Oil-palm by-products as lightweight aggregate in concrete mixture: a review

d The use of industrial waste as a construction material to build environmentally sustainable structures has several practical and economic advantages. Oil-palm-boiler clinker is a waste material obtained by burning off solid wastes during the process of palm oil extraction. The research performed over the last two decades concerning the use of oil-palm-boiler clinker as a lightweight aggregate to produce structural lightweight aggregate concrete is summarized in this paper. The physical, chemical and mechanical properties of oil-palm-boiler clinker aggregate and the mechanical properties and structural performance of oil-palm-boiler clinker concrete are addressed, discussed, and compared with normal weight concrete. The review of the literature showed that depending on the source of oil-palm-boiler clinker the specific gravity of this aggregate is 15-35% less than normal weight aggregates and it can be used as a lightweight aggregate for making structural lightweight aggregate concrete. Concretes containing oil-palm-boiler clinker as coarse and fine aggregates have the 28-day compressive strength in the range of 17-47 MPa, with a density in the range of 1440-1850 kg/m(3). While, concretes containing oil-palm-boiler clinker as coarse aggregate and normal sand as fine aggregate have the 28-day compressive strength in the range of 15-35 MPa with a density in the range of 1800-2000 kg/m(3). Partial replacement of oil palm shell with oil-palm-boiler clinker in oil palm shell lightweight concrete could significantly improve (about 40%) the compressive strength of the concrete. The research gaps are also identified in this study to explore the innovative lightweight concrete based on the financial and environmental design factors. (C) 2016 Elsevier Ltd. All rights reserved.