Development of a modified Marshall mix design for Hot-mix asphalt concrete mixed with recycled plastic based on dry mixing processes

Plastic waste, particularly single-use plastic products, is becoming a more significant environmental problem that must be mitigated effectively. Applying thermoplastic waste in the hot-mix asphalt concrete would create an alternative to recycling plastic waste before going to landfills. This study aims to introduce a modified Marshall mix design framework developed for hot-mix asphalt concrete mixed with recycled plastic (ACP). The Marshall mix design method was used as the baseline procedure for the ACP mix design development of the dry mixing process in which plastic was mixed directly with the hot aggregate instead. Two types of recycled plastic, multilayer, and mixed plastics, were employed in the ACP mix design development process. A new parameter of the plastic-to-binder ratio (PBR) and a replacement concept were introduced as add-on steps to the conventional Marshall mix design to appropriately determine an optimum amount of additional plastic and asphalt binder according to the developed mix design. A full series of laboratory tests were also conducted to compare conventional asphalt concrete (AC) and ACP performances. The laboratory test results indicated the superior performance of ACP over AC.

Automated summary

Plastic waste, especially single-use products, is a growing environmental concern that needs to be addressed. This study proposes the use of recycled plastic in hot-mix asphalt concrete as an alternative to landfill disposal. A modified Marshall mix design framework was developed to determine the optimal amount of plastic and asphalt binder for the ACP mix. Laboratory tests showed that ACP outperformed traditional asphalt concrete in terms of performance.