Find Precasters or Suppliers that provide products, equipment and services to make precast concrete.
By Mason Nichols
Editor’s Note: Earlier this year, NPCA launched its first-ever Reader’s Choice Cover Contest seeking projects to be considered for the feature article in Precast Inc. magazine. Voting was open to all NPCA members, and after a close competition, Shea Concrete Products of Amesbury, Mass., came out as the winner with its floating docks project. The feature article below, written by NPCA staff member Mason Nichols, is followed by short descriptions of the other contest entries.
Stiff winds, brutally cold temperatures and severe storms are a fact of life in the Northeast, which can experience some of the harshest weather in the United States. Along the oceanfront, conditions are often more volatile, where the combination of crashing waves and swirling winds creates an environment seemingly unfit for any building material.
Late in 2012, the coastal town of Lynn, Mass., petitioned Marinetek, a Finland-based manufacturer of harbor products, to replace its aging dock systems located within the town’s seaport marina. An important question for both the town and contractor became, “Which solution will provide the durability and functionality necessary to withstand the elements and get the job done right?”
The answer? Precast concrete.
To accomplish the task, Marinetek partnered with Shea Concrete Products, a precast concrete manufacturer with three locations in Massachusetts. According to Greg Stratis, manager, Shea Concrete Products was able to secure the job thanks in large part to the respect it has earned throughout its more than 60 years in the industry.
“Marinetek was referred to us because they had heard very good things about Shea,” said Stratis. “The job was also close to one of our production plants, so they gave me a call to see if I’d be interested in putting together a number for them.”
Stratis also stressed that Shea takes an interest in unique projects and is not afraid of tackling them, so when the opportunity for this project came along, the company jumped on it.
To manufacture the docks, Marinetek supplied Shea with the forms and engineering necessary to complete the project. Stratis appointed a small, experienced group within his production team to pour the forms, following the strict guidelines and checklists Marinetek designated for the process.
Though the largest piece manufactured was 9 ft wide by 50 ft long and weighed more than 50,000 lbs, only a small percentage of each dock was actually made up of concrete. The remaining portion consisted of large Styrofoam blocks designed to give the docks buoyancy, enabling them to float. Dave DeRose, production manager for Shea Concrete Products, described the production process in detail.
“These things are massive, you know, but the actual thickness of the wall was only 2 to 2.5 in. on the side, and the top was roughly 4 in. thick,” said DeRose. “We were just encasing these enormous blocks of foam inside concrete.”
If even the slightest error had been made during the manufacturing process, the effect on the functionality of the docks would have been devastating. If, for instance, one of the side walls had been poured too thick, the entire dock could have been compromised. Despite the possible issues associated with the project, DeRose echoed Stratis’ sentiments, stating, “We take on a lot of different jobs like this. We like challenges.”
With so little room to work inside of each of the dock’s walls, Shea selected a self-consolidating concrete mix to complete the job. This allowed them the flexibility to achieve the flow necessary to fill the form to Marinetek’s exacting specifications. “What we ended up doing was modifying our SCC mix to not be a straight self-consolidated, but also not be a straight conventional mix,” DeRose said. “It was kind of a hybrid. We got our flow down the walls in order to get the concrete where it needed to go.”
For each dock, the production team began by pouring a cover of concrete directly on top of the Styrofoam block. This resulted in the placement of a generous coating of wet concrete on top of the foam, which was also woven through the dock’s reinforcement system. Once the team felt comfortable with the top coating, it would then begin to fill the side walls by pouring concrete directly on top of the original layer. The modified SCC mix would then flow down the walls and into place, where a 1-in. pencil vibrator would work to ensure that the mix filled the form to its required thickness.
In order to protect the manufactured docks from the elements, galvanized rebar, reinforcement and corrosion inhibitors were used throughout the process. Additionally, the bottom of the Styrofoam blocks – which remain exposed in order to help achieve the buoyancy necessary for flotation – were coated by Marinetek with a special material designed to prevent damage caused by marine organisms.
Even after each dock was poured, the strict nature of the quality control process continued to dictate the path of the project. DeRose explained that the standards required by Marinetek were more difficult to achieve than those associated with standard Shea products. “Where our stuff, we will pick at 2,200 psi, we couldn’t touch Marinetek’s until it reached 80% of its total strength, which was the 6,500 psi they wanted in 28 days,” he said. “We had to be at 5,000 in order to be able to pick these.”
Once the docks were completed, each was placed onto a flatbed trailer for transportation to the Lynn Seaport Marina. After arriving on site, a crane lifted and lowered each dock into the ocean, though for many of the docks, small tugboats were also used to get them to their eventual destinations.
“For this job, we weren’t able to set up a crane in such a spot that it could reach, say, dry land and then also reach its final resting spot,” Stratis said.
Overall, from November 2012 to February 2013, Shea manufactured 42 docks for delivery to the marina in Lynn, including 14 main docks and 28 dock fingers. By May, all of the docks were in place, and Shea had already been petitioned to complete similar projects at other locations in Massachusetts and Connecticut.
While Stratis referenced the durability of precast concrete as critical to the prolonged resilience of the docks, he also noted the benefits of networking in ensuring unique jobs such as these are completed correctly. “Networks like NPCA are great places to contact other precasters if you have questions on how to make specialty products,” he said. “I talked to Jefferson Concrete about this project before we began. You learn through people in the organization that you network with.”
