Adición de una escoria geotérmica ultrafina sobre morteros de escoria de alto horno activadas por álcalis

Abstract

Investigations were carried out in mortars with alkali activated blast furnace slag (BFS) as the binder. The slag was replaced by up to 30% by weight of an ultrafine geothermal slag (GS) which was predominantly siliceous. The activating agents were waterglass and NaOH, commercial lime was added in 4% to promote pozzolanic activity of both slags. Measurements of non evaporable water indicated that the presence of the GS increased the reactivity of the cementitious systems. Also, for the NaOH activation, the replacement with 5-10% of the BFS by GS favored a porosity reduction (as observed by scanning electron microscopy) and the compressive strength improvement. For the waterglass activation, the addition of GS resulted in more compact microstructures; however, in spite of such improvement, during the mixing and castings of such mortars, air bubbles were trapped in the microstructure due to a fast setting, degrading the compressive strength with respect to the neat BFS mortars. After 90 days, the lime was not observed in the microstructure, suggesting that it was consumed by both slags.