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Tesis de doctorado
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Caracterización de la durabilidad de hormigones con arenas de trituración

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Abstract

One of the most used composed materials in civil engineering is concrete and it requires for manufacturing large volumes of nonrenewable resources. The depletion of sand beds, in conjunction with ecological constraints, is intensifying the need to find sources of sand characterized by hard, strong durable and stable particles. It is not always easy to find sources of aggregate suitable for concrete. In some important areas of Argentina, the existence of very few deposits of gravel, requires the production of aggregates from crushing rocks. This situation is unexceptional, for natural aggregates are becoming scarce in many countries. The use of crushed sand in concrete clearly affects flowability due to the morphological characteristics and dust content in this type of fines. These fine aggregates are considered as marginal aggregates for national standard. In fresh state, the analysis of the values found revealed that the water content or paste content had to be increased significantly in concretes with crushed sand to reach the same consistency as concretes with natural sand, which results in a increase in the pores content of the hardened concrete. In hardened state, since fine aggregates occupy about 25-30 percent of the volume of a concrete mixture, they can be expected to exert an important influence on the mechanical and durable properties of the composite material. These studies permits to say that high strength concretes is possible to achieve using crushed sands as fine aggregate without mineral admixtures addition. The degradation of concrete structures by the corrosion is a very complex phenomenon which involves multiple causes and effects. The link between the rate of growth of crack width and the evolution of corrosion, can predict the safety and suitability for service residual of reinforced concrete structures. In this sense, this work assesses the impact of the influence of the type of fine aggregate and w/c ratio on the evolution of cracking. Then, beams were made with w/c ratio between 0.45 and 0.50, which were subjected to accelerated corrosion, and their mechanical and electrochemical behavior was analyzed. Four types of sand were used: three crushed (granite, dolomite and calcite) and one type of natural sand. The results show that the type of sand and the w/c ratio significantly influence the growing mechanism of cracking. On the other hand, in the case of corrosion induced by carbonation, its concluded that the increase of a/c ratio is more important that the type of fine aggregate. The studies and conclusions of the present thesis show that it is feasible to use sands crushed to elaborate concrete of suitable quality. The economic importance of the utilization the crushed sands is related to the low cost of the material, the availability and the volume of concrete of the work. Major it will be the economic importance, if the material can be used without having to effect the wash or another process of improvement, and in percentages bigger than the established ones for the CIRSOC 201-05 Code.

Keywords
hormigón
arenas trituradas
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This work is published under license Creative Commons Attribution 4.0 International (BY 4.0)

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