Swelling damage in clay-rich sandstones used in the church of San Mateo in Tarifa (Spain)

HONEYCOMB WEATHERING OF SANDSTONE OUTCROPS AT AL-HIJRv(MADA'IN SALIH), SAUDI ARABIA

“…This creates an area of tension that results in development of fractures between the wet zone of the rock and the dry zone behind it. Swelling stresses lead to the development of scaling and flaking as well as contour-scaling [16]. Once the external wet layer has dried as a result of evaporation due to the action of the sun, temperature increase during the day, and evaporation accelerated by the effects of the wind, the clays contract causing the appearance of drying or retraction fractures perpendicular to the surface as observed all over the Al-Hijr rocks.…”

“…Clay minerals have a flat shape like small flakes. These flaked shapes are typical of Kaolinite [16]. Different spots of sandstone samples were investigated by EDS to identify their elemental composition, tab.…”

“…The main deterioration mechanism of the rock-cut monumental tombs at Al-Hijr is swelling and shrinking of the clay minerals that form the cement or the matrix of the sandstone. In the presence of humidity, all clay minerals that Kaolinite includes, may be subjected to osmotic-type swelling processes if the pores in the rock contain an electrolyte in solution [16] [24]. Halite salt NaCl is one of the most effective electrolytes in osmotic swelling of clays.…”

Weathering of sandstone lotus petals at the Angkor site: a 1,000-year stone durability trial

“…Jiménez-González et al 2008;Wangler and Scherer 2008). It is the case of smectites or interstratified chlorite/smectite clays in the Scrabo sandstone of St. Matthew's Church in Belfast (Smith et al 2002); the lower Keuper sandstones of SainteCroix's Church in Bouzonville, East France (Mertz and Guiavarc'h 2005); and the Tarifa sandstone of San Mateo's Church in Cádiz, Spain (Sebastián et al 2008). Swelling clays have been shown experimentally to enhance hydric/ hygric expansion, e.g.…”

Flaw propagation and buckling in clay-bearing sandstones

“…Another damage mechanism arises with sandstones that have swelling clay inclusions in the binding phase, where stresses on the order of the strength of the stone can arise due to differential wetting and drying. The problem of swelling clays in conservation has been recognized by a number of authors previously (Rodríguez-Navarro et al 1997;Delgado Rodrigues 2001), and continues to generate interest in recent years (Franzini et al 2007;Sébastian et al 2008). It has been demonstrated that the expansion of Portland brownstone results from intracrystalline swelling of mixed-layer chlorite/smectite clays in the cementing phase by incorporation of as many as four layers of water molecules (Wangler and Scherer 2008).…”