Building materials, penetration

The decay sequence for Rn-222 is given in Figure 2. Because of the 4 day half-life of Rn-222, it has the time to penetrate through the soil and building materials into the indoor environment. There is some recent evidence that in spite of its short half-life, 55 seconds, Rn-220 can also penetrate into structures in significant amounts (Schery, 1985). However, the data are limited and the extent of the thoron problem is quite uncertain. It is, therefore, the short-lived decay products of radon that are considered to be particularly important in the exposure of the general public and it is these isotopes on which this report will concentrate. 

Masonry products have been widely used in the construction industry and include building materials such as cementious materials, concrete, brick, tile, stone, grout, and like substances. Driveways, garage flooring, concrete block, brick fronts, fireplaces, fireplace hearths, as well as tiled floor, wall and counter top surfaces are exemplary applications. Masonry surfaces are porous and if left unprotected can deteriorate from exposure to water and they can become discolored. For example, water penetration can cause spalling or lead to discoloration via microbial growth. Tiles and grouts employed in homes come in contact with various foods and liquids, e.g., fruit juice, coffee, oils, ketchup, mustard, etc. that can cause discoloration. 

Mold. The growth of mold is associated with dampness, either of the substrate or of the surrounding atmosphere. It is recognized by black or variable-colored spots or colonies which may be on, in, or beneath the paint film and can occur on almost any type of building material. The growth may penetrate the underlying plaster or brickwork and become difficult to eradicate. 

Depending on the porosity of the building material and the condition of use, the depth of penetration of silanes varies from a few millimetres to a number of centimetres. 

High air humidity is not the only reason for microbial growth indoors. Microbial growth is often caused or at least promoted by moisture penetration through building materials. The causes of moisture penetration can be divided into construction flaws or user errors. Thermal bridges and defective isolation are considered as construction flaws. 

R. B. Polder, Electrochemical chloride removal from reinforced concrete prisms containing chloride penetrated from seawater . Construction and Building Materials,... 

McCartei W.J. and Vennesland, O. (2004). Sensor systems for use in reinforced concrete structures . Construction and Building Materials, 18 351-358. Raupach, M. and SchiessI, P. (Feb, 1995). Monitoring System for the Penetration of Chlorides, Carhonation and the Corrosion Risk for the Reinforcement. Proceedings of the 6th International Conference on Structural Faults and Repair. 

Because of the molecular size and remarkable reactivity of water-borne fluoroalkylsilane systems, the penetration depth in concrete and other porous building materials is very low. This desirable effect results in the high efficiency of this special product. Substrates of relatively low porosity such as concrete need about 150-200 g/m of Protectosil Antigraffiti to impart permanent anti-graffiti properties. Approximately 20-50 g/m are necessary for an excellent water and oil-repellent, chemical- and UV-resistant coating (about 200 g/m of the aforementioned product). 

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