Method of Modifying Portland Slag Cement with Ultrafine Component

Abstract

The paper presents the ways of modifying Portland slag cement with ultrafine substance for increasing its early strength. Blast-furnace granulated slag was used as ultrafine component having been preliminary ground in a laboratory airflow jet mill under restriction of upper limits of grinding to particle size of 1 μm. The obtained ultrafine slag was added into Portland slag cement in the dry state by dry blending and then in the suspension state instead of mixing water. Slag suspensions were prepared in water and water-polymer dispersion media. Plasticizer based on polycarboxylate resins was used as a stabilizer. Acoustic cavitation was used to stabilize water and water-polymer slag suspensions. The comparison of physical-and-mechanical and structural characteristics of modified samples detected that introducing slag suspension stabilized with plasticizer and acoustic cavitation instead of mixing water shows better efficiency. The effect of electrostatic factor is based on the formation of a double electric layer with the participation of functional groups of plasticizer at the surface of slag particles. The effect of structural-mechanical factor is conditioned by the formation of gelatinous films of main chain radicals on the surface of slag particles. Additionally, the stabilization of slag particles is provided by side branches of the plasticizer main chain, creating a spatial effect. Acoustic cavitation applied to water-polymer slag suspension results in the strengthening of electrostatic and structural-mechanical factors of aggregative stability and homogeneity of the suspension. The uniform distribution of stabilized slag particles in the hardening system leads to concentration of new formations on its surface and production of solid and firm structure of cement stone.