Content uploaded by Dr Anduri Sreenivasulu
Author content
All content in this area was uploaded by Dr Anduri Sreenivasulu on Dec 08, 2020
Content may be subject to copyright.
JOURNAL OF STRUCTURAL ENGINEERING 221
Vol. 43, No. 2, JUNE - JULY 2016
Journal of Structural Engineering
Vol. 43, No. 2, June - July 2016 pp. 221-226 No. 43-T2
An experimental study on the performance of M100 concrete at elevated
temperature
A. Sreenivasulu*, and K. Srinivasa Rao**
Email: srinu_anduri@yahoo.com
*Department of Civil Engineering, PVP Siddhartha Institute of Technology, Vijayawada - 520 007, INDIA.
**Department of Civil Engineering, College of Engineering, Andhra University, Visakhapatnam - 530 003, INDIA.
Received: 28 March 2014; Accepted: 19 January 2015
The higher strength in concrete could be achieved by
using one of the following methods or a combination
of some or many of the following:
into the construction industry. The American Concrete
concrete meeting special combinations of performance
and uniformity requirements that cannot always
be achieved routinely when using conventional
constituents and normal mixing, placing and curing
application, and the performance can be measured using
a well-accepted standard test procedure. Exposed to
elevated temperature causes physical changes including
large volume changes due to thermal dilations, thermal
shrinkage and creep related to water loss. The volume
changes can result in large internal stresses and lead
to micro-cracking and fracture. Elevated temperatures
also cause chemical and micro-structural changes such
as water migration, increased dehydration, interfacial
thermal incompatibility and the chemical decomposition
of hardened cement past and aggregate. In general,
all these changes decrease the stiffness of concrete
and increase the irrecoverable deformation. Various
investigations indicate that the strength and stiffness
of concrete decrease with increasing temperature,
exposure time and thermal cycles.
Fire is one of the most severe conditions when the
structures are exposed for it. Mechanical properties
are considerably reduced during exposure, potentially
resulting in undesirable structural failures. Therefore,
the residual properties of concrete are still important in
determining the load carrying capacity and the further
have shown that concrete type, concrete strength,
aggregate types, test types, maximum exposure
temperature, exposure time, type and amount of
affect the residual properties of concrete after exposure
to high temperatures. When the concrete is subjected
to elevated temperature, the incompatibility of thermal
deformations within the constituents of concrete initiates
data available to date, it has been found that the effects
of elevated temperatures on the mechanical properties
of high strength concrete vary with a number of factors
including the test methods, permeability of concrete,
the types of aggregate used and moisture content.
Objectives
The objective of this work is to produce M100
concrete and to understand the performance of M100
concrete when exposed to elevated temperatures. The
experimentation was carried out to study the changes in
222 JOURNAL OF STRUCTURAL ENGINEERING
Vol. 43, No. 2, JUNE - JULY 2016
modulus of elasticity and compressive strengths of high
strength concrete subjected to elevated temperatures
for different durations of exposure.
Research Signicance
size of elements. These concrete mixes typically have
an increased modulus of elasticity, which increases
are changed by heat exposure. The mechanical
as they are crucial for the further usage of concrete
structures affected by heat. Despite the fact that certain
models have already been proposed for the prediction
of compressive strength loss, they have limitations
or lower statistical performances. A unique and
comprehensive empirical model is needed to predict
compressive strength losses with high statistical values
for which the database of test results is required
REVIEW OF LITERATURE
Ravindrarajah et al
1
through their research concluded
that the residual compressive and tensile strengths
for high strength concrete with blended cement after
heating to 800ºC and water quenched were 31% of initial
strengths whereas the corresponding residual strengths
for concrete with ordinary Portland cement was 44%.
Potha Raju et al2 investigated the effect of elevated
of different grades of M28, M33 and M35. Concrete
specimens 100 × 100 × 500 mm with partial replacement
oC
for 1, 2 and 3hr durations. The specimens were tested
after removing from the oven. It was concluded that
compared with the control specimens by retaining
greater amount of its strength.
