Improvement of sonic tests methodology for the characterization of stone masonry

Abstract

The maintenance and rehabilitation of historical buildings is vital and it is not recommended to use destructive investigative techniques on them. Non-destructive geophysical tests (NDT) have been increasingly used to characterize historical buildings ((Binda et al., 1998; Anzani et al., 2006; McCann and Forde 2001; Silva et al., 2013; Manning et al., 2014; Leucci et al., 2011). However, this practice, although in wide use, still has significant uncertainties in obtaining reliable quantitative and qualitative data and information. This paper focuses on the application of sonic tests as a NDT (non-destructive testing) research option for characterizing granite masonry walls. The sonic test, one of the commonly used NDT techniques, is performed with an instrumented hammer as an active source for wave generation and accelerometers for wave reception. The conventional and expeditious use of sonic tests relies on a methodology for wave generation and acquisition as well as signal analysis processing and interpretation based on certain assumptions. This work calls into question some of the referred assumptions about wave generation and acquisition and interpretation procedures and aims to show a better understanding of the method allowing more accurate and reliable results in its application. In addition, we propose a non-conventional methodology for S-waves generation and acquisition as well as a technique for waves recognition.