Evaluation In Situ of the State of Deterioration of Monumental Stones by Non-Destructive Ultrasonic Techniques
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EVALUATION IN SITU OF THE STATE OF DETERIORATION OF MONUMENTAL STONES BY NON-DESTRUCTIVE ULTRASONIC TECHNIQUES. M. MONTOTO, L. CALLEJA, B. PEREZ AND R.M. ESBERT. Dept. of Geology, Group of Petrophysics; University of Oviedo. 33080 Oviedo, Spain. ABSTRACT A non-destructive ultrasonic procedure has been developed for evaluating in-situ the relative deterioration of monumental sto- * nes. Ultrasonic waves are injected into the rock and they are registered, processed and petrophysically interpreted after trave: lling through it. The procedure applied to a Spanish Monastery (San Lorenzo de El Escorial, Madrid) built with a granitic rock is described. The following methodology was applied: in-situ categorization of the observable deterioration forms, sampling in the original quarries, laboratory ageing tests and continuous ultrasonic monitoring, in-situ data acquisition, evaluation of the ultrasonic parameters by signal processing and stepwise discriminant analysis. All that information is petrophysically interpreted for an appropriate assignation of the in-situ studied masonry blocks to the categorized deterioration degrees. Final in-situ results from the Monastery of El Escorial are here presented. Among the studied ultrasonic parameters energy is the most useful of all of them and velocity the least. INTRODUCTION The objective of this research was the development of a nondestructive technique, NDT, for evaluating in-situ the relative state of deterioration of monumental stones. That NDT procedure is based on the injection of ultrasonic waves into the stones of the monument, those waves, after travelling through the stone under examination, are registered, processed and petrophysically interpreted. The procedure was applied to a Spanish Monastery (San Lorenzo de El Escorial, Madrid) built in a granitic rock, according to the following experimental methodology: in-situ categorization of the observable deterioration forms, sampling in the original qua7 rries, laboratory ageing tests and continuous ultrasonic monitoZ ring, in-situ data acquisition, evaluation of the ultrasonic parameters by signal processing and stepwise discriminant analysis. All that information was petrophysically interpreted for obtaining an appropriate assignation of the in-situ studied masonry blocks to the categorized deterioration degrees. History The Monastery of San Lorenzo el Real de El Escorial is located 40 km to the North-West of Madrid. It was built during the XVIth century (1556-1586), during the reign of the Spanish king Philip II. Its principal architectwas Juan de Herrera, although some other architects were also involved in different stages of the construction works. A detailed history of the building can Mat. Res. Soc. Symp. Proc. Vol. 185. c 1991 Materials Research Society
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be found in [1). The special importance that the El Escorial Monastery has for the Spanish National Heritage is derived from its historical significance on the one hand, and from its architectural characteristics on the other. It was built by Philip II as a
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