Construction of the California Precast Concrete Pavement Demonstration Project

Summary

The precast prestressed pavement project on I-10 in El Monte demonstrated the viability of construction of prestressed precast concrete pavement. Although the project length was small (76 m [249 ft]) compared to the Texas pilot project (700 m [2,297 ft]), this project demonstrated a similar fabrication and installation rate.⁽²⁾ Additionally, several new challenges were presented with this project:

Panel placement only at night.
Construction over LCB.
Incorporating a change in cross slope in the top surface of the panels.
Placement of the panels between fixed structures—the existing pavement and a sound wall.

The project also incorporated many of the recommended improvements from the Texas pilot project:⁽²⁾

Modified keyway dimensions to ensure tighter joints between panels.
Gaskets around the post-tensioning ducts to prevent grout leakage.
Modified post-tensioning anchors (non-spring-loaded).
Epoxy-coated post-tensioning strand to prevent corrosion.
Screw-type lifting anchors, which leave a much smaller hole to patch.
Underslab grout channels to facilitate filling voids beneath the panels.
Temporary post-tensioning during panel assembly to ensure tighter joints.

The main objective of this demonstration project was to further evaluate and refine the precast prestressed pavement concept developed during the original FHWA feasibility study⁽¹⁾ while also familiarizing Caltrans and local contractors with this innovative rapid paving technique. While the project was constructed behind a concrete barrier and was not required to be opened to traffic immediately, the goal of this project was to evaluate its potential for future use under stringent time constraints, such as during overnight or weekend construction windows. Based on observations from the construction of this project, this technology appears to be suitable for such applications.

Recommendations for Future Construction

The new challenges presented by this project demonstrated the adaptability of this precast paving technique to whatever demands a given project may have. Although this particular precast paving technique is better suited for large-scale pavement rehabilitation/construction, it can be adapted to either single-lane or full-width (up to 12 m [39 ft]) pavement construction.

Although this project was not required to be opened to traffic immediately after construction, panel placement was limited to nighttime only. Future demonstration projects should focus on limiting the entire construction operation to a nighttime or weekend timeframe, with the pavement open to traffic outside of these construction windows. Future projects should also be constructed under competitively bid contracts rather than change orders to better evaluate realistic construction costs. It is believed that as contractors and owner agencies become more familiar and comfortable with this technology, costs will become competitive with conventional fast-track concrete paving.

Figure 44. Photo. Finished precast pavement just prior to opening to traffic.

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Updated: 04/07/2011