splitting tensile strength of MKC in MPa



experimental values and the predicted values of splitting tensile

strength of SFRC-MK is 1.10% from table 4.4.2.4.

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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


σstm,predicted = proposed splitting tensile strength of SFRC-MK in MPa.

σstm = experimental splitting tensile strength of MKC in MPa



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 &


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:

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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

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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.


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


parameter called as fibre factor F15.


4.4.3.1 gave the following expression for the modulus of rupture of


σr,predicted = 2.93 (F) + σr ----------- (9)

r2 = 0.997

where


σrf,predicted = predicted modulus of rupture of SFRC in MPa

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σrf = experimental modulus of rupture of OPCC in MPa.


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.


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


σr,predicted = predicted modulus of rupture of SFRC in MPa.

σr = experimental modulus of rupture of OPCC in MPa






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

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bond characteristics of fibres, these factors are incorporated into a

single parameter called as fibre factor F15.


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


σrm,predicted = predicted modulus of rupture of SFRC-MK in MPa.

σrm = experimental modulus of rupture of MKC in MPa



experimental values and the predicted values of modulus of rupture of

SFRC-MK is 0.3% from table 4.4.3.4.



expression for the modulus of rupture of SFRC-MK as:

σrm,predicted = 4.478(F) + σrm --------- (11)

r2 = 0.991

Where


σrm,predicted = predicted modulus of rupture of SFRC-MK in MPa.

σrm = experimental modulus of rupture of MKC in MPa


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experimental values and the predicted values of modulus of rupture of


5.6 MODULUS OF ELASTICITY OF OPCC, MKC, SFRC &


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


(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.

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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


(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.


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


parameter called as fibre factor F15.


4.4.4.1 gave the following expression for the modulus of elasticity of


Epredicted = 3.204 (F) + E ----------- (12)

r2 = 0.990

Where

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Epredicted = predicted modulus of elasticity of SFRC in GPa

E= experimental modulus of elasticity of OPCC in GPa.



and the predicted values of modulus of elasticity of SFRC is 0.40%

from table 4.4.4.2.



expression for the modulus of elasticity of SFRC as:

Epredicted = 4.69 (F) + E --------- (13)

r2 = 0.972

Where


Epredicted = predicted modulus of elasticity of SFRC in GPA.

E= experimental modulus of elasticity of OPCC in GPa






modulus of elasticity of SFRC - MK Mixes of M20 & M50 Grade

The modulus of elasticity of SFRC - MK is increasing with fibre


concrete as shown in table 4.4.4.3 and 4.4.4.7. As the modulus of

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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.


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


Esm,predicted = predicted modulus of elasticity of SFRC-MK in GPa.

Em = experimental modulus of elasticity of MKC in GPa



experimental values and the predicted values of modulus of elasticity




expression for the modulus of elasticity of SFRC-MK as:

Esm,predicted = 4.51(F) + Em --------- (14)

r2 = 0.993

Where


Esm,predicted = predicted modulus of elasticity of SFRC-MK in GPa.

Em = experimental modulus of elasticity of MKC in GPa

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experimental values and the predicted values of modulus of elasticity


5.7 IMPACT RESISTANCE OF OPCC, MKC, SFRC &


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

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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


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


(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


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.


4.4.5.1 gave the following expression for the impact resistance of


Ipredicted = 243.26 (F) + I ----------- (15)

r2 = 0.993

Where


Ipredicted = predicted impact resistance of SFRC in number of blows.

E= experimental impact resistance of OPCC in number of blows.


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and the predicted values of impact resistance of SFRC is 1.90% from

table 4.4.5.2.



expression for the impact resistance of SFRC as:

Ipredicted = 503 (F) + I --------- (16)

r2 = 0.994

Where


Ipredicted = predicted impact resistance of SFRC in number of blows.

I= experimental impact resistance of OPCC in number of blows



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


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


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


Ism,predicted = predicted impact resistance of SFRC-MK in number of

blows.

Im = experimental impact resistance of MKC in number of blows



experimental values and the predicted values of impact resistance of




expression for the impact resistance of SFRC-MK as:

Ism,proposed = 956(F) + Im --------- (18)

r2 = 0.995

Where


Im,predicted = predicted impact resistance of SFRC-MK in number of

blows

Im = experimental impact resistance of MKC in number of blows


290


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.


and MKC mix of M20 grade at room temperature. These values vary

from 30.69 to 32.86 MPa.


and SFRC – MK (1.5-80) mix of M20 grade at room temperature. These

values vary from 30.69 to 36.50 MPa respectively.


and SFRC (1.5-80) mix of M50 grade at room temperature. These

values vary from 61.4 to 69.04 MPa.

