SYNTHESIS OF A GEOPOLYMER AND USE OF RESPONSE SURFACE METHODOLOGY TO OPTIMIZE THE BOND STRENGTH TO RED BRICK FOR IMPROVING THE INTERNAL COATING IN BURNER KILNS

In Mexico, fixed kilns made of red brick after several burn cycles at 1000 degrees C, may expand, crack and open. In light of that, we worked to obtain a geopolymer using clays (Caolin, Tepozan and Bauwer), that attaches to red brick. The clays were characterized using energy dispersive X-ray spectroscopy (EDS), atomic absorption spectroscopy (AAS), UV-VIS spectrophotometry and powder X-ray diffraction (PXRD), finding that the clays have refractory properties. The response surface methodology was used to optimize the adherence of the geopolymer on red brick, keeping the sodium silicate concentration constant. The optimal formulation of the geopolymer contains 50% commercial sodium silicate, 21% Caolin, 23% Tepozan, and 6% Bauwer, where the curing time was 7 days and the burning cycle was 8 h at 1000 degrees C. The best fit was achieved with a quadratic model that predicts an adherence of 3.2 MPa, comparable to the experimental value of 2.8 MPa. The geopolymer can be used as an internal coating in brick kilns to increase its useful life. In addition, the geopolymer has potential use as a coating for materials for refractory use.