Application of Near Infrared Reflectance Spectroscopy (NIRS) technology in the characterisation of construction materials in exceptional buildings: first results.

Abstract

This work discusses the use of Near Infrared Reflectance Spectroscopy (NIRS) analysis with the object of studying the degree of degradation of stone material and other elements in cultural heritage monuments, as an alternative to traditional laboratory methods, with the advantage of being a fast non-destructive process that requires little or no sample preparation, thereby reducing the amount of time required and the expense. NIRS is a spectroscopic method which uses the near infrared region of the electromagnetic spectrum (from about 800 nm to 2500 nm). The technique can help to identify a chemical component starting from their different Near IR absorption spectrum. It has been widely applied over the last forty years in food and agricultural science and in many other fields such as pharmatheutics, medicine, forestry and petrochemical. However, it has rarely been applied with the purpose mentioned in this paper. The study was conducted on the Church of "Santa Marina de Aguas Santas", situated in the historical centre of the city of Cordoba (Spain). This paper presents the first stage of the research. Samples taken in situ are analyzed by a NIR spectrometer in laboratory. The object is to obtain models for the quantification of majority components of stone material (calcium and quartz) as well as indexes of alteration, from NIR response of the samples. After this, it will be necessary to study if these models would have a correct behaviour being applied with data taken in situ, with a portable NIR. The results obtained prove that this technique can be efficiently applied saving both time and money.