Feasibility of Waste Plastic-Modified Asphaltic Mix for New Pavement Construction in Malaysia

Overview

Waste plastic modified asphaltic (WPMA) mix utilises a sustainable construction method by recycling waste plastic into an asphaltic mix. In the context of Malaysia, an initial trial section utilising waste plastic additives as part of an asphaltic overlay was conducted in 2021. Since then, there have been approximately 100 pavement rehabilitation projects, of which ten research sites out of these rehabilitation works have been selected for intensive monitoring. 

From the observations and testing at these sites, it was found that the WPMA pavement has been performing well, with no extensive cracks, and is suitable for pavement overlay works. However, the application of WPMA has yet to be implemented in new road construction in Malaysia. A new road construction was proposed using a WPMA mix, for which the key information required is the structural strength of this type of modified asphaltic layer. Due to insufficient data, for the purpose of pavement design, the elastic modulus strength selected is based on the conventional hot mix. Therefore, a study is needed to address the selection of strength parameter values input, particularly for the design elastic modulus strength. 

Indirect Tensile Strength Modulus tests were carried out on WPMA samples to obtain their stiffness for input as the elastic modulus of the WPMA pavement design assumption. Based on the laboratory analysis, the average resilient modulus of plastic waste modified asphalt was found to be 5750 MPa, which is higher than the conventional design elastic modulus of 2000 MPa at 25°C. Therefore, the conventional design assumption is sufficient to cater for the new pavement design using WPMA. For further optimisation, the design assumption could adopt a higher elastic modulus for the WPMA layer. In conclusion, new pavement construction using WPMA is both feasible and potentially cost-saving due to the reduction in asphaltic layer thickness.

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