Controlling chloride ions diffusion in concrete.

Zeng L, Song R - Sci Rep (2013)

Related In: Results  -  Collection

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f4: Simulate time-dependent six-layer diffusion cloak.(a) The surface, iso-concentration lines and diffusion flux arrows. The vertical lines are the iso-concentration lines which are parallel outside the outer circle. The horizontal arrows represent diffusion fluxes which are parallel outside the outer circle. The left is large concentration and the right is small concentration. The diffusion time is 100 minutes. (b) The diffusion time is 200 minutes.
Mentions: Utilizing the transient diffusion equation of COMSOL Multiphysic software, we simulate the diffusion cloak in different time. The parameters are the same as that in Fig. 2. The diffusion time is 100 minutes (Fig. 4a) and 200 minutes (Fig. 4b). Outside the outer circle, the vertical iso-concentration lines are parallel and the horizontal diffusion flux arrows are also parallel. For comparison, we also simulate the non-cloak in different diffusion time. The diffusion time is also 100 minutes (Fig. 5a) and 200 minutes (Fig. 5b). The inner and outer radii of the hollow cylinder are a = 1, and b = 4, respectively. The diffusion coefficients of the background media and hollow cylinder are Db = 1.000 × 10−8 cm2/s and Dc = 2.500 × 10−8 cm2/s, respectively. Outside the outer circle, the iso-concentration lines are not parallel and the horizontal diffusion flux arrows are also not parallel. So this hollow cylinder is a non-cloak.

Bottom Line: Indeed, this is a serious threaten for reinforced concrete structure, especially for the reinforced concrete structure in the sea.We formulated five kinds of concrete A, B, C, D and E, which are made of different proportion of cement, sand and glue, and fabricated six-layer (ABACAD) cylinder diffusion cloak and background media E.The simulation results show that the six-layer mass diffusion cloak can protect concrete against chloride ions penetration, while the experiment results show that the concentration gradients are parallel and equal outside the outer circle in the diffusion flux lines, the iso-concentration lines are parallel outside the outer circle, and the concentration gradients in the inner circle are smaller than those outside the outer circle.

View Article: PubMed Central - PubMed

Affiliation: Jiangsu Key Laboratory for Intelligent Agricultural Equipment, College of Engineering, Nanjing Agricultural University, Nanjing 210031, China.

ABSTRACT
The corrosion of steel in concrete is mainly due to the chemical reaction between the chloride ions and iron ions. Indeed, this is a serious threaten for reinforced concrete structure, especially for the reinforced concrete structure in the sea. So it is urgent and important to protect concrete against chloride ions corrosion. In this work, we report multilayer concrete can cloak chloride ions. We formulated five kinds of concrete A, B, C, D and E, which are made of different proportion of cement, sand and glue, and fabricated six-layer (ABACAD) cylinder diffusion cloak and background media E. The simulation results show that the six-layer mass diffusion cloak can protect concrete against chloride ions penetration, while the experiment results show that the concentration gradients are parallel and equal outside the outer circle in the diffusion flux lines, the iso-concentration lines are parallel outside the outer circle, and the concentration gradients in the inner circle are smaller than those outside the outer circle.

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