Durability properties of self-compacting concrete developed using rice husk ash and sawdust ash as substitutes for cement and used engine oil as a chemical admixture

Abstract: This study uses used engine oil (UAO) as a chemical additive to examine the effects of rice husk ash (RHA) and sawdust ash (SDA) as cement substitutes on the durability characteristics of self-compacting concrete (SCC). Eight (8) distinct mixes were prepared and proportioned, with RHA replacing cement by weight at percentages of 0%, 5%, 7.5%, and 10%. In addition, SDA replaces cement ingredients concurrently by weight at 0% and 5% and with a constant UAO of 0.5%. The properties of fresh SCC concrete that contained RHA, SDA, and UEO were assessed, along with the concrete's water absorption capacity and compressive strength at 400 oC, 500 oC, and 600 oC. The results demonstrated that the workability and passing ability of the self-compacted concrete is greatly decreased when RHA and SDA are added to the concrete mixture. Potential modifications to the concrete's porosity and permeability were indicated by the effects of the addition of RHA, SDA, and UEO on its water absorption properties. Mix 3 exhibits the highest percentage of water absorption value (3.37%), while Mix 7 achieved the lowest value (1.27%). The results for compressive strength showed that the SCC mixes behaved differently at higher temperatures. Under normal temperature, the compressive strength varied between 28.83 N/mm2 and 36.6 N/mm2, with Mix 3 exhibiting the highest compressive strength relative to the control mix and Mix 8 exhibiting the lowest compressive strength. All mixtures showed a constant decrease in compressive strength as the temperature rose to 400°C, 500°C, and 600°C.