Full text
| |
| Author(s): |
William Whitaker
Total Authors: 1
|
| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Escola Politécnica (EP/BC) |
| Defense date: | 2001-03-20 |
| Examining board members: |
Arthur Pinto Chaves;
Eldon Azevedo Masini;
Claudio Sbrighi Neto
|
| Advisor: | Arthur Pinto Chaves |
| Abstract | |
This research has as a goal to develop the theme of the mineral processing of the sands used as fine aggregate in the building construction industry, showing the applications of the usual and traditional techniques, towards presentations of other more sophisticated processes. In this context it has been tried for to give importance to the need of Brazil, especially in regions as the metropolitan area of the greater São Paulo, to grow in this segment, through the application of equipments with technologies linked to the needs of the market, towards versatile fluxograms of sand processing plants. Developed countries, such as Germany, Holland and United States, emphasize at their plants the cares with the constancy of the size distributions, as well as to obtain minimum presences of noxious substances in the products. It is only in this way that we can adapt the quality of these sands to that now demanded by the concrete industry and contractors of medium and great size, that are part of a building construction market more and more exigent. The exigences come from the specifications of the national standards, as ABNT, till particular specifications as in the cases of the sands supplied by the processing plants named \"recipe plant\" or \"in line blending plant\", that produce specific size distributions for each use. At this moment, it is observed that the concrete industry has been showing a tendency of offering \"tailor made\" products, suited to specific applications. Thatpractically implies that their raw materials suppliers should be prepared for the same. To assist this market with products still seen as special, the sands should be separated in size fractions in a relatively narrow range and then the fractions are combined acording to a formulation or \"recipe\" that provides the desired size distribution. The resulting composition, or the proper size distribution is defined by the concrete and construction specialists. In this careful selection of the fine aggregate, the civil engineer purpose, for instance, in terms of the mechanical resistance of the concrete, can go from its increase (preparation of high performance concrete) or, alternatively, to keep usual values of resistances with significant reduction in cement consumption. This study has as an objective not only to develop the technical way to supply the crescent demand for this mineral raw material, as well as to improve the quality of the products. This last factor is a threat to those who do not adapt themselves to the growing exigences of the consuming market. Close to that, is also intended to reaffirm the feasibility of the use of alternative sources to the mineral industry of sand, such as: weathering mantles (quarries over burden), crushing fines, fines (old tailings) of the rudimentary sand classification and still building construction dumps, such as materials of surpluses and demolition of buildings. (AU) | |