Study of eucalyptus wood ash as a partial replacement of cement in mixed mortar

Abstract

The properties of mortars are influenced by the raw materials used and their proportions. In this context, the partial replacement of Portland cement with wood ash (WA), at appropriate levels, can improve mortar performance by enhancing workability, water retention, permeability, and durability, reducing costs and representing a sustainable and conscious alternative in material use. This study evaluated the partial replacement of Portland cement with WA, by volume, at levels of 10%, 15%, and 20% in mixed mortars. Tests were carried out in the fresh state, including consistency, squeeze-flow, bulk density, and entrained air content; and in the hardened state, compressive strength, flexural tensile strength, and water absorption. The results showed that the 20% replacement level increased the plasticity of the mortars without reducing workability, behaving similarly to lime. However, in the hardened state, the mortars showed a decrease in mechanical strength at all replacement levels, suggesting the low pozzolanic reactivity of the WA. Thus, it was also understood that it is possible to improve the processing of wood ash, making it possible to obtain wood ash fractions with higher amounts of amorphous and/or crystalline silica. This can provide better utilization of the material and its proper application in mortar.