Abstract:This study explores the use of rice husk ash (RHA) and manufactured sand (M-sand) as replacements for cement and fine aggregate, respectively, in lightweight oil palm shell concrete (OPSC). In the first stage of this study, the effect of various cement replacement levels, with RHA (5%, 10%, 15%, and 20%) and 100% sand replacement with M-sand and quarry dust (QD), on the compressive strength of OPSC was investigated. The results showed that the highest compressive strength of OPSC of about 51.49 MPa was achieved with the use of 15% RHA and M-sand. In the second stage of the work, the variables of RHA (0 and 15%) and M-sand (0, 50%, and 100%) were used to investigate their combined effects on the mechanical properties of OPSC. It was found that the combination of 15% RHA and 100% M-sand gave the best performance of OPSC in terms of mechanical properties, such as compressive, splitting tensile, flexural strength, and Young's modulus.

This paper discusses on the availability of waste materials in Malaysia and their potential use as building materials in the local construction industry. The waste materials discussed include fly ash (FA), oil palm kernel shell (OPKS), rice husk ash (RHA), palm oil fuel ash (POFA), quarry dust (QD), recycled ceramic, and recycled coarse aggregate (RCA). The past research on the use of these materials shows that structural grade concrete can be produced. . Similarly, the use of FA, RHA and POFA as partial replacement of cement or additional cementitious materials can be used to produce low to medium strength concrete as well as high strength concrete (HSC). In addition, lightweight OPKS enables it in the production of lightweight concrete (LWC). Recent research on the use of FA, RHA and palm oil clinker (POC) to produce geopolymer concrete is also producing results. In general, the utilization of these waste materials in concrete leads to sustainable concrete and reduces environmental impact from the manufacture of concrete using conventional materials such as crushed granite and cement

The consumption of Ordinary Portland Cement (OPC) as construction material is one of the main sources of CO2 emission and global warming.. The manufacturing process of ‘clinker’ which is an essential element of cement requires burning of fossil fuels, thus increasing the CO2 emission and decreasing the global stock of fuels. Concept of a novel binding material named ‘Geopolymer’ appeared in the 1940s as a viable solution to these issues. Geopolymer concrete (GPC) is produced from industrial byproducts such as Fly Ash (FA) rich in aluminosilicate, Blast furnace slag (BFS) or natural minerals such as Kaolinite clay using alkalis as activators. In this paper, economical, social and ecological sustainability of GPC have been put forth. Comparison have been made between the behavior of low-calcium fly ash based GPC and metakaolin based GPC under different environmental conditions using alkali activators such as Sodium hydroxide (NaOH) or Potassium hydroxide (KOH) with Sodium silicate (Na2SiO3) . Evolution of GPC, hydration process as opposed to OPC, mechanical properties, structural behavior, alkali-silica resistance (ASR), fire and acid resistance behavior of GPC have also been discussed in this paper.