Abstract
Effect of four sulphate solutions on the strength of mortar made with four common brands of cement blended with cassava peel ash was investigated in this study. This is to determine the level of resistance of such mortar to sulphate environment. Cassava peel ash (CPA) produced through a controlled incineration was washed and used to replace each brand of the Portland cement at a constant percentage of 20% by weight, while the control had no CPA (0%). A mortar of mix proportion of 1:3(binder: sand) was prepared and a total of 300 mortar beams (160 x 40 x 40 mm) were cast and cured in fresh water for 28 days then in 50g/l concentration of sulphate solution of Calcium, Potassium, Magnesium and Sodium separately for 7, 14, 28, 56 and 90 days but the control samples were left in fresh water for the same periods. Flexural and compressive strengths were determined at the end of each curing age. The results showed a varying effect of the sulphate solutions on the different brands of cement. The strength of the mortar specimens with blended cement increased with increase in curing ages till at least 28days then decreased with the curing ages onwards. Sokoto cement showed the highest resistance with an average of 39% loss in compressive strength and 26% loss in flexural strength. It was concluded that CPA possessed the potential of mitigating the effect of some sulphate in some brands of cement.

Key words: cassava peel ash, concentration, sulphate solution, curing ages