Depth of carbonation was measured as per CPC 18 RILEM. The water cured samples (100 mm size specimens) were oven dried for 48 h. Each specimen was divided to four pieces of 50mm width and 100 mm depth. These pieces were oven dried 60e70 C at for 2 weeks. After that, 2 coat of epoxy paint was applied on the longitudinal surface of the pieces. After drying and marking, the samples were introduced to the CO2 chamber (The relative humidity was controlled at 50e55%, Carbon dioxide concentration kept at 5 ± 0.2%, Temperature at 27 ± 2 C).