A new type of lightweight beam system was recently proposed by embedding polystyrene in beams to improve structural efficiency. This removes the non-performing concrete in the neutral axis and tension region to provide a comparable strength as a solid beam. There are, however, limited studies conducted to investigate the structural behavior of such beams. Therefore, this research presents an experimental investigation to assess the effect of polystyrene shapes in the beams. This involved testing a solid beam and five lightweight beams under flexural load using a four-point load test. The inclusion of polystyrene was estimated to have reduced the self-weight of beams by 8.6% to 11.8% when compared with the solid beam. The results also showed the ellipse polystyrene with a width of 70 mm and height of 50 mm produced the highest effective strength to weight ratio (sw) of 1.12 and performed 12% better than the solid beam. Moreover, the lightweight beams have more weight reduced than the strength, and those with ellipse polystyrene were found to have performed better than circular ones based on first crack load, ultimate load, and effective strength to weight ratio (sw). The beams with ellipse polystyrene allowed better stress distribution and this gave them a higher strength than sphere shape. For industry application, the polystyrene content is recommended to be greater than 10% while the effective strength to weight ratio (sw) of the beam is greater than 1. The successful reduction of the weight without affecting the structural performance has the ability to help in reducing construction costs.

The construction industry is growing fast alongside the growth of the economy and the population. As one of the major building materials, brick is in high demand for construction purposes. The continuous growth will eventually lead to a shortage of raw materials in long run, such as sand and Ordinary Portland cement. This issue could be resolved by utilizing the waste materials, Expanded Polystyrene (EPS) beads and Silica Fume (SF), in replacement of sand and cement in the production of bricks, respectively. In this study, 120 specimens were produced with EPS beads removed 10% to 15% of sand while SF removed 10% to 20% of cement. The cement-to-sand ratio and water-to-cement ratio were 1:2.5 and 0.5 respectively. The performance of bricks was analyzed in the aspect of compressive strength, density, water absorption, and strength to weight ratio (s-w ratio). EPS beads were found to reduce the compressive strength and density, while SF strengthen the mix thus compensating for the performance loss caused by EPS beads. For construction application, the EPS beads and SF with the replacement of 15% and 10% respectively, were recommended, as it achieved the minimum requirement of the industry.

Lightweight materials, such as polystyrene, can be embedded in reinforced concrete (RC) beams to reduce its weight. However, this may, to some extent, affect the performance of the structure. This research investigates the behaviour of the lightweight beams under load and determines the best position of polystyrene blocks in beams. Nine specimens with a size of 175 mm x 300 mm x 1600 mm were tested under four-point load test. The number and position of polystyrene blocks in the beams were varied. The specimens were evaluated for effectiveness in terms of effective strength to weight ratio (s-w ratio). The lightweight beam was effective when the polystyrene blocks were placed at the neutral and tensile region, offering an s-w ratio of greater than 1. The beam lost 3.8% strength with 8.4% reduction of weight.