Mechanical Property and Durability Analysis of Crumb
Rubber Modified Concrete
Y B Jiao
1,2
, H C Cai
2
, M S Zhang
2,*
, T Sha
2
, Y Q Feng
2
and H Chen
2
1
Key Laboratory of Urban Security and Disaster Engineering of Ministry of
Education, Beijing University of Technology, Beijing, China
2
College of Transportation, Jilin University, Changchun, China
Abstract. With the increasing of waste rubber tires, their disposal leads to great threat to
environment. Crumb rubber produced from waste tires can be used to modify the ordinary
concrete, which can realize the utilization of waste resources. In this study, crumb rubber with
particle size 2-4mm was used to replace the coarse aggregates of ordinary concrete.
Corresponding mechanical and durability properties including compressive strength, splitting
tensile strength, axial compressive strength, elastic modulus, freeze-thaw resistance and
sulfate resistance performances were measured and analyzed. The results reveal that crumb
rubber presents negative effect on mechanical properties and positive effect on durability
performance of concrete.
1. Introduction
In recent years, waste utilization has got wide attentions for sustainable development. Reuse of waste
materials can be conducive to not only environmental protection, but also reducing consumption of
natural resources. Millions of used tires were generated because of the increasing number of vehicles.
The number of end-of-life tires (ELTs) is about 200 million each year in China, which presents an
increasing rate of over 10% [1, 2]. Disposal of these tires has become a serious social problem due to
the difficulty to degrade.
Crumb rubber can be applied to modify concrete, which is an effective way for disposal of waste
tires [3]
.
Si et al. [4] investigated the laboratory performances of self-consolidating concrete modified
by rubber. The results revealed that mechanical properties were reduced because of the addition of
crumb rubber. However, the durability performances were improved. Bisht and Ramana [5]
evaluated the mechanical and durability properties of crumb rubber concrete. It has been observed
that workability, compressive and flexural strength decrease with the increasing of crumb rubber.4%
replacement of fine aggregates for crumb rubber can be used for non-structural elements. Xue et al.
[6] demonstrated the compressive properties of rubber concrete at temperatures of -30 and 20°C. The
results showed that the deformation ability of rubber concrete at -30°C was much better than ordinary
one. Liu et al. [7] investigated the mechanical and durability performances of rubber concrete. The
results revealed that crumb rubber presents negative effects on mechanical properties and positive
effects on durability performance. 20% replacement of fine aggregate and 5% replacement of mixture
present favorable performances.
Jiao, Y., Cai, H., Zhang, M., Sha, T., Feng, Y. and Chen, H.
Mechanical Property and Durability Analysis of Crumb Rubber Modified Concrete.
In Proceedings of the International Workshop on Materials, Chemistry and Engineering (IWMCE 2018), pages 291-296
ISBN: 978-989-758-346-9
Copyright © 2018 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved
291

In this study, crumb rubber with particle size 2-4 mm was used to replace the coarse aggregates in
ordinary concrete. Compressive strength, splitting tensile strength, axial compressive strength and
elastic modulus were used to evaluate the effects of crumb rubber on mechanical performances of
concrete. Freezing-thawing resistance and corrosion resistance were demonstrated to evaluate
corresponding durability performances.
2. Materials and methods
2.1. Materials
Cement used in this study was P. C. 32.5, which is composite Portland cement with compressive
strength 32.5 MPa after 28d standard curing. Its physical properties were measured and listed in
Table 1. Coarse aggregates were limestone, whose properties were listed in Table 2. Fine aggregate
was river sand with finesse modulus of 3.0. The particle size of 2-4 mm for crumb rubber was used
as replacement material, whose apparent density is 1200 kg/m
3
. Crumb rubber was irregularly
polygon, corresponding appearance was shown in Figure 1. Particle size distributions of fine
aggregate and crumb rubber were shown in Figure 2.
(a) (b)
Figure 1. Crumb rubber (a: appearance, b: particle size).
