Factors for increasing the early strength of slag concretes with additives

The introduction of granular blast furnace slag into cement compositions is one of the key reserves for increasing both the economic efficiency of cement compositions in terms of cost and consumption of cement, and for improving technical properties. The paper presents the results of a study of the kinetics of the early compressive strength of concrete based on ground granular blast furnace slag (granslak), depending on the amount of granslak and additives in the compositions of Portland cement granslak. The most effective additive for increasing the strength of cement-based concrete with 70% granulated slag content at the age of 12 and 24 hours under normal hardening conditions is a two-component additive containing a superplasticizer based on sulfonaphthalene formaldehyde in an amount of 50% and Na2SO4 in an amount of 50%. During heat and moisture treatment at 60 °C, both a two-component additive and a polycarboxylate-based superplasticizer provide an increase in early strength of up to 80%.