Pavement Subgrade Performance
When paving an area, once the land is properly prepared, the next step in the process is laying down the subgrade. Most people only consider the top layer of asphalt or concrete when thinking about a paved surface but the subgrade can be overriding factor in your pavement performance.
Performance of your Subgrade
The subgrade must be able to support loads transferred through the pavement. Degree of compaction, moisture levels and soil type all affect the load bearing capacity of the subgrade.
Subgrade performance can also be affected by excessive moisture or freezing conditions. Clay soils can shrink or expand depending on their moisture content while looser soils can be susceptible to frost heave is colder latitudes.
Poor subgrades should be avoided when possible. If it’s not avoidable there are several ways to improve it:
Over-excavation: Poor subgrade soils can be removed through excavation and replaced with higher quality fill. While this can give you a much better base layer, it can become more costly depending on size and scope of your paving project.
Stabilization: Mixing binders like cement, lime or emulsified asphalt can improve the stiffness and reduce tendencies of swelling.
More base layers: Adding additional base layers may seem like a cost-effective and simple solution, but beware. While this process may work in specific instances, laying your pavement over a sub-standard base layer typically invites long-term and costly deterioration, maintenance and repairs.
When in doubt, always choose appropriate solutions at the beginning of your paving project. The slight cost increase up front may save you thousands of dollars over the life of your paved surface.
Pavement Constructors has the experience and know-how to help you determine the proper steps to take when preparing the subgrade of your pavement project. Give us a call at 281-445-9900 or contact us today to get started with a free estimate.