In situ peeling tests for assessing the cohesion and consolidation characteristics of historic plaster and render surfaces

Publication Type:

Journal Article

Authors:

Miloš Drdácký; Zuzana Slížková;

Source:

Studies in Conservation, Volume 60, Number 2, p.121-130 (2015)

Abstract:

Standard application principles for the peeling test, also known as the scotch tape test, for assessing the surface cohesion characteristics of materials have been presented by the authors in earlier papers on laboratory testing of stone and mortar consolidation effects. The method has been in use for a long time for evaluating the strengthening of surface layers of mortars, but there have been no standards or reliably verified recommendations on how the test should be applied. Nevertheless, the method has been attracting continuing research, because it is a simple and quite reliable method for in situ testing of consolidation effects, if it is applied correctly. Our paper summarizes the basic principles, and presents illustrative results of an investigation of important historic buildings. It goes on to suggest some practical approaches and designs that are useful for in situ applications. We present a mathematical procedure suitable for evaluating the results that are obtained. We recommend repeated peeling on exactly the same place on the surface in order to compensate for and eliminate the effect of the natural decrease in the material detached from the subsurface layers, which might be incorrectly interpreted as a consolidation effect. The examples and validation measurements presented here include in situ measurements.