The Influence of 30 Years Outdoor Weathering on the Durability of Hydrophobic Agents Applied on Obernkirchener Sandstones

The durability of eleven different water repellents applied on one sandstone type was studied after a long-term weathering at seven different locations in Germany. By measuring colour changes, it could be shown that the formation of black crusts, the deposition of particles and biogenic growth cause...

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Main Authors: Jeanette Orlowsky, Franziska Braun, Melanie Groh
Format: Article
Language:English
Published: MDPI AG 2020-01-01
Series:Buildings
Subjects:
Online Access:https://www.mdpi.com/2075-5309/10/1/18
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spelling doaj-adce1a9834a84f029f9e4b162241ccc92020-11-25T02:20:43ZengMDPI AGBuildings2075-53092020-01-011011810.3390/buildings10010018buildings10010018The Influence of 30 Years Outdoor Weathering on the Durability of Hydrophobic Agents Applied on Obernkirchener SandstonesJeanette Orlowsky0Franziska Braun1Melanie Groh2Department of Building Materials, Technische Universität Dortmund, August-Schmidt-Str. 8, 44227 Dortmund, GermanyDepartment of Building Materials, Technische Universität Dortmund, August-Schmidt-Str. 8, 44227 Dortmund, GermanyDepartment of Building Materials, Technische Universität Dortmund, August-Schmidt-Str. 8, 44227 Dortmund, GermanyThe durability of eleven different water repellents applied on one sandstone type was studied after a long-term weathering at seven different locations in Germany. By measuring colour changes, it could be shown that the formation of black crusts, the deposition of particles and biogenic growth caused a gradual darkening as well as significant changes in total colour over time. Additionally, the water absorption behaviour was investigated with two different methods: applying a low pressure using the pipe method and capillary water absorption measurements from a wet underlay. Afterwards, the test results were analysed with four different evaluation methods: calculation of the protection degree from pipe method and capillary water absorption, determination of the velocity of water uptake during capillary water absorption and calculation of the damaged depth of the stone surface using single-sided NMR technique. The growing damaged depth leads to an increase of the water uptake velocity and to a decrease of the protection degree of the applied hydrophobing agents. Three protective agents based on isobutyltrimethoxysilane showed already after two years of outdoor weathering a clear loss of performance, which significantly increased after 30 years of exposure.https://www.mdpi.com/2075-5309/10/1/18conservationnatural stonelong-term weatheredwater repellentsdurabilitysingle-sided nmr
collection DOAJ
language English
format Article
sources DOAJ
author Jeanette Orlowsky
Franziska Braun
Melanie Groh
spellingShingle Jeanette Orlowsky
Franziska Braun
Melanie Groh
The Influence of 30 Years Outdoor Weathering on the Durability of Hydrophobic Agents Applied on Obernkirchener Sandstones
Buildings
conservation
natural stone
long-term weathered
water repellents
durability
single-sided nmr
author_facet Jeanette Orlowsky
Franziska Braun
Melanie Groh
author_sort Jeanette Orlowsky
title The Influence of 30 Years Outdoor Weathering on the Durability of Hydrophobic Agents Applied on Obernkirchener Sandstones
title_short The Influence of 30 Years Outdoor Weathering on the Durability of Hydrophobic Agents Applied on Obernkirchener Sandstones
title_full The Influence of 30 Years Outdoor Weathering on the Durability of Hydrophobic Agents Applied on Obernkirchener Sandstones
title_fullStr The Influence of 30 Years Outdoor Weathering on the Durability of Hydrophobic Agents Applied on Obernkirchener Sandstones
title_full_unstemmed The Influence of 30 Years Outdoor Weathering on the Durability of Hydrophobic Agents Applied on Obernkirchener Sandstones
title_sort influence of 30 years outdoor weathering on the durability of hydrophobic agents applied on obernkirchener sandstones
publisher MDPI AG
series Buildings
issn 2075-5309
publishDate 2020-01-01
description The durability of eleven different water repellents applied on one sandstone type was studied after a long-term weathering at seven different locations in Germany. By measuring colour changes, it could be shown that the formation of black crusts, the deposition of particles and biogenic growth caused a gradual darkening as well as significant changes in total colour over time. Additionally, the water absorption behaviour was investigated with two different methods: applying a low pressure using the pipe method and capillary water absorption measurements from a wet underlay. Afterwards, the test results were analysed with four different evaluation methods: calculation of the protection degree from pipe method and capillary water absorption, determination of the velocity of water uptake during capillary water absorption and calculation of the damaged depth of the stone surface using single-sided NMR technique. The growing damaged depth leads to an increase of the water uptake velocity and to a decrease of the protection degree of the applied hydrophobing agents. Three protective agents based on isobutyltrimethoxysilane showed already after two years of outdoor weathering a clear loss of performance, which significantly increased after 30 years of exposure.
topic conservation
natural stone
long-term weathered
water repellents
durability
single-sided nmr
url https://www.mdpi.com/2075-5309/10/1/18
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