Scholarly record

EXPERIMENTAL ASSESSMENT OF NATURAL FIBRE-REINFORCED LIME-PUMICE MORTARS

Adam Pivak, Zbysek Pavlik, Milena Pavlikova, Martina Zaleska

Abstract

Lime mortars are widely used in the construction, repair, and conservation of historic masonry due to their compatibility with traditional materials and their flexible, porous structure. However, their relatively low mechanical strength compared to modern cement-based materials has led to efforts to enhance their performance, for example through fibre reinforcement. This study examines the effect of two types of natural fibres (bovine and goat) on the physical, mechanical, hygric, and thermal properties of lime–pumice mortars after 90 days of curing. The results indicate that fibre addition reduced bulk density and slightly increased total porosity. These changes influenced mechanical behaviour, leading to a decrease in compressive strength compared to the reference mortar. In contrast, flexural strength improved, suggesting that the fibres effectively bridged microcracks and enhanced the cohesion of the mortar matrix. Fibre incorporation also affected hygrothermal performance. Fibre-reinforced mortars exhibited lower thermal conductivity and volumetric heat capacity due to their higher porosity and reduced density. Additionally, a decrease in the water vapour resistance factor was observed, indicating improved vapour permeability. Overall, the findings demonstrate that natural fibres modify both the physical and mechanical properties of lime mortars while improving their functional performance. Despite the reduction in compressive strength, fibre reinforcement represents a promising approach for enhancing traditional lime mortars in the conservation of historic structures.

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