291


and MKC mix of M50 grade at room temperature. These values vary

from 61.4 to 68.90 MPa respectively.


and SFRC –MK (1.5-80) mix of M50 grade at room temperature. These

values vary from 61.4 to 75.68 MPa respectively.


SFRC-MK concrete mixes of M20 and M50 grade at 2000C.


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.


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.


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.


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.


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



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.


SFRC-MK mixes of M20 and M50 grade after cooling to room

temperature.


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.


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


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



SFRC-MK mixes of M20 and M50 grade after cooling to room

temperature from 2000C and compared with normal strength.


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



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.


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.




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.


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.



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.




OPCC and 32.86 to 27.60 MPa for MKC mix respectively.


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.


and SFRC (1.5-80) of M50 grade after exposure of the specimens to



respectively.





296


and SFRC-MK (1.5-80) mix of M50 grade after exposure of the


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.


and SFRC (1.5-80) mix of M20 grade after cooling to room


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.


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.


and SFRC-MK (1.5-80) mix of M20 grade after cooling to room



MPa for SFRC-MK (1.5-80) respectively.


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.



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.


and SFRC-MK (1.5-80) mix of M50 grade after cooling to room



MPa for SFRC-MK (1.5-80) respectively.


& SFRC-MK mixes of M20 & M50 grade at 6000C.


and SFRC (1.5-80) mix of M20 grade concrete after exposing the


30.69 to 20.65 MPa for OPCC and 34.10 to 13.32 MPa for SFRC (1.5-

80) respectively.


and MKC mix of M20 grade after exposing the specimens to 6000C for



298



to 6000C for duration of 12 Hrs. These values vary from 30.69 to


respectively.





respectively.


and MKC mix of M50 grade after exposing the specimens to 6000C for





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.



temperature from 6000C.


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.



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.


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.


and SFRC (1.5-80) mix of M50 grade after cooling to room

temperature from 6000C for duration of 24Hrs. The compressive


MPa for SFRC (1.5-80) mix respectively.


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.


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


mix respectively.



temperature from 6000C and compared with normal strength.







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.










26.23MPa for SFRC (AR-80) respectively.

301


& 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.






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.


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.


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.


strength of SFRC-MK (1.5-80) mix of M20 grade at 2000C, 4000C and


as -17.0% at 2000C, -30.50% at 4000C and -60.20% at 6000C

respectively.


strength of OPCC mix of M50 grade at 2000C, 4000C and 6000C in




strength of MKC mix of M50 grade at 2000C, 4000C and 6000C in




strength of SFRC (1.5-80) mix of M50 grade at 2000C, 4000C and


as -34.79% at 2000C, -45.60% at 4000C and -69.0% at 6000C

respectively.


strength of SFRC-MK (1.5-80) mix of M50 grade at 2000C, 4000C and


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


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


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.


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,


cooling to room temperature from 4000C.



4000C. These values vary from 9.0% to 14.0%. These variations are

shown in fig 74.0 and 76.0



4000C. These values vary from 11.0% to 19.0 %. These variations are

shown in fig 74.0 and 76.0.



from 4000C. These values vary from 13.0% to 12.0%.




305


5.8.2.3. Percentage increase in compressive strength of OPCC,


cooling to room temperature from 6000C



6000C. These values vary from 10.0% to 20.0%.

These variations are shown in fig 74.0 and 76.0



6000C. These values vary from 7.0% to 18.0 %.




from 6000C. These values vary from 15.0% to 22.0%.






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.


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


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.


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.


(AR-80) mixes of M20 and M50 grade after exposing the specimens to


m/s respectively.


MK mixes of M20 and M50 grade concrete at 2000C are shown in

fig.79.0.






respectively.




respectively.

308




m/s respectively.




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.






respectively.




respectively.




m/s respectively.

309




m/s respectively.


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.


MKC mixes of M20 and M50 grade after exposing the specimens to


respectively.


SFRC (AR-80) mixes of M20 and M50 grade after exposing the


6.41 to 9.98% respectively.

310


SFRC-MK (AR-80) mixes of M20 and M50 grade after exposing the



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





respectively.




respectively.









311



5.8.4.3 Percentage weight loss of OPCC, MKC, SFRC & SFRC-MK





respectively.




respectively.











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.


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.


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.


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.


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


of M20 and M50 grade at 90 thermal cycles.














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.



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.


concrete of M20 and M50 grade at 180 thermal cycles.














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




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



tensile strength of MK concrete mixes investigated at 28 thermal


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.


tensile strength of SFRC mixes investigated at 28 thermal cycles at




grade and 7.22 to 6.36 MPa for SFRC(1.5-60) of M50 grade at 1000C

respectively.


