The effects of periwinkle shell, curing duration and methods of curing on the compressive strength of concrete using response surface methodology were evaluated. However, the periwinkle shells were added to the concrete at 5%, 10% and 15% dosage by weight as partial replacement to the coarse aggregate. The concrete were cast at 0.5 w/c ratio and cured between 7 days and 28 days in both water and air. Regression equations relating the blended concrete compressive strength with both the curing duration and periwinkle shell were developed. The results show that the water cured periwinkle blended concrete gave a better compressive strength than the air cured blended concrete at 5% replacement, with a 22.1% increase in the compressive strength. The adjusted R2 of 0.9516 and 0.6838 for both water and air cured periwinkle concrete reveal that 95.16% and 68.38% of the systematic variations in the compressive strength of the periwinkle concrete is accounted for by the independent variables.