Institute of Geology and Dynamics of the Lithosphere at the University of Göttingen



International Conference on
Textures and Physical Properties of Rocks

October 13 (Wed) to 16 (Sat), 1999 in Göttingen, Germany

WORKSHOP 6:

Modesto Montoto (Oviedo, Spain):

Non-destructive evaluation of physical properties of rocks



Non-destructive tests in Materials Science and Engineering have been used for decades rendering very efficient results; unfortunately, this is not the case when they are applied to rocks and the NDT data has to be geologically interpreted. That behavior can be explained in terms of the existing differences between "man-made" materials and "nature-made" materials. Rocks are the result of very variable geological processes which developed in them very significative changes in their original characteristics; the final result is a very complex and non homogeneous material, full of internal discontinuities and anisotropies, with residual stresses,...which shows a very high attenuation of the waves traveling through it. The two main scales in "Rock Engineering", rock-massif scale and intact rock scale, have to be here clearly differentiated; this Workshop is mainly focused on the second one. Its main rock- forming components (pores and fissures, texture, grain interlocking, minerals, ...), due to a petrogenetic and tectonic complex history, are non uniformly distributed as wells as the physical properties those components condition. Those circumstances explain not only how complicated is the path-way followed by non-destructive signals through rocks, but also how difficult is to interpret the data NDT provide. Procedures like tomography are here extremely helpful; besides, they provide "physical images" or mapping of values of a given physical property along the rock interior. Many types of NDT have been used for characterizing rocks; among them those based on the propagation of waves: elastic, electric, electro-magnetic, X-ray, thermal,... stands out. To discuss about their advantages and disadvantages for each peculiar application in Geology, as well as the difficulties implied in the interpretation of NDT data, is one of the main goals of this Workshop. For a rationale NDT data interpretation a petrophysical approach is suggested: the physical properties of the rock have to be obtained, NDT data has to be analyzed and interpreted in terms of its rock-forming components. A reliable methodology should establish a good relationship among NDT data, rock physical properties and rock-forming components. Among the very different application of theses studies, one covering Cultural Heritage and Science & Technology, is Stone Conservation; the diagnosis of the state of deterioration of stones should be obtained under non-destructive tests. In fact, that deterioration is a degradation of their original petrographic characteristics and, consequently, of their physical properties. This workshop, following many EC recommendations, should be a good occasion for stimulating the participation of expertises in NDT in this subject of worldwide interest.

Specific topics are:


Oral contributions, posters and practical demonstrations are invited.

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Last updated: Apr 14, 1999