Investigation of the acoustoelastic effect in masonry elements of concrete blocks

The theory of acoustoelasticity describes the relationship between the propagation velocity of elastic waves and the stress state of a medium. Although many works concerning the acoustoelastic effect in steel, rocks and concrete have already been conducted, literature on acoustoelasticity in masonry is still scarce. The aim of this work is to investigate the acoustoelastic effect in masonry elements, focusing on masonry of concrete blocks. Therefore, this work is divided in three stages: static numerical modelling, experimental program, and dynamic numerical modelling. The first numerical simulation stage corresponds to modeling elements to determine their stress fields during a uniaxial compression test, aiming to provide theoretical background to plan the experimental program and to assist in discussions. The experimental program is divided in two phases: material characterization and acoustoelasticity evaluation in units, prisms of two and three units and wallets, with and without grout filling, subjected to uniaxial compression using the Ultrasonic Pulse Velocity (UPV) method. It was showed that acoustoelastic curves in units are highly influenced by the maximum applied stress. Also, it was observed that the mortar contributed to decrease the variation of the acoustoelastic effect in prisms. With respect to grout filled elements, the grout made mechanical behavior more complex and increased variability in results. The last stage of this work is the simulation of the propagation of an ultrasonic wave through a masonry block subjected to different compression levels. It was concluded that the non-uniformity of stress distribution in blocks and that the variation in the direction of wave propagation due to material heterogeneities hinder the determination of consistent acoustoelastic coefficients. (AU)