The Ultimate Guide to Choosing GFRC Wall Panels

Traditional concrete, known for its heft and solidity, has been a cornerstone of construction for centuries. Its substantial nature imparts a sense of permanence and luxury, making it a favored choice for statement pieces in landscape design.

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Composition of Traditional Concrete:

Traditional concrete is a composite material composed primarily of aggregates (like sand and gravel), Portland cement, and water. The proportions and types of aggregates can vary to achieve different textures and strengths.

Advantages of Traditional Concrete in Outdoor Furniture and Fire Pits:

• Durability: It’s highly resilient and can withstand harsh outdoor conditions, making it ideal for permanent outdoor furniture and fire pits.

• Weight: Its substantial weight makes it suitable for stable installations where movement is not desired, like in public spaces or windy environments.

• Low Maintenance: Requires minimal care, retaining its quality over time with basic cleaning.

• Timeless Appeal: Offers a classic aesthetic that ages well and fits into various design styles.

• Luxurious Feel: Its substantial weight and feel convey a sense of luxury and grandeur, perfect for high-end design projects.

Disadvantages of Traditional Concrete in Outdoor Furniture and Fire Pits:

• Weight: While the heaviness can be an advantage, it also makes transportation and rearrangement of furniture challenging.

• Cracking: Can develop cracks over time, especially in fluctuating temperatures.

• Limited Design Flexibility: Heavier and less versatile for intricate designs compared to lighter materials.

As you shop for outdoor products you may find some made from “cast stone.” Cast stone is a product more akin to traditional concrete but with a high level of refinement and control over its aesthetic qualities. It's typically made from fine and coarse aggregates, cement, and a mix of natural sands, and it may also contain color pigments. One of the defining characteristics of cast stone is its texture and appearance, which can be fine-grained and smooth, achieved often through acid etching.

Here are some of our favorite traditional concrete and cast stone outdoor items from Boxhill:

We’ve compiled a list of common terms used to describe different types of concrete products. These are general definitions and the specific composition and application may varry from maker to maker.

Air-Entrained Concrete: Concrete that contains tiny air bubbles intentionally introduced during mixing. These air pockets increase the freeze-thaw durability of the concrete, making it suitable for colder climates.

Cast Stone: A highly refined architectural precast concrete used to simulate natural cut stone. It's made from a mix of white and/or grey cements, natural or manufactured sands, and crushed stone. Cast stone is used for aesthetic applications where a stone-like appearance is desired.

Fiber Reinforced Concrete: A concrete mix containing fibrous materials to improve structural integrity and reduce cracking. Fibers can be synthetic, natural, or glass fibers. This type of concrete enhances overall energy absorption and durability.

Fiberglass Reinforced Concrete: Similar to GFRC, it involves the use of glass fibers for reinforcement. It's typically used for creating more intricate and aesthetic designs in concrete products.

GFRC (Glass Fiber Reinforced Concrete): A type of fiber-reinforced concrete that uses glass fibers for reinforcement. It is known for its lightweight, strength, and design versatility. GFRC is commonly used in architectural applications, including outdoor furniture and decorative panels.

GFRC Waterproof: This refers to GFRC products that are treated or manufactured in a way to make them resistant to water penetration. This feature is essential for outdoor items to ensure longevity and durability against weather elements.

High-Performance Concrete: This concrete type is characterized by properties such as high durability, increased strength, and resistance to harsh environmental conditions. It's commonly used in specialized projects like nuclear power plants and offshore structures.

High-Strength Concrete: A type of concrete with a compressive strength higher than standard concrete, often exceeding 40 MPa. It's used in structures that demand high load-bearing capacity, such as skyscrapers and bridges.

Lightweight Concrete: Concrete that uses lightweight aggregates such as expanded clay, shale, or slate, resulting in a lower density compared to traditional concrete. It's often used in applications where reducing the weight of the structure is important, like rooftop gardens or balconies.

Precast Concrete: Concrete that is cast and cured in a controlled environment, usually at a manufacturing plant, and then transported to the construction site. This method ensures higher quality control and faster construction time. Precast concrete is used for various applications, including wall panels, beams, and staircases.

Self-Consolidating Concrete (SCC): A highly flowable type of concrete that spreads and settles into place without the need for mechanical vibration. It's used in complex forms or where reinforcing bars make traditional concrete placement difficult.

Shotcrete: A method of applying concrete projected at high velocity onto a surface. It's often used for curved or thin structures and in applications where conventional molds are not feasible.

Stamped Concrete: A decorative concrete type where freshly poured concrete is stamped with patterns or textures before it sets, often resembling natural materials like stone, brick, or wood. It's popular for patios, driveways, and walkways.

