Do termites tunnel through concrete/mortar/cement/cinder blocks etc.?


Termites will put a lot of effort into breaking through something that stands between them and food or water, just so long as the prize justifies the effort required.  Plaster (drywall etc.) is no barrier.  Mortars slow them down, but lime mortars are readily penetrable while mortars with a high cement content may not be excavated.  Good quality concrete cannot be excavated BUT cracks in poor concrete may be opened with ease.  Autoclaved aerated concrete (those lightweight bubbly blocks) were readily penetrated in my field tests.  Concrete (cinder) blocks sometimes have gaps in them big enough to interest termites.  Masonry is often built with lots of continuous gaps that termites can simply walk through, especially with extruded, hollow-core bricks.

Mud-brick (adobe) can be penetrated but is more at risk between the blocks and at cracks.

In general, termites won't damage concrete if they can't pull the sand (and small aggregate) particles out.  If the cement has been properly proportioned and the mix allowed to cure, then the particles tend to be well bound and termites are deterred.

Termites can walk through cracks in concrete.  The cracks need to be uniformly about 10% wider than the termites' head.  Concrete that is properly placed, cured and is reinfocred (rebar) generally won't crack wide enough to be at risk.

Sometimes concrete has big pockets of air (not properly settled), has wooden levelling pegs left in (highways) or has been damaged by expanding bolts.  Floor slabs often have cutouts or pipes passing through and this can create useful termite paths.