Improving the early strength of concrete: Effect of mechanochemical activation of the cementitious suspension and using of various superplasticizers.

• Effect of SP and activation by RPA on structure of cement stone is revealed. • Increase the early strength of concrete, obtained by activation in RPA is established. • High physical properties of concrete are due to improved structure of cement stone. • Mineral content of hydration products contributes to the acceleration concrete curing. The novelty of the paper is to identify the scientific patterns of the influence of naphthalene formaldehyde and polycarboxylate superplasticizers during the activation process cementitious suspensions by the rotary pulsation apparatus (RPA), which have an energy density of 25 KW/m3 on the hydration mechanism and the structure of the cement stone. Cementitious suspensions obtained by mechanochemical activation in liquid state were prepared as novel compositions, on the basis of which concretes with high early strength are created. The strength characteristics of concrete mixes were researched by a series of tests (compressive strength, prism strength, flexural strength). In addition, the durability characteristics (frost resistance, sulfate resistance, water impermeability) were determined by standard techniques, confirm the creation of durable composites with high exploitation properties. Besides, the microstructural, morphological and thermal properties of such concrete at 28 days of curing were determined. For the first time, scientific data were obtained on the properties of cementitious suspension and concrete based on it, obtained by mechanochemical activation in an aqueous medium in the RPA with superplasticizers having different chemical bases. The results indicate that the mechanochemical activation of cementitious suspension by the RPA with the addition of Relamiks T-2 superplasticizer contributes to the improvement of the physicomechanical properties of concrete: the elastic modulus increases by 20%, flexural strength by 54%, prism strength by 67% compared to the control composition having the elastic modulus 33.57 GPa, flexural strength 5.41 MPa and prism strength 32.66 MPa. [ABSTRACT FROM AUTHOR]