Effect of accelerated carbonation curing on near surface properties of concrete
Devender Sharma, Shweta Goyal
Abstract
Accelerated carbonation curing (ACC) is one of the emerging techniques to sequester CO2 in concrete. The present study focuses on assessing the near surface properties of concrete subjected to ACC. Freshly cast concrete was subjected to ACC for a period of 6 hours after an initial preconditioning of 2 hours and was followed by water spray till 3 days. Thermogravimetric analysis (TGA) and X-Ray Diffraction (XRD) analysis revealed presence of CaCO3 and increased quantity of CSH gel in near surface of ACC concrete. The findings of XRD and TGA were also confirmed by Scanning Electron Microscopy which exhibited a densification of microstructure due to precipitation of CaCO3 in voids. Mechanical properties and permeation properties of both bulk concrete and near surface concrete were assessed and results were compared with traditional water curing. Compressive strength and abrasion resistance of concrete was found to increase by 30% at the age of 3 days in ACC concrete. Water absorption, sorptivity, chloride permeability and carbonation depth decreased in case of carbonation cured concrete, showing a reduction in permeability of concrete surface. The effect of ACC was more prominent on near surface properties than on bulk properties at later ages and the same were confirmed by performing analysis of variance.