In the US, approximately one in every five miles of highway and major road is in poor condition. It’s a problem that’s even worse in colder states where moisture and, most of all, salt accelerate the deterioration of pavement and asphalt. A team of researchers from Washington State University believes nanomaterials like graphene oxide could help harden concrete infrastructure against the elements.
Many state transportation departments use topical sealers to protect bridges and other concrete structures from melting snow, rain and salt. Those products can help, but as is often the case with moisture, it’s a losing battle. What the WSU team found was that they could add nanomaterials – specifically graphene oxide and montmorillonite nanoclay – to a commercial siliconate-based sealer to make the microstructure of concrete denser, thereby making it more difficult for water to make its way into the material. The sealer also helped protect their samples from the physical and chemical abuse inflicted by deicing salts.
Comparing their sealer to a commercial one, they found it was 75 percent better at repelling water and 44 percent better at reducing salt damage. They also made it from water, instead of an organic solvent. That means the final product is safer to use and less harmful to the environment. Normally, water-based sealants don’t perform as well as their organic counterparts, but the nanomaterials the WSU team used helped level the performance gap.
“Concrete, even though it seems like solid rock, is basically a sponge when you look at it under a microscope,” said Professor Xianming Shi, the lead researcher on the project. “It’s a highly porous, non-homogenous composite material.” According to Shi, if you can keep the material dry, most of its durability issues go away.
Compared to most research projects involving the use of nanomaterials, this one looks like it has a chance to make it out of the lab. Sometime in the next two years, Professor Shi’s team plans to work with either the university or the city of Pullman to test the sealant in the real world.
