Dispersed-reinforced decorative concrete: influence of composition factors on shrinkage deformations

Abstract

The results of the study of prescription factors influence on shrinkage deformations of multi-component material of architectural products are presented. Studies of the influence of composition factors on the value of composite samples shrinkage were carried out according to a symmetrical 5-factor design with 27 experiments. Depending on the nature of action on fine-grained concrete, variable raw materials are combined into two groups of factors – cement-sand system modifications, parameters of dispersion reinforcement. Based on the results of the conducted trials of the full-scale experiment, kinetic curves and correlation dependencies were built. The results of researchers on introduction of active fine pozzolana instead of part of binder are confirmed – zeolite promotes growth of free shrinkage of concrete, especially during early hardening period up to 7 days with low level of its plasticization. At the same time the degree of carbonation of concrete compositions with a high dosage of pozzolana and superplasticizer is absent. The shrinkage measurement results show that hybrid fibers with high dispersion are stochastically distributed in the cement system, they form a three-dimensional framework, can affect the distribution of volumetric changes. As a result – it will allow to preserve decorative and operational characteristics of architectural products in time. The amount of shrinkage deformations depends on the capillary pressure when the sample is dry, which is defined by the nature of porosity. In turn, the nature of porosity is responsible for the water absorption of the material. Therefore, in operation, optimization of decorative concrete compositions can be carried out for volume (or weight) water absorption and capillary water absorption. In order to estimate the durability of architectural elements, besides characteristics of strength and water absorption, it is necessary to take into account the carbonization stability of decorative concrete and the value of shrinkage deformations. It is planned, with the help of methods of computer materials science, to assess the influence of prescription factors on the dynamic elastic modulus of decorative concrete.