Mechanical and Bond Properties of Lightweight Concrete Incorporating Coconut Shell as Coarse Aggregate

Abstract

The demand of concrete is growing enormously now-a-days due to the increase of huge number of constructions all over the world. Therefore, the widespread research and development efforts towards discovering new constituents are essential to produce sustainable as well as environmental-friendly construction materials. The usage of waste materials such as coconut shell (CS) as a replacement of coarse aggregate is a prospective alternative in the arena of construction industries due to the continuous diminution of natural resources as well as increase of the cost of raw materials. This paper highlights the experimental outcomes of a research carried out on the mechanical (such as compressive strength and splitting tensile strength) properties as well as bond behavior of concrete encompassing crushed coconut shells as various percentage replacement of coarse aggregates. The cylindrical specimens (100 mm x 200 mm) were prepared and tested in accordance with ASTM standards. Concrete cylinder specimens incorporating different percentage replacement of coarse aggregates using coconut shells with rebar were constructed and performed pullout testing to evaluate the bond behavior of concrete containing natural stone chips and crushed coconut shells as a partial replacement of coarse aggregates. The effect of bond stress-slip behavior for various percentage replacement of coarse aggregates with crushed coconut shells were also evaluated in this research. Based on the compression and splitting tensile strength of concrete, it can be established that the concrete containing 10% and 25% crushed coconut shell aggregates with the replacement of stone chips as coarse aggregates fulfills the requirements of the lightweight structural grade concrete. There is no significant variation of bond strength observed up to 25% replacement of coarse aggregates using crushed coconut shells. Moreover, the failure behavior for CS concrete and control concrete is almost identical to other lightweight structural aggregate concretes. Therefore, it can be concluded that up to 25% natural coarse aggregates (stone chips) can be replaced in concrete production using crushed coconut shells. In addition, a strong correlation (R2 = 0.99) has been developed between the bond strength and compressive strength for natural weight aggregate and CS concrete under normal water curing conditions.