Characterisation of monzogranitic batholiths as a supply source for heritage construction in the northwest of Madrid

Abstract

The Church of the Assumption of Our Lady, in Valdemorillo (Madrid, Spain) is almost entirely built with granitoids. The studies and analyses were focused on the oldest part of the building (Ghosts Corner), which will be restored and rehabilitated in the near future. Homogeneous monzogranite is the predominant granitoid used in the Ghosts Corner, followed by granitic porphyry, porphyrytic monzogranite, gneiss and leucogranite. The original quarries that supplied homogeneous monzogranites for the first construction stages correspond to blocks present in the monument's surroundings. Quarries that supplied the granitic porphyries correspond to the dykes located to east-southeast of Valdemorillo, which are oriented N-S in relation to their intrusion direction. The combined use of ultrasonic velocity and Schmidt hammer techniques allowed, first, selection of the most representative blocks and ashlars for sampling. This reduced sampling to a minimum, but yielded representative results for the whole building. Second, the combined values were used to compare results for the building stones of the church to rocks from the surrounding quarries. Stones from the building showed lower ultrasonic and Schmidt hammer values, and higher porosity and water saturation values compared to the original quarry rocks. The anisotropy indices are directly related to the decay processes in the stone: spalling of homogeneous monzogranite and grain disintegration in granitic porphyries. Finally, the methods applied are inexpensive, easy to use and non-destructive techniques, very advisable properties when working with built heritage.

How does anisotropy in bedrock river granitic outcrops influence pothole genesis and development?

“…H R and UPV values depend on the elastic properties of the rock. H R and UPV values are related to the petrophysical properties of the rock (Kahraman, 2001;Prikryl et al, 2007;Vasconcelos et al, 2007;Fort et al, 2010Fort et al, , 2011Fort et al, , 2013Cerna and Engel, 2011;Sharma et al, 2011), but can be influenced by weathering and erosion. In general, lower UPV and H R values indicate less resistant rocks, which may reflect a higher degree of weathering.…”

Current methods and future trends in testing, durability analyses and provenance studies of natural stones used in historical monuments

“…Besides low-destructive tests numerous non-destructive techniques are available for stone testing. Portable ultrasonic pulse velocity testing was applied to assess the state of the preservation of marble tombstones in Germany and also for identifying granitic rocks both at monument and at quarry scale (Fort et al, 2010). Schmidt hammer becomes also a common tool for in situ testing of mechanical properties of stone monuments (Török, 2003(Török, , 2010Goudie, 2006) and quarry faces (Fort et al, 2010).…”

“…Comparative micro-fabric analyses in situ detection of mechanical properties in comparison with laboratory analytical results were used to identify granitoids in Spain (Fort et al, 2010) and also for depicting differences in Eocene sedimentary rocks in Paris Basin (Fronteau et al, 2010).…”

Exfoliation microcracks in building granite. Implications for anisotropy

“…The exfoliation microcracks found in tors are normally pseudo-concentric, giving rise to what is known as spheroid exfoliation. Traditionally, tors were used to hew ashlars for use in monument construction (Fort et al, 2010).…”