Electrically Conductive Concrete
The invention of heated car seats, blankets, and clothing has added greatly to personal comfort. Now scientists are entering a new public sector with this technology - heated pavement. Last month, researches from Iowa State University's Program for Sustainable Pavement Engineering and Research installed heated test slabs at Des moines International Airport. The results were impressive.
The Product
Halil Ceylan, Professor of Civil, Construction, and Environmental Engineering at Iowa State, is leading this project with his research team. The slabs that they designed are 15 by 13.5ft and made of electrically conductive concrete consisting of 1% carbon fiber and a unique blend of cement, sand, and rocks. Electricity is conducted within the carbon fiber, but it is the slight resistance against the active electrons that results in the creation of heat. Alireza Sassani. a doctoral student working under Ceylon, lead the charge to find the best concrete mixture for this project. Working with the National Concrete Pavement Technology Center, Sassani developed hundreds of samples in the laboratory to determine which would provide the desired amount of durability, workability, compressive and tensile strength, and electrical conductivity. The slabs that they decided to test out are 7.5in thick in dual layers. The lower 4in are typical concrete, and the top 3.5in are the specially designed conductive concrete. Separating the layers are 12 metal electrodes, 6 in each slab, spanning the width of the form. Within the concrete, various sensors run throughout: humidity sensors, strain gauges, temperature probes, etc. The two other extrinsic devices? Surveillance cameras and a thermal camera.
Research & Implications
What Ceylan and his team discovered was fascinating. By using remote controls through a smartphone app, Ceylan was able to turn the heated pavement system on and off. And through the power of live video, he was able to watch the snow and ice melt in response to increased slab temperature. Ceylon observed that the areas around the conductive concrete were pure white, covered in inches of snow, while the slabs themselves were visible; clear of snow and actively drying. "We have proven," said Ceylan, "this technology does work. Our goal is to keep airports open, safe and accessible. We don't want any slips or falls, or any aircraft skidding off runways. Our technologies can contribute to providing a safe environment and fewer delays." In addition to safer airports, and more timely flights, Ceylan and his team also say that this is a more cost-effective solution to clearing heavy amounts of snow and ice. And though it is more expensive to install, it results in an overall cost savings, as these slabs eliminate the need for snow plows, powerful de-icing chemicals, and the wastewater treatment of chemical residue. For now, they will continue to test, observe, and research installation and operating procedures and expenses.
How fascinating is this research? I am incredibly inspired by the ingenuity and innovation that scientists and engineers are exhibiting with projects like this. I have always been a concrete cheerleader, (it's in my genes!), but research like this makes me incredibly excited about the future of concrete and other sustainable building materials. Science works - and researchers and engineers today are thinking seriously about real-life applications, and how we can design new solutions that are safer, cheaper, and cleaner. Engineering is so hot right now.
Sources: Iowa State University Department of Civil, Construction and Environmental Engineering, and ScienceDaily.
