The document analyzes the effect of fiber content and type on the compressive strength of fiber reinforced concrete (FRC) at high temperatures. An experimental program tested 84 concrete cubes with different fiber contents and types at temperatures of 0°C, 200°C, 350°C, and 600°C. The results show that steel fiber reinforced concrete retained more of its compressive strength at higher temperatures compared to polypropylene fiber reinforced and normal concrete, with the 1.5% steel fiber mix performing best. Additionally, compressive strength generally decreased as temperature exposure increased for all concrete mixes.

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International Journal of Civil Engineering and Technology (IJCIET)
Volume 6, Issue 8, Aug 2015, pp. 53-60, Article ID: IJCIET_06_08_006
Available online at
http://www.iaeme.com/IJCIET/issues.asp?JTypeIJCIET&VType=6&IType=8
ISSN Print: 0976-6308 and ISSN Online: 0976-6316
© IAEME Publication
___________________________________________________________________________
THE COMPRESSIVE STRENGTH OF FIBER
REINFORCED CONCRETE (FRC) AT HIGH
ELEVATED TEMPERATURES
H. E. M. Sallam
Civil Engineering Dept., Jazan University – KSA on Sabbatical leave from Zagazig
University, Zagazig – Egypt
K. I. M. Ibrahim
Construction Engineering Dept., College of Engineering at Qunfudha, Umm-Al-Qura
University – KSA on Sabbatical leave from higher Institute of Engineering and
Technology of Kafr-EL-shiekh – Egypt
ABSTRACT
This paper investigates the effect of fiber on the compressive strength of
(FRC) at high elevated temperatures. Effects of key variables such as fiber
content, several high temperatures and fiber type were studied. An
experimental program was conducted to achieve the required objectives. 84
Cubes were tested under axial compressive loads. They were divided as
follows. 12 Cubes without fibers as a reference, 72 Cubes were cast to study
the effect of fiber content and fiber type at several high temperatures. It was
found that the content and type of fiber have approximately not effect on
improving the behavior of (FRC) at high elevated temperatures.
Key words: Steel fibers, PP fibers, elevated temperatures and compressive
strength
Cite this Article: Sallam, H. E. M. and Ibrahim, K. I. M. The Compressive
Strength of Fiber Reinforced Concrete (FRC) at High Elevated Temperatures.
International Journal of Civil Engineering and Technology, 6(8), 2015, pp 53-
60.
http://www.iaeme.com/IJCIET/issues.asp?JTypeIJCIET&VType=6&IType=8
_____________________________________________________________________
1. INTRODUCTION
Normal concrete is a brittle material and there is an adverse relation between strength
and ductility. To overcome this problem, fibers are used. This is due to its effect in
delaying and controlling the crack propogation. Since the early 1990 tests have shown
that the use of fibers in concrete mix tends to reduce the probability of explosive
spalling in fire. A. Noumowe [1] studied the mechanical properties of polypropylene

