UCLA Researchers Refine Use of Graphene Oxide for Stronger, More Durable Concrete
A new UCLA-led study reveals how graphene oxide, a carbon-based nanomaterial, can be incorporated into cementitious mixtures to produce higher-performance concrete. The researchers found that effectiveness depends more on how evenly graphene oxide is distributed rather than how much is added. The findings point to practical pathways for producing durable concrete while using less cement, potentially reducing carbon dioxide emissions associated with cement manufacturing.
Published in ACS Applied Engineering Materials, a journal of the American Chemical Society, the study shows that ultrasonic treatment improves graphene oxide dispersion and enables early strength gains at lower dosages. Carefully controlled use of polymer surfactants, long-chain molecules that regulate particle interactions, enhances long-term strength by refining pore structures and limiting microcracks.
Concrete is the world’s most widely used building material. Cement, the binding ingredient in concrete, accounts for about 8% of global carbon dioxide emissions. Enhancing the efficiency of cement use is therefore essential, as it would reduce the amount needed to build infrastructure — including buildings, roads and bridges — and help lower overall emissions. Graphene-enhanced concrete could last longer and require fewer repairs because stronger concrete cracks less easily and better resists water intrusion and corrosion, which in turn can increase its service life.
Researchers have known for more than a decade that adding graphene oxide to cementitious mixtures can increase concrete’s mechanical performance. However, earlier approaches produced inconsistent results, limiting suitability for commercial use.
To address this challenge, the UCLA team first dispersed graphene oxide powder in water and used ultrasound — the same type of technology found in inexpensive jewelry cleaners — to break up clumps and create a uniform mixture. They then added a moderate amount of polycarboxylate ether, or PCE, a common polymer additive that improves the mixture’s fluidity without adding extra water. This optimized sequence controls the exposed surface area of graphene oxide, thereby delivering strength gains at very low dosages, as little as 0.01% by mass of cement.
Graphene oxide is a nanomaterial derived from graphite and composed of carbon sheets one atom thick. In laboratory tests, adding graphene oxide to cementitious formulations using the optimized process improved the compressive strength by up to 25% after 28 days. The porosity was also significantly reduced by up to 50% as graphene oxide bridged microcracks, resulting in a denser structure.
“This study provides a comprehensive mechanistic framework to combine ultrasound processing, particle dispersants and small additions of graphene oxide to improve the performance of concrete,” said study co-corresponding author Gaurav Sant, a professor of civil and environmental engineering and the Pritzker Professor of Sustainability at the UCLA Samueli School of Engineering. The breakthrough builds on a long-term collaboration between Sant and co-corresponding author Richard Kaner, a distinguished professor of chemistry and biochemistry, through UCLA’s Institute for Carbon Management.
“Our group has spent nearly 20 years refining the synthesis and processing of graphene oxide, and more than a decade working with industry partners to scale production with consistently high quality,” said Maher El-Kady, a researcher working with Kaner. “It’s exciting to see that long-term effort culminate in a study with such clear societal relevance.”
Read the original article on University of California, Los Angeles (UCLA).