Sujit Ghosh et al3 concluded through their research
that compressive strength and Young’s modulus of
decreased with a rise in temperature from 21.4 to 232oC
for different pressures and this decrease was attributed
to a gradual deterioration of the binding matrix with
rise in temperature.
Randall Lawson et al4 aimed to characterise
being exposed elevated temperatures. The average
compressive strength for the different grades of
concrete adopted in the study was 40 to 100 MPa. The
selected temperatures were 100, 200, 300 and 450oC.
for concrete exposed to elevated temperatures.
Fig. 1 Testing of cube for compressive strength
Fig. 2 Testing of cylinder for Young’s modulus
1151 hour duration
2 hours duration
3 hours duration
4 hours duration
% Residual compressive strength
110
105
100
95
90
85
80
050 100
Temperature (Degree celsius)
150 200 300250
Fig. 3 Variation of % residual compressive strength with
temperature
Castilo and Durrani
5
carried out investigations to study
the effect of transient high temperature on compressive
both unloaded and preloaded conditions and to compare
JOURNAL OF STRUCTURAL ENGINEERING 223
Vol. 43, No. 2, JUNE - JULY 2016
TEMPERATURE
Temperature
(oC)
Compressive strength (N/mm2) % Residual compressive strength
1 hour
duration
2 hours
duration
3 hours
duration
4 hours
duration
1 hour
duration
2 hours
duration
3 hours
duration
4 hours
duration
27 131.67 131.67 131.67 131.67 100.0 100.0 100.0 100.0
50 140.39 146.93 134.29 138.65 106.62 111.59 101.99 105.3
100 148.23 145.65 143.01 125.57 112.58 110.62 108.61 95.37
150 144.74 142.12 138.43 122.95 109.93 107.94 105.13 93.38
200 136.25 131.19 135.16 117.29 103.48 99.67 102.65 89.08
250 120.77 126.58 130.58 115.39 91.72 96.14 99.17 87.64
Stress (MPa) Strain at
27oC 50oC 100oC 150oC 200oC 250oC
0000000
2.8308 6.67E-05 3.33E-05 6.67E-05 5.56E-05 3.33E-05 6.67E-05
5.6617 0.000144 0.0001 0.000166 0.000144 0.000122 0.000166
8.4925 0.000211 0.0002 0.0002 0.0002 0.000222 0.0002
11.3234 0.000322 0.000288 0.000266 0.000288 0.0003 0.000266
14.1542 0.000377 0.000344 0.000333 0.0004 0.000411 0.000333
16.9851 0.000455 0.000422 0.0004 0.000477 0.000544 0.000444
19.8159 0.000544 0.0005 0.000466 0.000588 0.000744 0.000533
22.6468 0.000622 0.000588 0.000533 0.000677 0.000922 0.000666
25.4777 0.000755 0.000722 0.0007 0.000822 0.001111 0.000844
28.3085 0.000988 0.0009 0.000966 0.001 0.001344 0.0011
30.0071 0.001344 0.001222 0.001333 0.001266 0.001555 0.001455
33.9702 - 0.001433 0.001511 0.0015 0.00181111 0.00185555
36.8011 - 0.001688 0.001666 0.0017 0.00206666 0.0022
39.6319 - - 0.002 0.001966 0.00225555 -
42.4628 - - - 0.002311 0.00245555 -
obtained from the study, it was concluded that when
exposed to temperatures in the ranged of 100 to 300oC,
strength between 300 to 400oC, reaching a maximum
value of 8-13 % above the strength at room temperature.
At temperature above 400o
its compressive strength, which dropped to about 30% of
the room temperature strength at 800oC.
