High-temperature CO2 for accelerating the carbonation of recycled concrete fines
Document Type
Article
Publication Date
7-15-2022
Abstract
Accelerated carbonation of recycled concrete fines (RCF) is one of the effective ways of improving their poor quality for sustainable reuse in the construction industry. Flue gas containing waste heat that is usually discharged into the atmosphere can be reused to enhance the gas-solid re-action of RCF carbonation. Therefore, this study investigates the influence of high temperature (20-140 degrees C) CO2 (with a concentration of 20%) on the carbonation performance of RCF, whereby it is demonstrated that the carbonation efficiency is greatly enhanced by increasing the tem-perature optimally up to 100 degrees C and achieving 21.65% CO2 uptake. Vaterite and calcite are the main carbonation products of the carbonated RCF (CRCF), especially where calcite becomes larger and more stable with a higher temperature of carbonation. The CaCO3 polymorph affects the rate of cement hydration in which the vaterite plays an important role in enhancing the early-age cement hydration reaction, whereas the calcite in the CRCF has less impact due to its more thermodynamically stable characteristic. Overall, it is concluded that the higher carbonation degree of CRCF results in better performance as a cement substitute. Cement paste containing CRCF at 100 degrees C possesses a shorter setting time, higher heat of hydration, and a comparable 28 day strength to that of pure cement paste.
Keywords
High-temperature carbonation, Recycled concrete fines, CaCO3 polymorph, CO2 uptake, Blended cement paste
Divisions
sch_civ
Funders
National Natural Science Foundation of China (NSFC) [Grant No: 51950410584 & 52078202]
Publication Title
Journal of Building Engineering
Volume
52
Publisher
Elsevier
Publisher Location
RADARWEG 29, 1043 NX AMSTERDAM, NETHERLANDS