DeRose noted that everyone involved in the process had to be “on their game” in order for the project to be completed successfully. Thanks to a solid group of individuals working on the docks and a dedication to strict QC, the team was able to produce a high-quality product that met the standards specified by Marinetek.
Stratis agreed, stressing his confidence in the team at Shea as critical to completing the project satisfactorily and on schedule. “Some precasters are comfortable with unique projects because they have the right skilled laborers in place,” he said. “I wouldn’t want to tackle a project like this if my employees weren’t educated.”
In completing the dock project for the Lynn Seaport Marina, Shea Concrete Products exhibited the “never back down” mindset Stratis exudes when speaking about his company, a mindset the company shares in common with the very product it manufactures.
No matter what the conditions, precast – like Shea Concrete Products – is up for the task.
OTHER CONTEST ENTRIES (in alphabetical order by company name)
Downtown Portland, Ore., is certainly picturesque, but the addition of 25 precast concrete planters courtesy of Advantage Precast further bolsters the Pacific Northwest city’s aesthetic charm.
Each planter was manufactured using a complex steel form, making the project highly customized and artistic. During the production process, many modifications to the mix design and prototypes were made. In the end, the mix design included imported aggregates with sandblasting and coating to achieve a unique exposed finish. The unusual crenulations of the planter also contributed to each piece’s distinctive appearance.
In downtown Indianapolis, John Wooden, former UCLA men’s basketball coach, strategizes with his players while down on one knee, just as he did during his legendary coaching career. However, unlike in days gone by, the “Wizard of Westwood” kneels not on a basketball court, but instead on a unique precast concrete statue base.
The statue, which was unveiled before the start of the NCAA basketball tournament in 2012, required a base with an exacting steel mold. The base consisted of four unique panels, each with a 4-in. depressed band for lettering, creating 360 degrees of continuously angled lettering matching exactly at all four seams, and so casting them proved to be difficult.
CGM Precast had molds designed using steel, stainless steel rods and bronze rails to attach and hold the lettering while casting the concrete. Though the process presented a challenge, the base was completed and delivered on time, further emphasizing the utility and flexibility of precast concrete.
When a customer called Colorado Precast to request precast concrete dinosaur eggs, the plant was certainly startled. Nevertheless, Colorado Precast excitedly accepted the job, producing a total of 27 eggs. Each egg weighs 2,750 pounds, measuring 6.5 ft by 3.5 ft.
Gould Construction and the Roaring Fork Transportation Authority requested the production of the eggs to promote fossil heritage for a nearby dinosaur park. Upon their completion, they were placed at bus stops along a route from Glenwood Springs to Aspen.
After agreeing to the project, Colorado Precast poured each egg with a minimum of 4-in.-thick walls and a mix that averaged 7,500 psi. At the tail end of the production process, each egg was coated with a polyurea application and hand stained with color to achieve the life-like surface effect desired by the project owners.
Building the new Plymouth North High School in one of the most historic towns in America was no small task, with nearly 300,000 sq ft designated for the school’s main facility and senior center.
MBO Precast was selected to manufacture a variety of precast concrete products for the $65 million project, including underground utilities, parking and on-site services. Additionally, 14 Stone Strong retaining walls were constructed, encompassing approximately 5,000 blocks and totaling more than 50,000 sq ft.
Overall, MBO Precast manufactured more than 500 products used in the construction of the new school.
With more than a century of operation under its belt, the North Highway Bridge – part of the Long Island Railroad system in New York – was in need of repairs. While the superstructure of the bridge was deemed to be in fair to good condition, the substructure, including abutments, wing walls and pedestals, required improvements.
To bring the bridge back up to standards, Roman Stone Construction Co. manufactured and installed two abutment slabs and six additional bridge elements. Because one of the primary goals of the project was to minimize
the effect on commuters, the work needed to be performed quickly. Roman Stone responded by completing all components of its portion of the project within 48 hours.
Thanks to the design and speed advantages of precast concrete, the project was completed successfully in rapid fashion.
Tasked with replicating the architecture of New York City’s 1940s-1950s era Park Avenue for a nine-story apartment building in Edgewater, N.J., Smith-Midland Corp. manufactured precast concrete wall cladding with historical details such as cornices, reveals and bull noses.
Due to the lightweight design of the system used, many project costs were reduced, including those associated with the building foundation, structure, shipping and installation. Additionally, the project featured 1,024 LEED-friendly exterior panels, combining a proprietary precast concrete product with traditional architectural precast totaling nearly 100,000 sq ft.
The proprietary 360 degree concrete-to-stud connection isolated the exterior precast concrete cladding from the structural stresses associated with wind loading, steel frame movement, expansion and contraction, and seismic shock. The result was a residential building both structurally sound and pleasing to the eye.
The products StructureCast supplied for the construction of two buildings on the campus of Diablo Valley College in Pleasant Hill, Calif., speak to the incredible versatility of precast concrete. From wall panels to curbings and beyond, StructureCast supplied more than 700 pieces for the structures, which were designed to house the college’s student services, culinary arts and food services facilities.
Sustainability was a key factor in the selection of precast for the project, with each building being designed to achieve LEED Gold certification from the U.S. Green Building Council. Additional unique aspects of the project included green roofs, building integrated photovoltaics and natural evaporative systems.
Overall, the $50 million project was completed in only 10 days. By using precast, the project owner’s were estimated to have saved $1 million in construction costs.
Mason Nichols is NPCA’s communication coordinator.