Improving the chloride binding capacity of cement paste by adding nano-Al_2O_3

摘要

The chloride binding capacity of cement paste is of critical importance to the durability of reinforced concrete structure. In this study, nano-Al2O3 (NA) was considered as an additive to be used in cement paste. Paste samples were prepared with the NA dosage varying from 0, 0.5, 1.0, 3.0 to 5.0%. The chloride binding capacity was examined through the conventional equilibrium tests, i.e., the paste samples were exposed to a NaCl solution of 0.05, 0.1, 0.3, 0.5, and 1.0 mol/L. Results indicated that the bound chloride content increased with the adding of NA for a low NaCl solution, whereas it decreased firstly and then increased for a high NaCl solution. Supplementary experiments including the X-ray diffraction (XRD)/Rietveld analysis and the Mercury intrusion porosimetry (MIP) were performed to unravel the mechanism in terms of the formation of AFm phase, Friedel's salt and microstructure. It was believed that an appropriate adding of NA was able to improve the chloride binding of cement paste. (C) 2018 Elsevier Ltd. All rights reserved.