Compressive behavior of wheat straw reinforced concrete for pavement applications

Abstract

Conventional concrete pavements are frequently recommended because of their relatively long service life compared to flexible pavements. But micro shrinkage cracking is usually observed in normal concrete. This just leads to start of deterioration of pavement from the very early age, thus affecting its intended functionality. Fibre reinforced concrete can help in reducing the micro-cracking to a large extend. Many types of fibres (e.g. steel and artificial fibres) have already been investigated by many researchers for concrete pavements. To the best of author’s knowledge, natural fibres are rarely studied for such applications. Natural fibres have been marvelous substitute to steel and artificial fibres for other applications. Keeping in mind this aspect of natural fibres, this pilot study is conducted to evaluate compressive behavior of wheat straw reinforced concrete for pavement applications. To study the influence of wheat straw in improving the properties of concrete, the properties of Plain Concrete (PC) are taken as reference. Mechanical properties i.e. compressive strength, corresponding strain modulus of elasticity, total energy absorbed and compressive toughness index are determined experimentally. Natural and treated wheat straws having lengths of approximately one inch and content of 3% by cement mass are considered. Thus, composites studied are Natural Wheat Straw Reinforced Concrete (NWSRC) and Treated Wheat Straw Reinforced Concrete (TWSRC). The proportions of cement, sand and aggregates are taken as 1, 3.75 and 1.75, respectively. The reason for using more sand compared to aggregate is that more mortar is available for grabbing wheat straw. Water cement ratio for PC, NWSRC and TWSRC are taken as 0.50, 0.60, and 0.63, respectively. Discussions on mechanical properties of PC, NWSRC and TWSRC are made. During the testing, it was observed that the fragments of plain concrete were removed from cylinder specimens. On the other hand, only cracks were formed in wheat straw concrete cylinders. It is concluded that, due to bridging behavior, wheat straw reinforced concrete has the potential to be used for concrete pavement applications.