Effect of a mixture of different types of deflocculants on the structure and properties of cement rock and castable refractories

Abstract

The effect of two deflocculants — sodium tripolyphosphate (PP) and Castament FS 20 (C1) based on polycarboxylate ester — effectively lowering the viscosity of cement paste and their mixtures on the structure of cement rock with microsilica after soaking at 65°C, drying, and firing was investigated. The mineral stratlingite forms additionally in the samples with C1 during soaking. It was found that C1 promotes active formation of the mineral anorthite and PP promotes crystallization of gehlenite during firing. In using a mixture of PP and C1 crystallization of anorthite predominates in the sample. The resulting density and strength of the samples of concrete with PP are higher than in samples with C1, but shrinkage phenomena are highest in them. A different ratio of PP and C1 in the mixture decreases shrinkage, making it possible to obtain the highest strength and density of concrete after firing at temperature 1200°C.