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.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.