Multi-objective optimisation of hot in-place recycling of asphalt pavement considering environmental impact, cost and construction quality

ABSTRACT

Hot in-place recycling (HIR) of asphalt pavement is deemed as an environmental-friendly maintenance measure. Cost and construction quality were concerned conventionally in the HIR practice despite the HIR construction process itself producing substantial environmental burdens. In this study, a multi-objective optimisation model was therefore developed considering the environmental impact, cost and construction quality for HIR practice. Environmental impact was quantified based on discrete-event simulation (DES), which can capture the uncertainty of construction activity and the idling state of equipment. Cost comes from material input, fuel consumption and equipment usage. Compaction degree and construction reliability were used as proxies of construction quality. The non-dominated sorting genetic algorithm II (NSGAII) was employed to solve the multi-objective optimisation problem and obtained 20 sets of Pareto optimal solutions. The results suggested there is an opportunity to reduce the environmental impact and cost to 96.5% and 97.3% and to increase the construction quality to 125.1% compared to the base case. However, these optimisation effects are mutually compromised and cannot be reached simultaneously. Trade-off analysis among objectives was performed and suggested that construction quality generally increases with cost but at the expense of a greater environmental impact. Frequency counting of decision variables of Pareto sets indicated that more influence was observed by truck type than the truck number in the construction process. The developed optimisation model can help the decision maker optimise and customise the construction plan for the HIR project and harvest overall benefits.

KEYWORDS:

• Hot in-placing recycling
• discrete-event simulation
• multi-objective optimisation
• environmental impact
• trade-off analysis

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by National Natural Science Foundation of China: [Grant Number 51878163]; Natural Science Foundation of Jiangsu Province: [Grant Number BK20171359]; Postgraduate Research & Practice Innovation Program of Jiangsu Province: [Grant Number SJCX18_0047, SJLX16_0071].