A Study on the Rheological Properties of High Strength Concrete Incorporating Silica Fume

Abstract

Nowadays high strength and high performance concrete are being widely used in various civil engineering practices. Most applications of high strength concrete have been in high rise buildings, long span bridges and some special structural applications. The use of high strength concrete would result in both technical and economical advantage. In high strength concrete it is necessary to reduce the water binder ratio, which in turn will increase the binder content. Superplasticizers are used to achieve the desired workability. There are two types of mineral admixtures which are commonly mixed into the Portland clinker or blended directly with cement nowadays. They can be categorized as crystalline, which are also known as hydraulically inactive additions and pozzolanic which are hydraulically active additions. Silica fume is one of the popular pozzolans used in concrete to get improved properties. The use of silica fume in conjunction with superplasticizers has become the backbone of high strength and high performance concrete. Silica fume is very reactive pozzolan, which is used in concrete because of its fine particles, large surface area and high SiO₂ content. A detailed experimental investigation has been carried out to study the effect of silica fume in conjunction with superplasticizers on some of the properties of fresh concrete. The investigation revealed that by maintaning a constant dosage of high performance superplasticizer along with silica fume, it is possible to maintain a optimum slump value i.e. workability, thereby satisfying most of the modern structural applications.