Evaluation of Water Permeability in Fibre Reinforced Hydraulic Lime Mortar Intended for Conservation

Much of the existing water infrastructure across the world was constructed using masonry in the last 200 years and many of these structures were built with pre-Portland cement binders. Although these mortars exhibit good workability and high water retention in the plastic state, the water tightness deteriorates over the years resulting in a pressing need for suitable repair materials. The addition of polypropylene micorfibre in cement-based systems was found to be effective in reducing water permeability. But the effect of polymeric fibres on the permeability coefficient of hydraulic lime mortar (HLM) is unknown. Therefore, this paper focuses on measuring water permeability in fibre reinforced HLM. Besides, this study examined the application of nanolime onto the aforementioned mortars and its effect on their water permeability. Accordingly, a permeability cell was setup to monitor the onset of the steady state condition in fluid flow. Companion data was generated for the mechanical performance of these mortars. The results show that in hydraulic lime mortar, there is likely an optimal fibre dosage in order to reduce the permeability coefficient. Unlike with Portland cement mortar, this dosage is significantly lower. As well, applying nanolime was most beneficial in limiting water permeability in the natural hydraulic lime mortars.