The influence of secondary crushed stone on the strength and shrinkage of concrete was studied. The results showed that when granite coarse aggregate is replaced with crushed recycled concrete, the compressive strength of concrete is reduced by an average of 20% and the flexural strength by 3-10%. Concrete on recycled crushed stone has a high shrinkage. The shrinkage of concrete with a minimum consumption of recycled aggregate differs slightly from the shrinkage of concrete on granite crushed stone.

Keywords: demolition waste, concrete scrap, recycling, recycled aggregate, compressive strength, flexural strength, shrinkage

The influence of the ratio of fly ash and blast furnace slag in a geopolymer binder on the properties of concrete hardening during heat and humidity treatment was studied. The article obtained data on the influence of the binder composition on the workability of the concrete mixture, the strength and shrinkage of concrete. The dependences of the influence of hardening temperature and the proportion of slag in the binder on the strength of geopolymer concrete were established. The results obtained made it possible to recommend the studied binder and concrete based on it for pilot industrial production of prefabricated reinforced concrete.

Keywords: geopolymer binder, fly ash, blast furnace slag, concrete, strength, workability, water absorption, shrinkage

The importance of inert mineral additives for the development of modern concrete technology is considered. The results of a study of the influence of the dosage of limestone powder on the consistency and strength of fine-grained concrete with different ratios of its components are presented. It was established that in concretes with a high content of superplasticizer, the proportion of mineral additives in mixed cement is the main technological factor in controlling the strength characteristics of concrete.

Keywords: fine-grained concrete, mineral powder, inert mineral additive, superplasticizer, mix consistency, strength, strength control

The results of a study of the influence of slags from various manufacturers on the spreadability, strength and shrinkage of self-compacting fine-grained concrete are presented. It was found that replacing up to 30% of cement with slag reduces the strength of concrete only in the initial period of hardening. It was shown that the use of slag can significantly reduce the shrinkage of concrete.

Keywords: granulated blast furnace slag, mineral additive, fine-grained concrete, self-compacting concrete, mixture flow, strength, shrinkage

The possibility of reducing the excessive strength of self-compacting high-strength concrete for use in general construction was investigated. As a cement for such concrete, a cement-ash binder was studied, part of which was replaced by an inert mineral additive - microquatz, obtained by grinding quartz sand. It was established that the studied additive at a dosage of up to 30% does not allow to reduce the strength of concrete to the values ​​characteristic of general purpose concrete. It has been experimentally shown that the replacement of a part of the binder with microquartz does not significantly affect the initial modulus of elasticity, but significantly reduces the fast-flowing creep

Keywords: high-strength self-compacting concrete, cement-ash binder, inert mineral additive, microquartz, strength, modulus of elasticity, fast-flowing creep

The paper describes influence of content of dispersed polymer fiber on mechanical properties of mortar on basis of geopolymer binder. The studies were carried out on a geopolymer binder based on crushed granite and ground-granulated blast-furnace slag . Polypropylene fiber with length of 6 mm at a dosage of 0.22, 0.44 and 0.66% by volume was used as a reinforcing fiber. Dependencies were established for the compressive strength, flexural strength, fracture energy, and density from the dosage of the fiber at various times of hardening. It was established that fiber increases flexural strength and tensile strength of geopolymer mortar. It was shown that investigated fiber is characterized by high resistance to alkaline environment of the geopolymeric stone

Keywords: geopolymer, polypropylene fiber, dispersed reinforcement, compressive strength, flexural strength, tensile strength, resistance in alkaline environment