Concrete ferro

We analysed the factors which influence the radon concentration in the dwellings. First of all, differences by house construction are shown in Figure 4. The results were suprising because the traditional wooden house structure unexpectedly gave higher radon concentrations than the ferro-concrete and prefabricated houses. 

Figure 4. Cumulative frequency distributions of radon concentration for dwellings with different house constructions traditional wooden, ferro-concrete and prefabricated. Numbers, arithmetic means and S.D.s, geometric means, medians, and ranges of radon measurements are also indicated at the bottom of the figure.

A seml-colorcd solution, such as were the old ferro-gallie inks, requiring the addition of gum to prevent the deposition of the tinctorial matter, was especially liable to thicken, and flow tardily from the pen this in sultry weather, when evaporation is rapid, became especially irksome. The introduction of the steel pen made these imperfections more, manifest, causing a greater liability in the ink to concrete and deposit its coloring matter. 

Silica fume. Silica fume (SF) is a waste product of manufacturing ferro-sihcon alloys. It consists of an extremely fine powder of amorphous silica. Average particle diameter is about 100 times smaller than that of Portland cement and the specific surface area is enormous 13000-30000 m /kg compared to 300-400 m /kg for common Portland cements. Silica fume shows an elevated pozzolanic activity and is also a very effective filler. For these reasons, addition of silica fume to Portland cement may lead to a very low porosity of the cement paste, increasing the strength and lowering the permeability. It is usually added in the proportion of 5 to 10 % and it is combined with the use of a superplasticizer in order to maintain adequate workability of the fresh concrete. 

Wang, Y. et al. (1992b) Stndy of high-strength blended ferro-aluminate cement mortar and concrete, in Proceedings 9th ICCC, New Delhi, Vol. 5, pp. 621-627. 

The NDHP is deagned as a twin unit plant. The leak-tight part of the reactor building is shaped as a cyUndrical ferro-concrete containment with hemi-spherical dome. The ferro-concrete is not prestressed the thickness of the containment walls is 1.6 m. The containment is intended for protection against external and internal impacts and is designed for ... 

The Lombard Pier Luigi Nervi (1891-1979) is recognised as the master of ferro-cement construction. He extended reinforced concrete and pre-casting techniques... 

Silica fume is a by-product from the silicon metal or ferro-silieon industry. Its particle size ranges from 0.1 pm to 0.2 pm, the surface area being 20-23 m /g. It is highly pozzolanic and improves the properties of concrete in fresh and hardened states. 

If discrete cracks are formed in the matrix the material is not much better than ordinary reinforced concrete or ferro-cement. If, on the other hand, the fibres are able to stop and stabilize all microcracks formed in the matrix material, as in e.g. the best types of asbestos cement, a new high quality composite material has been created with an optimal fibre effect. 

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