Concrete Products

JUL 2012

Concrete Products covers the issues that attract producers of ready mixed and manufactured concrete focusing on equipment and material technology, market development and management topics.

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FEATURE CONCRETE TECHNOLOGY Tacoma—engineers calculated that 10,600- psi strength concrete was required to meet allowable stress limitations and assure lateral stability during girder transfer. WSDOT, which Concrete Tech credits with helping producers and haulers advance extra-long prestressed girder practice, in- cludes member-to-trailer contact point bunking locations, lifting hardware specs and other trucking parameters on contract documents. The department typically lets longer-span bridge contracts with single- piece or spliced-girder options, contractors opting for the former on jobs where route and site access permit. Precast/prestressed concrete girders' strong track record with WSDOT was under- scored in the past decade, as Concrete Tech logged record or near-record length road- bound beams—in the 175- to 185-ft. range—for eight bridges under the agency. Besting those projects on the length scale was Salt Lake City's Hanson Structural Pre- cast, which in 2010 delivered 195-ft. gird- ers for a widened Interstate 15 crossing. Like it, the new Washington SR 99 struc- ture spans a four-lane or wider road with additional rail line clearance requirements. (Calgary-based Con Force Structures main- tains the North American record for road- hauled, precast/prestressed members—the Deerfoot Trail at Bow River Bridge's 211-ft. girders, 2004.) Concrete Products visits Concrete Tech and V. Van Dyke for some additional per- spective on their Alaskan Way WF100G fab- rication and delivery feat. Continued on page 64 The new plant is sized for up to 225-ft. girders, the largest Concrete Tech sees transferrable by truck. The two stressing lines are built to resist overturning moment by the weight of the abut- ments, measuring 20 ft. wide, 7 ft. deep, and 40 to 60 ft. long. The producer multi-stresses all strand, which prompts the use of large-diameter pull rods, plus four 400-ton Enerpac rams provid- ing capacity to pull multiple strands. The rods are color-coded: white for bottom or straight strand, red for harped strand. The stress- ing assembly includes four bulkheads: one fixed, upon which the rams bear; one each for the white and red rods; and, a fourth interchangeable one WWW.CONCRETEPRODUCTS.COM to move either the straight or harped strand bulkhead. The record-length Alaskan Way WF100G girders have 46 bottom, 28 harp and eight temporary strands. Both lines within the new plant are positioned to allow finished-girder staging along the walls, while keeping the center aisle open to forklifts and mix delivery vehicles. Through the Alaskan Way contract, Concrete Tech relied on V. Van Dyke equipment to transfer longer product to storage. More recently, the producer has acquired two nonroad-rated, super girder-equal jeeps from Van Dyke supplier, Aspen Custom Trailers in Luduc, Alberta. JULY 2012 | 63

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