Design of Concrete Colour Reference Charts for Monitoring of Deterioration in Concrete Structures

Variation in the colour of the concrete surface is a common phenomenon due to chemical attack. The present study aims at quantifying the imaging based on the degradation of concrete due to chemical attack [sulphate (MgSO 4 ), acids (H 2 SO 4, HCl) and salts (NaCl) at 5% concentration] at the end of 3, 7, 14 and 28 days. This colour variation is quantified using the YCbCr and YCgCr colour spaces. The variation of Y value due to lighting along with colour changes in CbCr and CgCr variation was observed. The combined variation of YCbCr and YCgCr enables accurate assessment of the extent of deterioration. Also, the rate of change of CbCr strength with time is established as an empirical relation between compressive strength through Cb, Cr and Cg, Cr. This novel method can be useful for video graphic monitoring of inaccessible concrete structures dilapidated due to chemical action and needs attention to repair/retrofitting.