Effect of water-cement ratio on the compressive strength of sandcrete block blended with sawdust ash

The problem of managing agricultural and industrial wastes has become a challenge in recent time. Therefore, research in the area of minimizing waste accumulation through reclamation and recycling has been ignited considering their aesthetic and ecological problems caused by the improper disposal. Areas of research aimed at reducing waste include the use of sawdust ash, rice-husk ash and groundnut-husk ash to partially replace cement in the production of concrete or sandcrete blocks. The use of sawdust ash (SDA) as replacement of cement in the production of sandcrete blocks was investigated. The aim was to determine the percentage of SDA and water-cement ratio that would give the 28-day maximum strength. The sawdust ash was used to partially replace Ordinary Portland Cement (OPC) in various proportions (0%, 5% 10%, 15% and 20%).Cubes were produced using mix ratio 1:4 and water-cement ratios of 0.40, 0.50, 0.55 and 0.60.The cubes were tested at the ages of 7, 14, 21 and 28 days for each proportion of OPC/SDA and water cement ratio. The results indicated that compressive strength of blocks at 28 days was 3.80N/mm2 and 3.50N/mm2 for 5% SDA at water-cement ratios 0.55 and 0.60 respectively. The compressive strength for 10% SDA was 2.87N/mm2 and 3.10N/mm2 at water-cement ratios 0.55 and 0.60 respectively. The 5% and 10% percentage replacements have compressive greater than the required strength of 2.00N/mm2 specified by the Nigerian National Building Code (2006) for non-load bearing walls. By these results sandcrete blocks with up to 10% SDA replacement at water-cement ratios 0.55 and 0.60 can be used for non-load bearing walls.