2. H. E. M. Sallam and K. I. M. Ibrahim
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fiber concrete up to 200 °C. It has been found that when polypropylene fiber high
strength concrete is heated up to 170 °C, fibers readly melt and volatillse, creating
additional porosity and small channels in the concrete. Mechanical tests showed small
changes in compressive strength, modulus of elasticity and splitting tensile strength
that could be due to polypropylene fiber melting. Bing Chen and Juanyu Liu [2]
studied the residual strength of hybrid fiber reinforced high strength concrete after
exposure to high temperatures. The results showed that the normal high strength
concrete (HSC) is prone to spalling after exposure to high temperatures, and the first
spalling occurs when the temperature approaches 400 °C. For HSC reinforced by high
melting point fibers, the first spalling occurs when the temperature reaches to
approximately 800 °C, while there is no spalling during exposing to high temperature
for HSC reinforced by polypropylene (PP) fiber with a low melting point. Mixing
high melting point fiber (i.e. carbon or steel fiber) with low melting point fiber (i.e. pp
fiber) [3] HSC greatly improves the properties of HSC after exposure to high
temperatures. C. S. Poon, Z. H. Shui and L. Lam [4] studied the compressive behavior
of fiber reinforced high-performance concrete subjected to elevated temperatures. The
results showed that after exposure to 600 and 800 °C the concrete mixes retained,
respectively 45% and 23% of their compressive strength, on average, the results also
show that steel fibers were effective in minimizing the degradation of compressive
strength.
2. MATERIALS
Local materials were used in concrete mixes and tested according to Egyptian
Standard Specifications (ESS) and American Standard of Testing Materials (ASTM).
Gravel as coarse aggregate was used with maximum size 25 mm and the particle
shape is approximately round. Fine aggregate used in this research was natural sand
and it composed mainly of siliceous material. Ordinary Portland cement was tested to
assure its compliance with ESS 373 – 1991. Supper-plasticizer was added to keep the
water cement ratio = 0.5 with slump ranges from (7–11) cm. Steel fiber (SF) used in
this study is produced by cutting steel wire and of 50 mm length and circular cross
section (0.5 mm diameter). Polypropylene Fibers (PPF) of 19 mm length and 0.1 mm
diameter were used.
3. CONCRETE MIXES PROPORTION
Table 1 Concrete Mixes proportion
Sand / gravel = 1/2
Water / cement = 1/2
Super
plast.
(kg)
Water
(lit)
Sand
(m3
)
Gravel
(m3
)
Fibers
content
Vf %
Fiber type
Cement
(kg)
Mix
No.
_1750.40.80_3501
1.751750.40.80.5%steel3502
1.751750.40.81%steel3503
2.2751750.40.81.5%steel3504
0.71750.40.80.1%polypropylene3505
0.8751750.40.80.3%polypropylene3506
1.051750.40.80.5%polypropylene3507

3. The Compressive Strength of Fiber Reinforced Concrete (FRC) at High Elevated
Temperatures
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Seven mixes were used as follows, one mix without fiber as a control mix, six mixes
with different contents of (SF) to study the effect of fiber content on the compressive
strength of ( FRC) at high elevated temperatures. These mixes are identical except for
the volume percentage of fibers. For all mixes the cement content was 350 kg/m3
and
the water content ratio 0.5 by weight. Super-plasticizer per cubic meter were also
used.
4. DESCRIPTION OF TESTED SPECIMENS
All specimens were cubes 15*15*15 cm length. Concrete was cast vertically in the
forms, and was mechanically compacted using external vibrator to ensure full
compaction of concrete inside the forms. The specimens were tested by using 1500
KN hydraulic compression machine.
5. TEST RESULTS
Table 2 and Figure 1 give the test results of the compressive strength of the different
tested concrete mixes at zero temperature. The compressive strength of the Plain
Concrete (PC) was 272 kg/cm2
as 294,308 and 327 kg/cm2
for SFRC with Vf = 0.5, 1
and 1.5% respectively with increase of about 8%, 13% and 20% with respect of PC.
Also, the compressive strength of PPFRC with Vf = 0.1, 0.3 and 0.5 % was 274, 287
and 300 kg/cm2
respectively with increase of about 0.7, 5, 9 % with respect of PC.
Table 3 and Figure 2 give the test results of the compressive strength of the
different tested concrete mixes at 200 °C. The compressive strength of pc was 262
kg/cm2
as was 286, 290 and 326 kg/cm2
for SFRC with Vf = 0.5%, 1% and 1.5%
respectively with increase of about 9%, 11% and 25% respectively with respect of
PC. Also, the compressive strength of PPFRC was 274,289 and 297 kg/cm2
for Vf =
0.1, 0.3 and 0.5% respectively with increase of about 5, 10 and 13% with respect of
PC. Table 4 and Figure 3 give the test results of the compressive strength of the
different tested concrete mixes at 350 °C. The compressive strength of pc was 235
kg/cm2
as 240, 253 and 266 kg/cm2
for SFRC with Vf = 0.5%, 1% and 1.5%
respectively with increase of about 2%, 8% and 13% respectively with respect of PC.
Also, the compressive strength of PPFRC was 240, 245 and 250 kg/cm2
for Vf = 0.1,
0.3 and 0.5% respectively with increase of about 2, 4 and 6% with respect of PC.
Table 5 and Figure 4 give the test results of the compressive strength of the different
tested concrete mixes at 600 °C. The compressive strength of PC was 154 kg/cm2
as
167, 182, and 204 kg/cm2
for SFRC with Vf = .5%, 1% and 1.5% respectively with
increase of about 8%, 18% and 33% respectively with respect of PC. Also, the
compressive strength of PPFRC was 160, 172 and 181 kg /cm2
for Vf = 0.1, 0.3 and
0.5% respectively with increase of about 4, 12 and 18% with respect of PC. Table 6
and Figure 5 summarize the results of compressive strength of FRC at 200, 350, 600
°C. For PC, the compressive strength decreases with about 3.7%, 13.7% and 43.3% at
200, 350 and 600 °C respectively with respect of the compressive strength at 0 °C as
for SFRC with Vf = 0.5%, the compressive strength decreases with about 2.6%,
18.4% and 43.3% respectively. Also, the compressive strength of SFRC with Vf = 1%
as decreases of about 5.7%, 17.7% and 40.7% respectively as for SFRC of Vf = 1.5%
decreases of about 0.3%, 18.7% and 37.9% respectively at 200, 350 and 600 °C with
respect of the compressive strength at 0 °C. For PPFRC of Vf = 0.1 %, the
compressive strength decreases with about 0.4 %, 12.4 % and 41.6 % respectively at
the same temperatures with respect to the compressive strength at 0 °C. Also, the
compressive strength of PPFRC of Vf = 0.3% decreases with about 0.7%, 14.6% and

