From an aerial perspective, the project looks fairly straightforward. But onsite coordination of crews and truck traffic, over three shifts, was challenging.
Successfully completing a large concrete pour depends on planning and teamwork. So when Miami-based Coastal Construction Group undertook the largest concrete pour in the history of Florida, and perhaps in the Southeastern United States, the company spent two months planning for the 24-hour event. And the result was a construction feat, and a community event, that went off as smoothly as one could hope for when scheduling more than 150 trucks to deliver nearly 14,000 cubic yards of concrete to an oceanfront site.
It took 150 trucks making 1,500 trips over 20 hours to deliver the 13,511 cubic yards of concrete for this mat foundation pour in Sunny Isles Beach, Fla.
The pour was for the mat foundation of the $180 million Trump Royale, a 55-story oceanfront condominium in Sunny Isles Beach, Fla., roughly half way between Miami Beach and Ft. Lauderdale. This foundation was for the third and final building in the development, which will ultimately connect with the Trump Royal Sonesta. For a smooth tie-in to the existing structures, that meant doing whatever was possible to keep the final settlement of the new building the same as had been experienced on the existing structures.
The pour began at 2 a.m. on Saturday, January 7, 2006. The start time was based on two factors. First, Coastal wanted to be sure the pour could be wrapped up in plenty of time to not go into a second daylight shift. The company also wanted to assure that drivers had eight hours off between the end of their Friday workday and the beginning of the huge pour. That was important, considering that 400 drivers would be needed over the 24-hour period. Coastal addressed another concern—fueling pumps, lights, generators, and other equipment—by positioning two full tank trucks, one diesel and one gasoline, on the site.
To move the concrete from truck to slab, Coastal engaged C&C Concrete Pumping. The company had eight concrete pumps onsite for the pour, including two spares. This level of redundancy was considered important because the pour was to be going on far longer than the usual duty cycle of the equipment. In the end, there were no breakdowns and neither spare was pressed into service.
Rinker Materials, based in West Palm Beach, Fla., supplied the concrete from six of its plants in Miami and Ft. Lauderdale. The company used 150 ready-mix trucks to make the 1500 trips and deliver the 13,511 cubic yards of concrete. To facilitate moving the trucks in and out, one lane of Collins Blvd. was closed to traffic during the pour. Notably, throughout the entire pour only one truckload of concrete was rejected and that was simply due to excessive slump.
Overall the average placement rate was 676 cubic yards per hour. One surprising slowdown in supply, followed by a surge, occurred twice, once at each of the drivers' shift changes. Both times there was a noticeable delay as one set of drivers checked out of their trucks and a new set of drivers stepped in. Fortunately, good planning and good communications kept the pour going smoothly through these periods. The pour was completed at 10:15 p.m., four hours ahead of schedule.
In addition to taking care of the concrete and the equipment, Coastal also made plans to take care of the people who were involved in the pour, which ultimately numbered about 1000. First, a catering company was brought onsite, setting up in an adjacent parking garage to provide food around the clock.
Beyond that, the company wanted to recognize each person's contribution to the project and to commemorate the day with a meaningful keepsake. A time-lapse camera was mounted on the Trump Tower, directly south of the pour, to assemble a visual record of the event. The camera snapped a photo every minute over the 24-hour period. A DVD with the resulting video and other footage from the project, along with a commemorative t-shirt, was given to every person involved in the project.
A new home for the presses
Beginning in June 2005, Sandy, Utah-based Layton Construction constructed a two-tiered slab as the base for Newspaper Agency Corporation's three new printing presses in its new West Valley City, Utah, facility just southwest of Salt Lake City. Although less massive than the Sunny Isles Beach mat foundation, this project made up for that in the challenge of forming and shoring. Adding to the complexity of the concrete construction, the equipment installation required a very flat slab.
The 420-foot long 3-foot-thick pile cap slab provides a solid base for the columns that support the “tabletop” slab, which serves as the base for the printing presses.
The new $84 million facility is architecturally unique and designed to blend in with the surrounding mountains. It incorporates architectural concrete screen walls to block various types of work and service areas from public view.
But the technical features of the building, including operation of the new presses, rely on the structural concrete foundation. Auger-cast piles, which are not often employed in this area, were used to ensure a firm foundation. The contractor installed 167 piles, ranging from 15 to 40 feet deep.
The press foundation structure was placed atop the piles. It consists of a lower slab, essentially a pile cap, and an upper slab, upon which the printing presses are installed. Both slabs are 420 feet long, 22 feet wide, and heavily reinforced. The pile cap is 3 feet thick, while the upper, “tabletop” slab is 30 inches thick. Concrete columns support the tabletop 14 feet above the footing slab, providing a chase area for the presses' electrical and mechanical systems, as well as access to the underside of the presses for feeding paper and other activities.
The 6000-psi concrete for the foundation had a water-to-cement ratio of 0.36 and was placed at a 3-inch slump in several stages. The first consisted of the pile cap, which was placed in two installments. Next came the columns, followed by the tabletop slab.
The “tabletop” slab formwork required numerous penetrations.
Because the tolerances required less than 1/8 inch variance over the 420-foot length of the top surface, forming and shoring was very important. The slab is heavily reinforced by a double layer of steel consisting of #9 and #11 bar, which means the forms supported a lot of weight even before the concrete was placed. After the shoring for the table top was put in place, it was repeatedly surveyed, bumped, and shimmed to ensure accuracy.
To further help produce a flat slab, the rails at the top of the slab were anchored into the columns below to prevent any flexing or movement. Concrete was placed using a highway-style straight-edge, while survey crews monitored the engineered formwork to confirm that there was no flexing or bowing.
Also notable in this installation was the precision with which hundreds of embeds and penetrations were placed within the structure. Most had tolerances of 1/16 inch over the 420-foot run of the tabletop, and minimal rework was required during installation of the 60-foot-high presses.
The preparations and quality control measures Layton used apparently worked, because only four 1-foot-square areas of the concrete surface had to be reworked to meet the flatness requirements. Again, good planning and advance preparation resulted in successful completion of a challenging project.