Justification of the Water-Cement Ratio Decision for Cement Mixtures Using CBPB Wastes

Abstract

An unconventional approach to the design of cement mixtures with the addition of cement bonded particle board (CBPB) production waste is presented, which is characterized by high water consumption. For various compositions of fine-grained concrete prepared in accordance with the simplex-lattice design of the experiment, compressive strength and bending, as well as density of the samples, depending on the mixture factors, were researched. The fractions of CBPB wastes, water and sand at constant cement consumption were chosen as the influencing factors. For practical purposes, related to the design of cement composite compositions with the addition of CBPB wastes and with the determination of optimal values of the selected factors, mathematical models have been constructed on the basis of laboratory experiment data and with their help, the optimal ratios of components in the mixture have been determined. It was found that the content of water for the mixture mixing in the mixture has a significant effect on the strength characteristics of composites: increase of the strength of materials with a decrease in the water-cement ratio is a characteristic for compositions with the minimum amount of CBPB waste; increasing the content of the CBPB waste in the mixture the increase of the water-cement ratio leads to gain in strength. Optimal ratios of the mixture components providing maximum utilization of CBPB waste without loss of strength of composites are given.