Influence of a new dispersant additive amount on the structural and rheological properties of chamotte concrete and samples from it

The use of dispersing additives in the composition of concrete mixtures helps to reduce water demand, increase flow, increase strength after hardening in air. The effect of a new dispersant additive amount on a polycarbonate base in comparison with the currently used phosphate-containing additive on the structural and rheological properties of chamotte concrete from a mixture of the “SSHBD” grade and samples from it has been investigated. The optimal amount of new dispersant additive on the polycarbonate base has been established and it has been shown that, in its effect on the structural and rheological properties of concrete from a mixture of the “SSHBD” grade and the properties of samples from it, it is similar to the phosphate-containing additive used at present. The change nature of the concrete flowability is practically the same. "Vitality" (i.e. the time period during which the concrete mass is suitable for performing high-quality lining by vibrocasting) of the compared concretes is ~ 4 hours; cold crushing strength of concrete samples with additives after hardening in air for 7 days and heat treatment at a temperature of 110 °C, as well as cold crushing strength of samples after firing at a temperature of 1350 °C are practically the same. The use of new polycarbonate-based dispersant can be recommended for the preparation of chamotte concrete as an alternative phosphate-containing additive.

The study of the destruction of heat-resistant chamotte concrete during its sharp heating and cooling

The article investigates the destruction of heat-resistant chamotte concrete of various classes: low-cement and medium-cement with the addition of quartz sand (to increase alkaline resistance) and with the addition of metal fiber (to reduce cracking) after exposure to thermal shock. Two methods for determining the heat resistance of concrete were used, in which the destruction of the material was evaluated using ultrasound using the method of a water-cooled plate and the method of one-sided heating-cooling. Studies conducted using the method of unilateral heating-cooling, revealed the formation of macrocracks in samples of low cement concrete. This method turned out to be more sensitive when evaluating concrete destruction.