ENGINEERING – TRUCTURAL ENGINEERING — CONCRETE CALCULATOR
Chloride Penetration
A precise tool.
What is the Chloride Penetration & How does it work?
Chloride ions penetrate concrete primarily by diffusion, driven by concentration gradients between the exposed surface and the interior of the member. The diffusion process can be described by Fick’s second law, which relates the rate of change of chloride concentration to the diffusion coefficient of the concrete matrix. For design purposes, engineers often use an analytical solution that assumes a constant surface chloride concentration and a semi‑infinite concrete slab. This leads to a closed‑form expression for the depth at which the chloride concentration falls to a critical value that can initiate reinforcement corrosion. The resulting depth, x, depends on the effective diffusion coefficient, the exposure time, and the ratio of the critical to surface chloride concentrations. By estimating x, designers can specify concrete cover thicknesses that mitigate corrosion risk over the service life of the structure.
x = 2 sqrt{D,t},operatorname{erfc}^{-1}!left(frac{C_{cr}}{C_{s}}right)
x = penetration depth (m)
D = effective diffusion coefficient (m²/yr)
t = exposure time (yr)
C_{s} = surface chloride concentration (kg/m³)
C_{cr} = critical chloride concentration (kg/m³)
D = effective diffusion coefficient (m²/yr)
t = exposure time (yr)
C_{s} = surface chloride concentration (kg/m³)
C_{cr} = critical chloride concentration (kg/m³)
Parameters
Result
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Frequently Asked Questions
What is chloride penetration in concrete?
Chloride penetration refers to the movement of chloride ions into concrete, primarily through diffusion.
How does chloride penetration affect concrete structures?
Chloride penetration can lead to corrosion of embedded steel reinforcement, reducing the durability and strength of concrete structures.
What is Fick's second law in the context of chloride penetration?
Fick's second law describes how chloride concentration changes over time due to diffusion within the concrete matrix.
When would an engineer use this calculator for chloride penetration?
An engineer would use this calculator to assess the potential for chloride ingress in concrete structures, aiding in design and maintenance decisions.
What assumptions are made in the analytical solution for chloride penetration?
The solution assumes a constant surface chloride concentration and treats the concrete as a semi-infinite slab for simplicity.
How does diffusion coefficient affect chloride penetration?
A higher diffusion coefficient results in faster chloride penetration into the concrete matrix.
Can this calculator be used for any type of concrete?
This calculator is generally applicable to various types of concrete, but specific parameters may need adjustment based on the concrete's properties.
Results are for informational purposes only and do not constitute professional advice.