Assessing Condition on Alkali-Silica Reaction (ASR) Affected Recycled Concrete

Abstract

Many highway and hydraulic structures in North America have been reported to be affected by alkali aggregate reaction (ASR). It is anticipated that most of these structures will be demolished as they approach the end of their service lives. Recycling demolished concrete as aggregates in new concrete is an option that not only reduces the amount of construction demolition waste (CDW) disposed in landfills but also lessens the consumption of non-renewable resources such as natural aggregates. However, the use of recycled concrete aggregate (RCA) in new concrete requires detailed research to make sure that the durability of the recycled material is not compromised, especially if the RCA had been previously affected by ASR. In this research project, coarse recycled concrete aggregate (RCA) is reclaimed and processed from distinct members (i.e. foundation blocks, bridge deck and columns) of an ASR-affected overpass after nearly 50 years of service. RCA concrete mixtures incorporating 50 and 100% replacement are manufactured and stored in conditions enabling further ASR development. Mechanical (i.e. Stiffness Damage Test - SDT) and microscopic (Damage Rating Index - DRI) analyses are performed at a fixed “secondary” induced expansion of 0.12%. Results show that the overall performance of the ASR-affected recycled mixtures depends upon the “past” condition of the RCA particles. Moreover, the DRI was able to capture the “past” and “secondary” induced expansion and damage of affected RCA while the SDT only detected the “secondary” distress development. Lastly, an adapted version of the DRI was proposed to further evaluate the overall damage of recycled concrete along with properly displaying “past” and “secondary” induced distress.