Concrete Products

JUL 2015

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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Page 52 of 103 July 2015 • 51 FEATURE COVER STORY Bracing the breakwater to new guidelines will require Durocher Marine to attain just over 23 dolosse per 1,000 square feet of base and slope area. A 16-ton dolos is 11 feet long and has a volume of 213 cu. ft. In lieu of diver-as- sisted structure and stone placement, the con- tractor will deploy Posibloc, a topographical 3D system attached to crane cables. Developed by Mesuris of Saint-Gregoire, France, the program operates without camera or sonar, instead le- veraging GPS to guide precise stone and dolosse setting. Companion Visibloc technology re- cords each unit's location, enabling the crane operator to target subsequent placements for optimal density and interlocking. Durocher Marine has assembled two 2,000- ton and two 2,400-ton barges—each vessel equal to transferring 50 to 60 dolosse—along with a land-based Leibherr 895 crawler crane. The contractor aims to set 40 of the precast structures and varying stone volumes per day. Continued on page 52 A tough Northeastern winter challenged Lake- lands Concrete early on, but crews kept an eight dolosse per day fabrication schedule that would lead to the contractor's baseline: a 750-structure inventory prior to mid-June shipments to the Lake Ontario site. By subcontracting cage fabrication to an area rebar spe- cialist, Klein Reinforcing, Lakelands Concrete met the dolosse casting schedule, while tackling stock production and orders booked prior to the Durocher Marine contract. When executed in concrete, the dolos geometry has thick, robust sections to withstand wave and water forces. The 16-ton unit has 11-ft. sections, connected by 5-ft. stems; main members taper from 42-in. diameter octagonal cross section. Each dolos bears 8 yd. of self-consolidating mixes, placed in one of two ports on clamped forms. As produc- tion reached target pace, crews averaged about 30 minutes flling each form through four 2-yd. batches.

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