Durability of alkali-activated concretes containing cement kiln by-pass dust

Abstract

The aim of the presented work was evaluation of an effect of various conditions on the performance of two developed concretes based on alkali-activated slag and cement kiln by-pass dust (BD). BD was used as a partial replacement of natural aggregates while slag as an aluminosilicate precursor activated by a combination of waterglass and sodium hydroxide solution (resulting silicate modulus of 0.5). The concretes differed only in an activator dose which was 4 and 6% of Na2O with respect to the slag weight. The prepared specimens were sealed-cured for the first 28 days and then their resistance to freeze-thaw cycles and aggressive solutions (ammonium nitrate, acetic acid and sulphates) was tested. Evolution of dynamic modulus showed that both concretes resisted well to freeze-thaw cycles as well as to most solutions, where their dynamic modulus tended to increase in most cases or did not change significantly. Only the concrete with 4% Na2O showed poor resistance to acetic acid solution as the specimens completely disintegrated until 50 days.