The construction industry is under increasing pressure to reduce carbon emissions and explore
sustainable building materials. This study investigates wood ash as sustainable cementitious
material by partially replacing cement in concrete. Wood ash has the potential and pozzolanic
properties that possibly can enhance concrete strength and performance.. Concrete mix were
prepared with wood ash replacement of cement, 0%, 5%, 10%, 15% and 20% using a concrete mix
ratio was 1 : 1½ : 3 with 0.5 w/c., for curing period 7, 14, 21 and 28 days. Regression models and
analysis were performed on the compressive and tensile tests results towards evaluating the
significance of wood ash in concrete. The results of slump tests showed gradual decrease with
increasing wood ash varying from 85mm (0% WA level) to 70mm at 20% WA level. Even though
workability was decreasing it was found to be within standard for medium workability concrete (50
– 90mm). Compressive strength was maximum at 10% WA level (15.51N/mm2) while control was
19.08N/mm2 at 28 days. Similarly the split tensile strength was maximum at 10% (1.97 N/mm2)
compared with 2.08 N/mm2 at 0% (control mix). The Regression model used was σ = a – b (% WA
Level) for the curing periods where a and b are parameters, the analysis provides comparable
results with observed laboratory results. The study concluded that, for optimal results, replacement
levels of cements by wood ash should be limited to 10% and possibility higher WA content could be
achieved by inclusion of plasticizer to improve workability