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.




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






500C, 3.08 to 3.32 MPa for MKC of M20 grade and 4.76 to 5.69 MPa



tensile strength of SFRC mixes investigated at 90 thermal cycles at




grade and 7.22 to 5.77 MPa for SFRC(1.5-60) of M50 grade at 1000C

respectively.




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.




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






500C, 3.08 to 3.37 MPa for MKC of M20 grade and 4.76 to 5.88MPa


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



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



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.


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



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.


rupture of SFRC-MK mixes investigated at 28 thermal cycles at 500C








322

















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.




MK(1.5-60) of M20 grade and 9.82 to 8.20 MPa for SFRC-MK (1.5-60)




323



















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.





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.


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


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.


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


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


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


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


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


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



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.


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


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



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.


compressive strength of SFRC-MK (1.5-60) mix of M20 grade in


331




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


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



compressive strength of SFRC (1.5-60) mix of M50 grade in


vary from -5.92% to -14.0% at 500C and -11.27% to -27.74% at 1000C

for 28, 90 &180 thermal cycles respectively.


compressive strength of SFRC-MK (1.5-60) mix of M50 grade in




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


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



tensile strength of SFRC (1.5-80) mix of M20 grade in comparison with





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 -




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


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



tensile strength of SFRC (1.5-60) mix of M50 grade in comparison with





tensile strength of SFRC-MK (1.5-60) mix of M50 grade in comparison




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


modulus of rupture of OPCC mix of M20 grade in comparison with




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.


modulus of rupture of SFRC (1.5-60) mix of M20 grade in comparison





modulus of rupture of SFRC-MK (1.5-60) mix of M20 grade in





modulus of rupture of OPCC mix of M50 grade in comparison with




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.


modulus of rupture of SFRC (1.5-60) mix of M50 grade in comparison

335





modulus of rupture of SFRC-MK (1.5-60) mix of M50 grade in


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


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.


MKC mixes of M20 and M50 grade after immersing in 5 % HCL


2.08 % for 60 days, 3.90 to 3.58 % for 90 days and 5.16 to 4.22 % for

120 days respectively.


SFRC (1.5-60) mix of M20 and M50 grade after immersing in 5 % HCL


1.48 % for 60 days, 3.37 to 2.14 % for 90 days and 3.98 to 2.62 % for



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



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 %


337


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



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


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




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




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.


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,


to 13.76% for 120 days respectively.


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%



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



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.


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.


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

340

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.





90 days and 22.05 to 9.19% for 120 days respectively.


compressive strength of SFRC-MK (1.5-60) mix of M20 and M50 grade









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


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.


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.


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.




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.




4.82 % for 30 days, 27.78 to 5.49 % for 60 days, 30.54 to 7.20 % for




after immersing in 5% H2SO4 solution. The values vary from 24.86 to

342

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,


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.


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.





% for 60 days, 4.65 to 8.42% for 90 days and 4.16 to 9.34 % for 120

days respectively.


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




loss of compressive strength of SFRC-MK (AR-80) mix of M20 and M50



% for 60 days, 7.73 to 10.70 % for 90 days and 9.44 to 13.01 % for


5.10.3.2 The resistance to loss of compressive strength of MKC,


with OPCC mixes when immersed in H2SO4 solution


loss of compressive strength of MKC mixes of M20 and M50 grade

after immersing in 5 % H2SO4 solution in comparison with OPCC


% for 60 days, 4.54 to 9.62 % for 90 days and 4.66 to 6.86 % for 120

days respectively.



grade after immersing in 5 % H2SO4 solution in comparison with






345



to 9.56 % for 60 days, 2.86 to 9.30% for 90 days and 1.72 to 9.10 %




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.




OPCC mixes. These values vary from 9.98 to 14.48 % for 30 days,


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



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.


M20 and M50 grades after immersing in 5 % HCL solution. These



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



respectively.


of M20 and M50 grades after immersing in 5 % HCL solution. These


347


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



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.


M20 and M50 grades after immersing in 5 % H2SO4 solution. These



respectively.


M20 and M50 grades after immersing in 5 % H2SO4 solution. These



respectively.


of M20 and M50 grades after immersing in 5 % H2SO4 solution. These

348



respectively.


of M20 and M50 grades after immersing in 5 % H2SO4 solution. These



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.


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.


(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.


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%


respectively.


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%


respectively.


(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.


(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.



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,



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




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,



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


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.

5.0 discussion of experimental resultsshodhganga.inflibnet.ac.in/bitstream/10603/2171/15/15_chapter...

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