Abstract

Over the last decade, the concept of stone decay being caused by one or two processes has been revised in favour of a more holistic notion that many operate together, cyclical or seasonal. Certain of these processes may become pre-dominant over others at a particular environment that enhances the impact of these process or processes. The rock's mineralogy is an effective factor in controlling rock's susceptibility to weathering and deformation of its original form. Salt weathering has been reported to act at almost all environments even at low intensity, many researchers from different disciplines agree that biological deterioration is of significance. The rate of weathering varies and controlled by different factors, it is increased at areas with multiple cycles of weathering that repeat on short time with high intensity. In the current study we aim to examine salt weathering, Bio-deterioration on the sandstone blocks constituting ancient buildings "walls" at Aachen City, as well as compute the rate of weathering at such humid region on such sandstone. The aims have been achieved from sampling from weathered parts, measuring depth of greatest back weathering forms, laboratory analyses for collected rock samples. The results indicated high impact of salt weathering that result from chemical interaction of air pollutants with mortars' carbonate content, the growth of lichens affects on such sandstone as noted in SEM presentation. The rate of weathering is noticeably high.

Key words: Weathering, rock mineralogy, rate of weathering, environmental conditions.