From composition to the microstructure and durability of limestone ternary blended cements: A systematic review

Abstract

Limestone ternary cements have attracted significant research and commercial attention recently, for technical and environmental reasons. Standardization of these cements is imminent under BS EN197-5. Presently, detailed understanding of the hydration and microstructure evolution of limestone ternary cements from different alumina-rich supplementary cementitious materials (SCMs) exists in the scientific literature; improved reaction kinetics and additional phase assemblages refine the pore structure. However, understanding of the performance of these cements under exposure conditions is less prevalent. In this contribution, we review these data in a way that allows stakeholders to appreciate the capabilities of the different compositions and their performance. We focus our discussion on critically examining the interplay between the cement composition and the microstructure on durability. It is demonstrated that limestone ternary cements offer a pathway for reducing the embodied CO2 of concrete without compromising their performance. The resistance to chloride ingress, sulphate attack and ASR are significantly improved in a manner similar to binary cements. Carbonation and freeze-thaw resistance is generally lower than OPC but adequate air entrainment can offer improvement in freeze-thaw resistance. The challenge to widespread adoption of these cements is evidence of durability under field conditions. To this end, we recommend large-scale field trialling of these cements and understanding of the role of combined exposures on durability and mechanical properties.

Resistance of Concretes to External Chlorides in the Presence and Absence of Sulphates: A Review

“…The early-age improvement in performance induced by the addition of limestone is complemented by its subsequent reaction with aluminates in the SCMs to produce carboaluminate phases. Again, a combination of pore structure refinement and modified phase assemblages can have an impact on chloride binding [102].…”