Freeze-thaw resistance of pozzolanic hydrated lime mortars

Degradation of hydrated lime mortars subjected to freezing and thawing is common in historic building conservation. The pozzolanic additions, Argical M1000, diatomite (diatomaceous earth) and brick dust, were evaluated for their ability to improve performance for up to 720 days. Pozzolanic reactions influenced the pore structure evolution, mechanical performance, and chemical reactivity of the mortar matrix. Argical-lime mortars exhibited a sudden failure, while a gradual reduction in mechanical strength was observed for mortars containing brick dust. A slower rate of failure in diatomite mortars was attributed to pore refinement, which was associated with superior freeze thaw performance. This study has advanced the current state of the art regarding how pore structure affects lime mortars' freeze and thaw resistance. Therefore it provides spesifications on how to optimise mortars for historic masonry. A key impact is the more effective use of lime mortars for conservation, thereby protecting heritage structures from degredation.

Automated summary

Degradation due to freezing and thawing is a common issue for hydrated lime mortars in historic building conservation. This study evaluated the use of pozzolanic additions, such as Argical M1000, diatomite, and brick dust, to improve the performance of the mortars for up to 720 days. The results showed that pozzolanic reactions influenced the pore structure, mechanical strength, and chemical reactivity of the mortar matrix. The study also found that diatomite mortars had a slower rate of failure due to pore refinement, resulting in better freeze-thaw performance. This research advances our understanding of how pore structure affects the freeze and thaw resistance of lime mortars and provides specifications for optimizing mortars for historic masonry.