Cementless binders based on blast-furnace slag activated by high-calcium fly ash and Na2CO3: stability under the influence of external and internal destructive factors

The stability of cementless mortars containing ground granulated blast furnace slag as a binder activated by high-calcium fly ash in combination with Na2CO3 under the influence of external and internal destructive factors affecting durability has been investigated. Such properties as regularity of cementless binder volume change, sulfate resistance of mortars based on it, possibility of alkali-silica reaction with the participation of aggregates, formation of efflorescence are considered. According to the results obtained, cementless compositions based on ground granulated blast furnace slag and high-calcium fly ash have no destructive expansion deformations under conditions that stimulate alkali-silica reactions with the participation of reactive aggregate. At ash dosage within 10 % wt. in the binder the compositions are sulfate resistant, but the possibility of formation and development of destructive expansion is not excluded at high ash dosage (30 % wt.). The dispersivity of high-calcium fly ash determines its ability to activate hydration of ground granulated blast furnace slag, the influence on the regularity of binder volume change, the early strength of the binder composition, the presence or absence of efflorescence.

Author: A.S. Brykov,, M.Ye. Voronkov

Section: Waste utilization

Keywords: granulated blast-furnace slag, blast-furnace slag activation, high-calcium fly-ash, sodium carbonate, durability, alkali-silica reaction, sulphate resistance, efflorescence