Traditional Concrete: A composite material composed of aggregates (like sand and gravel), Portland cement, and water. It's known for its heaviness, solidity, and wide range of applications in construction, including outdoor furniture and structures.

Waterproof Concrete: Concrete that has been treated or formulated to prevent water penetration. This is crucial for structures exposed to moist environments or where water resistance is a key requirement.

What is GFRC?

GFRC, or Glass Fiber Reinforced Concrete, is a versatile, high-performance concrete mix that incorporates alkali-resistant glass fibers to produce a material with exceptional strength and reduced weight. Widely used in architectural applications such as building cladding, GFRC concrete is an ideal choice for countertops, wall panels, and custom concrete surfaces.

By combining concrete with glass fibers, GFRC offers unique benefits over traditional concrete, from added durability to design flexibility.

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Why Choose GFRC Concrete?

Here are some standout benefits of the preferred choice for projects requiring lightweight yet robust materials:

• Design Flexibility

  GFRC concrete can be molded into a variety of shapes, textures, and finishes, allowing designers and fabricators to create unique surfaces that align with aesthetic goals without sacrificing durability.

• Lightweight Composition

  Compared to traditional concrete, GFRC is up to 75% lighter. This makes GFRC concrete ideal for large, intricate designs where weight is a concern, such as countertops, sculptures, and architectural panels.

• Durability in Diverse Environments

  GFRC withstands environmental stress, including moisture, temperature changes, and UV exposure, making it an ideal option for indoor and outdoor applications alike.

• Enhanced Flexural and Tensile Strength

  The glass fibers embedded in GFRC create a durable matrix that provides superior flexural and tensile strength, reducing the likelihood of cracks and breakage over time.

What types of projects is GFRC suited for?

GFRC was developed for architectural concrete and manufacturing architectural products such as: wall panels, window surrounds, column covers, soffits, cornices, brackets, quoins, railings, pilasters, copings, domes, site furnishings, planters, bollards, urns and tables. In recent decades, it has become the material of choice for creative concrete applications such as countertops, furniture, sinks, fire pits, fireplace surrounds, decorative wall panels and more.

Just like regular concrete, GFRC can accommodate a variety of artistic embellishments including acid staining, dying, integral pigmentation, decorative aggregates, veining and more. It can also be etched, polished, sandblasted and stenciled. If you can imagine it, you can do it, making GFRC a great option for creating concrete countertops and especially three-dimensional concrete elements.

Here are just a few of the amazing applications of GFRC in the realm of creative concrete:



Key Components of GFRC: What’s in the Mix?

Understanding the ingredients in GFRC is essential for creating a high-quality final product. A typical GFRC mix includes the following components:

• High-Quality Cement and Fine Sand

  A well-balanced mix includes Portland cement and fine sand, often at a 1:1 ratio, to ensure a smooth texture. Fine sand (#50-#30 sieve) is ideal for consistency and surface finish. Click here for more information about the best sand for GFRC.

• Acrylic Polymer

  Add polymers to enhance flexibility and reduce shrinkage. Acrylic polymers are especially beneficial as they offer UV stability, resist yellowing, and provide excellent bonding properties. Click here for more information about polymer.

• AR Glass Fibers

  Use alkali-resistant glass fibers to reinforce the concrete matrix, making it stronger and more resilient to cracking and environmental wear. These fibers are crucial for maintaining the structural integrity of GFRC. Click here for more information about AR glass fibers.

• Water and Superplasticizers

  As with all concrete, measure water precisely, maintaining a low w/c ratio of 0.30 to 0.35. Use superplasticizers to improve flowability without compromising strength, helping create thin sections and complex shapes with ease. The workability of the GFRC mix can be adjusted with the addition of water reducers. These agents help modify the consistency of the mix, making it suitable for various applications without sacrificing its integrity. By incorporating water reducers, you can achieve the desired workability while maintaining the essential properties of the mix. Click here for more information about superplasticizers in concrete countertop mixes.

• Other Admixtures

  You may include pozzolans (such as silica fume, metakaolin or VCAS) as cement replacements. Click here for more information about the use of pozzolans in concrete countertop mix design.

Calculating the actual GFRC mix proportions can be complex, involving intricate mathematical calculations. If you would like more detail about these calculations, please see this article. See also this powerful and versatile GFRC mix calculator that does all of the calculations for you.

If you just want to get a mix that is already proportioned, you can purchase kits that include the mix, the fibers, and the superplasticizer you will need:

• PowerBlend Kits: PowerBlend is an all in one white, ultra high performance concrete countertop mix – Just add water and fibers!
• PowerPack Kits: PowerPack is the admix-only version of PowerBlend – Use your own sand and cement and save on shipping.

