Pavement Calculator: Thickness From Expansion Pressure and the Stiffness Factor
Two more textbook pavement relations.
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How this calculator works
Choose the thickness from the expansion pressure, or the stiffness factor.
Enter the expansion pressure and the unit weight, or the two moduli of elasticity.
The calculator gives the thickness or the stiffness factor.
Formulas used
- t = \frac{\text{Expansion pressure}}{\text{Pavement unit weight}}
- SF = \sqrt[3]{\frac{E_s}{E_p}}
Worked example
With the default numbers in the calculator above:
- Expansion pressure: 14710.00 Pa
- Unit weight of the pavement: 24520.00 N/m3
- Thickness of the pavement in metres: 0.60 m
- Thickness of the pavement in millimetres: 599.92 mm
Change the numbers in the calculator to see the full working, every step, for your own case.
A second worked example
A different case, with these numbers: What do you want to find? Stiffness factor of the pavement.
- Stiffness factor of the pavement: 0.63
Common questions
What is the thickness from the expansion pressure?
The thickness at which the weight of the pavement per unit area equals the expansion pressure: the pressure divided by the unit weight of the pavement.
What is the stiffness factor?
The cube root of the modulus of elasticity of the subgrade divided by the modulus of elasticity of the pavement. It has no unit, as long as both moduli use the same unit.
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Got a question about this? Ask an engineering question and get a plain-language answer with references.
Further reading: Any highway or pavement engineering text.
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