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Integrated Pavement Systems Case Study
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> Integrated > Kalia
Road, Waikiki, Hawaii
Waikiki Says “Aloha” to Integrated Pavement Systems
Approach
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| Severe pavement rutting on Kalia Avenue due
to heavy bus, truck, and car traffic. |
Kalia Road is one of the most heavily used roadways in the entire
state of Hawaii, experiencing near constant bus, truck, and vehicle
traffic. One section in particular, adjacent to the entrances of the
Hilton Hawaiian Village Beach Resort and the Fort DeRussy Military
Reservation, was in need of immediate repair. Under the current traffic
conditions, the pavement in this area had experienced shoving (serious
rutting) and had created serious liability concerns for the owners.
This pavement distress had occurred during a four to five year period,
indicating serious base layer failures that an additional bituminous
overlay would not address.
Instead, engineers chose to correct
the base failure through full-depth reclamation (FDR) and then complete
the roadway with a ultra-thin whitetopping (UTW) surfacing. FDR
rebuilds failed flexible pavements by recycling the existing roadway.
The old asphalt and base materials are pulverized, mixed with cement
and water, and compacted to produce a strong, durable base. UTW
is a thin (typically two to four inches) conventional concrete layer
placed over a prepared base. This combination of FDR and UTW layers
was intended to bond together to create a monolithic structure capable
of supporting the current and predicted traffic loadings.
The Kalia Road project included four lanes of traffic and an intersection
crosswalk area covering more than 1,200 square yards. A reclaimer
first pulverized the existing asphalt surfacing and underlying base
materials to a depth of 13 inches. At this point, four inches of
reclaimed material was removed from the project to accommodate the
future four-inch thick UTW layer. An application rate of eight percent
portland cement by volume of reclaimed material (approximately six
percent by dry weight) was spread over the area and then incorporated
into the remaining nine inches of pulverized material through an
additional pass with the reclaimer. The pulverized and blended materials
were then brought to optimum moisture content, compacted with a
12-ton vibratory roller, and shaped to plan elevations.
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| Dry cement uniformly spread on project after
pulverization and removal of some material. |
Compacting and shaping of the reclaimed roadway
materials. |
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| Altering the surface texture of the placed
UTW. |
The reclaimed material was kept moist through the afternoon and
evening by applications of a water truck. The installation of traffic
loops took place directly on top of the reclaimed base material
and the UTW surface layer was placed the following morning. A water-cement
ratio between .35 and .38 was targeted for development of high early
strengths and long-term durability of the product. Slump was kept
between five and six inches with the driver of the ready mix truck
making final adjustments of the slump with a high range water reducer.
A crew placed and finished the concrete, and then changed the surface
texture as required by the owners.
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| Placing control joints in the UTW layer with
an early entry saw. |
One of the final steps was the application of a concrete curing
compound to provide the UTW additional protection from the weather
and ensure proper strength development. Control joints were then
sawn into the UTW in three feet by four feet sections. Unconfined
compressive strengths recorded for this project were 2,842 psi in
1 day, 4,230 psi in 2 days, 7,105 psi in 14 days, and 8,500 psi
in 28 days.
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| Completed Kalia Road FDR and UTW project. |
Traffic was allowed back on the completed sections by early the
next morning –right on schedule! In addition to its superior
strength and durability, this FDR and UTW approach proved to be
a safer, more cost effective, and less disruptive rehabilitation
method. |
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