Posted on January 07, 2021
In 2004, graphene was first isolated by researchers at the UK’s University of Manchester. Professors Andre Geim and Kostya Novoselov received a Nobel Prize for their efforts. Pure crystalline graphene is a wonder material a single atom thick. The 2D material is a million times thinner than a human hair. It conducts heat and electricity more efficiently than copper or gold. It is so dense that even the tiniest gas atoms cannot pass through it.
The contrast between concrete and graphene is quite stark. Humanity has fashioned important structures from concrete for thousands of years. Graphene is a 21st-century phenomenon. Production runs are dissimilar as well. Technicians produce concrete in large batches. Graphene production occurs on a much smaller scale. Production methods include chemical vapor deposition, chemical exfoliation and liquid-phase exfoliation. Industrial-scale production of graphene becomes more viable all the time.
Since graphene is 200 times stronger than steel, researchers quickly surmised that it could make concrete far stronger and more resilient. They experiment with different forms of graphene. Graphene nanoplatelets (GNPs) surfactant functionalized graphene (FG) and graphene oxide (GO) are examples. One way to produce graphene concrete is to use a process known as high-shear exfoliation. It allows technicians to infuse mixing water with graphene.
Researchers at the UK’s University of Exeter also came up with a way to suspend graphene flakes in the water. They see a scalable process “compatible with modern, large-scale manufacturing requirements.” Ultimately, significant graphene concrete production requires reliable suppliers capable of large-scale production.
Why Graphene in Concrete?
Graphene is certainly a “new kid on the block.” Still, it demonstrates real potential as a concrete additive. Concrete made with ordinary Portland cement delivers compressive strength at a modest cost. This quality makes it one of the world’s most popular building materials. However, low tensile strength requires reinforcement in many applications.
There are numerous ways to address the challenge of concrete’s brittle nature. Graphene concrete simultaneously improves compressive strength, flexural strength, and split tensile strength. More resilient concrete cracks less, and it better resists stress. More crack-resistant concrete lasts longer, and it requires less maintenance.
In 2019, researchers published the findings of a graphene concrete study. They looked at adding graphene oxide nanosheets to mixing water in concentrations from 0.02 to 0.08 percent. At 28 days, flexural strength across that range increased from 2.7 to 15.6 percent.
The University of Exeter team calculated the compressive strength of their graphene-reinforced formulation. They found that it had 146 percent more compressive strength than standard concrete. Stronger concrete allows for lightweight designs. The added strength allows architectural engineers to do more with less. A lighter weight material often means more dynamic designs and lower carbon emissions.
Researchers observe that “the durability of concrete depends on the capacity of a fluid to penetrate its microstructure.” Graphene concrete is up to four times less permeable than its traditional counterpart. Low permeability decreases the amount of water compromising the surface. Normally, moisture infiltrates through cracks and capillary pores. Graphene-reinforced concrete also minimizes the alkali-silica reaction (ASR). This is the swelling resulting from moisture infiltration. This swelling leads to cracking and other structural issues.
Graphene-reinforced concrete uses much less cement to deliver the desired strength. As a result, it may reduce CO2 emissions by 983 pounds per ton, according to one estimate. It is also possible to source graphene from sustainable sources. For example, Rice University researchers made graphene from garbage.
Graphene Concrete: Potential Uses
The potential uses for graphene concrete are many. They include those that take advantage of its resiliency, conductivity and/or impermeability. Researchers have only begun to contemplate the full range of possibilities.
Deployment in high-stress environments
The brittleness of traditional concrete is an inherent concern in high-stress settings. By contrast, graphene concrete demonstrates flexural strength that makes it a viable alternative. Higher costs are offset to a degree by longer life cycles.
Combat moisture infiltration
Low water permeability makes graphene concrete attractive wherever moisture is a concern. High durability means long lifespans and minimal maintenance. These qualities are of particular interest in places that are difficult to access.
Heating floors and walls
Researchers hope to take advantage of graphene’s conductivity to create walls and floors heated without cables. In 2019, cement producer Italcementi displayed a multi-layer floor mock-up at the 2019 Mobile World Congress in Barcelona, Spain. It included a layer of graphene-cementitious composite along with sub-flooring, polystyrene insulation, a concrete slab, bedding mortar and ceramic tiles.
Thanks to graphene’s conductivity, it is possible to deploy smart sensors across entire surfaces. Imagine the possibilities with real-time monitoring of stress, deformations, temperature and humidity. More proactive repairs could minimize damage and extend lifespans. Smart concrete could usher in a new generation of greener buildings.
Putting conductivity to work
Graphene concrete's heat and electrical conductivity inspire other potential applications. It may help de-ice airport runways. Graphene concrete may also contribute to the infrastructure required for high-speed rail. It may lead to more cost-effective wireless charging of electric vehicles. Protection from lightning strikes is another possibility. Anti-static flooring and electromagnetic interference (EMI) shielding are other possibilities.
The Pennsylvania Aggregates and Concrete Association (PACA) watches for developments impacting the concrete industry. PACA reports on research that makes concrete a more versatile and sustainable building material. For more information about innovative concrete formulations, please contact us.