Title: Investigation of the CO₂ Sequestration by Accelerated Carbonation as a Function of the Composition, Origin, Production Process, and Age of Recycled Concrete Aggregates

Author(s): Sandrine Braymand and Sébastien Roux

Publication: Symposium Paper

Volume: 362

Issue:

Appears on pages(s): 953-965

Keywords: accelerated carbonation, calcimetry, CO₂ capture, parent concrete, RCA

DOI: 10.14359/51742021

Date: 6/18/2024

Abstract:
Accelerated carbonation of recycled concrete aggregates (RCA) is one way to convert them into carbon stores by capturing CO₂ from cement plants. This study investigates the CO₂ captured depending on composition (paste, mortar, or concrete), origin (laboratory, platform), production process (crushing, molding, sawing), and age of RCA. The CO₂ captured is quantified by means of calcimetry (CaCO₃ content evolution). RCA studied ranged in size from 4 to 16 mm (0.16 to 0.63 in.). They were carbonated on a laboratory or semi-industrial scale. It has been shown that the CaCO₃ content of young RCA or RCA protected from natural carbonation, crushed and composed of CEMI is more likely to evolve. It was shown that the cement paste content and the duration of accelerated carbonation increase the amount of CO₂ captured. The composition of the parent aggregates affects the non-carbonated and carbonated CaCO₃ contents, which requires accurate sampling to limit bias in the results. Carbonation efficiency is more difficult to estimate on a semi-industrial scale and the assessment by calcimetric measurement is biased when the parent concrete is made of slag-based cement. The study was carried out within the framework of the French national program FastCarb.