Infrastructure is one area where Unbonded PT has the potential to increase its market share relative to existing industries.
94% of US road are paved in asphalt.
Concrete makes up the remaining 6% of US roads and is most commonly used in bridges.
One potential market where Unbonded Post-Tensioning can increase its market share is airport runways. Traditionally, these are RC pavement. The concrete thickness varies between 12" at non-hub airports to 18" at larger airports.Rockford, IL has a non-hub airport runway that has a 7" Post-Tensioned slab. The cost analysis in 2003 by Ed Rice showed that the PT runway cost $46/sqyd vs. $50/sq.yd for conventional RC. Another benefit was that PT helped eliminate control joints.
Another potential market for Unbonded Post-Tensioning would be parking lots, especially those on expansive soils. According to the US Census Bureau, there were 105 million commercial parking spaces in the US. - majority of which are in parking lots.
The US Highway Network has 4 million miles of roads - of which 47,000 miles are for heavy highway trafficaccording to the FHA.
Emergency Vehicle Operator Course (aka EVOC) was a built recently in Camp Ripley Minnesota and won the 2013 PTI Award of Excellence in the SOG category.
Encapsulated PT was used due to the corrosive environment.
EVOC is a 4-mile course used by police, fire and military vehicles for training purposes. The Post-Tensioned portion is a skid pan which is made slippery with water, oils and other chemicals so that drivers can practice controlled skids in their vehicles.
2 PT tendons were placed 16" o.c. in the long direction and 19" o.c. in the short direction. A perimeter expansion joint was used to separate the PT slab from the asphalt pavement.
6000 psi shrinkage compensating concrete was laid on top of 2 layers of polyethylene sheet and a 14" base course. Initial stressing of the PT occurred at 16.5 kips when the 1st pour reached 3000 psi and final stressing occurred at 33 kips when the 2nd pour reached 3000 psi.
Buford Ave. Pavement Reconstruction project involved replacing an existing RC pavement in St. Paul, MN with a Post-Tensioned Pavement.
The construction was completed in 2 months and was designed for a 40 year life span.
Buford is located at a major bus stop and was designed to handle heavy traffic from buses.
The Univ. of MN Underground Student Lounge was operational during reconstruction. The Post-Tensioned pavement solved one major problem for the students in the U/G Lounge. It was chosen to reduce major deflections and vibrations from the bus traffic from above compared to the RC pavement.
