Conditions for the Formation of Alkali-Silica Reaction in Hot Mix Asphalt

Abstract

Alkali-Silica Reaction (ASR) is the well-known durability problem of concrete during its service life. There are many studies on the formation, significance, diagnosis, and prevention of ASR in concrete. Although ASR in concrete is the subject of many studies, there are very few studies on ASR formation in Hot Mix Asphalt (HMA). This is because the high alkali content in the pore solution of concrete, which is one of the main components of ASR, cannot exist in HMA. The conditions required for ASR formation in HMA are also unknown. Recently, a limited number of studies have focused on the use of de-icers and recycled concrete aggregates to investigate the formation of ASR in HMA. The formation of ASR in HMA should be considered as an attractive research topic and raise the question of which conditions lead or will lead to the formation of ASR. Indeed, the main purpose of this study is to investigate the conditions that may cause ASR in HMA, as opposed to the assumption that ASR in HMA cannot be fully observed. The study favours the method of reviewing existing studies and creating a combination of possible conditions for the formation of ASR in HMA.

Application and Performance of RAP in Highway Construction: A Literature Review

“…With the increase in scarcity of virgin materials i.e., aggregates and bitumen, RAP has the potential to partially replace the virgin materials in the mixes. RAP used in the US climbed to 89.2 million tons in 2019 from 76.2 million tons in 2017 [36]. EAPA (European Asphalt Pavement Association) reports that 50 million tons of RAP are recycled throughout all member states of the European Union in its 2020 report [37].…”

“…This is due to the various environmental exploitation and excessive use of natural resources. However, in the construction industry, there has been an increase in the reuse and recycling of industrial waste, by-products, or demolished materials like rubber, polymers, fly ash, RAP, and RCA [4,[34][35][36][37][38]. Since hot-mix asphalt requires burning fossil fuels, the effectiveness of WMA and CMA has been improved by numerous studies.…”