The impact of accelerating admixtures on blended cement hydration for early age strength enhancement

With an ever-increasing focus on sustainable concrete, the use of supplementary cementitious materials (SCMs) has grown and, although SCMs provide improved later age properties, their use can result in reduced early age strength. Chemical admixtures, particularly those that accelerate hydration processes, have the potential to address these deficiencies. Examples of these opportunities for greater early age strength systems have been identified in the literature, whether through the development of new research and commercial products, or through the creative application of existing admixtures. Conventional inorganic and organic accelerators can be applied in novel high order combinations that exhibit a synergistic effect on early strength. A major focus in the literature at present is the use of C-S-H seeds in superplasticiser suspensions or composites, which can elicit very early strength improvement. Such nucleating agents provide sites for hydrate product growth, potentially leading to denser microstructures and improved early age mechanical properties. In this paper, key studies from the past decade are reviewed, covering the application of a range of accelerating admixtures to the enhancement of early age strength in blended cements