Obtenção de geopolímero a partir da lama de bauxita proveniente da indústria química.

Abstract

Geopolymer is an alternative material of standard concrete, which can convert a variety of waste streams in raw material to be used in order to contribute in reducing the environmental impact. The materials that contain both silica and alumina can be used as a binder to produce geopolymer. The alkaline solution also plays an important role in the production of geopolymers for dissolving the silica and alumina forming structures semicrystalline to amorphous aluminosilicate. This study aimed to optimize the synthesis of geopolymer using the experimental design mixing software Statistica 7. The material was prepared from bauxite slurry, rice husk ash, metakaolin, and a solution of sodium hydroxide 12M. The material was cured at 60 ° C for 6h and then at ambient temperature for up to 28 days. We used the same experimental design to synthesize the mixing geopolymer CCA calcined at 600 0 C. Through the techniques spectroscopy rivers energy dispersive X and X ray diffraction, it is found that the levels of alumina and silica raw material satisfying the conditions set forth identified as potential precursors for minimum activation geopolymer, evidenced by the molar ratio Si / Al samples. The presence of oxides of Si, Al and Na were identified in the starting materials through diffraction and chemical analysis. In infrared spectroscopy fresh bauxite and bauxite slurry verified the presence of silicates and aluminates. The diffractograms of geopolymer obtained showed characteristic peaks of calcium silicate hydrate. It was found that the particles had such large and irregular shapes, and the presence of voids affecting the strength of the material. The GEO taken as a reference standard in this study achieved its flexural strength of 4 MPa. The results of flexural strength obtained by mixing experimental design showed from the ANOVA, which had no significant influence on the results. The results showed that with CCA flexural strength of the sample obtained R6C2M greater resistance within 7 days of curing 0.60 MPa, but the other samples showed an increase of resistance after 28 days of curing. The materials obtained geopolymeric CCA ash showed improvements in their resistance to bending.