Abstract
This was an experiment in which chloride was externally permeated into cement paste. The influence of Cl- on the content and distribution of free-form NO2- in the cement paste was researched using the chemical quantitative analysis method. The action mechanism was investigated by the micro-means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the physical competitive adsorption of Cl- with NO2- on C-S-H and the chemical substitution of Cl- to NO2-AFm caused more free-form NO2- in the cement paste. In the cement paste with chloride salt erosion, the NO2- concentration in the erosion surface was the lowest, and the NO2- concentration reached the highest value at 10mm from the erosion surface. The concentration decreased gradually with the depth from the erosion surface.
Highlights
Corrosion of rebar is a very important factor that affects the durability of reinforced concrete structures
The sliced cement paste specimen was ground into powder and put into standard square hole stone sieves with apertures of 0.6mm, 0.3 mm, 0.15 mm, and 0.075 mm
Another bound form is when the ions are physically adsorbed into the surface of a hydration product, such as calcium silicate hydrate gel C-S-H [20–23]
Summary
Corrosion of rebar is a very important factor that affects the durability of reinforced concrete structures. Through a comprehensive comparison of the commonly used methods, findings showed that the most simple and effective way to improve durability is to mix steel rust inhibitor into the concrete. The use of electrolytes that mimic pore solutions facilitates control of the many parameters that influence rebar corrosion This was the approach chosen for the present investigation. The introduction of Cl- by external infiltration of chloride salt and the effects of Cl- erosion on the free-form NO2- concentration in cement paste and its microscopic mechanism were studied by means of chemical quantitative analysis combined with X-ray diffraction (XRD) and scanning electron microscopy (SEM), in order to International Journal of Corrosion. 160 280 25.6(3d) 48.5(28d) 5.12(3d) 7.05(28d) improve the durability and service life of China’s reinforced concrete structures and to provide a theoretical basis for the approaches
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