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.