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.