PREDICTION OF COMPRESSIVE STRENGTH OF MORTARS MADE WITH PORTLAND-CEMENT - BLAST-FURNACE SLAG - FLY-ASH BLENDS

A statistical design for three component mixtures was used to select the mixture proportions of the experimental points required to describe the strength development of portland cement - blast-furnace slag - fly ash mortars at various ages. A minimum of seven design points was required to fit the equations for a three-component mixture. With the experimental compressive strength values of the seven design points, a computerized statistical approach was used to find the equations governing strength development of the ternary systems at different ages. Once the equations were obtained, experimental checkpoints were run to verify the predicted compressive strength values of several mixtures at 1, 7, 28 and 91 days. With few exceptions, the accuracy of the predicted values was 95% or better. Compressive strengths of mortars of ternary blends at the ages mentioned above can also be predicted from the ternary diagrams with the iso-strength contour plots corresponding to the models chosen.