Influence of layered double hydroxides on microstructure and carbonation resistance of sulphoaluminate cement concrete

In this work, pore structure and carbonation resistance properties of sulphoaluminate cement (SAC) concrete incorporating magnesium aluminate-based layered double hydroxides (LDHs) were analyzed. Mercury intrusion porosimetry (MIP) was employed to characterize the effects of LDHs on the pore structure. Other techniques such as X-ray diffraction (XRD), IR-spectroscopy and thermal analysis (TG-DSC) were employed to characterize the component and structural changes of LDHs and cement paste before and after carbonation test. The traditional properties including compressive strength and carbonation resistance of concrete were experimentally evaluated. Additionally, carbonation of Portland cement and SAC concrete was compared. perimental results show that LDHs present effects on pore structure concrete. Carbonation depth decreases remarkably with the addition of LDHs, especially the calcinated LDHs, therefore, carbonation resistance capacity of concrete is obviously enhanced by LDHs due to the exchange and immobilization of carbonate ions. Carbonation depth of SAC concrete is distinctly smaller than that of PC concrete with or without LDHs regardless of curing time when fly ash was added.