Preparation of reactive urchin-like recycled concrete aggregate by wet carbonation: Towards improving the bonding capability of the interfacial transition zone in recycled aggregate concrete

Peiliang Shen, Zhenjiang Gu, Jianxin Lu, Yangyang Zhang, Yi Jiang, Dongxing Xuan, Shipeng Zhang, Chi Sun Poon

Research output: Journal article publicationJournal articleAcademic researchpeer-review

4 Citations (Scopus)

Abstract

To enhance the bonding capability between recycled concrete aggregate (RCA) and paste, an innovative carbonation method was developed to modify the surface characteristic of RCA by promoting the formation of needle-like aragonite using accelerated carbonation in Mg(NO3)2 solution under an elevated temperature (75 °C). The evolution of surface microstructure, phases and reaction kinetics was investigated using multiple testing methods including scanning electron microscopy, nanoindentation, X-ray diffraction, etc. The results revealed that reactive urchin-like RCA could be prepared within less than an hour after exposing to CO2. The urchin-like wrapping with a thickness of about 100 μm was seen rapidly grown on the surface of RCA, consisting of an outermost layer of aragonite coating, a thin layer of brucite and a silica-rich layer. The mineral wrapping induced by carbonation significantly modified the roughness, topography and geochemistry of RCA's surface entirely, contributing to enhanced bonding strength between RCA and new mortar (33.54%).

Original languageEnglish
Article number105235
JournalCement and Concrete Composites
Volume143
DOIs
Publication statusPublished - Oct 2023

Keywords

  • Bonding strength
  • Carbonation
  • Kinetics
  • Recycled concrete aggregate
  • Urchin-like aragonite

ASJC Scopus subject areas

  • Building and Construction
  • General Materials Science

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