4. H. E. M. Sallam and K. I. M. Ibrahim
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40% as for Vf = 0.5% decreases with about 1%, 16.7% and 39.7% respectively at the
same temperatures with respect to the compressive strength at 0 °C.
6. CONCLUSIONS
The following conclusions were drawn based on the experiment results.
1. The results show a loss of concrete compressive strength for all mixes with increased
maximum heating temperature.
2. For maximum exposure temperatures below 350 °C, the loss in compressive strength
was relatively small.
3. For all concretes heated to temperatures exceeding 350 °C, significant further
reductions in compressive strength are observed.
4. Normal strength concrete start to suffer a greater compressive strength loss than
SFRC of Vf = 1.5% and PPFRC at Vf = 0.5% at maximum exposure temperatures of
600 °C.
Table 2 Results of compressive strength of FRC (kg/cm2
) at zero temperature
Figure 1 the compressive strength (kg/cm2
) of FRC at 0 °C
272
294
308
327
274
287
300
mix1 mix2 mix3 mix4 mix5 mix6 mix7
Compressive Strength (kg/cm2
)
Fiber content Vf
(%)
Fiber typeMix No.
272 (control)0%_1
294 (+8%)0.5%steel2
308 (+13%)1%steel3
327 (+20%)1.5%steel4
274 (+0.7%)0.1%polypropylene5
287 (+5%)0.3%polypropylene6
300 (+9%)0.5%polypropylene7