You can use these GFRC concrete countertop mix recipes with the Kits.

How GFRC Concrete is Made

The production process involves unique premix or spray techniques to ensure even distribution of glass fibers, resulting in a high-quality, uniform finish.

• Spray-Up Method

  Spray-Up GFRC is applied similarly to shotcrete, with the concrete mixture sprayed into the forms. The process uses a specialized spray gun with a fiber chopper to apply the fluid concrete mixture and to cut and spray long glass fibers from a continuous spool at the same time. Spray-up creates very strong GFRC due to the high fiber load, long fiber length and correct fiber orientation. However, the equipment can be very expensive ($20,000 or more).

• Premix (“Direct Cast”) Method

  In this method, glass fibers are mixed directly with the concrete. The fluid concrete mixture is then poured or sprayed into molds. This approach works well for smaller projects or pieces requiring thick layers of GFRC concrete. Premix is weaker than Spray-Up because the the fibers are shorter and placed more randomly throughout the mix.

• Hybrid Method
  

  A hybrid method for creating GFRC involves using a hopper gun to spray a thin, fiber-free face coat (mist coat) into the mold, followed by a hand-packed or poured backer mix with fibers.

  This is an affordable way to get started, because the required hopper gun is inexpensive. However, it is critical to carefully create both the face mix and backer mix to ensure similar consistency and makeup. You must also know when to apply the backer coat so that it adheres properly to the thin mist coat but doesn’t tear it. Click here for a video about how to tell when the mist coat is ready for backer.

Most concrete countertop makers today use either a hybrid method or a premix method, which they often refer to as “direct cast”. The biggest risk with the direct casting method for GFRC is that fibers show in the finished surface of the countertop or element. This is mitigated by using specialized AR glass fibers specifically designed for concrete countertops, not for building panels.

Curing

The high polymer content of GFRC means that long term moist curing is unnecessary. Cover a freshly cast piece with plastic overnight. This could be shorter if it has gained enough strength to be uncovered and processed. Many pieces are stripped 16 to 24 hours after casting.

Processing

Your skill level, the composition of your mix and the method used will determine how much processing is needed once your GFRC countertop is removed from its molds. Grouting may be needed to fill in bug holes or surface imperfections. Any blowback (sand and concrete that doesn’t stick to the forms) needs to be cleaned or the concrete’s surface will be open and granular. Achieving a perfect piece right out of the mold requires skill and practice.

Common Questions about GFRC

• How thick is a typical GFRC concrete countertop?-For concrete countertops, this mix is typically made at 0.75” – 1” thick. However, when casting objects like tiles, the mix is often cast at ½” thick. This thinner casting requires careful consideration in the handling and support of the piece to prevent damage.By understanding these thickness variations, you can choose the right GFRC application for your project needs, ensuring both durability and aesthetic appeal.
• How does GFRC compare to traditional precast concrete countertops?– See this article for details.
• Is GFRC Green?– GFRC is roughly on par with other forms of concrete countertops in terms of the “green-ness”. In comparing 1.5” thick concrete countertops to ¾” GFRC countertops, the same amount of cement is used. This is because GFRC tends to use about twice as much cement as ordinary concrete. The use of polymers does make GFRC less green than using ordinary water, which could be recycled from shop use. Both traditional cast and GFRC can use recycled aggregates. Steel reinforcing is more green than AR glass fibers, since steel is the most recycled material. Therefore steel’s use in concrete of any form boosts the concrete’s green-ness.

Interesting Facts about GFRC

• GFRC was first created in the s in Russia. It wasn’t until the ’s that the current form came into widespread use for building façades.
• GFRC tends to run about $2.50-$3.00 per square foot for ¾” thick material. The cost increases to about $3.50-$3.75 per square foot for 1” thick material when accounting for the prices of sand, cement, admixtures, fibers and polymer.

More GFRC Training

• Free Training

  View our FREE, 2.5 hour seminar “Step by Step GFRC with Mix Design” by requesting access here.

• Online Video Training

  We also offer 2-hour online video training “Professional GFRC for Concrete Countertops and More”. Watching an actual GFRC countertop being constructed will help you better understand many of the topics covered in this article.

  Check out the 7 minute excerpt below. See what you can learn from Jeff in only 7 minutes – and imagine what you can learn in 2 hours! Click here to learn A LOT more in “Professional GFRC for Concrete Countertops and More”.

  For more GFRC Wall Panelsinformation, please contact us. We will provide professional answers.