DRAFT 12th International Congress on the Deterioration and Conservation of Stone Columbia University, New York, 2012 1 ON THE CONSERVATION OF GUADALAJARA, MEXICO BUILDING STONES WITH A NEW ALUMINOSILICATE COMPOUND Nora A. Pérez, 1 Enrique Lima, 1 Pedro Bosch 1 and Juan Méndez 2 1 Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Circuito exterior s/n, Ciudad Universitaria, Delegación Coyoacán, CP 04510, México D.F. 2 Universidad Autónoma Metropolitana, Av. San Rafael Atlixco No. 186, Col. Vicentina, Iztapalapa, México, D.F. CP 09340, México D.F. Abstract A procedure to understand and consolidate the volcanic tuff used in ancient churches and other historical buildings in Guadalajara is proposed. Initially, the deterioration mechanism of the local tuff was determined through textural, morphological and structural characterization. The techniques employed were, among others, 29 Si and 27 Al magic angle spinning nuclear magnetic resonance (MAS NMR), infrared spectroscopy (FT-IR ATR), X-ray powder diffraction (XRD), nitrogen adsorption-desorption, scanning electron microscopy (SEM), thermo-gravimetric analysis (TGA) and compressive strength tests. According to these results, different consolidating materials could be proposed. Inorganic polymeric materials based on silicon and aluminum were developed and tested as consolidation materials for this type of stone. A complete structural and textural study on the properties of the stone consolidated with those polymers was performed in order to establish the interaction of the new material with the stone and measure the improvement in the stone properties. The performance of the new material was compared with tuffs consolidated with the currently used siloxane based materials. The aluminosilicate showed better consolidation features for white tuffs which have a high amount of silicon in their composition, while the silicate was the best choice for tuffs with a high amount of aluminum. Keywords: consolidation, volcanic tuff, aluminosilicates 1. Introduction Among the principal procedures of conservation that are held in stone materials, is the consolidation process, which is performed to restore the structural stability and improve the mechanical resistance that has been affected by different deterioration processes, such as atmospheric contamination, salts crystallization, humidity, biodeterioration or anthropogenic factors. Some inorganic consolidants, used in stone conservation, are the barium hydroxide, silicates and alcoxysilanes. More recently consolidants based on silica and calcium hydroxide nanoparticles were also used (Price 2006; Dei et al. 2006). Organic consolidants like the epoxy resins have been also used in Mexico, natural products such as the mucilage of cactus have also been employed (Pérez 2008).