By Mason Nichols
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 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.
Mason Nichols is NPCA’s communication coordinator.