міцність

There is investigated the effect of carbonate-containing and sulfate salt processing wastes on the properties of cementitious systems and aerated concretes based on them.

In this article describes theoretical and experimental research of contact seams in the repair or strengthening concrete elements using concrete, sprayed-concrete anchors and substrate binding.

The effect of carbonate additives on physical and mechanical properties of type II Portland cement was investigated. It was shown that calcium carbonate which is added as fine ground mineral additive, participates in the phase composition and microstructure formation of Portland composite cement paste.

The main results of experimental studies of strength, bearing areas’ are usually uncut, pre-stressed, stretched and eccentrically compressed reinforced concrete beams. Тhe identified of the stated constructions’ bearing areas’ new destruction patterns and the establishment of their dependence on the research factors’ corresponding ratio; the development of new general engineering methods of the studied elements’ bearing areas’ durability calculation based on the choice and the alternating consideration of the most probable destruction schemes.

Expounded pre-conditions and essence of method of calculation of strength of joints of the key of concrete and reinforceconcrete elements, which is based on the variation method of theory of plasticity of concrete. The algorithm of calculation of joints is presented at destruction «after the key» and «after guy-sutures». The expounded bases of calculation of connections of three-keys are with the different width of guy-sutures. Resulted limitations which simplify procedure of calculation.

There is investigated the effect of carbonate-containing and sulfate salt processing wastes on the properties of cementitious systems and aerated concretes based on them.

The principles of creating of multimodal composite Portland cements with optimized void filling, that based on synergistic combination of ultrafine active mineral additives with superplasticizer were established. The optimization of multimodal multicompositе Portland cements was carried out and the relationship between the phase composition, microstructure and strength of the cement matrix were investigated.

A study of the rheological properties of self-compacting fiber reinforced concrete mixtures with additives of modifiers and microfillers and performance characteristics of concrete based on these mixtures has been carried out.

In this paper the influence of technological factors on the formation of properties of finegrained concrete is shown. Rapid hardening concrete, modified with complex chemical admixtures, for prestressed precast hollow core slabs produced by continuous extrusion forming were designed.

The possibility of obtaining Self-Compacting Concrete with a large amount of supplementary cementitious materials, including fly ash is shown in this article. Research results of rheological properties of fiber reinforced Self-Compacting Concretes with high volume of fly ash and chemical admixtures, which regulate fluidity and viscosity of concrete mixes, are shown. It was established that the replacement of 55, 70 and 85 wt. % of binder with fly ash allows to obtain Self-Compacting Concrete mixes with the consistency class SF2, viscosity T500 = 5 s and the volume of entrained air 0,4 %.