5. The Compressive Strength of Fiber Reinforced Concrete (FRC) at High Elevated
Temperatures
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Table 3 Results of compressive strength of FRC (kg/cm2
) at 200 °C
Compressive strength
(kg/cm2
)
Fiber content
Vf (%)
Fiber typeMix
No.
262 (control)0_1
286 (+9%)0.5%steel2
290 (+11%)1%steel3
326 (+25%)1.5%steel4
274 (+ 5%)0.1 %polypropylene5
289 ( + 10%)0.3 %polypropylene6
297 (+13%)0.5 %polypropylene7
Figure 2 the compressive strength (kg/cm2
) of FRC at 200 °C
Table 4 Results of compressive strength of FRC (kg/cm2
) at 350 °C
Compressive strength
(kg/cm2
)
Fiber content
Vf (%)
Fiber type
Mix
No.
235 (control)0%_1
240 (+2%)0.5%Steel2
253 (+8%)1%Steel3
266 (13%)1.5%Steel4
240 (+2%)0.1%Polypropylene5
245 ( +4%)0.3%Polypropylene6
250 ( +6%)0.5%Polypropylene7
272
294
308
327
274
287
300
mix1 mix2 mix3 mix4 mix5 mix6 mix7

6. H. E. M. Sallam and K. I. M. Ibrahim
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Figure 3 The compressive strength (kg/cm2
) of FRC at 350 °C
Table 5 Results of compressive strength of FRC (kg/cm2
) at 600 °C
Compressive strength
(kg/cm2
)
Fiber content Vf(%)Fiber typeMix No.
154 (control)0%_1
167 (+8%)0.5%Steel2
182 (+18%)1%Steel3
204 (+33%)1.5%Steel4
160 ( +4%)0.1%Polypropylene5
172 ( +12%)0.3%Polypropylene6
181 (+18%)0.5%Polypropylene7
Figure 4 the compressive strength (kg/cm2
)of FRC at 600 °C
235
240
253
266
240
245
250
mix1 mix2 mix3 mix4 mix5 mix6 mix7
154
167
182
204
160
172
181
mix1 mix2 mix3 mix4 mix5 mix6 mix7

7. The Compressive Strength of Fiber Reinforced Concrete (FRC) at High Elevated
Temperatures
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Table 6 Summary of results for tested cubes of (FRC) at high elevated temperatures.
Compressive strength (kg/cm2
) atFiber
content Vf
(%)
Fiber typeMix
600 °C350 °C200 °C0 °C
154
(-43.3%)
235
(-13.7%)
262
(-3.7%)
272
(control)
0%_1
167
(-43.3%)
240
(-18.4%)
286
(-2.6%)
294
(control)
0.5%steel2
182
(-40.7%)
253
(-17.7%)
290
(-5.7%)
308
(control)
1%steel3
204
(-37.9%)
266
(-18.7%)
326
(-0.3%)
327
(control)
1.5%steel4
160
(-41.6%)
240
(-12.4%)
274
(0%)
274
(control)
0.1%polypropylene5
172
(-40.%)
245
(-14.6%)
289
(+0.7%)
287
(control)
0.3%polypropylene6
181
(-39.7%)
250
(-16.7%)
297
(-1%)
300
(control)
0.5%polypropylene7
Figure 5 The effect of high temperatures on the concrete mixes
0
50
100
150
200
250
300
350
0c 200 c 350 c 600 c
mix
1
mix
2
mix3
mix4
mix5
mix6
mix7

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REFERENCES
[1] Noumowe, A. Mechanical Properties and Microstructure of High Strength
Concrete Containing Polypropylene Fibers Exposed to Temperatures up to 200
°C. Cement and Concrete Research Journal, 35(11) November 2005, pp. 2192–
2198.
[2] Chen, B. and Liu, J. Residual Strength of Hybrid-Fiber Reinforced High Strength
Concrete after Exposure to High Temperatures. Cement and Concrete Research
Journal, 34(6), June 2004, pp. 1065–1069.
[3] Dr. Muthupriya, P. An Experimental Investigation on Effect of GGBS and Glass
Fibre in High Perfomance Concrete. International Journal of Civil Engineering
& Technology (IJCIET), 4(4), 2013, pp. 2935.
[4] Poon, C. S., Shui, Z. H. and Lam, L. Compressive Behavior of Fiber Reinforced
High-Performance Concrete Subjected to Elevated Temperatures. Cement and
Concrete Research Journal, 34(12), December 2004, pp. 2215–2222.