The use of precast elements in pavement applications has successfully been used for over 40 years in the USA. However, with today's challenges on our Highway Infrastructure of greater Vehicle Miles Traveled, increased congestion in our high-density urban centers, and an ever-present need for improved highway safety, there is a growing trend to seek out new products, emerging technologies and innovative construction practices that demonstrate key beneficial characteristics. To meet these challenges, Pavement Engineers and Designers are seeking out innovative yet proven products to help them. Precast Concrete Panels for Pavement applications is one such technology that should be added as a supplement to the Pavement Designers toolbox of treatment alternatives.
The beneficial characteristics of new products, emerging technologies, and innovative construction practices can be quantified. The first quantifiable characteristic is that they must not sacrifice quality, durability and long-term performance when compared to traditional and/or industry-accepted practices. Secondly, they must provide a means of accelerating the construction scheduling and sequencing thereby reducing work zone time frames and potentially reducing work zone size limits, yielding reduced risk exposure to both workers and the traveling public. Directly associated with the benefits of reduced work zone limits and exposure is the third benefit to reduce congestion delays caused by excessive construction work zone time frames. Lastly, these new products, emerging technologies, and innovative construction practices must be economically feasible. They must be able to be economically justifiable and demonstrate economic benefits to transportation owners as well as to the taxpayers and users of the transportation system. It is our belief that when precast paving elements are properly selected as a pavement and/or repair treatment, all of these beneficial characteristics are attainable.
A snapshot of the Precast Paving Industry and related products/practices across the nation shows that four primary paving systems are being implemented around the nation. In the non-proprietary, public domain sector we have the Federal Highway Administration sponsorship (under the Concrete Pavement Technology Program (CPTP)) of a Prestressed/Post-Tensioned Paving Panel system. Also, Michigan State University working in conjunction with the Michigan DOT has developed a Full-Depth Repair/Joint Replacement system using precast panels. In the private sector, we have the Uretek USA Precast Panel method that employs Uretek High Density Polyurethane (HDP) for bedding, lifting and leveling the slab. Uretek also holds the patent to their "Stitch-in-time™" load transfer device. The Fort Miller Co., Inc. has developed its "Super-Slab™" precast paving system that has been employed on both intermittent full depth repairs and continuous paving applications and has the capability to go beyond traditional planar, two dimensional roadway geometry to include warped slabs capable of meeting super-elevation cross-sections and curvilinear highway geometry. Lastly, we would like to mention an emerging product that is making its way into highway and airfield projects in Hawaii. Kwik Slabs, LLC has a patented Kwik Joint Coupling system that has proven load transfer capabilities for precast panels.
From a Pavement Designers viewpoint, with an array of products on the market, each employing variations of slab geometry, reinforcement, load transfer, bedding systems and compounded by the potential complexity of public agency procurement regulations regarding proprietary products. The merits of Precast Concrete Pavements quickly begin to look like a minefield that needs to be approached cautiously or ignored completely by the designer.
It is within this context and framework that the AASHTO Lead States Team on the Use of Precast Concrete Panels for Paving has been formed.
To promote the use of Precast Concrete Panels for Paving, Pavement Rehabilitation, and Pavement Repairs to transportation agencies and owners nationwide. To present an unbiased representation to the transportation community on the technical and economic aspects of the current Precast Paving Systems utilized in the market place.