CBR to Subgrade Modulus Calculator
Resilient modulus and k-value estimates from the CBR test.
CBR 6 ('fair' subgrade) ≈ 55 MPa modulus. Every flexible-pavement design chart in India enters through this conversion — and doubling CBR via 300 mm of stabilized subgrade often deletes 100 mm of crust.
Formula
Note: Empirical correlations scatter ±50% — fine for pavement catalogues, not for research.
CBR to Subgrade Modulus Calculator is a free cbr to modulus for geotechnical engineers and foundation designers — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About CBR to Subgrade Modulus Calculator
Resilient modulus and k-value estimates from the CBR test. The calculation implements M_r = 17.6·CBR^0.64 MPa (IRC 37); k ≈ 10+5.2·CBR MPa/m (IRC 37; AASHTO correlations). CBR 6 ('fair' subgrade) ≈ 55 MPa modulus. Every flexible-pavement design chart in India enters through this conversion — and doubling CBR via 300 mm of stabilized subgrade often deletes 100 mm of crust.
How to use CBR to Subgrade Modulus Calculator
- 1Enter Soaked CBR in %.
- 2Read Resilient modulus M_r, Modulus of subgrade reaction k instantly — no submit button needed.
Why use CBR to Subgrade Modulus Calculator?
- ✓Implements the standard formula — M_r = 17.6·CBR^0.64 MPa (IRC 37); k ≈ 10+5.2·CBR MPa/m
- ✓Reference cited on-page: IRC 37; AASHTO correlations
- ✓Live worked example: the substitution recomputes from your numbers
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the CBR to Subgrade Modulus Calculator use?+
It computes M_r = 17.6·CBR^0.64 MPa (IRC 37); k ≈ 10+5.2·CBR MPa/m, per IRC 37; AASHTO correlations. The formula is displayed under the result along with a worked example substituted with your own inputs.
What should I keep in mind when using this calculator?+
CBR 6 ('fair' subgrade) ≈ 55 MPa modulus. Every flexible-pavement design chart in India enters through this conversion — and doubling CBR via 300 mm of stabilized subgrade often deletes 100 mm of crust. Note: Empirical correlations scatter ±50% — fine for pavement catalogues, not for research.
Can this replace a soil investigation?+
No calculator replaces boreholes and lab tests — but with investigated parameters in hand, this gives you the standard-method result instantly, with the formula shown so reviewers can check it.
Is the CBR to Subgrade Modulus Calculator free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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