Self-compacting Concrete with Silica Fume

Introduction

In today’s world, more attention is paid to healthy and pollutant-free environment, so that proper utilization of waste produced by various industries is of prime importance. Recently, a trend has developed to use GGBS, silica fume, fly ash and metakaolin in the construction industry¹.

With the beginning of the twenty-first century, we are entering into an area of sustainable development, since it will not be possible, in the future, to consider technological aspects only, without giving equal importance to the ecological balance in the planet earth. From this point of view, cement and concrete industries can be considered to be environment-friendly since a large amount of waste materials, such as fly ash, blast furnace slag, metakaolin and silica fume in cement and concrete industries is helpful for both manufacturing cementitious products with improved properties and for reducing the disposal of waste materials².

From waste to wealth is the concept with which concrete technologists, civil engineers and researchers are constantly working in this direction in exploring the properties of almost all the materials available both as natural and artificial resources, which can partially replace cement. Research work has shown that certain materials in nature possess pozzolanic property. Pozzolanic materials possess little or no cementitious value within themselves but when come in contact with moisture and calcium, hydroxide exhibits cementitious properties³.

With the advent of the portland cement concrete cult in India in the early part of the twentieth century, there was close adoption of the technological practices of the west; however the local materials had to be adopted to the local market conditions and the native sentiments had to be fully respected. This lead to preferred development of blended cements over the alternative practice of using cement substitute materials in site-mixed concrete, which was limited to large mass concreting project sites only⁴.

The use of pozzolanic and cementitious materials in the cement and concrete industry has risen sharply during the last fifty years as a mineral admixture. The reasons behind it are many. Cement requires high energy during its manufacturing process whereas fly ash, blast furnace slag, metakaolin and silica fume are the industrial by-products that are easily available and require little or not much of processing having inherent cementitious properties⁵.