Adopting the use of formliners has the potential to transform your business.
By Claude Goguen, P.E., LEED AP
Precast manufacturers often seek methods to diversify their product lines as a means to fuel future growth or to buffer against downturns in specific sectors. Sometimes, a company may choose a new product due to a customer request. In other cases, it can come from identifying a market opportunity.
But diversifying doesn’t always entail manufacturing completely new products. New opportunities might also arise from making your existing products in a different way. One example is adding custom patterns and finishes to your precast concrete structures. This ability could expose your business to a whole new market. There are times precast concrete structures will be out of sight to the public, such as underground utility products, and standard finishes are appropriate. For above-ground applications, however, there are many options to explore.
Concrete can be made into amazing pieces of art. For example, sound walls and retaining walls bordering our highways are now highly visible surfaces that are sometimes used to display community symbols and works of art. Nowadays, manufacturing such structures is increasingly simple through the use of formliner technology. In the past, creating patterned or textured concrete required laborious handcrafting. Materials like wood, stone and steel were used to place a pattern into a concrete surface, but this process offered limited options.
Elastomeric urethane formliners were introduced in Europe in the 1960’s, and soon afterwards, designers began using them to bring their artistic visions to life. The polyurethane formliner came along next, expanding finish options substantially and giving way to more natural and ornate designs. Today, precasters can achieve just about any pattern or texture.
A wide variety of formliners are available to manufacturers. Choosing which you’d like to take advantage of typically comes down to the formliner’s service life or expected number of uses, desired texture and type of finish.
There are two types of formliners: single-use and multi-use. Single-use formliners are often made of styrene plastic and are lightweight and less expensive. However, they may not offer the same degree of relief and texture depth as multi-use formliners. Precasters typically use these liners as gaskets or holders for thin bricks that are embedded into precast wall panels. Liners hold the brick in place, providing consistency in the simulated brick mortar joints.
Plastic foam, which precasters often use for blockouts in structures, can also be used to make single-use formliners. Polystyrene and acrylonitrile butadiene styrene (ABS) formliners provide moderate relief and texture. These liners are typically limited to 10-to-15 uses. Precasters use elastomeric urethane (rubber) formliners to achieve more detailed relief and texture and can be used more than 100 times, depending on the supplier and production practices. They are usually more expensive but can result in the best value when manufacturing products for larger projects that require more pattern and texture definition.
How formliners are made
Transforming concrete into a work of art involves many steps. It all starts with an idea. If a building designer wants the lower portion of the wall panel to boast a pattern that resembles tall grass, conceptual drawings must be created and approved. Sometimes, the formliner manufacturer may also generate a 3D mockup for approval. Once the pattern is confirmed, it is often converted by computer numerical control (CNC) software onto a master mold surface. The master mold surface is carefully checked for accuracy and quality, then sealed if necessary. Liquid resin or rubber is then poured onto the master mold. Once the material has cured, it is removed from the master mold and carefully inspected again before it’s sent to the precast concrete manufacturer.
The key for any project requiring new formliners is to involve the formliner supplier in the process as early as possible. Discussions should take place at the design phase to facilitate collaboration. When the precaster is bidding the job, it’s important to consult with the formliner supplier to ensure every detail and production consideration is discussed.
The supplier will submit a shop drawing for approval after the client chooses the design. The precaster will also need to obtain adhesive material to secure the formliner to the production surface. They will also need to determine the proper form release agent recommended by the formliner supplier. Generally, petroleum-based products are not advisable.
The precaster must also prepare an area to store the formliner. It may be necessary to lay out the formliner to let it “relax” prior to use so it lays appropriately within the form. Depending on the product, this could require considerable space. The precaster must also allot for storage space after use. Most formliners need to be kept out of direct sunlight and away from the elements. Loose formliners can be rolled up and stored; however, stacking formliners for a lengthy period can damage the texture or pattern.
When using formliners, the precaster must follow the recommended form release agent application instructions from the supplier. These instructions should be carefully reviewed with the production crew, especially if using formliners is a new experience to any team members. Use not only the recommended form release, but rebar chairs (if allowed), spacers and anything else that may contact the formliner. After stripping the product from the formliner, check for any defects in the formliner prior to reuse or storage. If there is damage, some formliner types, such as polyurethane, can be repaired. Some of these repairs can be made at the precast plant, but others may require shipping the product back to the manufacturer.
The attainable finish options using formliners is endless and includes everything from intricate textures to deep reliefs. Imagine taking a photo and being able to transfer that image onto concrete using a formliner. Architects in Montreal, Canada, were able to accomplish this feat when they designed the Edison Residence. An image captured by Thomas Edison of Montreal firefighters in 1901 was scanned into a computer, which separated the color tones of the image. Designers created a machining file that was then fed to a CNC machine, which engraved the different grooves and textures on a master model. Finally, workers poured fresh concrete onto the master mold to make the panels. When you stand back and look at the panels, Edison’s image comes alive.1 A similar process was used in Toulouse, France, for the Université de Toulouse Paul Sabatier. The concept of using a precast concrete facade to tell a story through images has spurred further innovations in formliner technology.
There are also products that come in plastic foil printed with an image or graphics that use a concrete activator. This activator causes the concrete to set at different rates, similar to using a surface-applied retarder. This process allows for a thin layer of paste to be partially removed as per the pattern of the activator. The contrast between the removed thin layers and smooth surfaces creates the image or graphic.
Diversify the look of your product
As a precast concrete manufacturer, you already provide a material that is strong, durable, low-maintenance, sustainable and resilient. Adding the ability to incorporate your customer’s creative designs and ideas into your product has the potential to add value to your company and to your clients. Formliner technology has evolved rapidly in recent years, enabling producers to adopt a whole new level of versatility. PI
Claude Goguen, P.E., LEED AP, is NPCA’s director of technical education and outreach.