Scheffe’s Mathematical Model for Optimization of Compressive Strength of Periwinkle Shell Aggregate Concrete.

 This project work aims at formulating Scheffe’s mathematical model which prescribes concrete mix ratios for a desired compressive strength of periwinkle shell aggregate concrete and obtaining the  combination of water, cement,  river sand and periwinkle shell which will produce the optimum strength.The model was formulated from first principle producing an equation with several unknown coefficients. These coefficients were determined by carrying out compressive strength test on thirty cubes using ten mix ratios. Another set of compressive strength test on thirty more cubes was carried out to validate the model together with a statistical tool of Two-tailed T-test.

The results obtained showed that both the fresh and hardened properties of the concrete are affected by varying the mixture component proportions. The compressive strength test showed that the optimum attainable compressive strength of periwinkle shell aggregate concrete predictable by the model at 28th day was 28.15N/mm2 with corresponding mix ratio of 0.575:1:1.25:1.25.

Conclusively,the result of the T-test statistics showed that the model was adequate for predicting the compressive strength of periwinkle shell aggregate concrete.