Colasanti was able to use their boom-pump trucks to place concrete for the caissons, pile caps, mat slabs, and the first several floor levels.
SCHWING Colasanti was able to use their boom-pump trucks to place concrete for the caissons, pile caps, mat slabs, and the first several floor levels.

At 68 stories tall, the new Fontainebleau Las Vegas hotel and casino ranks with the tallest buildings on the Las Vegas strip. The hotel is a structural concrete construction in a city that loves concrete. Almost all the hotels on the strip are structural concrete. However, the casino and the parking ramp at the Fontainebleau are structural steel.

For many years Las Vegas casinos were built on themes, but that concept faded with the recent construction of the Wynn Las Vegas and the CityCenter Las Vegas. The elegant design of the Fontainebleau follows this trend with a more sleek, modern design. Like City Center, the Fontainebleau will be LEED certified. This new complex includes a casino, hotel, condominiums, nightclubs, restaurants, and a luxury spa.

Building elements

Concrete construction for the new hotel structure includes caissons, a mat slab, columns, core walls, and flat-plate floors. Bedrock along the strip in the Las Vegas valley is far below the surface, making it impossible for all practical purposes to construct caissons that can be embedded in bedrock so engineers depend on the skin friction between the concrete and the rough edges of a caisson hole to carry the load. The continuous flight auger method for drilling caissons provides the greatest friction between concrete and soil, and was the method used in this case.

Scott Culver, general superintendent for Colasanti Specialty Services Inc., Macomb Twp., Mich., says they formed and cast a mat-slab over the caissons under locations in the building where core structures would be built to house the hotel's 48 elevator shafts. “The mat is 10 to 22 feet thick and is reinforced with #18 rebar,” he says. “The placement was 8000 cubic yards of 8000 psi concrete.” In addition to the mat, Colasanti also cast individual footing pads and pile caps at column locations.

Culver says that constructing columns was very straight forward for this project. They used form panels braced with column clamps to contain the 10,000 psi concrete.

Colasanti decided to use a table form system with birch plywood overlay panels to cast the 8-inch-thick, 8000-psi concrete flat plate floors. Engineers specified a 2-inch camber in the forms, anticipating the building would settle that amount by the time it was fully loaded, with no settlement after that.

Mike Daniels, operations manager for Colasanti, says there are three core structures in the hotel: one at each end of the building and one in the center. Inside each core structure are several banks of elevators in addition to emergency stairwells. Daniels says they decided to use a self-rising form system for the core construction that enabled them to cast both floors and core walls on the same day.

Hotel construction cycle

As with most structural concrete building constructions, Colasanti cast vertical elements before floors. They averaged a five-day cycle for each floor but with the size of each floor at 60,000 square feet, work proceeded on two floors at a time to keep up with their schedules. Floor placements were divided into 20,000-square-foot areas, taking three days to complete each deck level.

Todd Solar, an account manager for Doka, Little Ferry, N.J., says each cycle begins by moving the core forms up to the next level—jumping the outside form by crane and using the self-rising feature of the forms to raise the inside ones. Then floor table forms are moved into position with the tower crane and column form placement following. Column and core forms are set 8 inches higher than the table forms to accommodate floor thicknesses. An innovated tapered “spud” bolt holds the exterior core forms in position, bracing against the floor forms. The bolts are easily removed after concrete placement, leaving a small hole in the floor. Concrete is placed for floors first, with vertical concrete following a few hours later.

Because of the hot weather in Las Vegas, workers normally start placing concrete for floors at 1 a.m., and by 10 a.m., a second crew starts placing concrete for vertical members.

Colasanti self performs their concrete work and does their own pumping. They were able to use their boom-pump trucks to place concrete for the caissons, pile caps, mat slabs, and the first several floor levels. But when floor elevations exceeded the reach of their trucks, they set up four strategically placed masts on a deck and mounted two placing booms on the masts, leapfrogging them to the other masts as placements proceeded across a floor level. All of the concrete for the hotel was pumped. The building crane moved the masts, placing booms, and forms to each new location.

Concrete challenges

Foundations for the building included cassions, mat slabs, and pile caps to transfer loads when two or more caissons supported columns.
COLASANTI Foundations for the building included cassions, mat slabs, and pile caps to transfer loads when two or more caissons supported columns.

Las Vegas has a harsh climate for placing and finishing concrete, especially in the summer when temperatures reach 120° F. Most of the concrete was pumped, creating a challenge for the ready-mix producer due to the lack of natural aggregates left in the Las Vegas. Manufactured aggregate mixes are harsher and more difficult to pump. Harsh mixes also cause problems when pumped over long distances—as was the case with the Fontainebleau.

The building involved mass concrete—also a construction challenge in hot weather. In order to avoid thermal cracking, mass concrete placements can't be more than 160° F at the center with no more than a 40° F difference between the center and the perimeter of the concrete. One way to manage this is to wrap placements in thermal blankets to keep temperatures within range.

Opening soon

Fontainebleau and CityCenter are the only two major projects presently being built on the strip. Work on the Fontainebleau began in July 2007. The structural concrete work for the hotel topped out on Nov. 14, 2008, and the expected opening date will be in the fall of 2009.

This article stated "Colasanti self performs their concrete work". This is true for the columns, walls, and deck finishing, however the deck installation was subcontracted to Ceco Concrete Construction, Kansas City, Mo. Ceco also installed the column-mounted deck tables and cycled equipment up the building. Additionally, the duel level deck forms were supplied by Atlas Construction Supply Inc., San Diego, and not Aluma Systems.