The effect of crumb rubber modification on the physical properties of porous asphalt / Mohd Rasdan Ibrahim
Open graded friction course (OGFC) or porous asphalt (PA) system consists of a layer of porous asphalt, a layer of granular sub-base and a layer of crushed stone base course that acts as a reservoir. This allows water to infiltrate the surface course and stored at the base before the water reache...
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| Format: | Thesis |
| Published: |
2018
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| Online Access: | http://studentsrepo.um.edu.my/8852/1/Mohd_Rasdan_Ibrahim.pdf http://studentsrepo.um.edu.my/8852/6/rasdan.pdf http://studentsrepo.um.edu.my/8852/ |
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| Summary: | Open graded friction course (OGFC) or porous asphalt (PA) system consists of a
layer of porous asphalt, a layer of granular sub-base and a layer of crushed stone base
course that acts as a reservoir. This allows water to infiltrate the surface course and
stored at the base before the water reaches the subgrade. The popularity of this type of
pavement is due to a number of advantages it have such as reduction in splash and
spray, reduction of the risk of wet skidding and hydroplaning with lower noise
generated from the traffic friction. In tropical counties such as Malaysia where the
average monthly precipitation can be as high as 314mm, the use of open graded
pavement system can be extremely beneficial. Due to its high porosity, porous asphalt
can face problems such as faster oxidation rate of binder and loss of adhesion due to
contact with water. Modified bitumen was utilised in the hope that it would further
improve the performance of the porous asphalt. Crumb rubber modification by the wet
process has been shown to have the ability to improve the rutting resistance, resilience
modulus and fatigue cracking resistance of asphaltic mixes. This is due to the alteration
to the property of the bituminous binder in terms of the viscosity, softening point, loss
modulus and storage modulus. The outcome properties of crumb rubber modified
bitumen (CRMB) is very sensitive and are highly governed by the mixing process
which is dependent on external factors such as the mixing temperature, mixing duration
and type; and internal factors such as type of bitumen, crumb rubber quantity, particle
size, and type. This research studies the effect of particle size and crumb rubber content
to the durability of an OGFC manufactured according to the Specifications for Porous
Asphalt produced by the Road Engineering Association of Malaysia (REAM) modified
with crumb rubber using the wet process. This study also conducted to determine the relations of rubber size, rubber content, and binder content in determination of optimum
binder content (OBC) for OGFC with accordance to REAM specification. In order to
analyse the performance of the binders and porous asphalt, a series of binder tests and
bituminous mixtures tests were performed. In addition, multiple linear regression
(stepwise method) was used for statistical analysis for which the main objective was to
develop an equation (regression model) that could be used for predicting the
performance of the mixtures for all factors engaged. A secondary purpose was to use
regression analysis as a means of explaining the causal relationship among the factors
(significant level). In the final analysis, the author found that rubber size, rubber
content and binder content significantly affected the performance of porous asphalt.
Moreover, this study showed that binder content between 6% and 6.5% is advisable to
be used as the OBC to allow a certain level of tolerance when producing rubberized
bitumen and at the same time ensuring a high quality product. |
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