AN EXPERIMENTAL STUDY INTO THE STRUCTURAL EFFECT OF CASTING RECYCLED PLASTIC BOTTLES IN CONCRETE TO REDUCE SELF-WEIGHT OF SLAB

Abstract

The use of solid concrete slabs lead to the need for larger foundation and supporting members to support the additional dead loads acting on the building. This problem was eventually overcome with the development of Hollow Core Slab, Biaxial Hollow Slab and Filler Slab. These slab systems introduces voids as a mean to reduce concrete usage. In this study, laboratory test was conducted to evaluate if the introduction of voids would reduce the ultimate load-carrying capacity of a hollow core slab. Moreover, with the existing constraint on landfill, this research attempt to reuse plastic bottles to form the required voids. Yakult bottle that satisfy the size constraint of the slab specimen was chosen. Concrete slab specimens with and without voids were compared in terms of load-carrying capacity and self-weight. It was hypothesised that the load-carrying capacity would not be affected significantly despite the voids introduced. Results obtained however, contradicts the hypothesis where the solid slab holds 30.9% more load. Ironically, slab specimens with the least voids resisted the smallest load. The subsequent hacking of the slab specimens pointed out errors with the effective depths due to displacement of the bottles during concrete pouring. This problem was eventually resolved through rigorous theoretical analysis using the measured effective depths. The hypothesis was valid where experimental results were consistent to the theoretical results. Similarly, the slab specimens had become substantially lighter. However, quality control to prevent the floatation of bottles is desired in future research to obtain the exact load-carrying capacity.