Three different historical mortars, one from the 18th-19th centuries and two from the 12th century, were crushed and sieved to give eight fractions between less than 0.063 mm and 4 mm for each sample. Each fraction was chemically analysed for the amount of calcium carbonate binder, using the reactions with HCl and EDTA and by means of atomic absorption spectroscopy. The samples were also characterized by X-ray diffraction (XRD) and by lowtemperature nitrogen adsorption isotherms. The limitations and advantages of each of the various methodologies for the determination of the binder are discussed. Reactions with HCl and XRD were shown to be the methods that gave the more coherent results.

Interventions on “Concrete Heritage” imply special aesthetic requirements, especially from the chromatic point‐of‐view, between the repair material and the substrate. Currently, there is a lack of products and methods that address these concerns. This paper presents the Colored Concrete Restoration Method (CCR‐method), to the chromatic design and application of restoration mortars on colored concrete surfaces. The CCR‐method comprises: (a) chromatic characterization of surfaces by image processing; (b) design and color tuning of restoration mortar, through adding pigments to a white mortar; (c) production and application of restoration mortar; and (d) evaluation of the restoration. The CCR‐method was applied to the restoration of yellow concrete panels with smooth surfaces and enables the desired color matching of the restoration, which is not perceptible to the human eye. The results obtained evidencing the ability of CCR‐method to define, design and apply color restoration mortars, proving to be an extremely useful tool for interventions on “Concrete Heritage.”

Interventions in concrete heritage deal with challenges related to conservation, and must be performed from an integrated restoration perspective. In addition to the material technical performance, the aesthetic compatibility between the repair and the structure, in terms of colour and texture, needs to be ensured. Therefore, the characterisation of the restoration mortar concerning colour match and aging, and the mechanical and durability performances, is essential. In this article, the long-term behaviour of restoration mortar, previously designed and produced by the addition of pigments to white and grey cement-based reference mortar, is evaluated. The durability properties, colour change due to aging, and service life are estimated and analysed. An experimental program is performed to characterise the following properties: (i) water capillary absorption; (ii) accelerated carbonation; (iii) migration of chloride ions; (iv) electrical resistivity; and (v) shrinkage. The colour evolution, when exposed to carbonation, is measured through image processing. The obtained results allow the establishment of a correlation between durability and design parameters. Finally, service life considering deterioration due to steel corrosion is estimated, considering the carbonation resistance and the chloride diffusion values. It is concluded that the W/C ratio influences not only most of the characterised parameters, but also the type and content of the pigment. Furthermore, no colour variation due to carbonation is detected.