Additive helps pave major airport
By Scott Jamieson
Feb 20., 2012, Chicago, IL – AkzoNobel Surface Chemistry has
provided its Rediset LQ liquid asphalt warm-mix additive to help
pave new taxiways at Chicago’s O’Hare International Airport. The taxiways are an
integral part of the O’Hare Modernization Program (OMP), one of the largest infrastructure
rehabilitation and construction projects in the United States at one of the
world’s largest and busiest airports.
O’Hare handles heavy volumes of
both passenger and cargo traffic. As part of its modernization program, five new
taxiways located in the Northeast section of the airport are being paved to
accommodate the taxiing and parking of newer and larger aircraft, particularly
cargo planes. The taxiways, designed to measure 80 feet in width and flanked by
35-ft.-wide asphalt shoulders, are being paved with multiple layers of warm-mix
asphalt containing AkzoNobel’s Rediset LQ additive by K-Five Construction, a
leading asphalt and concrete paving company headquartered in Lemont, Illinois,
with plants throughout Northeast Illinois. The asphalt layers are then overlaid
with 19 inches of Portland Concrete Cement (PCC) by general contractor Walsh
Rediset LQ is a liquid variation
of AkzoNobel’s Rediset WMX, a warm-mix additive that allows the processing of
asphalt mixes at lower temperatures and the compaction of asphalt mixes
containing high contents of reclaimed asphalt pavement (RAP). According to K-Five
Project Manager Rocco Danna, the taxiways are being paved with warm mix that
includes PG 58-22-asphalt binder and 20percent RAP.
The asphalt layers form a 12-in.
lift that is actually two different lifts of warm-mix asphalt. The top lift
consists of a 6-in. course of N50 binder warm mix and the bottom lift 6 in. of asphalt-treated
permeable base (ATPB) warm mix. Rediset LQ is used in both lifts as well as in
the all-asphalt shoulders, which consist of a 4-in. course of an N50 warm mix
base and a 3-in., N70 surface course. Mixes prepared with REDISET LQ, in
addition to being produced and paved at lower temperatures, exhibit a great
improvement in their moisture resistance properties.
Green and Effective
Warm-mix asphalt paving is one of
the “green” technologies adopted by the OMP and presented as an option to
prospective paving contractors. Dennis DeVitto, K-Five Vice President of Operations,
and Scott Pirkins, K-Five Marketing Manager, chose this option in order to use Rediset
LQ warm-mix technology in this O’Hare paving project.
The use of RAP in the mixes also
fit very well with the OMP initiatives to use green technologies.
“We’ve done warm-mix paving for
other Illinois governmental agencies, including the Cook County Highway Dept.
and the Illinois Toll Highway Authority,” Danna observed. “We found Rediset LQ
the easiest warm-mix technology to incorporate into our paving operations without
having to invest in upgrades at our hot-mix plants. AkzoNobel Surface
Chemistry’s warm-mix technology, combined with our great working relationship
with their technical personnel, has made the transition from traditional hot
mix to warm mix very easy for us.”
Key Reductions Across the Board
Because it is a liquid product,
K-Five was able to meter Rediset LQ into its existing hot-mix asphalt binder lines
with an injection system. Moreover, at the plant, the inclusion of Rediset LQ in
the asphalt mix helped reduce mix-production temperature to 270ºF – a reduction
of 40-50ºF over traditional hot mix – which cut carbon dioxide emissions as
well as fuel costs significantIy.
In the field, paving temperature
was reduced to 260ºF – a reduction of 40-60ºF over hot-mix paving. This has greatly
diminished the smoke, fumes and odor that typically result from laying down
hot-mix asphalt, thereby providing a better working environment for the K-Five
paving crews. Danna also noted that consolidation of the warm-mix ATPB lift
took about half as long as consolidation of hot-mix ATPB, which reduced the manpower hours considerably.
More than 38,000 tons of warm-mix
asphalt with Rediset LQ have been laid since K-Five began paving in early
October. The paving season for 2011 was concluded in early December, and is
scheduled to resume in early April 2012, weather permitting. A temporary
taxiway, designed to have a life span of three to five years, was completed in
early November to enable connection of existing taxiways with new pavement,
thus ensuring that this new section was fully open to aircraft operations.
At this point, about 50 percent of
the permanent taxiways project has been paved, with completion scheduled for
early June 2012. All told, Danna estimates that a total of 65,000 to 70,000
tons of warm-mix asphalt with Rediset LQ will be laid.