CO2 sequestration of fresh concrete slurry waste: Optimization of CO2 uptake and feasible use as a potential cement binder
Document Type
Article
Publication Date
12-1-2020
Abstract
Acceleration carbonation is a promising advanced technique to transform solid waste with the aid of CO2 into stabilized value-added material. In this study, the potential of concrete slurry waste (CSW) as a CO2 sequester and as new supplementary cementitious material (SCM) were examined. The effects of two process parameters, namely water-to-solid (w/s) ratio and reaction time on maximum CO2 uptake capacity of CSW were evaluated using response surface methodology (RSM). The response surface indicated that the w/s ratio had a significant effect on CO2 uptake, and when exceeding 0.4 caused an obvious decrease in CO2 uptake. This mainly resulted in a liquid saturation and hence hinders the diffusion of CO2 reaction. As expected, an increase in reaction time enhanced the capability of CO2 uptake and reached the saturation level at about 72 h. The maximum CO2 uptake of CSW was 20.4 % (i.e. 204.35 g/kg) at optimal condition (w/s ratio of 0.25 and reaction time of 72 h). Thus, it is roughly estimated that about 4-8 million Mt of CO2 per annum can be permanently captured from the 19.8-39.6 million Mt of CSW produced yearly. In addition, the carbonated CSW demonstrated a strength activity index of more than 75 and could be potentially regarded as SCM.
Keywords
CO2 sequestration, Concrete slurry waste (CSW), Accelerated carbonation, Optimization, Strength activity index
Divisions
fac_eng,sch_civ
Publication Title
Journal of CO2 Utilization
Volume
42
Publisher
Elsevier
Publisher Location
THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND