Effect of Hardening Accelerators and other Chemical Admixtures on the Properties of a Quick-Setting Mixture

Abstract

The physicochemical and physicomechanical properties of quick-setting compositions based on fine-grained electric steelmaking slag (ESS) produced by Izhstal PJSC, Russia, have been examined. The study also focuses on the processes of interaction of the components of the compositions based on ESS in combination with hardening accelerators (Li2CO3, K2SO4) and plasticizing additives (SP-1, Melflux 2651F). It has been found that mechanoactivation of the composition improves the hydration in comparison with chemical admixtures. This can be proved by the obtained results of the setting and testing timing of the mechanical properties of the mixture. Plasticizers being added, the setting time increases at the average by 2.3 times, and accelerators being added, by 2 times compared with the mechanically activated composition. The influence of mechanoactivation on the strength of the compositions has been described. In comparison with the plasticized composition, the strength increases by 10%, while using accelerators – by 30%. Thus, the most effective way of producing a dry mixture with the properties of quick setting and hardening is a short-term mixed grinding of all its components, which makes it possible to exclude accelerating chemical admixtures and plasticizing additives in the mixture. Also, grinding positively affects the strength gain of quick-setting compositions while reducing the gypsum content to 5%.