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.
Issue link: http://concrete.epubxp.com/i/75186
FEATURE COVER STORY RECORD ROLL Concrete Tech sets new threshold for bridge beams Concrete Technology Corp. and heavy-hauler V. Van Dyke Inc. put an exclamation point last month on a contract calling for the longest precast/prestressed concrete girders delivered to date via a U.S. thoroughfare. Deploying highly stable trailers on post- evening rush hour schedules, the team shipped nine 205-ft.-long, 100-in.-deep beams—the second of two sets—from Con- crete Tech's Port of Tacoma (Wash.) plant to the Alaskan Way Viaduct Replacement site just south of downtown Seattle. The super girders support the northbound lanes of a pier-free crossing within the southern mile of a grade and tunnel project succeed- ing the viaduct, itself part of SR 99. Phased demolition of the two-level, cast-in-place Alaskan Way structure—deemed struc- turally obsolete by current seismic stan- dards—will reconnect key portions of downtown Seattle and the Puget Sound. Concrete Tech and Seattle-based V. Van Dyke shipped an initial set of eight, 205- ft. Wide Flange 100G in mid-2011 (Concrete Products, December, "Take It To The Limit" cover story), this year's delivery bringing the South Atlantic Street crossing to full width. The producer fabricated the single- piece, 255,000-lb. members according to Washington State Department of Trans- portation specs for the new generation WF100G girders. WSDOT adopted 10,000-psi design strength concrete mixes and new 0.6-in.-diameter strand patterns to enable single WF100G beams for bridge spans in the 195- to 240-ft. range. Commercial, high strength concrete has been a Seattle fix- ture for decades thanks to abundant re- serves of pristine glacial quartz. Its capacity to develop strength even in lean mix designs suggests some of the highest quality ASTM C33 product on the planet. Concrete Tech used a high slump mix reaching nearly 13,000-psi compressive strength for the super girders, which contain 74 permanent and eight temporary preten- sioned strands. The mix is in lieu of a self consolidating concrete, for which WSDOT has not yet issued a spec. Assessing the hauling prospects along SR 99—providing a direct, 30-mile, at-grade route from the Port of PHOTOS: Concrete Technology Corp. Anticipating next generation WSDOT super girders in the 200-ft.-plus range, Concrete Technology built an enclosed girder line at its Port of Tacoma plant in 2008. The 400- x 65-ft. operation has two prestressing lines, each with 100-strand capacity, and is served by twin 75-ton bridge plus two new 75-ton Shuttlelift gantry cranes. (The rail-mounted 50-ton Whirley crane, between the Shuttlelifts, is used primarily for prestressed piles and hollow core plank, and not deployed in girder loading.) 62 | JULY 2012 WWW.CONCRETEPRODUCTS.COM