Desenvolvimento de argamassa colante utilizando resíduo de caulim.

Abstract

Among various minerals extracted in Brazil, kaolin is one of most important. This mineral from the kaolinite family has great versatility as its use and during its beneficiation process, high amounts of the extracted material are rejected, reaching values as 70%. This residue is disposed on the environment with no treatment, causing inconvenience to surrounding communities and to the region ecosystem. This work aimed to use this residue as raw material for the construction industry, more specifically in the development of AC-I type adhesive mortars. The residue was characterized and by X-ray diffraction verified that it is basically constituted of kaolinite and mica. Based on Brazilian standards, the residue was tested for its pozzolanic and it was found that showed no suitable potential for using as a partial replacement for cement. However, its physical characteristics indicate that the kaolin residue had properties to be used as fine aggregate. Traces of adhesive mortars were made by replacing the fine natural aggregate, sand, by kaolin residue in proportions from 0 up to 100 %. The results indicated that, as it increased the amount of residue, the mortar required a larger amount of water to obtain adequate workability. Due to mechanical resistance data, there was a linear decay in. For the Open Time (TA), there was a reduction of approximately 90% in the mechanical strength of the material; and about to Resistance Adhesion Tensile (RAT), a reduction of 87 % in the mechanical strength of the admixtures air-cured and 81 % in the mortar cured in an aqueous medium. The admixtures that contained 25 % of its fine aggregate replaced by kaolin residue, showed values within the limits established by the NBR 14081 and a water demand close by the demand in industrialized adhesive mortars. Thus, the residue derived from kaolin beneficiation process, proved to be a viable option for reducing the use of sand in the development of adhesive mortars. This substitution is in favour both to give a destination to residue, also to reduce the use of sand as fine aggregate, since its extraction brings several environmental problems in.