The effect of deflocculants on the structure and physical-mechanical properties of fireclay refractory castables

Abstract

For production of fireclay refractory castables, various deflocculants are used. In recent years new polycarboxylate ethers-based deflocculants appeared and so far their properties comparing to those of common deflocculants are little investigated. This study compares the effect of content of two deflocculants, sodium tripoliphosphate and polycarboxylate ethers Castament FS-20, on hydration of aluminate cement, on structure forming during it, pH and electrical conductivity in suspensions. It was established that the increase in content of deflocculant sodium tripoliphosphate, as a binder, in the suspension results in a considerable increase of electrical conductivity, while the increase of Castament FS-20 reduces pH values. The study also evaluates the effect of content of deflocculants on duration of exothermal reaction in paste of castable with medium content of cement, on formation of structure, physicalmechanical properties of castable. It was established by means of compressive strength tests that the increase in content of sodium tripoliphosphate affects the strength properties of castables, meanwhile Castament FS-20, on the contrary, increases the compressive strength of castable samples. Dilatometric test helped to establish a different effect of deflocculants on processes of linear changes at high temperatures.