Composite binders for concrete of protective structures

The composite binders, obtained as a result of joint mechanochemical activation of Portland cement, rice husk ash, quartz sand, screening of limestone crushing and plasticizing additive were considered. The type of binder influence to the rheological and mechanical characteristics of selfcompacting concrete mixtures and fiber-reinforced concrete is established. By scanning electron microscopy, it was revealed that the application of the developed binder leads to the compacting of the microstructure, with lamellar and acicular neoplasms filling the isometric and anisometric pores. This leades to the formation of a rigid matrix with a lower porosity, which in turn leads to an increase in the compressive strength of the formed cement stone above 70 MPa. The use of a composite binder increases the physical and mechanical characteristics of fine-grained concrete accordingly (Rcompr over 80 MPa, elastic modulus greater than 40 GPa). The studied rheological characteristics showed that all mixtures with the use of composite binder meet the requirements of fluidity and segregation resistance for self-compacting concrete mixtures. The revealed indexes of shock endurance of fiber-reinforced concrete (30 % higher than for standard reinforced concrete) allow using this material for protective structures.