Kodur and Phan6
strength concrete and found that high strength concrete
is a high-performing material and offers a number of
was found that there is a concern on the occurrence
concrete (as compared to normal strength concrete).
performance of high strength concrete at material level
are: concrete strength, silica fume, concrete moisture
224 JOURNAL OF STRUCTURAL ENGINEERING
Vol. 43, No. 2, JUNE - JULY 2016
of aggregate. At the structural level, it was found that
and size of the members play an important role in
EXPERIMENTAL PROGRAM
Preliminary investigations were carried out to develop
M100 grade concrete. The mix proportion arrived as
per ACI 211.4R7 was 1:0.556:1.629 by weight with
30
25
20
Stress (N/mm2)
15
10
5
Strain
0
0
0.0002 0.0004 0.0006 0.0008
Room temperature
50
o
C @ 1 hr
50
o
C @ 3 hr
Room temperature
150
o
C @ 1 hr
150
o
C @ 3 hr
0.001 0.0012 0.0014
30
35
25
20
Stress (N/mm2)
15
10
5
Strain
0
0
0.0002 0.0004 0.0006 0.0008 0.001 0.0012 0.0014 0.0016
30
35
25
20
Stress (N/mm2)
15
10
5
Strain
0
0
0.0002
Room temperature
250
o
C @ 1 hr
250
o
C @ 3 hr
30
35
25
20
Stress (N/mm2)
15
10
5
Strain
0
0
0.0005 0.0010.0020.0015
0.0004 0.0006 0.0008 0.001 0.0012 0.0014 0.0016
Room temperature
200
o
C @ 1 hr
200
o
C @ 3 hr
30
35
25
20
Stress (N/mm2)
15
10
5
Strain
0
0
0.0002 0.0004 0.0006 0.0008 0.001 0.0012 0.0014 0.0016 0.0018
100
o
C @ 1 hr
100
o
C @ 3 hr
Room temperature
JOURNAL OF STRUCTURAL ENGINEERING 225
Vol. 43, No. 2, JUNE - JULY 2016
Stress (MPa) Strain at
27oC 50oC 100oC 150oC 200oC 250oC
0000000
2.8308 6.67E-05 3.333E-05 3.333E-05 4.444E-05 3.333E-05 4.444E-05
5.6617 0.000144 0.000111 0.0001222 0.000167 0.0001556 0.0001222
8.4925 0.00021 0.0002222 0.0002111 0.000233 0.0002556 0.0002
11.3234 0.00032 0.0003 0.0003444 0.000322 0.0003667 0.0002667
14.1542 0.00037 0.0003778 0.0005111 0.0004 0.0004889 0.0003556
16.9851 0.00045 0.0004556 0.0006333 0.0004889 0.00066667 0.00046667
19.8159 0.000544 0.0005333 0.0007667 0.0005778 0.00083333 0.00058889
22.6468 0.000622 0.0006111 0.0008889 0.0006778 0.00103333 0.0007
25.4777 0.000755 0.0007222 0.0010333 0.0008222 0.00121111 0.00088889
28.3085 0.000988 0.0009111 0.0011667 0.0009556 0.0014 0.00113333
30.0071 0.001344 0.0011222 0.0013 0.0012 0.0016 0.00156667
33.9702 - 0.0012889 0.0014333 0.0014556 0.00181111 0.00187778
36.8011 - 0.0014556 0.0016556 0.0016889 0.00208889 0.00215556
39.6319 - - - 0.0019666 0.00224444 0.00246667
42.4628 - - - 0.0021666 0.00245556 -
w/c ratio of 0.25. The estimated batch quantities per
cubic meter of concrete were: cement, 671.81 kg;
kg and water, 167.95 litres. The optimum dosages of
and 1.5% of quantity of cement respectively from the
previous investigation.
Tests were conducted on 150 mm size cubes and
150 mm diameter and 300 mm height cylindrical
specimens. The specimens were heated to different
temperatures of 50, 100, 150, 200 and 250oC for different
durations of 1, 2, 3 and 4 hour at each temperature.
After the heat treatment, the specimens were brought
to room temperature and tested for Young’s moduli and
compressive strength.
