Optimization of Compressive Strength of Periwinkle Shell Concrete Using Scheffe’s Model

Abstract

This study investigates the optimization of compressive strength of periwinkle shell concrete using scheffe’s model. Physical properties of the aggregates such as specific gravity, bulk density, and sieve analysis were determined. Specific gravities of fine and coarse aggregates were 2.62 and 2.64 respectively. The bulk densities were 1745kg/m3 and 1660kg/m3 respectively. From the sieve analysis test, the sand belonged to zone 2 and well graded with coefficient of gradation of 1.04. Ninety 150mm x 150mm x 150mm cube specimens were produced for the compressive strength test. Mode was fitted to data obtained on the compressive strength and mathematical model was developed based on Scheffe’s model. The formulated model was tested for adequacy at 95% level of confidence using t-statistic and was found to be adequate. The compressive strength of concrete was observed to decrease with increase in the percentage replacement of periwinkle shells (PS). After 28 days of water curing, the concrete gave an average optimum compressive strength value of 22.84N/mm2 corresponding to a mix proportion of 1, 0.1, 1, 1.9 (cement, periwinkle shell, sand, granite) at a water-cement ratio of 0.4. This compressive strength value obtained at 5% replacement is within the recommended value required for low strength concrete works.