|
| |
|
|
Strength
& Stability
are
the determining factors in
the longevity and
performance of
a traffic bearing surface
The longevity and performance of
any traffic bearing surface is contingent upon the structural integrity
of its foundation. As the sub-base of a roadway design is the portion
which actually bears the weight, a sub-base which has not been prepared
properly lacks the strength and stability to withstand the effects of
continuous traffic loading. Over time, the supporting foundation
weakens, and in-turn, directly impacts the overlying asphalt layer.
Components of a solid
foundation:
 |
The
quantity and depth of stone installed, determined by surrounding
ground conditions and the use of the area, are key components
ensuring a solid "bed."
|
|
Proper compaction of the stone sub-base is another factor in
ensuring a sound foundation. |
|
This is attained by installing the
material in lifts with individual compaction of each layer. |
|
Move
cursor over diagram for after picture.
|
Drainage Challenge #1
Particularly wet or saturated ground may call for
an additional application to the overall sub-base construction:
Design Solution
→ Geotextile Fabric
Placed between the sub-grade and sub-base, the
geotextile functions as a rugged separation of sub-grade material from
the gravel sub-base. In turn,
stabilization of the foundation is achieved.
Drainage Challenge #2
In addition to improper sub-base preparation, water accumulation
beneath pavements is also a deteriorating element for traffic bearing
surfaces. Areas in need of asphalt resurfacing have suffered the effects
of fatigue as a result of continual expansion and contraction of the
asphalt, aging over time, rut formation, and cracking caused by extreme
temperature changes. These deteriorating processes allow for the
penetration of water beneath the asphalt overlay and can reduce the life
of the asphalt by half.
|
|
Design Solution
→ Geosynthetic Fabric
|
 |
Once
the existing pavement has been cleaned of all debris, all voids
and potholes leveled, the non-woven geosynthetic fabric is
secured and is followed by the asphalt overlay course.
This interlay system works to create a full moisture barrier, insulating the overlay from
the effects of the underlying, distressed asphalt pavement.
|
|
Benefits
| Prevents
contamination of the subbase and base layers by fines. |
| Allows
use of more structurally efficient free-draining open-graded
base materials.
|
| Reduces
the depth of excavation required to remove unsuitable
subgrade materials.
|
| Minimizes
site preparation requirements.
|
|
|
Saves
inclement-weather downtime, because work can continue under
most conditions. |
|
Extends
pavement structure life.
|
|
Prevents
pavement failure.
|
|
Reduces
costly maintenance repair and upkeep. |
|
Incorporating geotextiles
into the overall pavement design represents one solution amongst a vast
array of drainage systems available. The most effective drainage
system will depend upon the surrounding terrain and the utility of the
area. Harbour Roads has extensive experience working with various
alternative systems and welcomes the opportunity to consult with you and
provide a recommended specification. |
|
| |
|
|
|
