Protection of artificial human habitat from negative impacts of external environment and extension of service life of building structures become priority tasks of structural concrete improvement. The most important vector of development is the increase of their strength due to involvement of the internal resources with minimal use of additional external ones, which corresponds to the sustainable development concept. However, practice shows that now application of high-strength concretes, which are the main focus of researchers, is very limited due to insufficient development of production infrastructure, regulatory documentation, design and construction methods, economic and other reasons.
At the same time, approximation to requirements, according to the sustainable development concept, for the most widely used concretes with grade strength classes (B20-B50) is required right now. In this regard, the idea of application of the most important principles of obtaining high-strength self-compacting concretes in the manufacture of medium strength material is relevant. The article presents the main stages of research on development of the design methodology of medium strength classes self-compacting concretes with reduced Portland cement consumption.
The methodological basis for designing these concretes is the successive introduction of additional components principle while recording their effect on the material properties. The use of ground quartz sand as a mineral additive is due to the concrete mix stability requirements and its widespread availability, which allows for the practical application of the obtained results with minimal barriers and contributes to the reduction of CO2 emissions. It has been established that when selecting sand fineness of 180...220 m2/kg and a fixed amount of active mineral additive (7.5%), the compressive strength of the cement paste can be reduced to the following linear dependence: Rbinder28 = 118.9 – 0.22CM. Rational contents of fine and coarse aggregates have been identified, and their quantitative effect on the strength of the resulting concrete has been established. It has been established that the obtained concretes with increased efficiency of Portland cement using can be used in practice in various construction areas, and are also necessary for the search and transparent monitoring of the influence of others, more reactive mineral additives based on industrial products and rocks.