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Germany (8). Construction of the modified Styrofoam defects for the mockup girder is described in this
section as well.
Description of the Mockup Girder and Constructions of Grout Defects
A full scale pre-cast bridge girder (U-shaped) was donated to the research team by EnCon Bridge
Company (Denver, Colorado) for use in grout defect sensitivity studies. The length of the girder is 30.48
m (100 ft) with a typical wall thickness of 254 mm (10 in). There were four empty metal ducts (101.6
mm or 4 inches in diameter) inside each wall (Figure 2). The west end of the girder (6.1 m or 20 ft long)
was selected for this study.
Figure 2 – U-Shaped Bridge Girder with Eight Empty Ducts - West End View
Stepped and tapered Styrofoam rods (101.6 mm or 4 inches in diameter) were inserted into the ducts
before grouting to form internal voids with sizes ranging from small to almost full diameter voids. Figure
3 shows a Styrofoam rod being inserted into the top duct of the north wall. A wire (3 mm or 1/8 inch in
diameter) was bent to form a leg for the Styrofoam rod so that the foam would be positioned on the roof
of the duct, which simulates the real world grout defects formed by air and water voids. Smaller defects
were glued directly to the roof of the duct since they were too thin for the wire leg. Figure 3 also shows
the front view of a Styrofoam defect inside a duct. The defect sizes are presented in Table 1 in terms of
their circumferential perimeter and duct depth lost. The defect designs are shown in Figure 4a for all four
ducts in the South web wall and Figure 4b for all four ducts in the North web wall. The actual percentage
of circumferential perimeter and diameter depth lost due to the defect are shown in the underlined
numbers placed directly above the defects in Figures 4a and 4b.
