Characterization and chromatic evaluation of gypsum-based pastes for construction and heritage restoration

Abstract

This research evaluates the chromatic behavior of gypsum-based pastes containing added pigments which enable their use in both new construction projects as well as in restoration interventions for built heritage. Furthermore, the impact of adding pigments to the aforementioned material after twenty-eight and ninety days has also been studied. This was confirmed by carrying out compositional, mineralogical and physical studies of the raw materials and the pastes. The results indicate that all of the pastes studied have suitable mechanical strength values for the type of pastes studied, thereby confirming their suitability for on-site use based on their characteristics and behavior. Colorimetric analysis showed color variations that were clearly perceptible to the human eye, related to increases in luminosity which significantly exceeded 100%, and also to saturation losses featuring percentage variations of more than 100% on assessment after ninety days. This colorimetric analysis by means of quantitative spectrophotometry is of vital importance when determining the loss of color intensity of the pastes used, since subjective observation results in serious errors of interpretation. This type of study reflects the use of instrumental color measurements for this type of materials and mixtures.