A Preliminary Study on Properties of A Weak Units–Strong Mortar Masonry: The Case Study of Matera Tufo Masonry (Italy)

In this paper, an experimental investigation addressed at the characterization of compressive strength of a weak units-strong mortar masonry is presented. This masonry, made with natural units of calcarenite improperly named “tufo”, is massively recurrent in the historic center of Matera, an UNESCO site since 1993. The tufo masonry was used for building ordinary and historical constructions, such as ancient churches and palaces, and nowadays it is extensively applied for restoration interventions in order to preserve the historic site and its surrounding area. At first, the research focuses on the evaluation of compressive strength of masonry components, by examining tufo cubic units and lime mortar prisms, and to propose relationships between non-destructive (sonic) and destructive (compression) tests statistically validated. Then, some formulations for estimating the masonry compressive strength by combining those of the basic masonry components are examined. Comparisons with results obtained with prism specimens (doublets and triplets) confirm that in this type of masonry compressive behavior (failure mode and compressive strength) is strictly dependent on tufo units. Finally, a probabilistic study of strength distribution highlights the importance of taking into account the compressive strength dispersion of each component, especially the one related to tufo units.