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Precast Concrete Pavements
Published in Rajib B. Mallick, Tahar El-Korchi, Pavement Engineering, 2017
Rajib B. Mallick, Tahar El-Korchi
These repairs are always full-lane width. The process is similar for FDRs and full-panel replacement, except for the length of the repair area. A schematic model of the repair is shown in Figure 18.1. The dowel bars are embedded in the precast panel. Slots for the dowel bars are cut in the existing concrete pavement, similar to the dowel bar retrofit (DBR) method, as illustrated in Figure 18.2. The dowel slots are then filled with fast-setting patching material or grout. In a variation of this scheme, no dowel bars are embedded in the precast panel, and dowel bars are installed after panel installation using the DBR technique, as shown in Figure 18.3. For alternative intermittent repairs, the dowel bars are positioned in the existing concrete pavement by drilling and epoxy grouting. This is similar to CIP FDRs or full slab repairs, where the slots for the dowel bars are fabricated in the repair panels along the bottom of the transverse sides, as shown in Figure 18.4. The slots and the joint perimeter gaps are then filled with fast-setting grout material.
Precast concrete pavements for rapid rehabilitation of high traffic volume highways—US state of practice
Published in Andreas Loizos, Imad L. Al-Qadi, A. (Tom) Scarpas, Bearing Capacity of Roads, Railways and Airfields, 2017
The narrow-mouth application options include the following: Full dowel bar retrofit—Narrow dowel bar slots along both sides of the joint for continuous applications.Partial dowel bar retrofit—Dowel bar slot along one side of the joint. For repair applications, narrow-mouth surface slots are located in the panel side of the joint. For continuous applications, a panel will have embedded dowel bars along one side of the panel and matching surface dowel slots (narrow mouth) along the other side of the panel.A version of the narrow-mouth surface slot system were developed is shown in figures 4.Rapid Roadway System’s Barra Glide Load Transfer Feature®—In this feature, dowel bars are pre-placed in narrow-mouth slots that are partially open at the surface, as shown in figure 5. After the panel is installed, the dowel bar is pushed into a circular or oblong hole in the adjacent panel or existing slab. The dowel bar slots are then patched using the dowel bar retrofitting technique. The dowel bar holes are grouted using a fast-setting, high-strength cementitious grout.Caltrans Generic Teardrop Surface Slot Feature—This feature is very similar to the SHRP2 system, except for the slot shape, as shown in figure 6. This feature requires dowel bars to be embedded in the adjacent (next placed) panel. The embedded dowel bars are slid into the teardrop slots of the previously placed panel, as shown in figure 7. The slots are then patched using the dowel bar retrofit technique.
Developing specifications for precast concrete highway pavements
Published in International Journal of Pavement Engineering, 2022
Daniel Offenbacker, Douglas Cleary, Ayman Ali, Yusuf Mehta
Load transfer systems involve the use of slots on one or both sides of the joint and are located at the top or bottom of the PCP panel. The slots are usually narrow and are open for the full or a partial length of the dowel. Several studies on PCP systems provide a summary of the currently used load transfer systems including the bottom slot, narrow mouth, teardrop, and sliding dowels (Tayabji et al., 2012, Tayabji and Brink, 2015a, The Fort Miller Company Inc., 2015, NPCA, 2018b). Bottom-slot load transfer system: Incorporates dowel slots at the bottom of the slab. In a repair situation, dowel holes are drilled into the existing pavement and the dowel bars are epoxied into the holes. The repair panel is then lifted into place over the dowels and a flowable grout is used to fill the dowel slot. The bottom panel dowel slots are shown in Figure 2(a).Narrow-mouth dowel systems: Developed as an alternative to a full dowel bar retrofit that requires slots on both sides of the joint. At the surface, the slots are about 1 inch wide and spread to about 3 inches wide and within an inch below the panel mid-height. The narrow width at the surface allows for temporary traffic prior to grouting the dowels. With this type of dowel system, the dowel bars are placed in a longer dowel slot (14 to 16-inches long). Once the panel is positioned, the dowel is slid into predrilled holes in the adjoining panel. Figure 2(b) shows a modification developed by the Illinois DOT system that includes a widened section near the joint that allows for sliding and rotating the dowel by hand and improving epoxy adhesion to the bar. The dovetail shape of this dowel system is beneficial because it provide resistance to dowel pop-out, however, this system must be field installed and cannot be cast-in-place. Therefore, the performance of this system is also dependent on the encasement grout used to secure the dowel.Teardrop dowel system: Has been used rather than the triangular shape for better installation (Figure 2(c)).Sliding dowel system: Has been recently developed and incorporated in some state DOT systems with only a partially open narrow slot (Figure 2(d)). Based on the SME responses, these are recommended due to their simple use and increased efficiency.