Sub-grade refers to the native material beneath roads, pavements, or railway tracks and is crucial for their stability. Preparation involves compacting the sub-grade, stabilizing it with materials like asphalt or cement, and ensuring it is free of debris before construction. The process includes removing unwanted material and creating a suitable foundation for the upper pavement layers.

1. EPA Infrastructure Pvt. Ltd.
Sub-Grade Preperation
B-267, North Ex Mall
Sector-9, Rohini,
Delhi-110085

2. What is Sub-Grade?
In transport engineering, subgrade is the native material underneath a
constructed road, pavement or railway track. It is also called formation level.
The term can also refer to imported material that has been used to build an
embankment.

3. Preperation of Sub-grade
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.
Preparation of the subgrade for construction usually involves digging, in order to
remove surface vegetation, topsoil and other unwanted material, and to create space
for the upper layer of the pavement. This process is known as "subgrade formation"
or "reduction to level".

4. Subgrade shall be free from all foreign
debries and rock outcrops

5. Geotextile being laid on the uncompacted
layer of soil

6. Compacting the soil surface after
geotextile layer

7. Surface elevation before paving

8. Finally prepared subgrade