Chloride Binding Capacity of Cement Paste Containing Layered Double Hydroxide (LDH)

The chloride binding capacity of concrete can affect the rate of chloride ingress, which ultimately determines the chloride-ion resistance. A layered double hydroxide (LDH) can absorb the chloride ions in cement paste and delay chloride ingress in the structure. A method for evaluating the chloride binding capacity of cement paste was used in the experiment reported herein. We compare Mg-Al LDH under different treatments (including CO₃²⁻ series and NO₃⁻ series) in order to determine the chloride binding capacity of the LDH. The binding mechanism is explored in this article. The experimental results indicate that LDH processes have a remarkable chloride ion binding capacity. The addition of LDH can improve the chloride binding capacity of cement paste significantly. Cement paste containing roasted LDH has a better chloride binding capacity than that containing unroasted LDH or rehydrated LDH. Based on the comparison of LDHs with different anions, the chloride binding capacity of NO₃⁻ series LDH appears to be more powerful than that of CO₃²⁻ series LDH.