By Mark Crawford
The advantages of precast concrete in today’s construction environment are seemingly endless. Because it is manufactured in a controlled environment, precast concrete has superior quality, strength, durability and consistency. Being able to cast multiple components from the same mold saves time and money. Precast provides more creative finishes that add to the aesthetics of a project. It also requires less labor to manufacture and install, keeping construction costs down. In fact, precast can speed up project completion time by weeks or months, allowing a site to be up and running faster.
Two recent corporate projects – a Volkswagen dealership in London, England, and an IKEA store in St. Louis, Mo. – made use of precast components to vastly improve operational efficiencies and the overall quality of the structures.
Massive RCP for IKEA
St. Louis, Mo.-based Fred Weber Reinforced Concrete Products (formerly BeCo Concrete Products) recently delivered a nearly 300-piece Class III reinforced concrete pipe package for a new 380,000-square-foot, multi-story IKEA store in St. Louis’s Cortex Innovation District. The project, completed in summer 2014, consisted of 1,080 feet of 144-inch-diameter combined sewer sections and 1,192 feet of 66-inch-diameter storm sewer sections. The massive, 144-inch RCP is the largest-diameter pipe Fred Weber has ever manufactured.
“As president of the company, my role was to talk to the bidding contractors pre-bid to get a good handle on the specifications for the material being supplied so that I could competitively quote exactly what was needed,” said Joe Barlow, president of Fred Weber. “I also wanted to get a feel for the contractor’s expectations concerning the project schedule for both manufacturing and shipping, as the size and weight of this 144-inch RCP would dictate a lot how we would approach the work.”
The project required some expertise and construction savvy – not just to deal with the size of the project and tight timeline, but to fabricate the 16 bend sections required to get from Point A to Point B. Barlow said the connected pieces possessed a snake-like appearance.
To expedite the production of the bends, Fred Weber engineers implemented a non-traditional method of fabrication. The standard approach of laying the product down and fabricating one side, then waiting for it to cure before rolling the product over and completing the opposite side, would be time consuming and complicated by transportation challenges. Instead, they opted to fabricate the bend in the standing position, from the top, just below the lifting pins.
“With the pipe in this position, we were able to complete the fabrication process in a time span that was two days shorter and safer than our traditional method, because we were able to work around the full diameter of the pipe,” Barlow said.
Engineers also manufactured three lifting points in the 144-inch RCP to make handling easier. The pipe was hauled standing up because of the size.
From both the manufacturing and shipping perspectives, the most challenging part of the project was the aggressive schedule. Other than a few bumps in the beginning, the project went according to plan and was delivered on time.
“All our personnel on the job, from the operations manager to the clean-up crew, performed flawlessly, making the project a great success,” Barlow said.
In West London, contractors quickly erected a new structural frame for a Volkswagen dealership in 2014. The 165,500-square-foot sales and service center is four stories tall and includes a large repair workshop, three-story showroom and a 78,110-square-foot parking garage. Longcross Construction, the project’s general contractor, worked closely with specialist contractor PCE Ltd., the company responsible for the design and construction of the facility.
With the exception of the steel deltabeams – which enable the slim-floor construction that supports the hollowcore flooring in the car showroom areas – and some limited cast-in-place concrete, everything was precast. Precast components consist of columns, wall panels, beams, lift and stair boxes, stair flights and flooring units for the multi-story parking garage.
Precast modular boxes form the frame of the car park area, which helped reduce construction time and improve job safety. A special modular box system was designed for the three precast cores, moving away from the conventional flat-pack system and speeding up the construction process. It also includes a precast column and beam frame using the PCE contiframe concept, in which the column and beam connection are made at the position of zero-bending moment.
PCE’s “GT” flooring consists of reinforced 16-inch-thick prestressed concrete units that can be cast up to 7.7 feet wide and more than 50 feet in length, incorporating solid, lightweight void formers that reduce the overall weight. By minimizing structural depth, the GT flooring solution “does not require any on-site structural topping compared to the other long-span precast concrete systems used in the U.K.,” said Nickie Brown, managing director of PCE Ltd. “This results in a structural weight saving of approximately 3.85 tons per car parking space.”
Brown also noted that carefully controlled factory conditions assured high-quality surfaces for all of the pieces involved.
Overall, the project includes about 1,500 precast concrete components, some weighing almost 20 tons. They were manufactured at six different off-site precast concrete facilities.
“Our choice of precast hybrid construction, combined with just-in-time delivery methods, enabled an overall frame erection time of 18 weeks, saving 14 weeks against a conventional in-situ structure,” Brown said. “Precast also provided high-class factory formed finishes, required fewer construction workers and reduced vehicle deliveries, creating less on-site congestion.
“The use of precast provided the customer with an engineered solution that met its cost constraints with a dramatically shorter erection time scale.”
For corporate projects, owners require a building material that can save construction time on site while remaining durable and pleasing to the eye. Precast concrete products accomplish all of this and more, enabling owners to quickly and efficiently complete projects of any size or scope for any company or business.
Mark Crawford is a Madison, Wis.-based freelance writer who specializes in science, technology and manufacturing.