On the Effect of Poor-Quality Aggregates on the Physico-Mechanical Performance of Repair Lime-Based Mortars

Abstract

The selection of building materials for any restoration project presupposes knowledge of their physico-mechanical properties, as compatible materials with the authentic ones need to be chosen at all times. In the case of composite building materials, such as lime-based mortars, the constituent raw materials, especially the aggregates which comprise the largest proportion of their volume, may affect the physico-mechanical performance of the end-product, both in the fresh and hardened states. It is therefore essential to identify the properties of the aggregates before these are incorporated in the mortar mixture. This paper reports on the effect of two different reef limestone crushed fine aggregates quarried in Cyprus on the physico-mechanical properties of repair lime-based mortars. The aggregates have been subjected to a series of standardized (i.e., soundness, Micro-Deval and water absorption) and non-standardized (powder X-Ray Diffraction) laboratory tests to identify their properties, before being used to produce lime-based mortars with fixed binder:aggregate ratio and workability. The results confirm the negative effect of poor-quality aggregates on the mechanical strength, the porosity and capillary absorption of the hardened end-products; this is corroborated through supplementary Mercury Intrusion Porosimetry (MIP), thermogravimetric (DTA/TG) analyses and Scanning Electron Microscopy.