Comment by bestnameever
2 hours ago
Why not use concrete instead of asphalt? This person registered a 20 degree difference between the concrete sidewalk and asphalt road.
https://www.reddit.com/r/phoenix/comments/14o5bdu/a_comparis...
2 hours ago
Why not use concrete instead of asphalt? This person registered a 20 degree difference between the concrete sidewalk and asphalt road.
https://www.reddit.com/r/phoenix/comments/14o5bdu/a_comparis...
Just to be a pedant, and because this fact tends to surprise people, asphalt is concrete.
Concrete is a generally defined as any mineral aggregate (so rocks and stones) mixed with a binder (normally cement, but bitumen in the case of asphalt).
As for why roads are normally made out of “normal” concrete, it’s very expensive to build roads like that. Pavements are cheaper to build out of concrete because they only carry the weight of pedestrians, not lots of rolling vehicles. You need a pretty thick slab with rebar in it if you want to build a road surface from it, due to how weak cement concrete is under tension. Asphalt concrete cheats by being flexible, so minor imperfections in the surface or sub-base don’t become sources of critical failures (although they can become pot holes). Asphalt is also cheaper and easier to patch repair, but doesn’t last as long as proper cement road surfaces.
https://en.wikipedia.org/wiki/Asphalt_concrete
To be even more of a pedant, because asphalt is a subset concrete, any comparison between asphalt and concrete is automatically implied as a comparison between asphalt and non-asphalt concrete, and to specify would be redundant.
It's just like when saying "man vs animal", everyone knows that man is a type of animal, but it's implied that it's "man vs non-man animal".
> any comparison between asphalt and concrete is automatically implied as a comparison between asphalt and non-asphalt concrete, and to specify would be redundant.
Sounds like the comparison isn't between asphalt and non-asphalt concrete, but between asphalt concrete and cement concrete. Unless the only two possible aggregate binders are asphalt and cement, but that seems unlikely to me.
Possibly. But I noticed offhand in the DFW, Texas area there many local streets - sometimes flat ground-level parking lots - paved entirely in concrete, not just highways. Apparently for them the up front investment in "normal" (portland?) concrete is more economical.
There was a stretch of U.S. highway in my hometown that was built with concrete slabs. It is actually very durable and lasts for decades without need of repair, but it is also done in segments and the segments shift and create unevenness over time. Its not a terribly bumpy ride but it definitely isn't smooth like fresh asphalt. Anyways, at some point they grinded off a small layer of concrete and paved over the top with asphalt. When asphalt is fresh its definitely a more enjoyable drive.
> You need a pretty thick slab with rebar in it if you want to build a road surface from it, due to how weak cement concrete is under tension.
A lot of states use JPCP now for highways that doesn’t require rebar.
Huge temperature swings is a big part. Most people don't realize how cold it can get in the desert at night.
There's a lot of protectionism around asphalt maintenance.
I knew a city manager that got a city out of a major projected shortfall, without cutting any services, by investing in redicing long-term expenses.
He was celebrated for it, then fired, because the asphalt company that lost its contract had more political sway than the parks and recreation or public education departments that he fought for.
Cost.
The cost would be a lot lower given sufficient advance planning to stop digging it up and patching it so often. Different parts of local government often don't coordinate enough with each other, so a brand new road gets put in, and then dug up and patched 1-2 months later. Asphalt is easier and thus cheaper to patch, and the result looks...well, as bad as asphalt always does, rather than the obvious patch spots/lines on concrete.
Ideally, put in concrete roads that include conduits.