Early CO2 capturing mortar by incorporating a new potential carbide lime waste under controlled CO2 curing

Abstract

Early-age cement paste or mortar can be enhanced by curing it in a CO2 chamber. The study was initiated with investigation on the optimum compressive strength by replacing cement to carbide lime with 0, 5, 10, 15 and 20% of Carbide Lime Waste (CLW) content. The desired CLW mortar at 28 normal curing age was selected and the similar mix proportion was again casted and the fresh CLW mortar was cured for 1,3 and 7 days under controlled CO2 curing. The CO2 concentration and temperature were fixed at 20% and 60% respectively. The compressive strength and depth of carbonation of CLW mortar was investigated. In addition, their microstructural properties under TGA test was analysed at the early curing ages by using cement pastes. It was found that the mortar containing 5% of CLW had the desired optimum compressive strength and UPV under water curing condition. Overall, the strength properties of control mortar and CLW mortar significantly enhanced at early strength gained by controlled CO2 curing as compared to the water curing technique. The used of 5% of CLW as the potential to substitute the cement portion has provide better understanding on CO2 sequestration in cement mortar. The microstructural result shows the CaCO3 precipitation in the CLW mortar was higher than the control mortar as CLW has Ca(OH)2 behaviour which effectively react with CO2 and formed stable CaCO3 precipitation in the mortar.