Moisture impact on compressive strength and deformability of brick masonry

In many existing brick buildings, severe dampness of the walls is often observed. One of the most common causes of severe dampness is a lack of adequate damp-proofing and frequent flooding. The strong capillary water absorption capacity causes that in some cases, brick masonry reaches the full water saturation state. Strong moisture has a negative impact on the mechanical parameters of brick masonry. However, the scale of this effect in brick buildings is an issue that is still largely unknown. In this paper, results of research conducted on brick, mortars, and masonry specimens are presented. The material specimens were cut out from a historic military building and tested in air-dry and wet conditions. Studies have shown that strong moisture significantly reduces compressive strength in all the tested materials. The reduction in compressive strength of the brick masonry ranged from 6% to 39%. Based on experimental results, this paper proposes a method for predicting the reduction in compressive strength of brick masonry caused by significant moisture. This method is based on testing specimens of brick and mortar taken from the structure and can be classified as a minor-destructive technique. Therefore, it can be particularly useful in assessing the sensitivity to the effects of significant moisture in historic structures, where the collection of larger masonry specimens for testing is not permitted due to conservation reasons.