ND Evaluation of Chemically Induced Deterioration in Concrete: A Colour Spaces Study

Variation in the colour of the concrete surface due to chemical attack is a common phenomenon. The present study aims at quantifying imaging based on the degradation concrete due to chemical attack [sulphate (MgSO₄), acids (H₂SO₄, HCl) and salts (NaCl) at 5% concentration] at the end of 3, 7, 14 and 28 days. The colour variation was quantified using YUV and YIQ colour spaces. The variation of Y value due to lighting along with colour changes in UV and IQ variation was observed. The combined variation of YUV and YIQ enables accurate assessment of the extent of deterioration. Also, the rate of change of strength with time is established as an empirical relation between compressive strength through U, V and I, Q. This novel method can be useful for video graphic monitoring of inaccessible concrete structures that are dilapidated due to chemical action and need repair/retrofitting.