In the October 2007 issue of TCP, “Paving the Way” presented an emerging market for precast concrete: highway pavement. Several precast/prestressed concrete pavement demonstration projects had been completed throughout the U.S. Today, precast pavement can safely be considered a mature technology, providing highway agencies with yet another tool to help them get in, get out, and stay out.
The increased adoption of precast pavement has been fueled by several factors. First, the success of initial demonstration projects and recent “production” projects has increased contractors’ comfort level with the technology as an alternative to other rapid construction options, such as rapid-strength concrete and asphalt.
Some of the initial precast pavement demonstration projects are now more than 10 years old and have exhibited excellent performance, proving that precast pavement is indeed a long-lasting solution. Precast producers have also embraced this technology and have taken many steps to promote and improve awareness within the industry.
Finally, with its increased use and greater awareness, the unit cost of precast pavement has sharply decreased. This makes it more competitive with other rapid construction techniques — particularly considering the long-lasting nature of the product.
Precast pavement in brief
Precast pavement is an alternative to hot-mix asphalt and cast-in-place concrete pavement. Although it can be used for new construction, its most beneficial use has been for reconstruction and rehabilitation of existing concrete pavements. This includes reconstruction of long continuous sections of pavement, as well as isolated slab repairs.
The primary advantage of precast panels is they do not require curing time in the field. The panels can essentially be installed and opened to traffic immediately, making this an ideal technology for projects where construction is limited to short (four- to eight-hour) work windows. Precast pavement is considered to be a long-term reconstruction/rehabilitation solution, and not just a temporary quick fix.
The two primary types of precast pavement used in the U.S. to date are precast/prestressed concrete pavement (PPCP) and jointed precast pavement systems (JPPS). With PPCP, the panels are typically pretensioned during fabrication and post-tensioned together onsite, providing a continuous prestressed pavement slab.
With JPPS, the panels are interconnected similarly to cast-in-place pavement using dowels. JPPS panels are typically either heavily reinforced or pretensioned.