Concrete has captured the imagination of designers for thousands of years offering options and flexibility to mold it in different shapes and surface finishes.
GFRC (Glass Fiber Reinforced Concrete), also known as lightweight concrete, is able to extend the range of possibilities that can be realized using concrete. It uses the casting flexibility of traditional concrete to create a wide range of shapes and surface finishes difficult to achieve using traditional production methods. GFRC panels are much lighter and much easier to shape and are typically offered with pre-engineered support systems, making easier to install.
The Glass Fiber Reinforced Concrete (GFRC) panels can match the color and finishes of virtually any kind of stone products including natural lime stone, dry vibrant-tamp cast stone, wet our precast concrete stone, terracotta stone, etc. GFRC can be integrated with brick veneer or other exterior façade applications that include steel and glass as well.
Architectural detailing needs to be a shared responsibility between the architect, the manufacturer and the manufacturers engineer. An attachment design by the manufacturer, rather than the architect, is often appropriate for many GFRC projects. The shop drawings will provide the architect and installer an opportunity to review the attachment and make the final detailing.
General Rules for attachment
GFRC pieces up to about 4 feet x 6 feet can often be produced without an additional structural back-up. The manufacturer will add a stiffener-rib to the product back side for added support. A stiffener usually runs the height of the piece every 24 to 30 inches of the product and has very concentrated glass fiber to cement mix. The product can be attached via a veneer tie and strap, kerf and clip, or similar attachment to the structure of the building.
Larger pieces or pieces where a stiffener-rib is not appropriate are generally hung with a metal stud back-up. The metal stud system is designed and attached to GFRC piece by the manufacturer as part of the cost of the GFRC on the project. Metal stud back-up is very similar to metal stud framing on most commercial projects, but designed with more precision. The metal stud back-up is usually attached with a grade #2 bolt to the structure of the building. There are occasions where the metal stud framing is welded to the structure. Again the specifications on the welding should follow AWS standards.
Very large pieces (larger than 8 feet x 20 feet) will have tube steel back-up. The process is much the same as with metal studs discussed above. This back-up will be engineered by the manufacturer.
AAS is able to provide type of connection that is preferred by customer. GFRC provides flexibility with selection of the connection type.
Once the connections are selected, the AAS manufacturing and design process is able to pre-engineer the connections support in the products.
GFRC is much simpler and less expensive to install compared to other much heavier stone products. GFRC installation doesn’t require extensive support structure and heavy construction equipment at the project site.
AAS GFRC products provide flexibility to select/use right application of caulk or sealants making it easier for masonry contractors not only in their installation process, but also with long term reliability of the installed projects.
What does it take to design and manufacture Architectural GFRC products?
What makes Architecture GFRC ideal for higher elevation applications?
See the manufacturing process and technology used for cornices of the new sorority house building at the Southern Methodist University (SMU) in step-by-step sequence of videos in this blog post. These video clips are captured at the Mesa Precast plant of Advanced Architectural Stone; this plant is located in Tempe, AZ.
Step One: Custom Molds
AAS team used the in house custom mold making technology and craftsmanship to create the required molds of specific shape for each GFRC panel used on this project. For the exterior cornices of the building, these molds are big in size as well. See more on it in their video.
Step Two: Spray Mix for GFRC
The Architectural GFRC (Glass Fiber Reinforced Concrete) products are manufactured by spraying specific mix. AAS has automated batch plant system to create the right mix with precise control over proportions and consistency.
See spray mix getting ready for the manufacturing in this video.
Step Three: Facing Mix
The first step in creating 3/4 ” thick GFRC panel is, applying the face mix. It doesn’t have any fibers in it. It helps create a smooth finish on the outside. In this project, the cornices are going to be acid etched, so the smooth surface is very helpful for creating that finish later on.
See facing mix being applied…
The face mix is brushed to make sure all surfaces are covered, and also there are no air bubbles…
Step Four: Applying Back up Mix
Next step in the manufacturing is applying back up mix that has fibers in it. This is applied over three layers typically with brushing and packing in every step to eliminate bubbles and gaps in the panels.
Material technology to create the right mix is one of core differentiators of the Advanced Architectural Stone.
Watch back up mix being compacted using brush and rollers in this video clip…
Step Five: GFRC Frame for Attaching Cornice to the Building During Installation
The idea with this GFRC cornice is to simplify installation with per-engineered steel installation frame attached to the GFRC skin, so that from outside it looks like a solid concrete piece…
While the frame is being integrated into the GFRC panel structure, edges are also thickened to make the product stronger and structurally more sound.
GFRC Cornice Ready for Surface Finishing and then for the Installation
The the manufactured Cornice piece realized with custom molds, right materials selection, and specific technology and expertise in creating an engineered piece precise in tolerance, ready to install.
While it looks like solid concrete from the outside, this Architectural GFRC cornice is so light in weight when compared to concrete or other cast products such as cast stone or architectural precast. This makes Architectural GFRC ideal for higher elevation applications.