From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
Layers in the construction of a mortarless pavement: A.) Subgrade B.) Subbase C.) Base course D.) Paver base E.) Pavers F.) Fine-grained sand

In transport engineering, subgrade is the native material underneath a constructed road,[1] pavement or railway (US: railroad) track. It is also called formation level.

The term can also refer to imported material that has been used to build an embankment.


Subgrades are commonly compacted before the construction of a road, pavement or railway track, and are sometimes stabilized by the addition of asphalt, lime, portland cement or other modifiers. The subgrade is the foundation of the pavement structure, on which the subbase is laid.

The load-bearing strength of subgrade is measured by California Bearing Ratio (CBR) test, falling weight deflectometer backcalculations and other methods.


  1. ^ The Idiots' Guide to Highways Maintenance
Retrieved from ""
This content was retrieved from Wikipedia :
This page is based on the copyrighted Wikipedia article "Subgrade"; it is used under the Creative Commons Attribution-ShareAlike 3.0 Unported License (CC-BY-SA). You may redistribute it, verbatim or modified, providing that you comply with the terms of the CC-BY-SA