CO2 Curing of Reactive Powder Concretes Modified by Waste Limestone Powder

Incorporating waste stone powders into the production of reactive powder concretes (RPCs) can be eco-friendly. Since high cementitious material content is used in producing RPCs, CO2, as a harmful greenhouse gas, was used for carbonation curing in this study. For this purpose, waste limestone powder was substituted by 0%, 18%, 36% and 54% of silica sand and the specimens were cured in water for up to 90 days in a CO2 chamber for up to 48 hours. The physical and mechanical properties of the concrete and the specimens' CO2 uptake were measured at different ages. Results showed that the 28-day compressive strength of the moist cured RPCs was higher than 100 MPa and the properties of the RPCs were improved by increasing limestone substitution. CO2 curing of the RPCs significantly increased the samples' compressive strength and limestone-powder substitution as silica sand significantly decreased the carbonation and autogenous shrinkages of the RPCs. Moreover, carbonation curing can make eco-friendly limestone-modified RPCs, where their properties are improved. KEYWORDS: CO2 curing, Reactive powder concrete, Waste limestone powder, Shrinkage.