Jesmonite, GFRC, UHPC: Essential Guide to Specifying for Innovation and Impact

We're diving deep into the fascinating world of advanced materials, specifically pitted against each other for the discerning eye of a designer. We're talking Jesmonite versus GFRC versus UHPC: a real heavyweight bout in material specification. Despite my allegiances and bias I will try to be fair!

Choosing the right material is about performance, durability, sustainability, and ultimately, bringing a vision to life with integrity. As designers, you have the incredible power to shape our built environment, and the materials you choose are the very language of that creation. This is where the magic happens, and where intelligent material selection becomes paramount. 

Let's break down these contenders, starting with one I hold particularly close to my heart.

Jesmonite: The Chameleon of Composites

First up, our very own Jesmonite. Now, I know I'm biased, but for good reason! Jesmonite is a game changer for creative expression, efficient manufacturing, practicality and sustainable design. Our AC730, for example, is a rapid setting acrylic polymer modified cement based composite. What does that mean for you? It's water based and solvent free making it incredibly user friendly and a breath of fresh air for installers and the environment alike

But beyond its eco-credentials, its technical prowess is where it packs some heavy punches. Jesmonite AC730 boasts a compressive strength of 58 MPa (N/mm²) and an impressive flexural strength, with a Modulus of Rupture (MOR) of 23.6 MPa, capable of much higher with reinforcement. This is the difference to have freedom to design incredible, sweeping curves and intricate details without compromising structural integrity. I get genuinely excited seeing what designers are doing with it, pushing the boundaries of form and function.

What really sets Jesmonite apart is its exceptional manufacturing turnaround and its durability. AC730 can be demoulded within a couple of hours of pouring. This means your production cycles can be multiple times quicker than other comparable products! AC730 is shrinkage compensated and dimensionally stable, meaning your designs will hold their form beautifully over time. It’s also incredibly resistant to moisture, chemicals, and UV light, making it ideal for outdoor applications and even water features. Its freeze-thaw tested withstanding 300 cycles compared to a typical maximum of 56. That’s resilience! Plus, it offers excellent abrasion resistance and impact strength, ensuring longevity in high-traffic areas.

And the finish? Oh, the possibilities are endless! Jesmonite is often called the "chameleon of composites" for a reason. It can perfectly mimic the look and feel of natural materials like stone (yes, with those beautiful aggregates), metal, ceramic, and even wood, leather, or fabric. And with our precise pigmentation system, including custom RAL and Pantone matching, your aesthetic vision is truly unlimited. You can achieve anything from a satin smooth finish to a tactile, acid etched texture that rivals natural stone.

What many don't realise is its lightweight nature. Jesmonite is lighter than traditional concrete, precast stone, and even GFRC, which translates directly into easier handling, faster installation, and reduced structural load on buildings. That's efficiency and cost saving in one fantastic package!

GFRC: The Established Player

Next, let's talk about Glass Fiber Reinforced Concrete, or GFRC. This is a material that has earned its stripes in architectural applications, and for good reason. GFRC is a high-performance concrete mix enhanced with alkali-resistant glass fibers. The inclusion of these fibers significantly increases its flexural and tensile strength compared to traditional concrete, allowing for thinner, lighter sections. Typically, GFRC is up to 75% lighter than conventional concrete.

GFRC is an excellent choice for large architectural panels, cladding, and ornamental features. Its robust nature means it withstands environmental stresses well, including moisture and temperature changes, and the glass fibers prevent the rusting issues sometimes associated with steel-reinforced concrete. It can be moulded into various shapes and textures, offering good design flexibility, and often emulates the look of natural stone or precast concrete.

Its compressive strength generally falls in the range of 35-55 MPa. While admirable, GFRC can sometimes be less consistent in colour, especially when trying to achieve vibrant or specific hues, often leaving a more utilitarian or natural concrete aesthetic compared to the broad palette Jesmonite offers.

(P.S. Theres nothing GFRC can do that Jesmonite can’t do - quicker and better)

UHPC: The Strength Innovator

Finally, we have Ultra-High Performance Concrete, or UHPC. This is the heavy hitter in terms of sheer strength. It’s a bit of an unfair contender and maybe is in a different league to Jesmonite and GRC. This is a structural product, but what the hell, let’s look at it anyway! UHPC is defined by its optimised granular composition, extremely low water-to-cement ratio, and often, a high percentage of discontinuous internal fiber reinforcement, such as steel or PVA fibers. This creates an incredibly dense and compact microstructure.

For architectural applications, UHPC can achieve compressive strengths up to an astounding 117 MPa (17,000 psi) and flexural strengths up to 20 MPa (2,900 psi). For structural applications, these numbers can climb even higher, exceeding 200 MPa. This immense strength allows for incredibly thin and lightweight structural elements, pushing the boundaries of what's possible in design. Its durability is also top-tier, offering exceptional resistance to abrasion, impact, and fire, with very low permeability.

UHPC is revolutionising bridge construction, high-rise buildings, and complex structural designs where maximum strength and minimal material are critical. It can replicate intricate forms with precision, lending itself to innovative architectural features. However, this exceptional performance comes with a higher initial cost and often requires specialized handling and installation due to its unique material properties and viscosity. Its aesthetic typically leans towards a very clean, dense concrete look, which may not offer the same versatile textural or colour opportunities as some other materials.

Specifying the Right Finish: A Designer’s Perspective

So, how do we choose? It truly comes down to the specific demands and aspirations of your project.

For unparalleled structural strength and ultra-thin, load-bearing elements, especially in demanding infrastructure or large-scale structural architecture, UHPC is very difficult to beat. It’s a marvel of engineering, enabling forms previously thought impossible.

For robust, large-format facade panels and non-structural elements where significant weight reduction from traditional concrete is key, GFRC is a well-established and reliable choice, It’s proven and performs admirably in many exterior applications. Jesmonite can do everything GFRC can do but with more choice. 

So for true design freedom, aesthetic versatility, ease of fabrication, and a strong commitment to environmental responsibility, all wrapped up in a high-performance package. This, coupled with the quick manufacturing cycles and high quality of finish is where Jesmonite truly shines.

Let me be clear: Jesmonite isn't trying to be UHPC's structural equal. It competes with GFRC and occupies a unique and incredibly valuable space. 

The construction industry needs to embrace smart, sustainable solutions that don’t compromise on design or performance, and Jesmonite offers a clear pathway toward that future.

What are your thoughts on this material showdown? Have you discovered a new application for Jesmonite, GFRC, or UHPC that has genuinely excited you?

Let’s keep pushing those boundaries together!