“You only need tiny quantities - just a sachet's worth in a seventonne truck”
Meet the pioneers who want to Add the super-strong material to Concrete on an industrial scale. We have heard a lot about graphene in recent years – the one-atom thick, super-strong version of carbon that will revolutionise material science by making everything stronger, lighter and more efficient in every way. Some 200 times stronger than steel, and 1 million times more conductive than copper, it’s truly astonishing stuff.
But applying graphene technology has often proved difficult, and using it to produce a high-performance concrete has been stymied both by cost (until recently up to US$150 per gram), and by the difficulty of distributing graphene evenly through a mix. This could now be changing as a result of advances made by First Graphene, a firm with its origins in the material’s early development by the University of Manchester.
“To get the best from graphene, you first need a high-quality, consistent product,” says Todd McGurgan, First Graphene’s Australia-based commercial manager. “When people have added graphene to concrete before, the results have tended to be disappointing because either the quality wasn’t there, or the graphene was not dispersed properly, leaving ineffective agglomerations.”
To obtain the desired improvements in performance, atom-sized platelets of a graphene additive are used to enhance the calcium silicate hydrate phase of concrete, supercharging the strength of the cement as it begins to set. “To properly disperse the platelets so they work as nano-particles, they are pre-dispersed in a liquid formulation, preventing agglomeration and ensuring an even distribution within the cement hydration phases.”
First Graphene is working with a number of admixture and concrete producers to test the effects of its product in various types of concrete. “So far we have found significant compressive, flexural and tensile strength gains of around 30%, together with reduced permeability. Further testing shows improvements with sulfate and chloride ingress, drying shrinkage, modulus of elasticity and abrasion resistance.”
Of course, existing admixture technology can already achieve many of these desirable effects. But with the addition of graphene as well, a higher performance can be measured: “With the graphene additive, you get the strength with less cement. In addition, it has shown to reduce standard deviation in ‘same sample’ test specimens, often a problem with very-high-strength concrete mixes.”
McGurgan believes it is an exciting time for this technology. “Now we have a reliable product, the plant to produce it at a commercial scale, and costs are significantly down, to below US$350 per kilo. That sounds expensive, but you only need tiny quantities – around 0.05% of the mix, or just a few grams in a batch of concrete.”
He stresses that graphene is not a cement substitute, so much as a powerful admixture for high-performance mixes. “You won’t need graphene for basic concrete – but for the rest, the potential is massive. The benefits can be applied to many types of concrete, shotcrete, mortars, grouts and concrete repair products.”
Graphene is quite definitely a wonder-material. And if First Graphene and McGurgan are calling it right, the long wait to realise its benefits may soon be over.
Interview by Tony Whitehead
Words by Tony Whitehead
Published in CQ Summer 2021