Evaporation, settlement, temperature evolution, and development of plastic shrinkage cracks in mortars with shrinkage-reducing admixtures

This paper deals with the development of plastic shrinkage cracks in mortars containing a commercially available shrinkage-reducing admixture (SRA). Mortars containing SRA show fewer and narrower plastic shrinkage cracks than plain mortars when exposed to the same environmental conditions. It is proposed that the lower surface tension of the pore fluid in the SRA mixtures results in less evaporation, reduced settlement, reduced capillary pressure, and lower crack-inducing stresses at the topmost layer of the mortar. It is hoped that by improving the understanding about how SRA work, mixtures containing SRA can be more appropriately designed and utilized in cases where early-age plastic cracking is a potential problem.