The weathering of brick; causes, assessment and measurement

Abstract

The composition and processing of raw materials can effect both short-and long-term alteration. On exposure to moisture, brick raw materials rich in sodium and potassium expand more than materials rich in calcium, alumina, and magnesium. Mineral grains such as calcite, dolomite, pyrite, and siderite are associated with cracks, spalls, and pops in bricks, and some lime-rich Pleistocene materials develop complete friability unless treated with steam or water during cooling. Bricks made from illite-rich raw materials expand much more than those made from kaolinite-rich materials, but this greater expansion may be partly attributable to the fact that kaolinitic materials require greater firing temperature. Mortars can be made from several materials, but the preferred composition is Portland cement, quartz sand, and lime, in ratios depending on the strength required. If sulfate attack on the mortar is a likelihood, mortars low in sulfate and tricalcium aluminate should be used, and bricks with low sulfate content should be specified.The firing of bricks is an essential determinant of brick durability and tendency to expand. Bricks fired at low temperatures expand much more, absorb more water, are less strong, and are more likely to deteriorate than are bricks fired at higher temperatures. Many brick materials have a relatively short vitrification range (the interval from under-fired to optimum firing and to over-fired due to bloating and/or melting). This short firing range, plus the high cost of fuel, makes temperature control a top priority in the production of brick. Firing to optimum levels seems to cause the crystallization of a series of high temperature phases, with corresponding increased strength and decreased water absorption and moisture expansion. Moisture expansion is thought to result from rehydroxylation of illite and other clay mineral anhydrides. Acid rainAlthough the literature suggests that acid rain has not worsened dramatically in the past 25 years, several studies show that this problem is a very serious one that could increase in intensity in the future. The problem of sulfate and nitrate pollution is complicated by the fact that there are many forms in which the SO and NO can be transported and deposited, and by the fact that acid precipitation often results from the combined effects of several sources of pollution. These widespread phenomena essentially are outside current point source laws, and are not dealt with adequately in national or international law; however, almost everyone agrees that the effects of acid rain ought to be more extensively studied. Such research must deal with very -11 -complex phenomena and often the results show only subtle differences. In many cases the complexity of the natural setting can only be simulated by using outdoor situations and attempting to control as many variables as possible. The acid rain problem involves the effects of SOX and NOX deposition or absorption from rain, sleet, snow, fog, dust, and gaseous diffusion. It is clear that the amount of dry ...

Acid rain weathering of Salem limestone; surface characterization of control material

“…The Winkler compendium includes contributions from seventeen recognized authors covering topics such as stone properties, stone weathering, and stone preservation; the treatment also includes comprehensive literature reviews in all of these areas. Another extensive literature review, specialized in the area of brick weathering, has been released by Hughes and Bargh (1982).…”

PolyBrickH2.0

“…Ceramic materials, like fired brick, often deteriorate due to their ability to retain moisture. A wet environment grows mold and organic material, which weakens the brick (Hughes, Bargh 1982) . This mold is a detriment to the building's lifespan and inhabitants' health (EPA 2014).…”

Brick manufacture with fly ash from Illinois coals. Technical report, March 1, 1995--May 31, 1995

“…Efforts to find better raw materials and improve the manufacture of fired-clay products have taken place over the last six decades at the Survey. Relevant parts of these efforts are summarized in Hughes and Bargh (1982), Hughes (1983), White (1983), andHughes (1993). Slonaker (1977) showed that acceptable bricks were produced from feeds of 72% fly ash, 25% bottom ash, and 3% sodium silicate.…”