Performance of pumice-lime mortars reinforced with natural fibers

Abstract

The preservation of cultural heritage structures requires restoration materials that balance historical authenticity with modern performance standards. Lime-based mortars, which are traditionally composed of lime hydrate or hydraulic lime, have long been favoured for their breathability, flexibility, and compatibility with historic masonry. Recent research has focused on the enhancement of these mortars through the incorporation of natural fibres, with the aim of improving their mechanical and thermal properties while maintaining material compatibility. The present study investigates the use of cow hair as a natural reinforcement in hydrated lime mortar enriched with pumice powder. The experimental findings suggest that, while cow hair slightly reduces early-stage mechanical strength, it significantly enhances water vapour permeability and thermal insulation – key factors in the conservation of moisture-sensitive structures. The findings support the potential of underutilised animal fibres, such as cow hair, to contribute to the development of sustainable, durable, and heritage-compatible restoration materials.