Replacement of minimum steel bar reinforcement with steel fibres in structural concrete members

Abstract

Using lightweight concrete enables a decrease in dead load and thermal conductivity in the case of the manufacturing of structural concrete members. With the addition of steel fibres in concrete, its properties are altered from brittle to ductile, so that the use of additional minimum reinforcement for securing ductility and crack control can be avoided. This study is aimed at investigating the possibility of replacing conventional minimum steel bar reinforcement with steel fibre reinforcement in lightweight aggregate concrete under flexural loading. Therefore, six full-scaled beams with two different lightweight aggregate concretes (LWAC) (oven-dry densities of <1,200 kg/m3 and <1,600 kg/m3) as well as different types of reinforcement were prepared. For each LWAC, a beam with traditional steel bars, a beam with steel fibres and a beam with a combination of steel fibre reinforcement and reduced steel bar reinforcement were produced. The cracking behaviour of the lightweight concrete beams was studied in a four-point bending test. The results of this study show that it is possible to replace a high amount of the conventional mesh or bar reinforcement with steel fibres.