Mathematical model for the prediction of the compressive strength characteristics of concrete made with unwashed local gravel

Abstract

This research work made use of Scheffe’s (4, 2) lattice polynomial with regression equations to develop a mathematical model for the prediction of the compressive strength characteristics of concrete made with unwashed local gravel from Abagana, Anambra state. Concrete cubes were made, cured and tested according to BS 1881:1983.The mathematical model developed, i.e., Ŷ = 20.67x1+ 22.01 x2+ 13.04 x3+ 8.26 x4+ 1.72 x1 x2 – 0.46 x1 x3 – 3.78 x1 x4 – 1.7 x2 x3 – 5.5 x2 x4+ 8.6x3 x4, was subjected to both the student’s t-test and the Fisher test to determine its adequacy. The strengths predicted by this model were in complete agreement with the experimentally-obtained values. The research also showed the effects of organic impurities on the strength of concrete with strengths of the unwashed local gravel concrete markedly less than those of washed local gravel concrete.