In October 2013, paving crew members of the Tutor Perini Ft. Lauderdale-Hollywood Venture tested the limits of the Terex Bid-Well 4800 paver when paving Taxiway Cell 3 at the Fort Lauderdale-Hollywood International Airport in Florida. One of 33 complex concrete pours completed by the 4800 paver, crews paved this part of the taxiway at a 45 degree skew, perpendicular to the beams, which required machine length to be set at 186-ft. (56.7-m) wide.
“Had the machine been able to pave at the square, it would have been set to pave at 110-ft. wide,” said Larry Eben, regional sales manager of Terex Bid-Well. “The 186-ft. paver configuration is a record width for me and quite possibly for any bridge deck placed.”
The 4800 paver features a standard 48-in. (122 cm) frame depth. When paving at extended widths beyond 150-ft. (45.7 m) wide, the paver starts with standard truss frame segments at both ends of the paver. Transition inserts are then used to increase the frame’s depth to 66 in. (167 cm) in the center, improving frame rigidity and preventing deflection to maintain surface smoothness. The frame is constructed of ultrahigh-strength steel nearly 120 percent stronger, yet weighing less than steel in conventional Terex Bid-Well pavers.
“This allows us to keep the frame’s rigidity while keeping the weight relatively the same,” added Eben.
Additionally when paving at these extended widths, the 4800 paver is constructed with strong gussets, made of the same ultrahigh-strength steel, to connect the truss sections. The 1.5-in. (2.8 cm) crown bolts used in these connections also are larger than those used with standard 4800 paver configurations. The stronger leg mounting system consists of larger lift screws and heavier thrust bearings, mounting plate and coupler motor, all working in concert to help ensure more reliable operation at the project site.
Taxiway Cell 3 required 970 cu. yds. (741.6 cu m) of a 4,000 psi standard Class-2 Florida Bridge Spec concrete, loaded at a 5.5-in. (14.0-cm) slump into concrete pumpers. Since paving direction was perpendicular to the bridge’s support beams, crews loaded concrete to the first three beams out and then to the 45 degree angle to get the right deflection. With this large amount of concrete on the deck, crews loaded the material to the top of the rebar and then capped it off just before the paver finished the concrete in order to prevent it from setting too fast.
Once the deck was properly loaded with concrete, the 4800 paver and its paving carriage, set to the 45 degree skew, went to work. To help keep the carriage assembly moving freely along the frame, the drive is supported by a dual-chain hanger system to prevent the chain from sagging and reduce the load on the drive mechanism and sprockets.
The paving carriage’s dual augers efficiently metered the concrete in front of the Terex Bid-Well Rota-Vibe system. This feature delivers up to 5,000 vpm (83.3 Hz) over the vibrating roller’s 11.5-in. (29.2-cm) length to effectively reconsolidate the top 2.5 in. (6.4 cm) of concrete, delivering a denser and more uniformly consolidated concrete surface. Dual rollers smoothed the surface of the concrete, while crews used a combination of drag pans and burlap drag to get the desired surface finish.
The Terex Bid-Well LED light kit, including eight lights, illuminated the paving carriage and the legs to help the finishers see the concrete surface and finish the slab. The sealed 5-in. (12.7 cm), 12-volt utility lights draw only one amp of power, yet contain 13 LED lights that flood a broad area with bright light to reduce the harsh shadows cast by tower lights.
A few short hours after loading the deck and starting the 4800 paver, crews successfully finished placing and paving the 970 cu. yds. of concrete and added soaker hoses and blankets to help the concrete’s seven-day cure cycle. With the success achieved on Taxiway Cell 3, crews used the Terex Bid-Well 4800 paver to pave two more times in excess of 180-ft. (54.9-m) wide at the Fort Lauderdale-Hollywood International Airport project.
For more information, visit www.terex.com.