A laboratory experiment on salt weathering by humidity change: salt damage induced by deliquescence and hydration
| Autor: | Tsuyoshi Hattanji, Masato Sato |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Weight loss
010504 meteorology & atmospheric sciences Rock breakdown Sodium chloride Sodium chemistry.chemical_element Salt (chemistry) Weathering 010502 geochemistry & geophysics 01 natural sciences law.invention chemistry.chemical_compound law Sodium sulfate Crystallization 0105 earth and related environmental sciences chemistry.chemical_classification Magnesium lcsh:QE1-996.5 lcsh:Geography. Anthropology. Recreation food and beverages Humidity humanities lcsh:Geology Efflorescence lcsh:G chemistry Environmental chemistry General Earth and Planetary Sciences Longitudinal wave velocity Equotip hardness value |
| Zdroj: | Progress in Earth and Planetary Science, Vol 5, Iss 1, Pp 1-10 (2018) |
| ISSN: | 2197-4284 |
| Popis: | A laboratory experiment on salt weathering was carried out under changing humidity conditions. Three types of rock (tuff and dense and porous sandstone) with sodium chloride, sodium sulfate, or magnesium sulfate were subjected to humidity oscillations from 20%RH to 98%RH during 6 h periods at 20 °C. Prior to the weathering experiment, the rock specimens were oven-dried, and the water supply was restricted to only that from the air during the experiment. Salt on the rock specimens was deliquesced/hydrated at almost 100%RH during the high-humidity period and crystallized/dehydrated during the low-humidity period. Sodium chloride, which has high deliquescence ability, caused the most intensive weathering. Porous sandstone with sodium chloride was completely broken down after 100 cycles of humidity changes. The other two types of rock with sodium chloride showed flaking or swelling on their surfaces. For dense sandstone with sodium chloride, the Equotip rebound value decreased as the humidity cycles increased. Sodium chloride has a high susceptibility of deliquescence at humidities of more than 80%RH. Weathering by sodium chloride would occur extensively on the surfaces of stone heritages and geoheritages in humid coastal spray zones. Magnesium sulfate induced a weight loss in porous sandstone, flaking from the surface of tuff, and cracks on the surface of dense sandstone. Sodium sulfate had almost no effect in the humidity-change experiment, although salt efflorescence was obvious. The results for magnesium sulfate, salt deliquescence, hydration, and crystallization in the humidity-change experiment were easily repeated. Magnesium sulfate might have more influence than sodium sulfate when air humidity fluctuates in a short period. |
| Databáze: | OpenAIRE |
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