The manufacture of cement carries a significant CO2 burden which is estimated to be more than 6% of all CO2 emissions from human activity. The industry faces major challenges, notably the pressure to reduce the carbon footprint (CO2 contribution) of cement-based products. The application of new technologies to improve strength and durability of finished concrete products offers a route to improve the efficiency of cement usage and promote lighter, stronger concrete structures that will help reduce the CO2 footprint of the industry.
In a new paper published in RSC Advances, researchers at the University of Adelaide have validated the mechanism of compressive strength enhancement in concrete materials through the addition of high performing PureGRAPH® concrete additives supplied by First Graphene Ltd. In earlier studies, this group demonstrated that compressive strength is increased by 34.3% and tensile strength by 26.9% with the addition of PureGRAPH® graphenes at dopant levels of 0.02%w/w in mortars and 0.01%w/w in concrete.
In the new publication the researchers, confirmed the statistical significance of earlier studies and further investigated the mechanism for increased strength in cement mortars. Extensive analysis showed the reinforcing mechanism of the graphene additive is based upon denser interfacial zones between the cementitious gel and aggregate particles, leading to more effective stress distribution and inhibition of crack propagation. Pristine graphene platelets with a high aspect ratio and average (volume) lateral size of 56 microns, gave the best performance. These materials are uniquely manufactured by electrochemical exfoliation at First Graphene Ltd. and supplied as PureGRAPH® concrete additives.
The PureGRAPH® additives were introduced to the cement mortar as an aqueous dispersion within a plasticiser solution which is a widely used in the construction industry. All testing was carried out using international standard test methods.
This research confirms the ability of high-quality pristine platelets to increase both the compressive and tensile strength of cementitious composites and concretes. The mechanism of strengthening has been fully validated in the laboratory.
The researchers conclude “The results of this study have not only provided a better understanding of incorporating pristine graphene platelets (PRG) into cementitious composites, but they have also shown the great potential for low-cost industrially produced PRG materials for improving the performance of cement-based construction materials.”
Carbon reduction programmes are driving the use of cement alternatives, recycled concretes and the development of lighter/thinner concrete structures and components. High-performing graphene additives could be the solution, be it thinner and lighter concrete materials with similar performance as existing materials or enhanced performance of lower carbon and recycled concretes.
The paper is published in the RSC Advances Journal Issue 70, 2020, 10, 42777, and is currently available online at: http://rsc.li/34l0Mzv
To find out more about PureGRAPH® concrete additives please refer to our technical article.