The Effects of Domestic Plastic Waste on Concrete Properties: Sustainable Replacement of Aggregates

Abstract

Malaysia is the largest contributor to plastic waste disposal in Southeast
Asia. It is due to the fact that, with the existing way of life, users choose
to use plastic in their daily lives without knowing the impact of its use.
Plastic is a material that does not easily break down and dissolve
naturally. It requires a long period of time to break down and
decompose. So, the concept of recycling is one way to save nature and
this concept can also be practiced in the construction sector such as
construction materials. Therefore, this study identifies the appropriate
ratio of cement, water, plastic replacement, and aggregate in the
concrete. In addition, this study determines the effect of domestic
replacement of waste plastic on concrete properties. The third objective
is to compare the concretes with admixtures without plastic with
admixtures with plastic replacement along with fine aggregate and
coarse aggregate. This study focuses on the use of polyethylene
terephthalate (PET) plastic with 10% and 20% replacement levels in
both fine aggregate and coarse aggregate. The appropriate ratio for the
concrete aggregate is identified by using the DoE (Department of
Environment) method. Several tests were conducted to test the
workability of the concrete, namely slump test, density for hardened
concrete, water absorption and compressive strength. Based on the
results obtained, the density of coarse aggregate plastic concretes
(DP10C, DP20C) is higher than that of fine aggregate plastic concretes
(DP10F, DP20F). Meanwhile, the water absorption rate for coarse
aggregate plastic concretes (DP10C) is more lower than fine aggregate
(DP10F) for both 7 days and 28 days curing. As for compressive
strength test, the replacement of concrete with coarse aggregate
(DP20C) is more higher than fine aggregate (DP20F). The replacement
for fine aggregate has a limit up to 10%, if exceeding that percentage,
the strength of concrete will decrease drastically. In conclusion, the
replacement of plastic in concrete has a good effect on the environment
and the concept of sustainable concrete is achieved.