Engineering properties of oil palm shell lightweight concrete containing fly ash

The effect of cement replacement with type F fly ash at 0%, 10%, 30% and 50% on some engineering properties of an oil palm shell (OPS) high strength lightweight concrete was investigated. The properties studied include workability, density, compressive strength, splitting tensile strength, flexural strength, water absorption and drying shrinkage. The effect of initial water curing periods of 2, 4 and 6 days after demoulding and air drying environment on the 28-day compressive strength was also investigated. The test results showed that even with 50% substitution of cement with fly ash, a low cost grade 30 OPS lightweight concrete can be produced. Although the inclusion of fly ash in OPS concrete makes it more sensitive to curing, even 2 days moist curing after demoulding significantly reduces this sensitivity. The results of the tensile strengths of OPS concretes imply that OPS concretes containing up to 50% fly ash are suitable for use as structural concrete elements. The use of 10% fly ash in OPS concrete did not affect the drying shrinkage of OPS high strength concrete.