In Situ Analysis of Plaster Detachment by Impact Tests

Alessandro Grazzini

doi:10.3390/app9020258

Abstract

The frescoed surfaces of historical buildings may be subject to detachment due to various causes of deterioration. A new non-destructive experimental methodology is described to assess in situ the safety against plaster detachments from historical wall surfaces. Through small and punctual impacts exerted with a specific hammer on the plastered surface it is possible to evaluate the level of the plaster’s detachment. A case study at Palazzo Birago in Turin (Italy) is described to give an example of the application of this innovative technique on frescoed surfaces of historical vaults. The test allows to evaluate the safety of frescoed decorations without affecting the material consistency or creating damage, therefore, making it very suitable in the field of architectural heritage.

Highlights

In the field of historical buildings, the role of monitoring and diagnostics is increasingly important for the purpose of securing the masonry structures and the decorative apparatuses
The potential detachment of plaster can be further dangerous if it comes from masonry vaults, with the risk of material inside historical buildings containing residential or public functions falling
The Non-Destructive Testing Laboratory of the Politecnico di Torino introduced an impact method to be applied on the wall surface

Summary

Introduction

In the field of historical buildings, the role of monitoring and diagnostics is increasingly important for the purpose of securing the masonry structures and the decorative apparatuses. An experimental analysis of the stability of the decorated plaster covering three masonry vaults of the Birago Palace (16th century, planned by Filippo Juvarra) in the center of Turin was described by the use of the impact method test. The frescoed vaults of the Pelagi, Blu, and Giunta rooms showed some small cracks branched out in a layer of plaster that needed an evaluation regarding the risk of detachment (Figures 1–3). Birago branchedin inthe thedecorated decorated plaster masonry vault in the Blu room. (a) Giunta room at Birago Palace; (b) cracks branched in the decorated plaster of the masonry. 3. in atatatBirago cracks branchedin thedecorated decorated plaster of masonry ininthe the decorated plaster ofthe thethe masonry vault the Giunta room

Equipment Setup and Methods

Impact

Experimental Results at Birago Palace Tests

10. Map of the points and areas tested on the the vault vaultof of theBlu

Discussion

Conclusions