In this paper, an experimental study conducted on Red Clay brick masonry ‘‘triplets” built with Cement and Lime-based mortars is presented. Monitoring of fracture is executed by Acoustic Emission (AE) and Digital Image Correlation (DIC). First, for a profound understanding of individual properties, small scale experiments were conducted for characterization of AE signatures of mortar and brick separately. Representative masonry triplet elements are tested in shear for investigation of the fracture mechanisms in relation to the properties of different mortars. Localization of the cracks as well as source identification is performed by means of AE parameter-based analysis. Their correlation with DIC, accurately showed the location of macro cracking and the developing of strain concentrations even before fracture. This is one of the first investigations where full field strain pattern from DIC are successfully correlated with AE indices in masonry. Numerical simulations were also performed for validation and prediction purposes.

Introduction

A large number of historical structures are built up in masonry. Brick masonry is a heterogeneous and anisotropic material formed by bricks and mortar. Its behavior up to failure is nonlinear and primarily depends on its components (brick, mortar and brick-mortar interface). Characterization of its material properties and structural condition is necessary for repair and conservation aiming to a long and safe service life [1–۳]. Mortars play a significant role in the masonry’s overall performance. The primary purpose of mortar in masonry is to bond masonry units into an assemblage which acts as an integral element having desired functional performance characteristics [4]. Because Portland cement concretes and masonry mortars contain some of the same principal ingredients, it is often erroneously assumed that good concrete practice is also good mortar practice. Realistically, mortars differ from concrete in working consistencies, in methods of placement and in the curing environment.