Australian advanced materials technology company Talga Resources has achieved high levels ofelectrical conductivity in concrete by using an additive developed from the company’s graphene-graphite research & development laboratory in the UK. The breakthrough offers substantial potential in existing and emerging industrial applications, particularly as concrete is the world’s largest construction material by volume.
The concrete samples were manufactured at Talga’s German process test facility and the Betotech (Heidelberg Cement Q&C) laboratory in Germany, using industry-standard cement with additions of Talga’s pristine graphene, graphite and silica-rich by-product of ore processing. The optimised formulation targeted high electrical percolation at low material concentrations and with potentially lower cost factors. Graphene is a layer of crystalline carbon a single atom thick, with properties of strength, conductivity and transparency that stem from its unique 2D structure.
The samples were tested in-house by a European industrial partner and further measurements were undertaken by Professor Ian Kinloch’s group at the University of Manchester (UoM) in the UK. In the UoM study, the conductivity of samples was measured using electrical impedance spectroscopy in both through-plane and in-plane directions over a range of frequencies. For reference, a standard mortar (without Talga additives or aggregates) was used.
In summary, the UoM tests recorded that the Talga graphene-enhanced concrete had high electrical conductivity (low resistivity) to 0.05 ohm-cm (Ohm is the measure of a material’s resistance to conduct electricity, the lower the better). This rating compares to a general resistivity level of around 1,000,000 ohm-cm for the reference mortar at a similar dryness (the background level of moisture can affect electrical conductivity, so samples are measured at the same dryness).
The results have also shown the silica-rich by-product of ore processing is remarkably conductive in itself, tough and highly suitable for use in construction materials. Trial concrete products developed by Talga are targeting the innovative use of this material, thereby increasing potential economic benefits and sustainability of the future Swedish operation.
“The initial test results show that Talga’s graphene-enhanced concrete achieves such high electrical conductivity that it can act like the heating element of an electric stove,” says Mark Thompson, Managing Director of Talga. “This type of concrete has some exciting, large-volume applications, and in some cases can combine with our thermally conductive concrete. Furthermore the conductivity is achieved with a very low loading of our graphene, but a larger amount of ore processing by-products, providing maximum potential for the most cost effective, scalable and eco-friendly development options.”
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Applications
As concrete is effectively an insulator (does not conduct electricity) in a dry state, adding the function of high electrical conductivity has been a goal of material scientists for a long time. Attempts typically relied on the addition of high loadings of magnetite (iron), steel fibres, synthetic and natural carbons (including graphite) but did not achieve high levels of performance. In addition the required (high) loadings of active materials tended to cause negative effects on cost, strength, corrosion and abrasion resistance, maintenance costs and weight.
The electrically conductive ‘graphene concrete’ has applications in current markets such as underfloor heating, where it can provide a long-term, low-maintenance alternative to plumbed hot water installations. Other current applications include the provision of anti-static flooring and EMI shielding (radio frequency interference) in buildings, and cost-effective grounding and lightning strike protection for a range of infrastructure from bridges to wind turbines.
Additionally, as a ‘solid state heater’ the technology may enable more rapid, and environmentally friendly ways of clearing ice and snow from key transport routes and airports compared to the cost of ploughs, salt, de-icing chemicals and wastewater treatment of chemical runoff. The replacement of widely used salt; as a material cost, its transport and distribution, and its corrosive effect on road/bridge infrastructure and vehicles would be an emergent but high potential application for heatable concrete.
In future, Talga will investigate the potential of the electrically conductive concrete for a cost-effective role in enabling inductive (wireless) charging technologies for electric vehicles under dynamic (driving) as well as stationary (parking) conditions through the increased range of heating, sensing and other conductive concrete functions.
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Next steps
Talga’s commercialisation strategy is focused on targeted value-added graphene and graphite products covering the energy, coatings, composites and construction sectors. Initial partner work and customer testing is already underway on:
- Lithium-ion batteries and a range of energy storage technologies.
- Metal pre-treatment, marine epoxy and other coatings.
- Cement/concrete additives.
- Epoxy resins for carbon fibre (composites).
These applications and products have been developed over the past two years with global scale industrial and R&D partners, using high-grade graphite ore liberated in successful trial mining from Talga’s wholly-owned deposits in north Sweden.
The global concrete market exceeds 5bn tons per year and is worth over USD$450bn per year. Specialty concretes are a subset of this and while having no formal volume that may be attributed to a new product, Talga considers the market for conductive concrete is significant. The company currently has a Memorandum of Understanding (MoU) with the world’s second-largest concrete manufacturer, Heidelberg Cement, focussed on thermally conductive concrete, but is free to explore other market opportunities. Talga is currently recruiting a European-based commercial team, that will include construction sector and concrete market experience, to use these test results in commercialisation discussions with a range of industrial partners.
“Talga’s successful tests follow work published by Exeter University showing 146% improvement in concrete strength using graphene,” adds Thompson. “They estimated that a 50% reduction of cement used for the same strength concrete would result in a 446kg/ton reduction in carbon emissions by the cement industry, currently the third-largest industrial energy consumer and second-largest industrial carbon dioxide emitter in the world. Talga is encouraged by these first tests and will move to take the prototype results to potential development partners in the world’s largest construction industry material.”