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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/

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_comparison_of_wet_driveway_sidewalk_and_asphalt/ https://www.reddit.com/r/phoenix/comments/14o5bdu/a_comparis...

a2ff6eeb0 24d ago
Cost.
- JoshTriplett 24d ago
  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.
deleted 24d ago
[deleted]
avianlyric 24d ago
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 https://en.wikipedia.org/wiki/Asphalt_concrete
- dlcarrier 24d ago
  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".
  - mpyne 24d ago
    > 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.
  - avianlyric 23d ago
    Not really, there’s a number of different concrete binders available including cement, bitumen (used for asphalt), lime (very old binder), even epoxy. Concrete is a material that uses any binder with rock aggregate. But in everyday usage people mean to refer to cement concrete. Asphalt is a specific type of concrete that uses a bituminous binder. So asphalt vs non-asphalt isn’t very helpful because non-asphalt either means nothing at all, or any other concrete that uses a non-bituminous binder, and there are plenty of other options. Clearly GP was intending comparison to be to cement concrete, rather than say, toothpaste concrete, PVA glue concrete, or a number of other technically valid concretes, but obviously not practical.
- libria 24d ago
  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.
  - chrisco255 24d ago
dlcarrier 24d ago
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.
esikich 24d ago
Huge temperature swings is a big part. Most people don't realize how cold it can get in the desert at night.

a2ff6eeb0 24d ago

Cost.

JoshTriplett 24d ago
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.

deleted 24d ago

[deleted]

avianlyric 24d ago

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 https://en.wikipedia.org/wiki/Asphalt_concrete

dlcarrier 24d ago
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".
- mpyne 24d ago
  > 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.
- avianlyric 23d ago
  Not really, there’s a number of different concrete binders available including cement, bitumen (used for asphalt), lime (very old binder), even epoxy. Concrete is a material that uses any binder with rock aggregate. But in everyday usage people mean to refer to cement concrete. Asphalt is a specific type of concrete that uses a bituminous binder. So asphalt vs non-asphalt isn’t very helpful because non-asphalt either means nothing at all, or any other concrete that uses a non-bituminous binder, and there are plenty of other options. Clearly GP was intending comparison to be to cement concrete, rather than say, toothpaste concrete, PVA glue concrete, or a number of other technically valid concretes, but obviously not practical.
libria 24d ago
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.
- chrisco255 24d ago

dlcarrier 24d ago

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.

esikich 24d ago

Huge temperature swings is a big part. Most people don't realize how cold it can get in the desert at night.