Assessment of stabilisation of adobes by confined compression tests

Stabilised adobe blocks are sun-dried earth blocks moulded from a plastic mixture of soil and stabiliser that improves their strength characteristics through bonding and limiting water absorption. Despite their use, the stabilising effect of some stabilisers used globally has not been established. The effect of molasses, cow-dung, sawdust and ordinary Portland cement (OPC) stabilisers on the compressive strength of adobe blocks was investigated. The dry and wet confined compressive strengths experiments used ran parallel for each treatment. The experiments were factorial with four treatments, two sub treatments (6 and 9-inch blocks) and three replications. Each treatment had five soils with stabiliser proportions 0%, 5%, 10%, 15%, and 20%. The subsoil used contained 10% clay, 85% sand and 5% silt, which is equivalent to the classification Ustoxic quartzipsamments in the Soil Taxonomy. The results demonstrated that with suitable soil, molasses, cow-dung and sawdust could be used as effective stabilisers. Molasses produced an optimum strength of 8.1 N mm−2 with a proportion of 5% stabiliser. Cow-dung produced an optimum strength of 2.8 N mm−2 with a proportion of 10%. Sawdust and OPC reached optimum strengths of 3.3 N mm−2 and 11.1 N mm−2 at 15% and 20% stabiliser proportions respectively. OPC stabilised blocks attained higher confined compressive strengths than all stabilisers.