On the compressive strength of Botswana masonry units

This paper presents results and discussion on research to investigate the compressive strength of masonry units in Botswana against the standard requirements. It was limited to concrete masonry bricks and burnt clay masonry bricks from large-scale manufacturers who either had their products certified by the Botswana Bureau of Standards or indicated the strength of their products. Nine sets of different products (six concrete masonry units and three clay masonry units) were tested. It was found that only three products complied with the Botswana Bureau of Standards requirements. Four of the six products that did not meet the Botswana Bureau of Standards requirements were two classes below the levels claimed by the manufacturers. For example, some units supplied as 14 MPa only fulfilled requirements of units with strength below 7 MPa. Users of masonry units in Botswana are therefore supplied with low strength products. This may greatly compromise the safety of the public.