Influence of moisture content on CO2 uptake in lightweight concrete subject to early carbonation

• Published in: Journal of sustainable cement based materials Vol. 2; no. 2; pp. 144 - 160
• Main Authors: Morshed, Abu Zakir, Shao, Yixin
• Format: Journal Article
• Language: English
• Published: Routledge 01.06.2013
• Subjects: early-age carbonation curing; lightweight concrete; strength gain; uptake
• ISSN: 2165-0373; 2165-0381
• DOI: 10.1080/21650373.2013.797373

Early-age carbonation curing of fresh concretes has shown its capacity to accelerate the production, recycle CO 2 , and to improve the concrete performance. The challenge facing this technology is the moisture content in fresh concrete which impedes CO 2 diffusion. This paper studies the effects of moisture content on carbonation reactivity of lightweight concretes (LWCs). The moisture content in LWC was adjusted by varying (1) the water to cement ratio, (2) the moisture carried in by lightweight aggregates, (3) the moisture removed by forced fan drying, and (4) the externally added water by surface spray as compensation of water loss. The performance of the carbonated concretes was evaluated by carbon uptake, strength gain, plastic shrinkage, and pH values. A process involving vibration compact forming, preconditioning, carbonation, water compensation, and subsequent hydration proved to be effective in achieving high degree of carbonation and hydration.