After retrofitting its three batch plants with new twin shaft mixers so architectural and structural lines could standardize self consolidating mixes,
After retrofitting its three batch plants with new twin shaft mixers so architectural and structural lines could standardize self consolidating mixes, Phoenix-based precast/prestressed mainstay Tpac Division/Kiewit Western is poised for another technology leap. The company enters 2008 with much-improved hollow core casting capability, owing to construction of two 560-ft. beds and deployment of Elematic extrusion technology.
The beds are built along existing and new slabs amid Tpac’s 75-acre operation. Tpac is launching the Elematic platform with an EL900E Extruder and 8-in. and 10-in. nozzles, and EL1300 Saw equipped to perform cross, rib and angle cuts up to 180 degrees while plank remains on the bed. The producer also has the latest version of the Elematic Bedmaster dispatcher, which cleans and oils the beds, pulls strand, and has an optional gutter brush to clear excess material and water to one of end of the line.
Tpac ordered a motorized roller to immediately place an extra insulated tarp on freshly extruded slab Û a feature critical during excessive summer heat. To that end, Arizona’s harsh summer climate drives Tpac to operate in the spirit of a 1980s recruitment campaign, in which Army representatives claimed their forces achieved more by 9 a.m. than others did all day. In July and August, for example, the Tpac yard has more activity at 2 a.m. than 2 p.m. Hollow core crews will typically start a shift between 2 a.m. and 4 a.m., depending on the season.
The Elematic machinery will replace the dated fabrication process of Spandeck, the company’s established hollow core offering. Spandeck plank requires two passes, with an intermediate step – placement of pea gravel – to form voids. Finished plank must be hoisted by taller gantry cranes to remove the gravel. Tpac will continue to fabricate solid Spandeck panels, which can be efficiently produced with the existing bed and gantry hopper.
Tpac and a sister plant in Concord, Calif., Kie-Con, are part of Omaha, Neb.-based heavy construction giant Kiewit Corp.
WET MIXES, DRY CLIMATE
Tpac Division/Kiewit Western operates main (shown here) and satellite batch plants for structural building and transportation products; a third plant covers an architectural line. All three batch plants have been equipped with twin shaft mixers to augment a yard-wide switch to self consolidating concrete. The yard fleet includes seven Tucker transport vehicles.
Tpac products for which SCC is standard include voided box bridge girders (far right, top and bottom). Coinciding with the Elematic hollow core production ramp up is a switch from BASF Glenium-based Polyheed 3400 to the Polyheed 7700 HRWR.