Some aspects of physical and mechanical properties of hollow blocks procuced from hot water treated sawdust.

Abstract

The study investigated sawdust as a partial replacement for sand in production of hollow blocks with a view to reducing cost and converting waste to resource use. Sawdust of Daniella oliveri was collected from Timber Shed along New Bridge Wurukum, Makurdi. It was boiled and spread to dry. Standard ratio of 1:8 (cement and sand) was used in the study. Replacement levels of 0%, 2%, 4%, 6% and 8% of sawdust were used for sand, while cement was kept constant throughout the mixture. Density, percentage water absorption (PWA), and compressive strength (CS) of the blocks were tested after 28 days of curing. PWA results showed that blocks produced from 0% sawdust replacement level had least mean of 10.06%, while 8% sawdust replacement had the highest mean of 11.40%. Mean density values showed that 8% sawdust replacement had the least value of 1090.40Kg/m³ and while the highest value (1346.60Kg) was observed for 0%. The mean CS for 0% sawdust replacement was highest (3.20N/mm²)and falls within the Nigeria Building Codes of 2.5N/mm² - 3.45N/mm² and Ghana Building Code of 2.75 N/mm². Mean CS value of 2.0N/mm² was obtained for 2% and 4% sawdust replacement levels respectively. The value  meets the minimum standard of 2.0N/mm² according to National Building Code for non-load bearing walls and 1.7 N/mm² according to Ghana Building Code. However, 6% and 8% sawdust replacement levels showed the least CS of 1.00N/mm² which is below standards. In conclusion, blocks produced with 2% and 4% sawdust replacement levels as obtained in this study are recommended for building and construction purposes.

Keywords: Blocks, Building code, cement, sand, sawdust, standard