Concreto com substituição do agregado miúdo pelo carbonato de cálcio proveniente da concha de marisco : propriedades mecânicas no estado fresco e endurecido

Abstract

The shellfish shell is basically formed by calcium carbonate (CaCO3) which is used as raw material for various products used in almost all branches of industry. Waste from shellfish shells are discarded and unusable, thus existing environmental problems involved. Studies carried out already prove that there are countless possibilities for the use of the main component that makes up the shellfish, examples such as: ceramic blocks, blocks and paving in civil construction, cement, concrete, rations, bricks. The reuse of this material is considered a sustainable way that helps to reduce and reuse the waste generated in cities. The objective of the present study was to evaluate the possibility of making concrete based on the partial replacement of different percentages of aggregate with shellfish powder. For this purpose, the oram shells were sanitized and processed in three stages, the first in the crusher, the second in the ball mill and the third in which the material was subjected to calcination at a final temperature of 500° C and deagglomeration was carried out through of the metal pestle. Shellfish shell powder was subjected to laser granulometric analysis, X-ray fluorescence and X-ray diffraction, for physical-chemical characterization. Subsequently, concrete specimens were molded, replacing the sand in the percentages of 15 %, 20 %, 25 %, 30 %, 40 %, 50 %, 60 %, 80 % and 100 % by shell powder in different sizes. The concrete specimens were submitted to technological tests of resistance to compression, carbonation and water absorption. From the results, within the limits of this work, it can be stated that it is a possibility and it is suggested that the partial replacement of natural sand by shellfish powder in the production of concrete can be carried out in a percentage of 20%. Already from 25% to 100% can be used both in blocks for structural masonry and for sealing purposes.