0
10
20
30
40
50
60
70
80
90
100
0.1110
Passing percentage (%)
Sieve size (mm)
Crumb rubber
Fine aggregate
Figure 2. Particle size distribution of fine aggregate and crumb rubber [7].
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292

Table 1. Physical properties of cement.
Items Measured values
Technical criterion
[8]
Fluidit
y
(mm) 184 ≥180
Initial settin
g
time (min) 180 ≥45
Final settin
g
time (min) 260 ≤600
Flexural stren
g
th (28d, MPa) 6.7 ≥5.5
Compressive stren
g
th (28d, MPa) 35.9 ≥32.5
Table 2. Physical properties of coarse aggregate.
Items Measured values Technical criterion [8]
Cla
y
content (%) 0.4 ≤1.0
Elon
g
ated particle content (%) 7 ≤15
Specific
g
ravit
y
(
g
/c
m
3
) 2650 ≥2600
Crushin
g
value (%) 8 ≤16
2.2. Mixture Proportion
The mixture proportion for plain concrete (PC) was determined according to specification for mix
proportion design of ordinary concrete (JGJ 55-2011) [9]. Crumb rubber concrete (CRC) was
produced by replacing coarse aggregate in PC by crumb rubber. The replacement principle is to
guarantee an equal volume between crumb rubber and coarse aggregate. The replacement levels
varied from 5% to 20%. The mixture proportions used in this study were listed in Table 3.
Table 3. Mixture proportions for crumb rubber concrete
Rubber
content
(%)
Mix
Wei
g
ht per cubic meters (k
g
)
Water Cement Fine aggregate Coarse aggregate Crumb rubber
0 PC 180 430 593 1197.0 0
5 CRC-1 180 430 593 1135.8 26.6
10 CRC-2 180 430 593 1074.6 53.2
15 CRC-3 180 430 593 1016.1 79.8
20 CRC-4 180 430 593 957.6 106.4
2.3. Characterization methods
Concrete specimens were produced according to JTG E30-2005 [10]. Cube specimens
(150mm×150mm×150mm) were used to evaluate the performances of compressive strength, splitting
tensile strength and durability properties, while prism specimens (150mm×150mm×300mm) were
produced for axial compressive strength and modulus of elasticity. Compressive strength, axial
compressive strength, modulus of elasticity, splitting tensile strength for PC and CRC were measured
after the specimens cured for 28 days according to GB/T 50081-2002 [11]. As for durability
performance including freezing-thawing resistance and sulfate resistance, they were tested after the
specimens cured for 60 days according to GB/T 50082-2009 [12]. Three specimens were used for
each test and corresponding average value was treated as representative one.
Strength loss rate was used to evaluate the freezing-thawing resistance performance of CRC,
which can be calculated by
Mechanical Property and Durability Analysis of Crumb Rubber Modified Concrete
293

100
co cn
c
co
ff
f
f
−
Δ= ×
(1)
where
c
f
Δ is strength loss ratio of concrete after freeze-thaw effects,
co
f
and
cn
f
are compressive
strength before and after 25 times of freeze-thaw cycles.
As for sulfate resistance performance, specimens were firstly immersed into sulfate solution and
then dried at temperature 80°C. Anti-corrosion coefficient of specimens after 15 cycles sulfate
soaking and drying was calculated by
100
cn
f
co
f
K
f
=×
(2)
where
f
K is anti-corrosion coefficient of concrete after sulfate soaking and drying,
co
f
and
cn
f
are
compressive strength before and after 15 times of sulfate attack.
3. Results and discussions
3.1. Mechanical properties
y = -0.5044x + 34.93
R² = 0.9439
0
5
10
15
20
25
30
35
40
0 5 10 15 20
Cubic compressive strength
(MPa)
Rubber content (%)
y = -0.2642x + 23.776
R² = 0.9684
0
5
10
15
20
25
0 5 10 15 20
Axial compressive strength
(MPa)
Rubber content (%)
(a) (b)
y = -0.0246x + 2.412
R² = 0.9174
0
0.5
1
1.5
2
2.5
3
0 5 10 15 20
Splitting tensile strength
(MPa)
Rubber content (%)
y = -0.5188x + 31.318
R² = 0.9818
0
5
10
15
20
25
30
35
0 5 10 15 20
Modulus of elasticity (GPa)
Rubber content (%)
(c) (d)
Figure 3. Relationships between mechanical properties and rubber content (a: cubic compressive
strength, b: axial compressive strength, c: splitting tensile strength, d: modulus of elasticity).
