Structure formation of the cement matrix with water-reducing additive under hydrothermal synthesis conditions

The article presents the results of research related to the possibility of increasing the strength of cement stone based on high-base calcium hydrosilicates synthesized during autoclave processing by reducing the water-cement ratio using superplasticizers. Despite the fact that autoclave stone based on high-base calcium hydrosilicates is inferior in strength to low-base ones, but it allows improving weather resistance. This approach is due to the fact that the effect of diluent additives in silicate mixtures increases with basicity increasing, and concrete samples based on a cement matrix containing C2SN(A) in a compacted state exhibit higher strength. The study shows water-cement ratio reducing in cement dough by 20% wi-th the help of superplasticizers increases the compressive strength of autoclave cement stone samples by 30%. At the same time, the strength growth of similar composition samples hardened for 28 days under normal conditions did not exceed 12%. It is noted that the strength of the matrix is determined not only by the shape and size of the crystals of the highly basic hydrate phases C2SN(A) and C2SN(C), but also by the degree of fusion and the number of contacts between them.