The repeated action of simulated freeze-thaw cycles on Cadalso de los Vidrios Granite, promotes
differential micro-cracking and loss of cr ystals at the surface and therefore decay. It is possible to
establish a relationship between the evolution of the ultrasound waves velocity (Vp) with the number
of freeze-thaw cycles and the generation of microcracks. Intergranular cracks are formed during the
first cycles and these propagate towards the inner part of each individual crystals as the freeze-thaw
cycles advance. Therefore, after 280 freeze-thaw cycles different patterns of microcracking can be
observed depending on the mineralogy. Quartz is the mineral displaying more intense cracking while
biotite shows less cracking, in part due to its more ductile behaviour. Micro-cracks appear preferentially
at the surface of the samples with a maximum length and depth of 1 cm. Thus, these samples showed
limited decay highlighting the good performance of Cadalso de los Vidrios granite against freezethaw