Experimental Study on Measurement of Carbonation Depth of Concrete

Based on the test results, the differences of the carbonized depth of concrete measured by phenolphthalein indicator and rainbow indicator were discussed, the effects of the water to cement ratio of concrete, the carbonized age and the relative humidity of environment on the carbonized depth of concrete and the depth of half-carbonized zone corresponding to green zone measured by rainbow indicator were also analyzed. It is proved that the depth measured by phenolphthalein indicator is always smaller than that measured by rainbow indicator, and the half-carbonized zone can only be measured by rainbow indicator. The carbonized and half-carbonized depths of concrete are influenced by the carbonation age, the water to cement ratio of concrete and the relative humidity of environment. It is suggested that the phenolphthalein indicator can be used to measure the carbonized depth of concrete when the strength grade of concrete is below C45, otherwise, the rainbow indicator should be utilized.