Sustainability Assessment of Green Asphalt Mixtures: A Review

Abstract

During recent decade, the pavement sustainability has received much attention by road agencies, companies, governments and research institutes. The aim of this paper is to introduce and evaluate the sustainability of the technologies developed or underdeveloped to address environmental issues of asphalt mixtures, and the waste materials and by-products that can be recycled and reused in asphalt production. Warm Mix Asphalt (WMA) technology, the most popular waste materials to substitute neat binder (crumb rubber modifier (CRM), recycled plastic (RP), vacuum tower bottoms (VTB)) and/or virgin aggregates (reclaimed asphalt pavement (RAP), reclaimed asphalt shingles (RAs), construction and demolition (C and D) wastes, steel and copper slags), and bio-binders were evaluated with respect to their environmental and economic benefits and engineering performance as the main components of pavement sustainability. The performance evaluation was carried out by examining rutting, moisture susceptibility, thermal and fatigue cracking resistance. Two main environmental impacts, greenhouse gas (GHG) emission, and energy consumption were considered to study the environmental effects of these technologies and materials. Additionally, the economic effect was investigated considering initial cost and long-term benefit. Results of investigation illustrated that although each individual technology and waste material is valuable in terms of performance and/or the environment, specific combinations such as WMA + RAP, WMA + CRM, RAP + CRM, and WMA + CRM + RAP lead to further benefits. Notably, these combinations suffer from a lack of comprehensive economic analysis, thus, their sustainability cannot be fully assessed and is prone to future studies.

Recycling of Waste Materials for Asphalt Concrete and Bitumen: A Review

“…The use of waste materials as an additive can reduce the mixing temperature depending on the devised mixing method. This process can reduce the usage of fuel and minimize emissions [75]. Waste materials can be added to asphalt concrete and bitumen in different forms depending on the type of waste and characteristics.…”

A Review of the Utilisation of Recycled Waste Material as an Alternative Modifier in Asphalt Mixtures

“…The use of recycled waste materials in asphalt mixture and asphalt binder is a method for managing waste material sustainably and to produce a superior binder for constructing asphalt mixture [135,136]. Waste materials have promising potential in terms of economic and environmental benefits.…”

Laboratory Investigation of Aging Resistance for Rubberized Bitumen Modified by Using Microwave Activation Crumb Rubber and Different Modifiers

“…Excessively high viscosity leads to a higher operating temperature during rubberized bitumen mixture production, which makes the STA behavior of binders more important. WMA is an effective way to decrease the viscosity of rubberized bitumen, while due to lower viscosity, the processing and compaction temperature of bitumen mixtures will decrease significantly [ 22 , 23 ]. Some researchers indicated that WMA effectively improved the rutting resistance after the aging process, and the Sasobit-modified mixture showed the highest load cycle among the mixtures [ 24 , 25 ].…”