Evaluation of the Mechanical Performance of Mortars for Structural Rehabilitation of Historic Masonry Buildings

Consolidation and conservation interventions of masonry buildings belonging to the historical monumental heritage are designed and performed to ensure their safety against environmental and anthropogenic actions according to the place where the buildings were constructed. Often arises the need for the use of mortars for structural or conservation purposes which replace or integrate existing mortars to ensure a homogeneous behavior of the masonry apparatus. Compatibility criteria are defined according to the characteristics of the original mortar but often the performance of the mortar after its application to the masonry is not evaluated. On the market there are standard products that are used indiscriminately without a careful evaluation of the masonry to which the products are applied. Only in some cases the request of the designer leads to the definition of mixtures prepared ad hoc to perform an adequate intervention on the masonry. In this work the results of experimental campaigns aimed at defining the characteristics of mortars used for conservative restoration interventions on historical masonry buildings are presented. In the performed experimental campaigns both the mechanical strength of unconditioned mortars and the mechanical strength of mortars subjected to cycles of environmental degradation were evaluated. Ultrasonic, bending, compression, and penetrometric tests were performed to evaluate the performance of the mortars and the effects of accelerated degradation on their performance.