The relationships between cubic compressive strength, axial compressive strength, splitting tensile
strength, modulus of elasticity and crumb rubber content were shown in Figure 3, respectively. As
can be seen from the results, mechanical properties of rubber concrete decrease with the increasing of
rubber content, which have favourable linear relationships. It revealed that replacement of coarse
aggregate for crumb rubber presents negative effects on mechanical properties of concrete. Moreover,
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the downtrends are relatively slow for mechanical properties of concrete, when the rubber content is
less than 10%. The reasons lie in that rubber particles is elastic material, whose compressive strength
is weaker than coarse aggregate. Moreover, adhesive ability between aggregate and cement mortar is
better than that between crumb rubber and cement mortar. Therefore, replacement of coarse
aggregate by crumb rubber lead to the reduction of concrete.
Ratios between splitting tensile strength and cubic compressive strength (λ) were also calculated,
which were shown in Figure 4. The results revealed that λ of PC increases after the addition of crumb
rubber. Replacement of coarse aggregate for crumb rubber can improve the brittleness of concrete.
6.6%
6.8%
7.0%
7.2%
7.4%
7.6%
7.8%
8.0%
0 5 10 15 20
λ
Rubber content (%)
Figure 4. Relationships between λ and rubber content.
3.2. Durability performance
Strength loss rates of PC and CRC after 25 times of freeze-thaw cycle were calculated. Meanwhile,
anti-corrosion coefficients for PC and CRC after 15 times of sulfate attack were also obtained. The
results were shown in Figure 5. The results revealed that compressive strength loss rate of concrete
decreases with the increasing of rubber content, and anti-corrosion coefficient increases with the
increasing of rubber content. Replacement of coarse aggregate for crumb rubber can improve the
freezing-thawing resistance and corrosion resistance abilities. Freeze-thaw resistance improves by
34.5% when the rubber content is 5%.
0
1
2
3
4
5
6
7
0 5 10 15 20
Strength loss rate (%)
Rubber content (%)
0.96
0.965
0.97
0.975
0.98
0.985
0 5 10 15 20
Anti-corrosion coefficient
Rubber content (%)
(a) (b)
Figure 5. Relationships between durability performances and rubber content (a: strength loss rate, b:
anti-corrosion coefficient).
4. Conclusions
In this study, crumb rubber with particle size 2-4mm was used to replace the course aggregate and
realize the modification of concrete. Mechanical and durability performances of crumb rubber
modified concrete were demonstrated. Following conclusions can be obtained:
Mechanical Property and Durability Analysis of Crumb Rubber Modified Concrete
295

(1) Addition of crumb rubber into concrete to replace the course aggregates presents negative
effects on cubic compressive strength, axial compressive strength, splitting tensile strength and
modulus of elasticity.
(2) Ratios between splitting tensile strength and cubic compressive strength show rising trend
with the increasing of rubber content. Replacement of coarse aggregate for crumb rubber can
improve the brittleness of concrete.
(3) Compressive strength loss rate of concrete decreases with the increasing of rubber content, and
anti-corrosion coefficient increases with the increasing of rubber content. Replacement of coarse
aggregate for crumb rubber can improve the freezing-thawing resistance and corrosion resistance
abilities of concrete.
Acknowledgment
The authors express their appreciation for the financial support of National Natural Science
Foundation of China (51408258); High Level Talent Support Program of BJUT (2017); China
Postdoctoral Science Foundation funded project (2014M560237); Science & Technology
Development Program of Jilin Province (2018-1-6, 20180201026SF).
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