Concrete using waste oil palm shells as aggregate

Concrete with oil palm shells (OPS) as coarse aggregate was investigated for its workability, density, and compressive strength development over 56 days under three curing conditions. The effect of fly ash as partial cement replacement was also studied. Fresh OPS concrete was found to have better workability while its 28-day air-dry density was 19-20% lower than ordinary concrete. Compressive strength after 56 days was found to be 41-50% lower than ordinary concrete. These results were still within the normal range for structural lightweight concrete. Fly ash was found to lower the compressive strength of OPS concrete, which was the opposite of its effect on normal concrete. (C) 1999 Elsevier Science Ltd. All rights reserved.