L. Valdeón

Assessment of the quality of building stones using signal processing procedures

Abstract A combination of spectral and velocity analysis, using an ultrasonic pulse technique, has been performed on two lithologies of building stone: limestone and sandstone. Measurements of compressional and shear wave velocities have been made and the results obtained compared with the data provided from analyses of the frequency spectra so obtained from these rocks. It appears that the centre frequency and attenuation calculated from the frequency spectra provide useful quantitative measures of rock quality which augments that obtained from measurements of velocity alone, especially in saturated specimens. The potential value of using the centre frequency and attenuation as references to study the progressive change of rock quality during weathering has yet to be assessed.

ULTRASONIC VELOCITY AND HUMIDITY IN MONUMENTAL STONES

The velocity of propagation of ultrasonic waves in three sedimentary rock types, with different petrographical and physical properties, has been studied in relation to water content. The rocks investigated were a dolomite, a limestone and a sandstone used in the Cathedrals of Leon, Seville and Salamanca respectively. The objective was to determine the variation in the propagation velocity of waves under different conditions of water saturation. The technique can also be used to determine indirectly the water content of the rocks studied.

Relaciones entre porosidad, contenido en arcillas y durabilidad de areniscas

Se realiza la caracterización petrográfica de tres variedades de areniscas procedentes de Villamayor (Salamanca), Somió y Tazones (Asturias), poniendo de relieve la significación que el porcentaje y tipo de arcillas que cementan los granos minerales tiene, en estos casos concretos, en la configuración del sistema poroso. Asimismo, se correlacionan estas características con la durabilidad de dichas areniscas, evaluada mediante ensayos de heladicidad y cristalización de sales. R. M. ESBERT; J. ORDAZ; L. VALDEON Departamento de Petrología y Geoquímica Facultad de Geología. Universidad de Oviedo

Caracterización petrológica de los morteros de la fuente prerrománica de Foncalada: tipos y origen

The pre-romanesque fountain of Foncalda (Oviedo, Spain), made of ashlar stone, shows a remarcable lost of joints mortars which leads to its structural unstability. There are several types of mortars, but only one has been checked to be well preserved. The objectiv of this paper is characterizing all these mortars, triying to separate that considered original from the ones replaced and stablish proper formulation and proportions for a new restoration one. Results define the petrography of the best preserved mortar at the fountain – a hydraulic lime one- considered to be the original mortar, therefore recomending a similar one for restoration.