Up Against a Wall
Up Against a WallProject Time Crunch Turns Contractor to Shotcreting Walls for Greater Efficiency, jumping Slabs with High Volume Equipment for Faster Completion
STURTEVANT, WI (July 28, 2008) – The tight construction deadline of the Atlantic Times Square, a large scale, mixed-use development in Monterey Park, California, put the concrete contractor literally up against a wall to build the project’s walls faster, plus place the concrete slabs at high speed. To solve both challenges, contractor CS Concrete Solutions, Inc. (Concrete Solutions) of Mission Viejo, California turned to uncommon construction techniques and high performance Putzmeister equipment to step up the pace.
“We’re shotcreting the walls with greater speed than possible with block construction (CMU) or poured-in-place,” says Marty Vasquez, general superintendent of Concrete Solutions, “and we’re relying on a Thom-Katt® trailer-mounted pump to handle all the shotcrete work under an aggressive schedule.”
Vasquez adds, “Plus, we’re using Putzmeister boom pumps for their extremely high outputs in placing the concrete faster for the slab work.”
The need for speed is critical on the Atlantic Times Square, considered one of the largest projects under construction in the Los Angeles area today and one that requires highly efficient construction methods to achieve its targeted winter 2009 opening.
To help meet the fast track completion date, Concrete Solutions is depending on the state-of-the-art equipment and prompt services of three key sub-contractors: Global Shotcrete, Inc. (Global) of Ventura, California to supply the high performance trailer-mounted pumps; Fleming Concrete Pumping, Inc. (Fleming) of Santa Ana, California to provide the high volume truck-mounted concrete boom pumps; and Cemex to deliver the specified concrete mixes from its two local plants in Los Angeles and Azusa, California. The $200 million project is under the direction of general contractor Pan Construction, Inc. of Rosemead, California.
The Atlantic Times Square is under construction in the heart of Monterey Park. Residents and visitors will soon enjoy the convenience of the first mixed-use development in the San Gabriel Valley.
Developer Kam Sang Company, Inc. of Arcadia, California has specifically designed the huge complex to satisfy the need for retail and residential in one place. Inspired by Times Square in New York City, the center stretches a full city block, located at the corner of Atlantic Boulevard and Hellman Avenue, adjacent to the I-10 San Bernardino Freeway.
Offering over 230,000 square feet (21,368m²) of retail and entertainment space, the complex will be anchored by a 14-screen AMC Theater Cineplex and 24 Hour Fitness as well as include a mix of national and local businesses. The enclosed community also integrates 210 luxury condominiums and parking for 1,640 vehicles.
The magnitude of the job site is difficult to comprehend. With three levels below grade and six levels above, it is about the size of six football fields. Therefore, the sheer volume of concrete to be pumped, in addition to the incredible number of walls to shotcrete, underscores the importance of reliable, high performance pumping equipment to meet an important completion date.
Traditionally, concrete walls are constructed of block (CMU) or poured-in-place. However for this project, the contractor is taking a rather unusual tactic and is instead using shotcrete to construct the interior and exterior walls. The technique is significantly improving efficiency to meet the demanding deadline.
“If there’s a wall to be done on this major job, we’re shooting it with shotcrete,” says owner Joe Able of Global. “The speed of shotcreting allows contractors to push jobs forward faster than other alternatives. Plus, the setup process is ‘green-friendly’ because only half the wooden forms are needed and can be reused several times over.”
For this particular job, poured-in-place walls would have been the typical choice, consisting of a rebar core and using two braced wooden forms and then pouring concrete in place from the top. However, with the shotcrete process, wooden forms are set on only one side of the wall instead of two and formed all the way to the top instead of in stages; the same amount of rebar is used. This process is reducing labor costs and cutting the amount of material required in about half. Plus, precious space on the job site is saved, as the crew works from only one side of the wall – an important benefit on the extremely congested construction site.
Once the forms are set, the nozzleman shoots shotcrete into the open side of the forms. Then, the crew hand-finishes the exposed side, the forms are pulled and they are reused to set the next wall.
“It’s just so much faster to shotcrete the walls, and there’s plenty of them to shoot on this major project,” says Vasquez. “There’s the structural exterior walls around the perimeter of the 330,000 square (30,658m²) complex; plus all the interior walls, which include three levels of underground parking, a retail level and five residential floors.”
Vasquez adds, “Global is doing a great job while paying attention to all the details.”
Shooting 80 to 130 cubic yards (60 to100m³) of shotcrete during an average eight- to 10-hour day, Global is on the job site about twice a week with their Thom-Katt TK 50HP. Putzmeister has renamed the model “Katt-Kreter™” to call attention to the unit’s special shotcreting features.
The pump has plenty of power, as it is capable of outputs up to 54 cubic yards an hour (41m³/hr) and maximum pressures to 1,450 psi (100 bar). Therefore, it can pump the 5,000-psi mix, which features a low water/cementitious material ratio for a shortened curing time and reduced shrinkage. Because of the unit’s shotcreting capabilities, Global has two of the same model in its fleet.
“We’re relying on our Thom-Katts® because the pumps just don’t break down,” says Able, “and that’s a ‘must’ because we’re doing such a substantial amount of shooting on this particular job.”
Although shotcreting is not the norm for placing commercial walls in southern California, Global has handled various jobs in this manner before. However, the prominent Atlantic Times Square is their largest single project to date utilizing the distinctive approach; and consequently, it should ultimately help the method gain wider acceptance.
Able started his shotcrete business three years ago, initially renting equipment and then buying two Putzmeister trailer pumps. He says, “Although shotcrete is only a small percentage of our industry today, our company has been experiencing explosive growth. The popularity of shotcreting is definitely catching on with contractors, as they are finding it an attractive alternative in saving time and money.”
Able does note that “although the growth of shotcreting offers our business a great opportunity, it is extremely hard work and each day brings unexpected challenges to tackle.”
Concrete pumping keeps up the pace
While the walls are getting the shotcrete treatment, the footings, columns and slabs are being pumped with concrete. Fleming Concrete Pumping (Fleming), reliably serving southern California since 1997, has been on the job with almost every boom pump size in the company’s expansive fleet, ranging up to 63Z-meters.
Due to the especially crowded job site conditions, setup of the boom pumps often takes place in the street or in specific areas on the job site, which are far from the point of concrete placement. Therefore, the longer reach of the 63Z-meter is favored for extending its boom 203' 9" (62.10m) vertically and 190' 7" (58.09m) horizontally to access the pours. Plus, all the boom pump models, whether with a .16H and .20H pump cell, can deliver the high concrete volumes the contractor demands.
“For the decks, we’re pumping around 190 cubic yards an hour (145m³/hr) with the .16H pump cell on our 63Z-meter,” says Alan Fleming, co-owner of Fleming. This is providing the contractor with the high outputs required, as it just shy of the pump cell’s maximum 210 cubic yards an hour (160m³/hr) output.
“Our minimum pour is 22,000 square feet (2,044m²) using about 900 cubic yards (688 m³) of concrete, so we need high volume pumps to place the concrete quickly,” says Vasquez. “It ultimately saves us a tremendous amount of man hours.”
“Fleming and their boom pumps are doing an absolutely outstanding job,” adds Vasquez. “Plus, we haven’t had a single problem with Putzmeister equipment, so we don’t need to request a backup pump.”
Totally Fast, Totally Efficient
To meet a fast-paced project completion, over 65,000 total cubic yards (50,000m³) of concrete will be pumped and about 4,000 total cubic yards (3,058m³) of shotcrete placed while utilizing the advanced technology of today’s pumping equipment to handle the job at high speed.