Utilization of hemp concrete using hemp shiv as coarse aggregate with aluminium sulfate [Al2(SO4)3] and hydrated lime [Ca(OH)2] treatment

This research presents the potential of hemp shiv for use as coarse aggregate in concrete. Hemp shiv was mineralized with aluminium sulfate Al2(SO4)3 and calcium hydroxide Ca(OH)2 before being used as a coarse aggregate to produce hemp concrete. The cement to sand ratio was 1:2, the Al2(SO4)3 to Ca(OH)2 ratio was 1:2, and the amount of superplasticizer was 1% by mass of cement. The compressive strength, density and water absorption of hemp concretes were tested. The results showed that at 28 days the compressive strength of hemp concrete was in the range of 15.0-17.0 MPa, density of 1420-1470 kg/m3 and water absorption of 14.5-16.5%. The results indicated that the application of Al2(SO4)3 and Ca(OH)2 for mineralization increased the compressive strength of hemp concrete by four times compared to that with non-mineralized hemp shiv. The use of Al2(SO4)3 improved the compressive strength of composites and the increase in the amount of Al2(SO4)3 also accelerated the setting and hardening of the matrix.