Effect of Sand Grading on the Compressive Strength of Sandcrete Block

Abstract

The effect of grading of sand on the compressive strengths of sandcrete blocks produced from different sands obtained in River Wudil, Kano State was investigated. The mode of curing in all the block samples was by spraying/sprinkling water on the blocks twice daily for two days. This method of curing especially at the early stages could have negative effect on the strength. This is due to the fact that most of the water required for hydration process must have evaporated. Blocks produced from finer sand came first in terms of compressive strength which is higher than that required by standard, while blocks produced with fine sand have their compressive strengths to be second at 14days of curing. Blocks produce from sharp sand came third in terms of compressive strengths based on the analysis of this study. Compressive strength test indicates that the average compressive strength of sandcrete blocks ranges between 0.11N/mm² to 1.3N/mm². The values fall below the standard prescribed for load bearing sandcrete blocks. Nigerian Industrial Standard (NIS 87: 2000) specified that the lowest compressive strength of individual load bearing blocks shall not be less than 2.5 N/mm² and average compressive strength of five blocks shall not be less than 3.45 N/mm². The results also indicate poor quality control in the sense that the strength results show wide range within the same lot.