Utilization of oil palm kernel shell as lightweight aggregate in concrete – A review

This paper reviews previous research carried out on the use of oil palm kernel shell (OPKS) as lightweight aggregate (LWA). OPKS is a waste material obtained during the extraction of palm oil by crushing of the palm nut in the palm oil mills. It is one of the most abundantly produced waste materials in South East Asia and Africa; OPKS has been experimented in research as lightweight aggregates (LWAs) to produce lightweight concrete (LWC) since 1984 and today there are many researchers working in this area. In this paper the physical and mechanical properties of OPKS are summarized along with mechanical, durability and functional properties and structural behavior of OPKS concrete (OPKSC). Recent papers on foamed and fiber reinforced OPKSC are also included. It is seen from the results that OPKSC has comparable mechanical properties and structural behavior to normal weight concrete (NWC). Recent investigation on the use of crushed OPKS shows that OPKSC can be produced to medium and high strength concrete. Sustainability issues combined with higher ductility and aggregate interlock characteristics of OPKSC compared to NCW has resulted in many researchers conducting further investigation on the use of OPKS as LWA.