Caracterización y degradación de los materiales graníticos de la Colegiata de San Isidro, Madrid, España

Abstract

Original granitoids from the façade of the Colegiata de San Isidro are medium-grained-biotitic adamellites, from quarries of the Valdemorillo area (Madrid). The petrophysical properties of the materials allow to establish a clear difference between the two original granites: the most abundant one (A), with a lower porosity, lower water sorption capacity, a lower water vapour permeability coefficient, a higher ultrasonic waves transmission velocity, and a higher strength, respect to the least abundant granite (B). So it can be said the former is more resistant and of better quality than B-granite, or in other words, is a less-alterable granite than B-granite. In relation to the granites alteration trend, data make possible to establish that A-granite suffers less alteration than B-granite, because in the latter, values of the properties determined in internal and external sections, vary much more than for the A-granite. A brief reference to the conservation state of the main façade and to the monitoring of the atmospheric pollutants registered by two stations close to the building, with the aim of determining its inluence on the material degradation, which mainly consists of soiling and blackenning.