Effect of crystallizer treatment on chloride diffusion and microstructure of recycled aggregate concrete. (28th February 2022)

• Record Type: Journal Article
• Authors: Wang, Xianfeng; Du, Guanhong; Cai, Lianmin; Ren, Jun; Wang, Weilun
• Is Part Of: Construction & building materials. Volume 321(2022)
• Publication Date: 2022-02-28
• Subjects: Recycled aggregate -- Crystallizer treatment -- Chloride diffusion -- Interfacial transition zone -- Microstructure; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2021.126273
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: CA treatment reduced the water absorption rate and crushing value of RCA. CA treatment decreased the capillary water absorption of RCA. CA treatment improved the resistance to chloride ion diffusion of RAC. The micro-pores and micro-cracks in ITZ were filled by CA. Abstract: The crystallizer (CA) treatment on recycled concrete aggregate (RCA) can improve its quality and further benefit the utilisation of RCA in manufacturing recycled aggregate concrete (RAC). Unfortunately, the long-term properties of RAC with CA treated RCA have not been fully explored yet. Therefore, this paper is aim to evaluate the performance of CA treatment on RCA and the durability and permeability of corresponding RAC. To achieve the goal, the permeability of RAC with different RCA replacement ratios was investigated by capillary water absorption test and rapid chloride migration test, and the effects of CA on the interfacial transition zone (ITZ) and pore structure were determined through mercury intrusion porosimetry and scanning electron microscope. The results showed that CA treatment significantly improved the chloride diffusion resistance of RAC due to the calcium silicate hydrate (C-S-H) formed by the reaction between CA treatment and calcium-rich hydrates. The formed C-S-H can partially fill the pores and micro-cracks in adhesive mortar and ITZ, compact the microstructure and reduce the pore size, thus improving the permeability of RAC.