Hot Mix Asphalt Overlays
"Most
Durable Pavement Is Also Least Expensive"
The performance of a pavement is affected by the type, time of
application and quality of maintenance it receives. Preventative timely
maintenance slows the rate of pavement deterioration due to traffic and
environmentally applied loads. Delays in maintenance and deferred
maintenance increase the quantity of defects and their severity so that,
when corrected, the cost of repair is greater. Continued deferral of
maintenance and rehabilitation action shortens the time between overlays
and reconstruction.
The traditional method for protecting a deteriorating pavement, reducing
roughness, restoring skid resistance, and strengthening the pavement
structure of a flexible pavement is with an overlay of hot mix asphalt.
It is typical practice of most state Department of Transportations (DOT)
to place a thin hot mix asphalt overlays, 11/2 inches thick, when
considering the need for restoring skid resistance and protecting a
deteriorating pavement. The total overlay thickness will vary depending
on the type of roughness components present in the pavement profile.
Where strengthening the pavement structure is the primary objective for
the overlay, thin overlays are seldom cost effective, even if several
are placed over a period of several years, primarily because thin
overlays cool quickly and therefore are more difficult to compact. Also,
thin overlays are generally prone to debonding from the existing
surface. Therefore, it is imperative, when pavement strengthening is
needed, that the engineer perform; A. an adequate analysis to establish
the condition of the existing pavement; B. determine the strength
properties of the existing pavement material; C. determine the length of
the performance period required for service and based on the traffic to
be served; D. and then determine overlay thickness. Only by using good
engineering design procedures and sound life cycle cost analysis can
most effective combination of overlay design thickness and future
maintenance activities be determined.
A smooth asphalt pavement saves in vehicular wear and makes drivers
happy. Hot mix asphalt pavements go down quickly and are open to traffic
faster, saving labor costs and costs due to user delays. The use
reclaimed asphalt pavement (RAP) in the road base, base course, or
surface course can make those dollars go even further, while sustaining
the environment.
Initial costs, maintenance costs, long term costs, user delay costs,
residual costs. They all add up to one thing: Hot Mix Asphalt is the
lower cost pavement, hands down