Properties of Sawdust Concrete

Abstract

This work examined the structural properties of concrete obtained bypartially replacing cement with sawdust ash. The sawdust ash which is apozzolan was obtained by burning sawdust which is a waste product fromprocessing of timber in an open air. The burnt ash was passed through a150 µm metric sieve to obtain the ash used. Physical and chemical analysiswere performed on the ash to verify its suitability as a partial substitute forcement in concrete. Chemical analysis was also carried out on the OrdinaryPortland Cement (OPC) sample. Concrete mixes were produced by replacing OPC with 0%, 5%, 10%, 20% and 30% of Sawdust Ash (SDA). Bothfresh and hardened properties of the concrete produced were investigated.The chemical investigation on the ash showed that it contained most ofthe basic compounds found in OPC making it suitable to serve as a partialsubstitute for OPC in concrete. Investigation on the concrete showed thatboth the workability and density of the concrete reduce as the SDA contentincreases. Analysis on the hardened concrete revealed that the compressivestrength of the concrete decreases as the ash content increases for the earlyages of curing. However, from 21 days curing age upwards, the compressive strength decreases as SDA increases up to 10% of SDA at which thecompressive strength jumped to a maximum value, and then starts reducingagain as the percentage SDA increases. Thus, the SDA concrete gained rapid strength at later ages indicating its pozzolanic activity.