CO2 Curing for Enhanced Early Age Strength in Saw Dust Biochar Augmented Cement Mortars

Abstract

Cement and concrete industry is striving to offset its carbon dioxide (CO2) emissions predominantly using alternative materials such as fly ash and slag. But growing global demand for infrastructure requires vast amount of cement and hence associated CO2 emissions. It is need of the hour to not only reduce the CO2 emissions of cement but also to remove and sequester CO2 from the atmosphere. Biochar as a material and CO2 curing as a process were chosen in this study. Three experimental studies are conducted to evaluate the optimum dosage of saw dust biochar (SDBC) in cement, optimum CO2 curing regime, and the effect of CO2 curing process on the early age strength attainment of SDBC augmented cement mortars. XRD and SEM analytical techniques are used to understand the influence of CO2 curing on microstructure. It is understood from this study that 2% SDBC and 2-h CO2 curing is capable of doubling the strength in one day and extended water curing shall further enhance the early age strength. However, the efficacy of CO2 curing process is more prominent in cement mortars without SDBC. This study further presented the possible reasons for lower efficacy of SDBC. Further investigation on compatibility of different biochars, particularly with calcium or magnesium baring phases, may prove beneficial with CO2 curing regime resulting in early age strength gain and CO2 sequestration.