Effects of layered double hydroxides incorporation on carbonation resistance of cementitious materials

The development of new or modified cementitious materials is an important part of existing strategies to improve performance and minimize life-cycle costs and to eliminate the CO2's impact on durability. The high anion exchange capacity of layered double hydroxides (LDHs) materials makes their interlayer ion exchange by organic and inorganic anions versatile and easily achieved. LDH-like materials could be used in cementitious materials for their CO32- capturing capacity and to enhance carbonation resistance of cementitious materials. In this work, original LDHs were synthesized, LDHs calcined at 500, 550 and 600 degrees C, respectively, were prepared. Power X-ray diffraction (XRD), IR-spectroscopy and thermal analysis (TG-DSC) were employed to characterize the component and structural changes of these types of LDHs before and after CO2 capture. Carbonation resistance of cement paste incorporating LDHs was experimentally evaluated for assessment of CO2 capture capacity of LDHs. Ion exchange mechanism of LDHs was also analyzed from adsorption experiments. The results show that LDH-like materials could be used for their CO32- capturing capacity to enhance carbonation resistance of concrete as well as to eliminate CO2's impact on durability aspect especially the LDHs calcined at 600 degrees C. Calcined LDHs fulfill the structure regeneration after CO2 capture. LDHs have positive effect on improvement of carbonation resistance of cement paste especially at later curing stages. (C) 2018 Brazilian Metallurgical, Materials and Mining Association. Published by Elsevier Editora Ltda.