Road Base Material also known as road rock, road gravel, aggregate base, AB, asphalt base and 3/4" minus. By any name it
is still a product with a specific size and gradation. In California the standard is set by Cal Trans and most common is 3/4" aggregate
base class 2.
Sub base, or the material sometimes used below the road base can be 1 1/2" up to 3".
Base and sub-base share
a characteristic of being a mixture of large (3/4"), medium (3/8") and small (less then 1/8") particles.
As the large particles
"bump" together medium particles will fill the voids. The voids in the medium size particles will be filled by the smaller
particles untill the layer is dense.
When this layer is compacted (pushed tightly together) the layer becomes almost
impurvious to water penetration and secures the rock from movement. It is important that the roadway be contoured into a "crown" before
it is compacted.
Road base will last much longer if contour is graded to a crown. It allows the storm water to be
shed and keep the road bed from becoming a bed of mud.
Improper grading and compacting will affect the life of the road base
and the integrity of the road bed leading to washboarding, potholes and the loss of rock. (thats OK, we can sell you more)
Shoulder
drainage is next as the water needs to go somewhere once shed from the road surface. Open and clear and have a place to go. Gravity
is your friend here.
Culverts should be checked for obstructions. Leaves, twigs, brush or the summer home of a critter
could block the free flow of storm water.
Road base spec material can be made from most any rock that meets hardness
and durability criteria.
Locally you will see road base made from limestone, basalt and aluvial gravels.
We suggest
that if you want to match your existing road material that the source needs to be identified. Our staff can assist you with that if
a sample is obtained.
