Chromatic design and application of restoration mortars on smooth surfaces of white and GRAY concrete

Abstract

AbstractAlthough the recognized importance of color match both in white and gray Concrete Heritage interventions, the production and application of restoration mortars are often performed without an accurate color matching between the concrete surface and the repaired area. This paper presents the Gray Concrete Restoration Method (GCR‐method), developed to define and apply restoration mortars to smooth white and gray concrete surfaces. The GCR‐method comprises: (i) production of restoration mortars (from white to different gray levels) by adding black pigment to reference mortars; (ii) chromatic characterization by image processing; (iii) production and application of restoration mortar; (iv) chromatic evaluation of the restoration; and (v) chromatic reintegration in the transition zone and/or in the restoration, by applying pointillism and glaze techniques depending on whether are white or gray surfaces. The GCR‐method was experimentally calibrated in color spaces HSV and CIELAB, respectively for brightness (V) and color differences (ΔE00) evaluation; then, it was applied and validated to the restoration of white and gray concrete panels with smooth surfaces. The results show the desired chromatic compatibility between the original surface and the restoration, not noticeable to the naked eye. Further, the chromatic reintegration procedures demonstrate that color analysis is fundamental for the decision‐making of restoration interventions in Concrete Heritage.