An easy method to estimate the concentration of mineral pigments in colored mortars

• Easy method for the estimation of mineral pigments contents in different mortars.
• Use of the Kubelka–Munk function in its derivative form.
• The calibration curves have been calculated from one mortar only.
• Study from low to high pigment concentrations (saturation level).
• Estimation improves with slight band overlap/less tinting pigment in greater amount.

The goal of this work is to propose an easy method for the estimation of mineral pigment contents in different mortars. The accurate estimation of mineral pigment contents is very important to reduce the cost of production of the colored mortars, especially taking into account that small discrete changes in composition do not always produce noticeable color changes by the human eye. The Kubelka–Munk function in its derivative form provides a highly useful tool for characterizing pigment mixtures in mortars. It has been effective at concentration levels where XRD detection had proved to be ineffective. Calibration curves have been calculated from one mortar only. The partial overlapping of the bands, the different tinting strength and the different concentration of the pigment have been analyzed. The accuracy of the estimation of the pigment content improves when there is a slight overlap of the spectra and/or when the amount of the less tinting pigment is in greater proportion.

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