Any idea what might causes these holes in concrete walkway?

[pagetrip]

We recently noticed a lot of holes on our concrete walkway. I am pretty sure they were not there a month ago but all of a sudden there are a lot of holes. Any idea what might have caused this? This does not look like ants and I am not sure what treatment would apply here. Any help is appreciated. Thanks.

Location is Seattle.

 

[havasu]

Subterranean termites?

 

[Flyover]

It looks like your concrete has small stones embedded in it. Could it be that in the winter water gets in between the stones and the cement, freezes, expands, and crumbles away the surrounding material allowing the stones to come loose, leaving a cavity behind?

 

[Steve123]

You put much salt on it in winter ?

 

[Hal201]

It looks like bug holes or surface voids. Crack fill might be able to patch up the holes.

 

[JoeD]

Looks voids you get when you have organic material in concrete mix. The organic eventually rots out and leaves the hole.

 

[BuzzLOL]

Concrete may have had air bubbles in it. How old is it? Most people would just ignore the holes... or you can scrape around inside them, vacuum out the dirt/dust, and use patching mix.

 

[tomtheelder2020]

I don't know why ants, termites or any other bug might gnaw holes randomly across the top of a concrete slab but if some mutant variety is now doing it we are all in big trouble.

Many holes appearing all at once seems unlikely to be due to organic material embedded in the concrete.

Is this occurring throughout everywhere on this concrete? Does other concrete nearby have the same problem? The holes look shallow - are they?

Could some kind of acetic material been splattered across the concrete? Burned material can be acetic - were fireworks used nearby?

 

[bud16415]

I don’t think they happened that fast. Did you recently pressure wash the walkway?



Acid rain, snow melt.

The reason I say this is the divots look really clean inside and normally old work like thei would have dirt/mud filling the holes to some degree.

 

[tomtheelder2020]

The reason I say this is the divots look really clean inside and normally old work like thei would have dirt/mud filling the holes to some degree.

Good catch! Why they are clean must be part of the story.