You went out to move the trash cans and there was grit on the driveway that wasn't there last week. Then you looked properly. The surface is coming away in thin flakes, there's a patch near the garage where the stones are showing through, and a bit of it lifts if you work at it with the toe of your shoe.
Start with the reassuring part, because it's usually true. What's coming off is the top eighth of an inch or so, and the slab underneath is almost always structurally sound. The part worth getting right is which surface problem you actually have, because three or four different things look close to identical from standing height and they don't get fixed the same way.
First, work out how deep it goes
This takes about two minutes and it tells you more than anything you can see standing up.
Crouch down and pick up a piece of what's flaking off. If it's paper thin and crumbles between your fingers like dried mud, that's the cement paste at the very top giving up, and it's the shallowest version of this. If the pieces are thicker, come away in sheets roughly the size of your palm, and have a smooth underside, you're looking at something else entirely and the cause points back at the original pour rather than the weather. If chunks are breaking out with stones embedded in them, it has gone deeper than the surface layer.
Then tap across the area with something hard, a screwdriver handle or the heel of a shoe. Sound concrete gives you a solid click. A hollow or drummy note means a layer underneath has already separated and just hasn't broken through yet, and everywhere you hear that is coming off eventually whether you touch it or not. Chalk the edges of the hollow patches, because they're almost always bigger than the part that has visibly failed.
Then take photos, in flat morning light rather than harsh midday sun, close up and from a few feet back. Surface damage photographs badly in direct light and you'll want the comparison next spring.
The handful of problems that look the same from a distance
The trade uses spalling and scaling loosely and more or less interchangeably, and honestly the label matters less than the depth and the cause. There are four things we actually turn up to find.
Scaling is the flaky, chalky, pockmarked one, where the mortar between the aggregate erodes away and the surface gets rougher and rougher until stones start showing through. That's freeze-thaw and deicer working on an unsealed surface, which in Denver makes it the most common thing we see by a wide margin.
Delamination is the one that comes away in sheets with a smooth underside and sounds hollow before it lets go. It starts on the day of the pour, when the surface gets closed up by troweling before the bleed water underneath has finished rising, and that trapped water leaves a weak plane a fraction of an inch down. It can sit there for years looking perfect and then shed in a single bad winter. If your driveway is failing in flat sheets rather than crumbs, this is usually why.
Popouts are the small cone-shaped craters, often with a bit of split stone sitting at the bottom. A piece of aggregate near the surface took on water, froze, and pushed the concrete above it off. They look alarming close up and they stay cosmetic.
Crazing is the fine web of shallow cracks that looks like a dried lake bed and doesn't shed anything at all. It's a curing artifact and it stays cosmetic unless something else joins it.
Telling these apart on site is most of what the first ten minutes of a concrete repair visit consists of, because the fix changes completely depending on the answer.
Why it started where it started
Where the damage begins is usually the clearest evidence you have about what caused it.
If it's worst across the apron and the first stretch in from the street, that's magnesium chloride. Colorado runs brine rather than rock salt on the roads because it keeps working at lower temperatures, and it comes home on your tires and drips off exactly where you slow down and turn in. It attacks the cement paste chemically and it lowers the freezing point of water sitting in the surface pores, so that section cycles more often than the rest of the slab does. Denver already runs somewhere near a hundred freeze-thaw cycles in a winter, one of the highest counts in the country, and the apron takes more of them than anywhere else on your property.
If it's worst under a downspout or along a low edge where puddles sit, the answer is standing water. Concrete that never dries out goes through every one of those cycles saturated, and saturated concrete gives the ice nowhere to expand into.
If it's spread evenly across the whole slab, look at the age instead. A driveway in the ranch tracts through Arvada, Lakewood or Englewood that was poured somewhere between 1950 and 1975 has taken fifty-odd winters unsealed, and at that point uniform surface loss is just arithmetic.
And if the driveway is only a year or two old, the deicer question is worth reading properly, because a new slab takes it far worse than an older one does. We wrote the long version of that in should I put salt on my new concrete driveway this winter.
One thing worth saying plainly. Almost none of this is your original contractor's fault, and almost none of it is bad concrete. Delamination is the exception where the finishing genuinely played a part, and even that one usually took a decade and one hard winter to show itself.
What not to do while you're deciding
There's one move that makes this worse and it's the one people reach for first.
Don't seal over a surface that's actively breaking down. A sealer is a barrier, and putting a barrier over a damaged layer traps moisture inside it instead of keeping moisture out. Sealing is genuinely the thing that prevents all of this, so getting on a two to three year sealing cycle is the right answer for a sound slab, and our interval is shorter than the numbers quoted nationally because UV at 5,280 feet breaks sealers down faster than it does at sea level. It's the wrong answer for a slab that's already shedding. Repair first, then seal.
Skip the bagged patch products too, at least until you know what you've got. They bond to sound concrete and they don't bond to a layer that's already separating, so patching over delamination gives you a patch that comes off with the sheet it was sitting on. Pressure washing has the same problem, and a tight nozzle held close will strip more surface than it cleans.
What does help right now costs nothing. Keep water moving off the slab, clear the downspout splash, and get the snow off early this winter rather than letting it pack down and refreeze.
Repair, resurface, or wait until spring
The decision is simpler than the diagnosis, though the calendar is part of it.
If the damage is patchy and the rest of the surface is tight, spot repair is the cheaper route and a perfectly reasonable one. If it's spread across most of the slab but the concrete underneath is sound, resurfacing puts a new wearing surface over the whole thing and gives you a uniform result instead of a driveway that looks mended. Once the base has failed and you've got heaving or offset panels alongside the surface loss, that's a different conversation and replacement is the honest answer.
Timing matters more than people expect. Overlays and most patch materials need temperatures above roughly fifty degrees to cure properly, and our working season runs about April through October. Early September is close to the last comfortable window this year. If we get to late October and it's borderline, we'll tell you to wait for spring rather than take your money for work that won't hold, and one more winter with the water managed is genuinely survivable.
The thing worth not doing is nothing at all for another three years. Caught now, this is a surface problem on a good slab. Left alone, water keeps working further in, and eventually the answer stops being a repair and starts being a replacement.
If you're not sure which of these you're looking at, take a couple of photos in flat light and call us at (720) 782-8086. We'd rather tell you it's cosmetic over the phone than have you replace a driveway that didn't need replacing.