Impact of quality control practices in sandcrete blocks production

Sandcrete blocks are widely used in Ghana as walling units. The quality of blocks produced, however, differs from each manufacturer due to the different methods employed in the production and the properties of the constituent materials. This paper focuses on the impact of quality control practices by suppliers on the quality of blocks produced in the Kumasi (6°548N 1°358E) metropolis. Sandcrete blocks were taken from suppliers and tested for compressive strength, bulk density, water absorption, and dimension tolerances. Fine aggregate samples were also taken from the suppliers and tested for grading, silt, and organic matter content. The study confirmed that mix ratio, quality, and mixing of the constituent materials affected the quality of sandcrete blocks. Visual inspection rather than laboratory testing was adopted as the means of ascertaining the quality by a few of the staff of contractors who had no formal training in quality control. Mix ratios used ranged from as lean as 1:8 to as weak as 1:19 (cement:sand). Blocks produced were also found to be unsuitable for use as load bearing walls.