Weathering stone

The net effect of the entire deterioration process is to alter physical and chemical properties so that the weathering stone becomes even more susceptible to atmospheric attack. 

The net effect of the entire deterioration process is to alter chemical and physical properties such that the weathering stone becomes even more susceptible to atmospheric attack. The function of conservation treatments is to regenerate, at least partially, the original properties so that the stone acts as though it had been established anew in its existing environment. 

Tait CD, Janecky DR, Clark DL, Bennett PC (1991) Oxalate complexation with aluminum(III) and iron(III) at moderately elevated temperatures. In Kharaka Y K, Maest A S (eds) Water-rock interaction. Balkema, Rotterdam, pp 349-353 Tan KH (1980) The release of silicon, aluminum, and potassium during decomposition of soil minerals by humic acid. Soil Sci 129 5-11 Tandura SN, Voronkov MG, Alekseev NV (1986) Molecular and electronic structure of penta- and hexacoordinate silicon compounds. Top Curr Chem 131 99-189 Thurman EM (1979) Organic geochemistry of natural waters. Nijhoff, Dordrecht, 497 pp Webley DM, Henderson MEF, Taylor EF (1963) The microbiology of rocks and weathered stones. J Soil Sci 14 102-112... 

Roofs are a basic element of shelter from inclement weather. Natural or hewn caves, including those of snow or ice, ate early evidence of human endeavors for protection from the cold, wind, rain, and sun. Nomadic people, before the benefits of agriculture had been discovered and housing schemes developed, depended on the availabiUty of natural materials to constmct shelters. Portable shelters, eg, tents, probably appeared early in history. Later, more permanent stmctures were developed from stone and brick. SaUent features depended strongly on the avadabihty of natural materials. The Babylonians used mud to form bricks and tiles that could be bonded with mortars or natural bitumen. Ancient buildings in Egypt were characterized by massive walls of stone and closely spaced columns that carried stone lintels to support a flat roof, often made of stone slabs. 

Magnesium oxychloride cements are widely used for the fabrication of floors. They find application for this purpose because of their attractive appearance, which resembles marble, and also because of their acoustic and elastic properties and their resistance to the accumulation of static charge. They have also been used for plastering walls, both interior and exterior for exterior walls the cement often includes embedded stone aggregate (Sorrell Armstrong, 1976). However, there have been problems with this latter application, since the base cement has been found to be dimensionally unstable and, in certain circumstances, to release corrosive solutions and show poor weather resistance. 

Below-grade walls may be constructed of poured concrete, masonry blocks, or other materials such as all-weather wood or stone. This chapter discusses details for use of poured concrete and masonry foundation because these are the materials most commonly used for new construction. Recently, trade associations such as American Plywood Association (APA) and the National Forest Products Association (NFoPA) have issued publications on designing radon resistance permanent wood foundations. Information on these types of foundations can be found by contacting the appropriate trade association.21... 

FIGURE 44 Weathering. A weathered sandstone column. Calcite (composed of calcium carbonate) is dissolved by rain and groundwater (see Textbox 73). When stone in which calcite is a main component as, for example, sandstone, limestone, and marble, is in contact with water for long periods of time, it is weathered and partly or entirely dissolved. Pollutants such as sulfur dioxide are fundamental in accelerating the weathering and dissolution process. When sulfur dioxide, for example, dissolves in rainwater, it forms sulfuric acid, a strong acid that, at ambient temperatures, rapidly dissolves calcium carbonate. 

Quartzite. Quartzite is a very compact, exceptionally hard and tough meta-morphic rock derived from sandstone. It consists mainly of rather large crystals of quartz (composed of silicon dioxide) naturally cemented by secondary quartz. Most varieties of quartzite contain over 90% quartz, and in some cases the quartz content exceeds 95% of the total weight of the stone. The color of most quartzite is white or light yellow, but if it contains iron oxide impurities it is red, while other metal oxide impurities may cause the rock to display patchy color variations. Quartzite is very hard, which makes it difficult to quarry. Nevertheless, because of its strength and resistance to weathering, it has occasionally been used for construchon, sculphng statuary, and ornamentation. 

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