Bond Behavior of Historical Clay Bricks Strengthened with Steel Reinforced Polymers (SRP)

In the strengthening interventions of past and historical masonry constructions, the non-standardized manufacture processes, the ageing and the damage of masonry units, could significantly affect the properties of the surfaces where strengthening materials are applied. This aspect requires particular care in evaluating the performance of externally bonded strengthening layers, especially with reference to the detachment mechanism. The bond response of old masonries could be very different from that occurring in new masonry units which are the ones generally considered in most of the bond tests available in technical literature. The aim of the present paper is the study of the bond behavior of historical clay bricks strengthened with steel reinforced polymers (SRP) materials. In particular, the results of an experimental study concerning new manufactured clay bricks and old bricks extracted from different historical masonry buildings are presented. The obtained results, particularly in terms of bond resistance, detachment mechanism and strain distributions, are discussed for the purpose of analyzing the peculiarities of the historical bricks in comparison with new manufactured ones. Some considerations on the efficacy of the theoretical formulations of the recent Italian code are also carried out.