EXPERIMENTAL RESULTS
Compressive strength
The cubes were casted, cured for 28 days and heated
at different temperatures for 1, 2, 3 and 4 h. They were
tested for compressive strengths as per the code IS : 516-
19598. The average values of compressive strengths are
calculated and tabulated as shown in Table 1.
Young’s modulus
The cylinders were casted with M100 grade concrete
and cured for 28 days. They were heated at different
temperatures for 1 and 3 hours. They were tested for
Young’s modulus. The average values of stresses and
strains are tabulated as shown in Tables 2 and 3.
The areas under stress-strain curves
S. No. Cylinders exposed to Area under stress-strain
curve (N/mm2)
1 27oC 0.1245042
2 50oC for 1 hour 0.220316088
3 50oC for 3 hours 0.207637025
4 100oC for 1 hour 0.364687748
5 100oC for 3 hours 0.254950068
6 150oC for 1 hour 0.236052792
7 150oC for 3 hours 0.397578104
8 200oC for 1 hour 0.480317703
9 200oC for 3 hours 0.49377998
10 250oC for 1 hour 0.273284591
11 250oC for 3 hours 0.271969877
The areas under stress strain curves are calculated
226 JOURNAL OF STRUCTURAL ENGINEERING
Vol. 43, No. 2, JUNE - JULY 2016
for the curves shown in Fig. 4 when the cylinders are
exposed to elevated temperature at 1 hour and 3 hour
durations
RESULTS AND DISCUSSIONS
The max compressive strength of 148.23 N/mm2 was
obtained when the cubes were heated at 100oC for 1
hour duration. It is noticed that the compressive strength
increased continuously when the cubes were heated
upto 100oC and beyond that those values get reduced.
In Young’s modulus experiment also, the maximum
values of strain were noticed when the cylinders heated
at 100oC. The strain values are noticed to increase with
the raise of temperature upto 100oC and they started to
decrease again beyond 100oC. It is noticed from the Fig.4
that with the increment of temperature, the stress strain
increases more than the rate of increment in stress.
CONCLUSIONS
On the basis of the experimental work with ranging
temperature from 50 to 250oC, the following conclusions
are drawn.
1. The compressive strengths of M100 concrete
are increased initially upto a temperature of 50 -
100oC and beyond that they got reduced rapidly
with increasing the temperature
2. The compressive strengths are lost very much
when they are heated at 250oC
3. The stress vs strain graphs were drawn and it was
loading and it is varying gradual at later stages.
4. The stress strain curve at any temperature with
3 hr duration falls below the curve drawn at the
same temperature with 1 hr duration.
5. The areas under stress-strain curves are also
calculated and it was noticed that the max. area
obtained at situation where cylinders were heated
at 200oC for 3 hours.
REFERENCES
1. Ravindrarajah, R., “Residual compressive and
tensile strengths for high strength concrete exposed
to high temperature upto 800oProc. Intl. Conf.
on HPHSC
2. Potha Raju, M,, Shobha, M., and Rambabu,
Magazine of Conc. Res.,
3. Sujith Ghosh, and Karim W. Nasser, “Effects
of high temperature and pressure on strength
ACI Mat. Jl., Vol. 93, No. 1, 1996,
4. Randall Lawson, J., Long T.P., and Davis, F.,
“Mechanical properties of high strength concrete
after exposure to elevated temperatures
National Institute of Standards and Technology,
Gaithersburg, NISTIR 6475, 2000.
5. Castilo. C., and Durrani, A.J., “Effect of transient
high temperature on high strength concrete, ACI
Mat. Jl.
6. Kodur, V.K.R., and Phan, L.T., “Critical factors
concrete systems, Fire Safety Jl., Vol. 42, 2007,
7. ACI 211.4R-93 - Guide for Selecting Proportions
for High strength Concrete with Portland cement
and Fly ash.
8. IS : 516-1959 - Indian Standard Methods of tests
for Strength of concrete.
(Discussion on this article must reach the editor before
September 30, 2016)