People often think that some termites can eat concrete. They cannot. And the defensive fluid they secrete can't dissolve concrete. Yet, the belief that they can chew through concrete persists, because termites sometimes are found in places that would require them to first make their way through concrete. The only plausible explanation may seem that they chewed their way through, but that is a misconception.
Aerated concrete, those lightweight blocks with big pockets in the middle, may not stand a chance against termites. Cinder blocks may be penetrated as well, because they have large gaps in the middle. Homes and other buildings are often built with continuous gaps, essentially providing a walkthrough for termites looking for wood to munch on. If possible, avoid these types of building blocks; otherwise, you're just creating a superhighway on which termites can traverse your home.
Concrete that is solidly built and well-maintained can provide a barrier that the critters will be unable to penetrate. The solid concrete slabs used for foundations, for instance, are unlikely to be penetrated by termites. However, as soil settles and termites burrow in the soil underneath, even the thickest, most solid concrete slabs can shift and crack as a result.
Unfortunately, even the best concrete will eventually crack under the elements. As long as cracks running through concrete are no more than 10 percent wider than termites' heads, they will not be able to navigate through the cracks. Thus, when possible, it's essential to fill cracks in concrete promptly. Wooden posts and stairs that are embedded or run through concrete in a home can lead to termites making their way through the concrete. Once they find a crack in the concrete attached to wood, they can use it to make their way around a home in search of more wood.