Composite materials speed up the production of concrete exterior walls | Composite Materials World

Located on the 11-acre Domino Park campus in Brooklyn, New York, the 45-story One First First building has a geometrically complex concrete façade, partly made of composite molds manufactured using large-scale additive manufacturing. #discontinuousfiber#Work progress#cuttingtools
One South First Building is part of Domino Park in Brooklyn, New York. Its concrete exterior wall is partly made of composite molds produced using large additive manufacturing machines. Source | Max Touhey
Every multi-storey building built today needs a facade. Derived from the word “façade” in French, which in turn is derived from the Italian “facciata”, which means “face”. In short, the façade is an external, public-facing structure that gives the building its characteristics, color and shape. For the architect, the exterior wall largely sets the tone for the rest of the building and fully illustrates the designer’s architectural intent.
The exterior walls are also functional. It provides a structure around doors and windows, which protects the building from weather and shocks, and affects the energy efficiency of the building. A variety of materials can be used to construct the exterior wall, including composite materials, stone, steel, glass or concrete. By virtue of its formability, the concrete in the facade can be used to give the building a high-dimensional and visually striking appearance, especially when the concrete shape changes.
The facade design of a 45-story South First building (far left) in Domino Park mimics the crystallinity of sugar and pays homage to the 138-year-old Domino Sugar Refinery (with chimney). This is the core of the plant. Source | Cooks
Domino Park is an example. This is an 11-acre redevelopment project located on the Williamsburg waterfront in Brooklyn, New York. At the center of Domino Park is the 138-year-old Domino Sugar Refinery, which closed in 2004. It is currently being renovated as an office and retail space. Part of Domino Park includes several new buildings, including the 45-story South First First and the connected 10 Grand. For these buildings, the architect COOKFOX (New York, New York) decided to use concrete facades with multiple surface angles, multiple window frame shapes, and multiple window frame widths to loosely convey the crystallinity of sugar from a distance. Be consistent with the history of the site.
Gate Precast (Jacksonville, Florida, USA) won a contract to build a concrete facade (basically a series of window frames) for the One South First project. The company will follow the typical practice of concrete facades to manufacture the frame in its own factory, then transport the completed frame to the work site, and then hoist it in place by crane. If Gate decides to follow tradition, it will build wooden molds to shape all concrete frames. However, Gate decided not to follow tradition.
“If the (composite) molds are handled properly, we think they can be used hundreds of times.”
To understand, please go back to 2017, when Gate worked with the Precast/Prestressed Concrete Institute (PCI, Illinois, USA) and Oak Ridge National Laboratory (ORNL, Oak Ridge, Tennessee, USA) to conduct a preliminary evaluation of the use of large scale augmentation Material manufacturing to manufacture composite molds for precast concrete molding in the factory. The evaluation was conducted using ORNL’s BAAM (Large Area Additive Manufacturing) machine. BAAM was jointly developed by ORNL and Cincinnati (Harrison, Ohio, USA), a large additive manufacturing machine with a construction area of ​​25 square meters. Gate is committed to manufacturing composite molds for the facade of One South First. The project requires a total of 80 molds, 37 of which will be printed. The remaining 43 will be made of wood. When this decision was made, the timetable for mold delivery was already tight.
After an AES composite mold is made in a BAAM machine, it is processed by CNC. The material provided by SABIC is ABS with 20% chopped carbon fiber reinforcement. Source | AES
In 2016, Additive Engineering Solutions (AES, Akron, Ohio) purchased the first BAAM machine from Cincinnati Inc.. Therefore, ORNL and Gate Precast sought the help of AES. AES vice president and co-founder Andrew Bader (Andrew Bader) said that his company and ORNL split the work package, and AES produced 18 of the 37 molds. Bader said that each window frame mold measures about 5-6 feet wide, 9-10 feet high, 16 inches deep, and weighs about 500 pounds.
Bader said the geometric shapes of the molds are relatively simple inside because they are designed to produce frames around rectangular windows. However, as mentioned above, the design of the outer surface of the frame is more complicated, and different depths and angles are integrated in each mold. A printed form replaces a wooden form composed of many nails that are individually cut together. “The geometry is simple, but very complicated,” Bud said. “This project requires several unique frame designs, depending on the location of the frame.”
For part of the production, AES chose LNP THERMOCOMP AM composite, which is a high modulus, low warpage material based on ABS, 20% chopped carbon fiber reinforced material provided by SABIC (Houston, Texas, USA). Bader said that it takes 8-10 hours for the BAAM machine to make each monolithic mold, and then 4-8 hours of machining and finishing in a CNC machine at Quintax (Stowe, Ohio). He reported that the mold had been ground to the required size, but was not sealed.
In the three window frames of Gate Precast in Winchester, Kentucky, two composite molds (background) made by AES are combined with traditional wooden molds (foreground). AES
The molds were shipped to the Winchester, Kentucky, United States factory, where they were used with 43 traditional wooden molds that Gate built for the project. The wooden molds are assembled manually by Gate employees, and then a glass fiber mat and resin coating are applied, and molding oil is sprayed to promote the release of the molded concrete frame. Molding oil is also sprayed on the composite mold to promote demolding.
For concrete pouring, multiple molds are placed on wooden casting tables 40 to 50 feet long. Combine molds together to produce single frame, double frame or triple frame. Place steel bars in each mold and pour concrete around the steel bars. Then the casting table is vibrated to consolidate the concrete. After curing for 14-20 hours, the window frame is demolded, pickled and polished. Then, the windows were installed and the entire package was trucked to the construction site in Brooklyn.
Bader said that AES composite molds work together with traditional wooden molds and quickly showed their advantages. He said that first, the wooden mold can only be poured with 15-20 pieces of concrete before it can be removed from service, refurbished or replaced. In contrast, the AES mold can be upside down 200 times with concrete, with minimal refurbishment or outage. Bader said that these 200 pours represent the end of the project, not the end of the life of the mold. He said: “This is where they stop.” “If our molds are properly taken care of, we think they can be used hundreds of times.”
The finished concrete frame manufactured by Gate Precast is waiting to be transported to the One South First site in Brooklyn. Source | AES
In addition, if the usage amount is 150 pours or more, Gate calculated that to meet the performance of an AES mold, it needs at most 10 wooden molds. Moreover, since it takes 40 man-hours to produce the Getter mold, instead of 37 composite molds, the company will not be able to meet the schedule requirements of the One South First project.
Bader admits that the cost of AES composite molds is four times that of wooden molds, but the durability is at least ten times higher. “The way the prefabricated templates are constructed has remained relatively unchanged for decades,” Bader asserts. “Suddenly one day, we were making a 500-pound 3D form, and everyone was shocked.” That is to say, he admitted that the increase of this kind of mold in concrete forms with complex geometric shapes or high repeatability applications Material manufacturing is the most cost-effective-the same template many times.
Bader reports that AES now owns and operates four BAAM machines that can produce parts up to 8 feet tall. Larger parts can be constructed by connecting multiple parts.
Lift the concrete frame with the windows to install it on the One South First building. Source | Cooks
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Post time: Sep-18-2020
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