Although we've been hearing about various stronger forms of concrete, one of the keys to making concrete last longer is to keep water from seeping into it in the first place. A new surface sealant could help, as it reportedly makes existing concrete 75 percent more water-repellent.
Concrete may seem like a solid, impermeable material, but its porous structure does allow small amounts of water to trickle inside. In winter climates, when that water subsequently freezes and turns to ice, it creates cracks within the concrete as it expands. The concrete can be further degraded by corrosive road salt that is carried in along with the water.
Surface-sealing chemicals are often applied to concrete in order to keep this from happening, but they typically only work to a limited extent. Seeking a more effective alternative, scientists at Washington State University created a water-based solution that contains nanoparticles of graphene oxide and montmorillonite nanoclay – that solution was added to a commercial potassium-methyl-siliconate-based concrete sealant.
When the enhanced sealant was applied to samples of concrete, it was found to densify their internal microstructure. As a result, they turned out to be 75 percent more water-repellent than control samples which were treated with regular sealant, and 44 percent more resistant to salt damage.
The enhanced sealant also kept water vapor and other potentially destructive gases from passing into the concrete. And as an added bonus, the sealant can be applied to freshly poured concrete to help it cure quickly and thoroughly.
Plans now call for the technology to be tested on roads over the next two years, to see how it stands up to the wear and tear of traffic, inclement weather and other factors.
A paper on the research, which is being led by Prof. Xianming Shi, was recently published in the Journal of Materials in Civil Engineering.
Source: Washington State University
