Recently, the problem faced by the construction industry is a significant shortage of raw materials of concrete. Thus, the main idea of this research is to replace the use of concrete at the middle area of neutral axis of beam with voided system by incorporating PVC pipe. This research aims to reduce the concrete usage; structure’s self-weight without neglecting its strength performance. The experimental work consists of casting and testing the 1200 x 160 x 160 mm beams with (Ø40 mm, Ø50 mm, and Ø100 mm) and without void at the neutral axis. 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 38.25 kN 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 findings show 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.

The high demand of concrete has increased the rate of the ecosystem as well as increase the carbon emissions of the cement industry. The rapid growth of construction puts a severe strain on our natural resources and endangers the environment. Therefore, there is a pressing need for a green alternative that will protect the environment and preserve resources. Hence, this study is carried out to reduce the usage of cement in concrete production. The new replacement technique utilized the magnesium-rich synthetic gypsum (MRSG) and silica fume (SF). The MRSG and SF will be used as partial replacement of cement in the range of 5% to 30% with a water to cement ratio of 0.55. These mixtures were formed into cube specimens of 100 x 100 x 100 mm size. Then, the compressive strength was conducted to determine the strength of the specimens. The results indicated that 10% cement replacement from 5% of MRSG residue and 5% of SF gives an optimum strength compared to the control specimen with 24.6 MPa and 25.8 MPa, respectively. In addition, the increased percentage of MRSG residue, increased the water absorption of the mix. The replacement of MRSG residue in concrete would not only provide economic relief but also help to create a sustainable and pollution-free environment as the disposing of this waste creates many inconveniences to the living organism.