Browsing by Subject "structural strengthening"

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Access status: Open Access ,
Mikrostruktury produktów polikondensacji związków krzemoorganicznych w wybranych piaskowcach karpackich
(Wydawnictwa AGH, 2009) Rembiś, Marek
Polycondensation of silica-organic compounds introduced into the pore spaces of sandstones results in the formation of silica gel. The distribution of this gel depend on the rock structure, texture as well as the type and the amount of cement. Of significance are also the properties of the polymer itself, the kind of a solvent used and the method of saturating.
Access status: Open Access ,
Piaskowce modyfikowane związkami krzemoorganicznymi oraz zmiany ich porowatości i wytrzymałości na zginanie pod działaniem siły skupionej
(Wydawnictwa AGH, 2010) Rembiś, Marek
The sandstone samples representing 24 deposits localized in various geological regions of Poland were impregnated with liquid polymers, in which esters of the orthosilicic acid are active agents. Such preparations are commonly applied as stone strengtheners in conservation practices. The products of condensation of these polymers formed in the course of seasoning of the impregnated stone samples for 4 weeks have developed diversified microstructures. Their presence has lowered the porosity of the sandstones and changed the structure of the rock pore spaces. As a result, the sandstones have been strengthened as indicated by their values of the flexural strength under concentrated load. A distinct change of this parameter should be linked to exceeding of the threshold value of tetraetoxysilan oligomers concentration (percolation threshold) in the sandstones in question, mainly in their Liassic, Cretaceous and Istebna varieties. It has taken place in the samples with the porosity lowered at 41-66%. The percolation threshold has not been achieved in this part of the impregnated Magura, Krosno and Godula sandstones, in which their porosity has decreased at the value not exceeding 10%. In these cases, the value of the flexural strength under concentrated load remains at the same level as it was measured prior to impregnation.
Access status: Restricted ,
Przyczyny niszczenia i możliwości skutecznej rewaloryzacji piaskowców zastosowanych w elewacji zewnętrznej kościoła p.w. Nawrócenia św. Pawła w Krakowie
(Data obrony: 2012-06-06) Kubiak, Antonina
Wydział Geologii, Geofizyki i Ochrony Środowiska
The Saint Paul’s Conversion Church in Cracow is a monumental 18th-century baroque edifice, located in the busy Stradomska Street close to the Vistula River. Its front is decorated with middle-grain sandstone slabs, composed mainly of quartz and other siliceous components and originating from the Rakowiczki quarry. In the course of macro- and microscopic investigation, extensive weathering of the slabs has been established, including back weathering due to loss of scales and due to loss of stone layers dependent on stone structure, relief rounding, break out due to anthropogenic impact, coloration, soiling and crust by particles from the atmosphere. The condition of the stones has been influenced by a variety of factors. Prominent among them are climatic factors, such as high local air humidity, daily and annual temperature fluctuations, insolation and precipitation characteristics, frost action, also, various anthropogenic factors, namely gaseous pollutants, such as sulphur oxides (SOx), nitrogen oxides (NOx) and carbon monoxide (CO) from vehicular exhaust systems and from solid fuels burned in tiled stoves, furthermore, the vibration emitted by trams going down the Stradomska Street. To restore the elevation to its original excellence, its surface must be cleaned of soiling and crust, and the missing fragments reconstructed with either appropriate filling material or, where necessary, replaced with the sandstone from the Rakowiczki quarry. When it comes to the prophylaxis in conservation there tetraalkoxysilane consolidants without repellent effect should be applied. The research results have shown, that Funcosil Steinfestiger 100 and Asolin OH-30 are highly suitable for that purpose, because after applying them the highest increase of compressive strength values was obtained in comparison with samples where none of these substances were applied, while water absorption was either lower or on the same level.