Base Course of Flexible pavement
The first coat to be placed, on top of your proper sub-base, is the base course. It provides additional load distribution and contributes to drainage and frost resistance.
- The base is built of clean sand or rock.
- The base layer provides uniform support to the pavement and allows water that penetrates any joints or cracks in the pavement to move quickly to the sub-drain without saturating and softening the sub-grade.
- This coat is put in place for strength, plus it works as a true-leveler course, to take out any small imperfections in the grade.
- After the binder is put into place with paver, it is compacted with a vibratory roller for tighter density and added strength.
Base courses are usually constructed out of:
- Aggregate: Base courses are most typically constructed from durable aggregates that will not be damaged by moisture or frost action such as dense bitumin macadam (dbm).
- HMA: In certain situations where high base stiffness is desired, base courses can be constructed using a variety of HMA mixes.