Study of the Influence of Composition and Drying Mode of Sandy-Clay Mixtures by the Method of Planning a Factor Experiment

The influence of quantitative and qualitative compositions, as well as technological parameters of mixture drying on the strength of sand-clay mixtures cured by heat drying has been investigated. Sand-clay mixture containing quartz sand, bentonite, water, bottom residue and sulphide-alcohol bard as additives is chosen as the object of research. Temperature and duration of mixture drying are chosen as process factors. By the method of planning the factor experiment, it was established that the drying temperature has a determining effect on the strength of the sand-clay molding mixture in selected intervals of varying independent variables; the effect of temperature is statistically significant at p = 0.002. Pair interactions "bentonite-water," "bottom residue - alcohol bard" have been studied; it has been found that strength of molding mixtures depends on ratio of tested components to each other. Two regression models with determination coefficients R2 0.81 (Model 1) and 0.965 (Model 2) were obtained by least squares; using the Akaike information criterion, it was found that model 2 predicts the strength value of the studied sand-clay mixture better than model 1 and it satisfies all statistical assumptions (F = 0.410 gives the value of the achieved level of significance p = 0.851; G = 2,166, p = 0,705). The analysis of the obtained regression model makes it possible to evaluate the influence of various factors on the strength of sand-clay molding mixture in the dry state, including the evaluation of their mutual influence; this allows to optimize the qualitative and quantitative composition of the mixture taking into account the technological parameters of thermal drying - temperature and duration.