Mix proportioning of high performance concrete

High performance concrete (HPC) is that concrete which meets special performance and uniformity requirements that cannot always be achieved by conventional materials, normal mixing, placing and curing practices. Special performance requirements using conventional materials can be achieved only by adopting low w/c, which necessitates use of high cement content. But judicious choice of chemical and mineral admixtures can reduce the cement content and this results in economical HPC. However, the effect of a mineral admixture on the strength of concrete varies significantly with its properties and replacement levels. Mix proportioning methods of normal concrete cannot adequately account for the large variations in the properties of ingredients. This paper presents a modified mix design procedure, which utilises optimum water content and the efficiency factor of mineral admixture. Results of the experimental investigations on mixes using the modified mix design are presented.