| Abstract: | Blackened alteration crusts of gypsum plus particulates that form on sheltered areas on marble and limestone buildings pose a challenge for rehabilitation and cleaning. Fresh marble and limestone samples exposed at monitored exposure sites present conditions of simple geometry and well-documented exposures but have short exposure histories (one to five years). The gypsum alteration crusts that develop on these samples provide insight into the early stages and rate of alteration crust formation. Alteration crusts from buildings give a longer, but less well known exposure history and present much more complex surfaces for gypsum accumulation. Integrated observations and measurements of alteration crusts from exposure samples and from buildings identify four factors that are important in the formation and development of alteration crusts on marble and limestone: (1) pollution levels, (2) exposure to rain or washing, (3) geometry of exposure of the stone surface, and (4) permeability of the stone. The combination of these factors contributes to both the distribution and the physical characteristics of the gypsum crusts which may affect cleaning decisions. |
| Genre: | Article |
| ProdID: | 70017798 |
| Citation Author: | McGee, E. S. |
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| Citation End Page: | 397 |
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| Citation Language: | English |
| Citation Larger Work Title: | ASTM Special Technical Publication |
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| Citation Number Of Pages: | 22 |
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| Citation Search Results Text: | Development of gypsum alteration on marble and limestone; 1996; Article; Journal; ASTM Special Technical Publication; McGee, E. S. |
| Citation Start Page: | 376 |
| Citation Volume: | 1258 |
| Citation Year: | 1996 |
| Type: | citation/reference |
| Text: | Development of gypsum alteration on marble and limestone; 1996; Article; Journal; ASTM Special Technical Publication; McGee, E. S. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Mon, 1 Jan 1996 00:00 -0600 |
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