IngentaConnect Behavior of Brick Samples in Aggressive Environments

Abstract:

The weathering of different brick samples in a range of aggressive environments has been studied. Brick samples were prepared using two clay types (from Granada, Spain), different additives, and a range of firing temperatures (850–1100 °C). The bricks compositional and textural characteristics were evaluated using XRD, SEM, hydric tests and mercury intrusion porosimetry (MIP). The samples were subjected to accelerate aging, including wet-dry, freeze-thaw and salt crystallization cycles. The decay of the bricks in polluted atmospheres was simulated in a static chamber containing sulfur dioxide (SO_2) at 25 °C and 50% relative humidity. Samples fired at 1000 °C proved to be the most durable, with better hydric behavior (fast drying and slow water absorption) and fewer micropores. However, they were not suitable for salt-rich environments (bad performance in the salt decay test). Samples fired at 850 °C turned out to be more resistant to salt decay, but they showed a poor hydric behavior (slow drying and rapid water absorption) and little resistance to freeze-thaw and wet-dry cycles. Samples fired at 1100 °C had good hydric behavior, they performed well in the salt decay test, but they did not perform as well as the samples fired at 1000 °C in most accelerated aging tests. Gypsum formed on all the brick samples submitted to SO_2atmosphere regardless exposure time (e.g. gypsum appears following just 24 h of exposure), composition, or firing temperature. Samples with deposited particulate matter collected from vehicle exhausts (diesel, as well as leaded and non-leaded gasoline motor cars) resulted in the fastest gypsum development and greater abundance. On the other hand, the blank samples, and the samples with pollution-derived dust collected from historical buildings showed little gypsum development. The implications of these results in historical brick-building preservation in a range of aggressive environments, and in polluted atmospheres in particular, are discussed.

Keywords: bricks; decay tests; firing temperature; particulate matter; polluted atmosphere; SO; weathering

Language: English

Document Type: Regular paper

Affiliations: 1: Departamento Mineralogía y Petrología, Universidad de Granada, Fuentenueva s/n, 18002 Granada, Spain 2: Departamento Geología, Universidad de Jaén, E.U.P., Alfonso X El Sabio, 28, 23700 Linares, Jaén, Spain 3: Getty Conservation Institute, L.A., U.S.A.

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