“Ventilated render” system a replacement render for historic construction


Abstract eng:
The treatment of rising damp in historic building walls is very complex due to the thickness and heterogeneity of the walls. Some techniques, such as watertight barriers, injection of hydrofuge products, etc., that have been used until now to deal with rising damp are, sometimes, ineffective, justifying the need for a new approach. When there is the presence of rising damp with soluble salts, it may be even more complex to solve the problem. Salt damage is one of the major causes of render decay, not only near the sea but also in continental areas. These salts can appear in the walls from different sources: from the ground due to rising damp, carried by the wind as salt spray, by flooding, or they originally be present in materials as is the case of unwashed beach sand. Salts can crystallize depending on the salt transport behaviour of the substrate/render and the surrounding ambient environmental severity (temperature and relative humidity). An experimental program was developed using six different small scale specimens with traditional bricks as substrate, rendered on both sides with several optimized render systems. These specimens were submitted to several cycles of dissolution/crystallization with a NaCl solution. Particular attention is given to the influence of different renders when contaminated with NaCl and to the location of sodium chloride crystallization in the test specimens. The final goal of this study is the development of a replacement render system called “ventilated render” (“emboço ventilado” in Portuguese) for historic construction with renders damaged due to the presence of high moisture content and soluble salts. The ventilated renders have two layers (base and external layer) which are supposed to act as a transporting and accumulating system in which the salt is induced to crystallize in the base layer (executed with vertical grooves) of the render and not in the masonry nor in the external layer.

Contributors:
Publisher:
Glasgow : University of the West of Scotland, 2013
Conference Title:
Conference Title:
3rd Historic Mortars Conference
Conference Venue:
Glasgow, Scotland (UK)
Conference Dates:
2013-09-11 / 2013-09-14
Rights:
Text je chráněný podle autorského zákona č. 121/2000 Sb.



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 Record created 2014-11-03, last modified 2014-11-18


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