Title : USE OF CO2 FOR PERFORMANCE ENHANCEMENT OF RECYCLED CONCRETE AGGREGATES
Authors : Caijun Shi, Jiake Zhang
Publication : 8 - 10, October 2015
Volume : 1
Pages :
Price : 250
Abstract : The cement paste attached on natural aggregates has a significant effect on the quality of recycled concrete aggregates (RCAs) because it usually has higher porosity and lower strength than natural aggregates. This work attempted to improve the quality of RCAs through carbonation of the attached cement paste. During carbonation reactions?CO2reacted with Ca(OH)2 and calcium silicate hydrate (C-S-H) to form CaCO3 and silica gel, which filled the pores in the attached cement paste. Thus, carbonation increased the density, and decreased the water absorption and crushing values of the RCAs. It thus increased the flowability and compressive strength of the recycled concrete aggregate mortars, and reduced drying shrinkage and chloride migration coefficient. Scanning electron microscope (SEM) examination on the interfacial transition zone (ITZ) in the RCA mortars found that carbonation treatment of RCA improved the ITZ in the RCA mortars.