Early Age Properties of High-Performance Concrete

High Performance Concrete is used to not only minimize the environmental footprint of the cement and concrete industry, but also to enable the design and rapid construction of taller and more slender structures. Despite the significant change in concrete property requirements, the properties of concrete as used during design of concrete structures are mostly still based on 28-day water cured compressive strength, stiffness, long term drying shrinkage and creep. The relevance of these measured properties on the actual behaviour of the structure should be questioned as high strength concrete is known to have low water/cement ratios resulting in significant early age shrinkage, which is currently not taken into account by designers. This paper is based on a study where the early age properties of concrete was investigated, with specific focus on the first 24 hours after casting. The effect of factors such as low water/cement ratio, admixtures, ambient and material temperatures, shutter type and cast volume on properties such as setting time, early age shrinkage, strength development and stiffness was studied and observed trends discussed in this paper.