What is a Subbase?

Subbase is a layer of aggregate material, such as crushed stone or gravel, that is placed beneath the base course of a road or other infrastructure project. The purpose of a subbase is to provide a stable and even surface for the base course to rest upon, and to help distribute the weight of the traffic or other loads over a larger area.

A subbase can be made up of a variety of materials, including:

* Crushed stone or gravel: This is the most common type of subbase material, and it is typically made up of a mixture of different sized stones that are crushed and graded to meet specific specifications.
* Sand: In some cases, a subbase may be made up of sand rather than aggregate material. This is often the case in areas where the soil is too soft to support the weight of the traffic, and a more stable material is needed.
* Geosynthetics: In recent years, geosynthetics have become increasingly popular as a subbase material. These are synthetic materials that are designed to provide reinforcement and stability to the subgrade, and they can be made from a variety of materials such as polyester, polypropylene, or polyethylene.

The thickness of a subbase will depend on a number of factors, including the type of traffic that will be using the road or infrastructure, the soil conditions, and the desired lifespan of the project. In general, a thicker subbase will be required for heavier traffic or for projects that are expected to last longer.

Subbases are an important component of many infrastructure projects, as they help to ensure that the final product is stable, durable, and able to withstand the weight and wear and tear of traffic over time.