Panel/mortar combo could boost the strength of concrete structures
Although we've recently been hearing about technologies that allow for the production of stronger concrete, existing structures made of regular concrete could also use some help. That's where new strengthening panels combined with a new mortar are designed to come in.
Already, concrete structures such as bridges and buildings are often reinforced with carbon fiber panels that are applied to their surface. Those panels are typically stuck on utilizing organic adhesives which unfortunately don't stand up to fire, and may fail when exposed to moisture.
Scientists from the Korea Institute of Civil Engineering and Building Technology recently developed an alternative, in the form of what are known as textile reinforced mortar (TRM) panels.
At the heart of each panel is a 20-mm (0.8-in)-thick sheet made up of a grid of interwoven carbon textile strips. These are attached to the underlying concrete structure via a specially designed cement mortar. Both the sheets and the mortar are non-combustible, and are impervious to water. In fact, the panels can actually be applied to wet concrete.
In lab tests, application of the TRM panels to concrete slabs increased the failure load of those slabs by at least 1.5 times as compared to unstrengthened concrete. A separate durability test suggested that the panels should last for over 100 years, even when exposed to chloride salts such as those used to de-ice roads.
Additionally, not only is the mortar comprised of 50-percent ground granulated blast furnace slag – which would likely otherwise end up going to waste – but it's also claimed to be half as expensive as traditional mortar. As a result, the TRM panels should reportedly be about 40 percent cheaper to use than existing carbon fiber panels and their organic adhesives.
What's more, once developed further, the TRM panels could conceivably double as a form of thermal insulation for buildings, reducing the need for internal insulation.
"For easier production and shipping, the TRM panels are manufactured in a relatively small size of 1 m by 2 m [3.3 by 6.6 ft] and must be connected at the construction site," says the lead scientist, Dr. Hyeong-Yeol Kim. "A method for effectively connecting the panels is currently being developed, and performance tests of the method will be conducted by the end of 2020."
The research is described in a paper that was recently published in the journal Materials.