Mechanical and Durability Testing and XCT Imaging of a Lime-Based Micro-Scale Modified Smart Intervention Mortar

Intervention materials for historic structures need to be mechanically and physically compatible with the in-situ material for maintaining durability. For historic masonry structures, joint repointing is ideally executed using lime-based mortars, which are inherently low-strength and deterioration-prone. Mortar modification through micro-scale fillers, in addition to enhancing self-sensing, could enhance mechanical properties, thereby improved intervention agents. Therefore, micro-scale modification of mortars can lead to the creation of smart intervention materials, suitable for structural health monitoring. This paper presents the mechanical and physical testing conducted on a natural hydraulic lime-based mortar modified using carbon microfibres. The objective of the study was the evaluation of the mechanical advantages of a micro-scale modified material over its unmodified counterpart as a repointing mortar for masonry structures. The strength enhancement of paste and mortar was measured. Changes in workability, durability and porosity due to modification were investigated. The test results helped establish the superiority of the modified mortar as an intervention material compared to the unmodified lime mortar. The modified materials exhibited enhanced mechanical strength. The consistence of the modified mortar was not negatively impacted by the micro-scale fillers. The modified mortar had slightly lower salt intrusion durability, while the durability of the paste was improved.