# Resilient Modulus

The Resilient Modulus (M_{R}) is a measure of subgrade material stiffness. A material's resilient modulus is actually an estimate of its modulus of elasticity (E).

- Canonical URL: https://pavementinteractive.org/reference-desk/design/design-parameters/resilient-modulus/
- Last updated: 2018-09-19
- Review: reviewed by licensed professional engineers on the previous Pavement Interactive site, where reviewers were not recorded by name

The Resilient Modulus ($$M_{R}$$) is a measure of subgrade material stiffness. **A material's resilient modulus is actually an estimate of its [modulus of elasticity (E)](https://pavementinteractive.org/reference-desk/design/design-parameters/elastic-modulus/)**. While the modulus of elasticity is stress divided by strain for a slowly applied load, resilient modulus is stress divided by strain for rapidly applied loads – like those experienced by pavements.

Resilient modulus is determined using the [triaxial test](https://pavementinteractive.org/reference-desk/testing/aggregate-tests/triaxial-test/). The test applies a repeated axial cyclic stress of fixed magnitude, load duration and cycle duration to a cylindrical test specimen. While the specimen is subjected to this dynamic cyclic stress, it is also subjected to a static confining stress provided by a triaxial pressure chamber. It is essentially a cyclic version of a triaxial compression test; the cyclic load application is thought to more accurately simulate actual traffic loading.

Calculator: CBR to resilient modulus — https://pavementinteractive.org/tools/cbr-mr/