Evaluating the Mechanical Properties and Carbonation Resistance of High Slag Cement Concretes

Ground granulated blast furnace slag (GGBFS) has been incorporated into cement as a low-carbon alternative to clinker, yet its slower hydration can affect early-age performance. This study evaluates several mechanical properties as well as the carbonation resistance of concretes prepared with high-GGBFS cements, CEM III/A (42 % GGBFS) and CEM III/B (70 % GGBFS), compared against a commonly used reference CEM II/B-M (17 % GGBFS). Several mixes were tested for compressive, direct tensile, flexural tensile, and pull-off bond strengths, as well as elastic modulus, Poisson’s ratio, and carbonation resistance for selected mixes. High-GGBFS concretes exhibited moderately lower tensile and pull-off bond strengths at 28 days despite similar compressive strengths, but all mechanical properties equalled or surpassed the reference mix at 91-182 days. Carbonation resistance was slightly reduced in the CEM III/B mixes, and minimal differences were observed in elastic properties. Overall, the findings highlight the potential of high-GGBFS cements to substantially lower the carbon footprint of concrete production without sacrificing long-term mechanical performance, if design and construction practices account for their slower early-age strength development.