Application of 29Si and 27Al magic angle spinning nuclear magnetic resonance to studies of the building materials of historical monuments.

We report the application of 29Si and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) studies on building stones from historical monuments to obtain direct information about the degree of degradation and to observe the changes in the consolidated material after treatment with tetraethoxysilane (TEOS). Using the data obtained from deteriorated materials, a diagnostic laboratory, a suitable treatment and recommendations for building conservation may infer. A case study is presented using stones from Guanajuato City Main Church (Central Mexico). X-ray diffraction patterns to characterize the species present in the stones agree with the solid state NMR results.