Graphene Oxide: The game-changer for stronger, smarter concrete

Graphene oxide in concrete has the potential to create ‘smart’ buildings where walls can act as sensors to detect and monitor small cracks. Credit: Jonathan Tran

Engineers are always on the lookout for ways to make stronger and smarter building materials.

Now, a groundbreaking study from RMIT University and the University of Melbourne has shown that adding a little something called graphene oxide to concrete can make a big difference.

This isn’t just about making stronger buildings; it’s about making them smarter, too.

Graphene oxide is a nanomaterial you might find in batteries or electronic gadgets.

When mixed into concrete, it does some pretty amazing things.

The study, titled “Exploration of using graphene oxide for strength enhancement of 3D-printed cementitious mortar” and published in Additive Manufacturing Letters, is the first to explore how graphene oxide can improve 3D-printed concrete.

Let’s break down what this means. First, graphene oxide makes concrete stronger – up to 10% stronger. That’s a significant boost, especially for structures like bridges or buildings.

But perhaps even more exciting is that it makes concrete electrically conductive. This could turn walls into giant sensors that can detect tiny cracks, changes in temperature, and other environmental shifts.

Today, finding small cracks in concrete structures is a tough job. Engineers use methods like ultrasonic or acoustic sensors, but these can be bulky and not always practical for huge structures. Enter graphene oxide.

By creating an electrical circuit in the concrete, it opens up new possibilities for monitoring buildings more efficiently.

Associate Professor Jonathan Tran from RMIT, who supervised the research, is excited about this. He explains that while we’re good at detecting big cracks in concrete, it’s the small ones that often go unnoticed until they become big problems.

Graphene oxide could change that.

But why 3D-printed concrete? Well, traditional concrete structures are made using formwork – building a mold and pouring concrete into it.

This process is time-consuming, labor-intensive, and creates waste. 3D-printed concrete, on the other hand, is quicker, cheaper, and can even reuse some construction waste. Plus, it allows for more complex designs.

However, 3D printing concrete isn’t without its challenges. One issue is that it can lead to weaker bonds between each layer of concrete.

Graphene oxide helps here, too. It makes the concrete easier to extrude, leading to better bonding between layers and, ultimately, a stronger structure.

Professor Tran explains that graphene oxide has “sticky spots” on its surface made up of various oxygen-containing groups. These spots help it bond strongly with the cement, improving the overall strength of the concrete.

Lead researcher and RMIT Ph.D. candidate Junli Liu’s experiments found that the amount of graphene oxide added to the concrete needs to be just right.

They tried two different amounts and discovered that a smaller dose (0.015% of the weight of the cement) made the concrete stronger than a larger one (0.03% of the weight of the cement).

Adding too much graphene oxide can upset the delicate balance of the concrete mix. It can affect the hydration process, which is essential for concrete strength. It can also make the concrete flow less smoothly, creating gaps and weak spots.

The next step for this research is to explore the electrical conductivity of this graphene oxide-enhanced concrete.

The team wants to see if it can really work as a smart material. If successful, this could mean a future where buildings not only stand strong but also keep a watchful eye on their own health.