Crack resistance of decorative composites

Abstract

The results of a study of crack resistance obtained during the development of fine-aggregate concrete for architectural elements are presented. The crack resistance study of 27 different proportions of compositions was carried out in accordance with DSTU B V.2.7-227: 2009 using experimental statistical modeling methods. Due to the fact that the method of initiating the initial crack in the samples changes the distribution of the technological fields of strain, the tests were carried out on two series of samples. The data obtained show that the crack sealing method changes the deformative-stressed state of the composite. So, crack resistance for one concrete composition can vary, from the conditions of the experiments, from 3 to 40 %. Based on the obtained values of the characteristics of the material, in particular, for the coefficient of technological impact on crack resistance, which describe the fields of these criteria in the coordinates of the factors of concrete composition, models were built. The results of the model are presented on 5 factor diagrams of the form “cubes squared”. An analysis of the constructed diagrams showed that the initial conditions for the organization of the structure of concrete determine its ability to resist the development of various types of cracks. During the introduction of finely dispersed fibers at an optimal dosage of fine sand grains (50 % in a sand mixture) and a slight replacement of cement with zeolite (from 2 to 3.4 %), it is possible to reduce the technological damage to the decorative composite, thereby improving crack resistance.