Carbonation and CO2 reabsorption of cement-based materials: Influence of limestone filler and ground-granulated blast-furnace slag

This study investigates and compares the carbonation depth, carbonation rate and degree of carbonation of mortar specimens made with different binder systems. The interplay and influence of limestone filler (LF) particle size, LF content and ground-granulated blast-furnace slag (GGBFS) on the compressive strength, carbonation depth, carbonation rate and degree of carbonation are evaluated. Specimens were exposed to an accelerated carbonation environment of 3 +/- 0.5% CO2 concentration, 50 +/- 5% relative humidity and a temperature of 23 +/- 2 degree celsius for up to 12 weeks. It was found that: (i) similar to 9.8% LF in Portland limestone cement does not significantly impact the carbonation depth and compressive strength; (ii) the use of 25% GGBFS as a cement replacement in addition to LF increases the carbonated area of specimens; (iii) the use of coarse size LF as cement replacement increases the k-factor of the carbonation rate, which is neglected in BS-EN-16757; and (iv) the use of LF and/or GGBFS in this study increases the clinker degree of carbonation from 60.7% up to 78.8% in the carbonated area.