The influence of aggregate texture, morphology and grading on the carbonation of non-hydraulic (aerial) lime-based mortars

This paper reports on investigations of the influence of the texture, morphology and grading of fine aggregates on the microstructure and macroscopic properties of aerial lime-based mortars. To understand the role of the aggregate in the outcome of the carbonation process, mortars set with two aggregates were cured for 2 years under standard conditions and studied at different time intervals by means of textural and mineralogical analyses and hygric and physical-mechanical tests. Both the initial and further development of the mortar properties are strongly influenced by compositional and textural differences induced by the type of aggregate used. Results show that a calcareous aggregate with continuous grading, consisting of sub-angular grains with a rough surface, induced better textural and physical-mechanical properties than a siliceous aggregate, with polished surface grains and less continuous grading. The use of a calcareous aggregate also provided compositional continuity between the binder and aggregate, apparently promoting further improvement in carbonation and physical-mechanical properties. Further work to quantify this influence is recommended.