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Coweta County Uses Innovative Construction Techniques
to Rebuild County Roads
By Bob Nickelson, Southeast Cement Association  As
counties are expanding at an exponential rate, they are faced with
maintaining more roads with shrinking maintenance funding and increased
roadwork costs. Coweta County in Georgia is overcoming this by implementing
full-depth reclamation (FDR) with portland cement.
Coweta’s roads, like other Georgia counties’ roads,
were built on a sand/clay base where the asphalt was placed directly
over the underlying soil rather than on a rock/aggregate or soil-cement
base. This construction technique was used for many years and most
roads performed quite well. However, as counties experienced growth,
the roads were subjected to heavier loads and began to deteriorate.
“Resurfacing a roadway that has a failed base is a waste in
time and money,” said Bill Cawthorne, public works director.
“We had to do something different!”
“With deep-patching contracts now costing the county in
excess of $100 per ton of asphalt, full-depth reclamation using
cement was an alternative that made sense,” said Fred Landrum,
transportation project manager. “FDR can rebuild the road
in-place in a matter of days and the cost savings are about one-third
of traditional methods. We can essentially rebuild an entire section
of roadway for relatively the same investment of dollars spent for
deep patching.”
Full-depth reclamation with cement makes the reconstruction of
roads a largely self-sustaining process. The complete recycling
process can be finished in one day, and traffic can be maintained
throughout construction. The old asphalt and any existing base material
are pulverized, mixed with portland cement and water, and then compacted
to produce a strong durable base for either an asphalt or concrete
surface. There is no need to haul in aggregate or haul out old material
for disposal, reducing construction truck traffic and waste. FDR
conserves virgin construction materials, saves fuel, and prevents
loaded trucks from tearing up the road.
The process starts by evaluating the condition of the existing
pavement including the sub-layers and mix design. Next, pulverization
sizes the materials back down to a two- inch minus material. An
exact amount of portland cement and water is blended into the material.
Reshaping, proper compaction, grading and curing follow. This gives
the new base the strength and durability to achieve long lasting,
cost effective pavements.
By addressing the entire pavement section, FDR is able to correct
delinquent cross sections, widen roads, increase the load-bearing
strength of the base, and utilize 100 percent of the existing materials.
The process addresses crown and slope corrections, drainage problems,
reflective cracking, and rutting and potholing. Substantial savings
can be attained while meeting environmental goals. Cement stabilization
increases the stiffness and strength of the base material, reducing
deflections due to traffic loads that results in lower strains on
the asphalt surface and sub-grades. A cement-treated-base also forms
a moisture-resistant layer that keeps out water that can destroy
untreated aggregate bases, resulting in potholing and alligator
cracking.
According to the 20-year research study of the FDR process by the
Portland Cement Association, roads reconstructed using the FDR process
had a life expectancy up to three-times of non-treated roadways.
“Even before the cost of asphalt went sky high, FDR with
cement was a better value than deep patching,” said Landrum.
“By utilizing FDR, we are expecting our asphalt investment
to double or perhaps triple in longevity.”
In 2007, Coweta County awarded the state’s largest FDR contract—$2.6
million—to the Miller Group based in Morrow, Georgia for reconstructing
nearly ten miles of country roads. The county plans to bid an additional
ten plus miles this year.
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