Chloride immobilization of cement-based material containing nano-Al2O3

The utilization of marine resources in reinforced concrete is severely limited, due to the risk of steel corrosion caused by the introduced chloride. In order to reduce this risk, nano-Al2O3 (NA) was added into cement-based materials system by improving the chloride immobilization. The immobilized chloride ratio (ICR) of the system was evaluated, and the results indicated that the addition of NA could significantly enhance ICR. Based on the results from TG, XRD, Al-27 NMR, MIP, Si-29 NMR, and EDS, the mechanism behind was discussed from three aspects of chemical binding, migration resistance, and physical adsorption. The reasons for the increased ICR were as follows: a) chemical binding was promoted by increasing the amount of chloroaluminates; b) migration resistance was improved by refining the pore structure; c) physical adsorption, depending on the amount and the Ca/Si ratio of C-S-H gel, was reduced negligibly. These findings can provide guidance for the theoretical study of chloride immobilization and the application of marine resources. (C) 2019 Elsevier Ltd. All rights reserved.