Synergistic effect of pre-carbonated slurry and mixing sequence on the performance of self-compacting recycled aggregate modified mortar

• Main Authors: Li, Lufan, Ling, Tung-Chai, Cheng, Quan, Mo, Kim Hung
• Format: Article
• Published: Springer Netherlands 2021
• Subjects: GF Human ecology. Anthropogeography; TA Engineering (General). Civil engineering (General)
• Online Access: http://eprints.um.edu.my/26688/

Recycled concrete aggregate (RCA) obtained from construction and demolition waste has been widely studied for its feasible uses to replace natural aggregate in different types of concrete products. For the past few decades, efforts have been made to modify or/and improve conventional mixing approaches for the use of RCA in concrete, such as two-stage mixing approach, paste wrapped recycled aggregate approach, etc. However, there was no direct comparison between these approaches. Therefore, this paper investigates the synergistic effect of pre-carbonated slurry and concrete mixing sequence on the performance of self-compacting modified mortar (SMM) containing RCA and aims to compare with other four mixing approaches. Fresh properties and mechanical strengths of SMM and the characterization of interfacial transition zone were studied and compared. Results proved that a denser matrix and an interfacial transition zone (ITZ) with a better quality reflected a better mechanical performance. Among five mixing approaches, SMM samples produced by pre-carbonation approach had slightly larger drying shrinkage, but exhibited enhanced flowability and reduced permeable voids. The compressive strength and flexural strength increased by about 12.3% and 12.0% compared to those made by normal mixing sequence. Backscattered electrons (BSE) images and Vickers microhardness results also revealed a denser interface between new cement matrix and RCA for the sample prepared with pre-carbonation approach. GRAPHICS] .