Here in Denver, at least, our runways are all made of cement instead of tarmac. I knew one of the civil engineers who worked on the special blend of cement the used, and from what I remember of what he told me, it is much thicker than I expected, and has other stuff in it compared even to highway-grade cement to make it more durable. The freeze-thaw cycle is still rough on the cement, in 2007 $11 million of cement slabs had to be replaced due to that. The airport as a whole has 15,000 20-square-foot slabs across its multiple runways.
Of course, one could still have buckling with cement if the expansion joints are too close together for the expansion of adjoining slabs over a certain temperature. Perhaps this is what actually happened here?
> Here in Denver, at least, our runways are all made of cement instead of tarmac. [...] has other stuff in it compared even to highway-grade cement
That's something that looks so different about (some/many?) American roads that I never twigged about until you said that. Roads are tarmac here too, not just runways. For some reason it didn't occur to me reading other comments about hotter places not using tarmac that it'd effect roads for cars too.
I am from the Denver region and from personal experience I know the area has a lot of Bentonite clays [0] which can expand as water is absorbed and contract as it dries. My neighborhood was built on land with a lot of this clay and our streets are wavy and our driveways are cracked to hell. I imagine they deal with similar issues at DIA.
My neighborhood is the same. The ground and site prep out at DIA the Civil Engineer friend told me about took things like that into account.
I for one have had much of the cement replaced around my house (some more than once) and when I had the driveway redone, explicitly asked them to mitigate against the clay with whatever they had that made sense. I forget what all they had extra in the proposal that I approved (it was 10+ yrs ago) but my new driveway isn't having any issue while some neighbor's new ones are already cracked again.
Here in Denver, at least, our runways are all made of cement instead of tarmac. I knew one of the civil engineers who worked on the special blend of cement the used, and from what I remember of what he told me, it is much thicker than I expected, and has other stuff in it compared even to highway-grade cement to make it more durable. The freeze-thaw cycle is still rough on the cement, in 2007 $11 million of cement slabs had to be replaced due to that. The airport as a whole has 15,000 20-square-foot slabs across its multiple runways.
Of course, one could still have buckling with cement if the expansion joints are too close together for the expansion of adjoining slabs over a certain temperature. Perhaps this is what actually happened here?