PREDICTION OF FLEXURAL STRENGTH OF EXPANDED POLYSTYRENE LIGHTWEIGHT CONCRETE USING SCHEFFE'S MODEL

This research examined the optimization of flexural strength of expanded polystyrene lightweight concrete mix. The work applied Scheffe's optimization technique for a five by two degree polynomial. This linear optimization technique assumed the proportions of the material components of concrete to be variables in, x and that these proportions sum up to a whole, that is, unity. It obtained a mathematical model of the form f (X1, X2, X3, X4, X5) where, j = 1, …5 are proportions of the concrete components namely; cement, sand, polystyrene, coarse aggregates and water/cement ratio. The polystyrene-cement blended proportions were mathematically optimized by using Scheffe's approach and the optimization model developed. The optimal proportion by the program was used prepare beam samples measuring 150mm x 150mm x 750mm which were tested for flexural strength at 28 days and their results were compared with those of a standard 1:2:4 concrete mix.