Characterization and durability assessment of fibre-reinforced tung oil lime putties for restoration

Abstract

As a traditional organic-inorganic hybrid binding material, tung oil lime putty has a prospective application in ancient architecture restoration. In this paper, we prepared nine mixtures by adding hemp fibre to tung oil lime putties. The physical-mechanical characteristics, pore structure, mineralogy, infrared spectra and micromorphology of the curing-aged pastes were first determined. Then, the resistance of the specimens to the action of freeze-thaw and salt crystallization cycles was assessed. Tung oil acted as a modifier for lime carbonation and imparted water repellence. Paste-enriched oil exhibited a more compact microstructure and a significant reduction in water absorption. The fibre addition converted lime pastes to fibre-reinforced composites and promoted the carbonation progress of lime. Fibre reinforcement further hampered the development of cracks and pores, macroscopically characterized by the bending ductility in curing and a slight compressive strength increment after frost ageing of the salt solution. The composite with 1.0% fibre and 5% tung oil addition presented favorable resistance towards freeze-thaw cycles and salt crystallization degradation.