[M-IS09] Weathering and conservation of cultural heritage and geosites

[MIS09-04] Non-destructive strength tests of heritage buildings: an overview of Schmidt hammer and Duroskop tests

*Akos Torok¹ (1.Budapest University of Technology and Economics)

Keywords:weathering, surface strenght, Schmidt hammer, Duroskop, non-destructive testing

Strength tests of heritage structures require special care since in most cases, only non-destructive tests are possible to detect the surface strength of materials. The most widely used tool is Schmidt hammer. It has been applied for a few decades to assess the strength of building stones. Another less widely used tool is Duroskop, a non-destructive test device with lower impact strength, and it can detect smaller surface strength than Schimdt hammer. In this paper, the non-destructive strength test results of the façades of several buildings are presented. The aim is to assess Schmidt hammer rebound and Duroskop rebound variations representing various states of weathering. The studied buildings were constructed from porous limestone, travertine, non-porous crystalline limestone and sandstone. The Schmidt hammer rebound values and Duroskop rebound values of ashlars were recorded representing various weathering conditions. The large data set of measurements was evaluated using geostatistical methods. The results indicate that besides the lithology, the differences in exposure and air quality alos influences surface strength. The data sets help to outline the weathering-related changes in Schmidt hammer and Duroskop rebound.