In this paper, properties of concretes incorporating recycling waste and corrosion susceptibility of reinforcing steel bars were studied. It was established that fineness of ground granulated blast furnace slag (GGBFS) and fly ash (FA) and their simultaneous combination have an influence on the kinetics of strength development of Portland cements and concretes. The compressive strength of concrete containing 10% by mass of GGBFS and 10% by mass of FA even exceeds the compressive strength of control concrete by 6.5% and concrete containing 20% by mass of GGBFS by 8.8% after 56 days of hardening. The formation of the extra amount of ettringite, calcium hydrosilicates as well as hydroaluminosilicates causes tightening of a cement matrix of concrete, reducing its water absorption, and improving its resistance to freezing and thawing damage.

In this study, properties and peculiarities of hydration processes as well as paste microstructure of blended cements containing 10% by weight of natural zeolite were investigated. Free calcium hydroxide content, crystalline hydration products and microstructural architecture of hydrated cement pastes were examined by physical and chemical methods. It was found that the addition of natural zeolite provides formation of an extra amount of fine crystalline ettringite and tobermorite-like calcium hydrosilicates of CSH (B) type in the mineral non-clinker part of Portland cement resulting in strength synthesis of cement stone with high performance properties.

This study aimed to evaluate the influence of zeolitic tuff, an air-entraining agent, and different types of fibers on the compressive strength and fracture parameters of concrete with increased strength. Notched beams were tested in three-point bending to determine the fracture parameters of concrete. It was established that the partial replacement of Portland cement (10% by mass) with zeolitic tuff, the addition of an air-entraining agent and different types of fibers resulted in the improvement both of the compressive strength (by 3.7% after 28 days of hardening) and fracture properties of concrete (namely, the fracture energy by 35.1% and characteristic length by 61.5%) compared to the reference concrete. The beneficial effects of the air-entraining agent and the mechanisms through which it enhances the properties of concrete by incorporating zeolitic tuff and various types of fibers were explained. It has been demonstrated that the appropriate selection and optimization of various technological factors enable the production of economically effective, high-quality concrete with a 10% lower cement content. As a result, this leads to reduced CO₂ emissions, aligning with a sustainable development strategy.

The influence of the air-entraining agent (AEA) on a density, the volume of entrained air of mortar mix and compressive strength of hardened mortar was studied in this article. Results show that the addition of AEA results in the reduction of water to cement ratio to provide the targeted flow and the density that depends on the volume of entrained air. The addition of AEA causes the decrease of the density of mortar (C:S=1:2) by 8,2% and the increase of the compressive strength by 13,9% after 28 days of hardening compared to the mortar (C:S=1:2) without AEA. The further increase of a sand content in a mortar (C:S=1:3) results in slight decrease of a density of fresh mortar and compressive strength. If C:S ratio is 1:4 the increase of the density and the compressive strength decrease is observed in comparison with the mortar with C:S=1:3. The obtained results show that properties of mortar incorporating AEA depend on its mix proportion.