Laboratory study regarding recipes and strengths of concrete produced with reactive powders and metallic fibers

Abstract

Because of its multiple advantages such as durability, flexibility in use, fire resistance and low production and maintenance costs, concrete is, by far, the most popular building material currently in use. However, cement – one of the base ingredients of concrete – requires large quantities of raw materials and fossil fuels in order to be produced. In fact, in terms of pollution, it is one of the most environment-damaging products of the construction industry. A relatively recent trend in the problem of mitigating cement-related pollution is the possibility to substitute a certain percentage of cement with reactive powders, which are considered to be waste products of other industries. Concurrently, another trend is to try and obtain better performance of plain concrete, by using so-called “disperse reinforcement”. Thus, in the present article, a laboratory study is presented, regarding the obtainment and performance of concrete in which cement has been partially replaced with ultrafine silica and fly ash. Furthermore, in the case of the fly ash recipe, a percentage of metallic fibers was added, in order to study the potential performance gain with respect to plain concrete. The obtained results in compression were encouraging, in the sense that, for all recipes of concrete (plain concrete – used as reference sample versus concrete with fly ash, concrete with ultrafine silica, concrete with fly ash and fibers), the desired concrete strength class was attained. Even more, in the case of obtained results in tension by bending and splitting, the concrete with fly ash and fibers attained almost twice the tensile strength of the plain concrete. The obtained results suggest that concrete with reactive powders and/or metallic fibers can successfully substitute the plain concrete normally used in the construction industry.