State specs that called for hand forming a section of 52-in. (132 cm) Jersey barrier every 300 ft. (91.5 m) threatened to slow slipform production on an interstate project.
The hand-formed sections were to be used for drainage and electrical poles and components along the interstate.
For the slipform pour, headers were erected in sections that were to be hand-formed. It was determined that the best way to pour the barrier was to avoid bringing the machine off the stringline as it approached the headers. For the mold to fit over the headers, the height of the headers was reduced by 3 in. (7.6 cm) from the original plan. The machine then passed over the header.
In order to maintain production, the crew needed to complete 1,000 ft. (305 m) of wall per day. For the entire project, the Power Curber 5700-B slipformed 9,400 linear ft. (2,867 m) of the barrier, which has a profile of a 10-in. top (25.4 cm) and a 30-in. base (76.2 cm). A cubic yard of concrete poured 5 linear ft. (1.52 m).
There was no steel reinforcement over which to pour; instead, two horizontal pieces of steel re-bar were fed through the mold through two pipes with flared ends. When the machine approached a header, the pipes had to be removed.
The pour required an open-front mold with “a front porch” or “dog house” shaped like the design of the mold.
The porch had to be short enough so that the front crawler of the machine did not hit it, preventing accurate steering. But this created a problem: With the short front porch, concrete rolled out the front of the mold.
The crew built a 2-ft. (.6 m) removable front-porch addition that was held in place by a cable strung to the trimmer post. When the crew needed to steer the machine, they removed the front porch addition so that they can use the front crawler.
The 2-ft. addition (.6 m) prevented concrete rollout and it also prevented concrete from setting up inside the mold.
(The preceding article appears courtesy of Power Curbers.)
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