The use of voided reinforced concrete in structural member

Abstract

Concrete is widely used as one of the important construction materials. Recently, the problems faced by the construction industry is a significant shortage of raw materials. Thus, various methods are being adopted to reduce the use of concrete. In case of simply supported RC beams, the transition from compression to tension zone at the middle area of neutral axis in stress distribution of a beam was identified as the ineffective region. So, the use of concrete in this ineffective region was replaced by the voided system to the beam by incorporating PVC pipe in order to reduce the weight of the structure. Therefore, the research objectives in this study are to investigate the flexural strength of voided reinforced concrete (RC) beam with various diameters, to determine the total reduction of concrete usage, self-weight, and strength increment of voided RC beam, and to compare the structural strength performance between voided and ordinary of RC beam. The experimental work consists of casting and testing the 1200 x 160 x 160 mm beams with (Ø40mm, Ø50mm, and Ø100mm) and without void at the neutral axis. In order to investigate the flexural strength of the beams, the 3-point loading test has been carried out and the flexural strength between voided and ordinary RC beams were compared. The test results indicated that the strength performance of all RC beams with voided section is stronger than the ordinary RC beam where the V50 RC beam is able to withstand loads up to 38.25kN and has a strength increment of 49.2% compared to the ordinary RC beam. By this material optimization, the reduction of concrete usage and self-weight of the V100 RC beam recorded a reduction of up to 35.14% but in terms of its strength is relatively low compared to the V40 RC beam and V50 RC beam. This study has shown that the replacement of concrete in RC beam with PVC pipe shows a positive result in reducing the dead load without affecting the strength of the structure. Besides aiming to the reduction of concrete usage and structure’s self-weight, the idea of this research could be used and implemented in producing a lightweight structure with easy handling and installing, and at the same time focusing to meet the IBS system.