With the final patches in place:
This post summarizes what I learned using QPR cold patch (from Lowe’s) on a badly deteriorated section of asphalt driveway. A prior post (Post #1974) explains the situation, and go back to Post #1971 for an assessment of options for patching asphalt.
Above, that may not look so hot to you, but I guarantee you it looks a lot better than it did. Once I seal-coat this, in the fall, I think it’ll be … acceptable. Given how torn up the driveway is. I have no idea yet whether these surface-laid patches will survive the winter, but will update this next spring.
First, it took between 3 and 7 weeks for this to cure fully, in the heat of early summer in Virginia. The reason I’m a little vague is that the patches seemed to be cured after one week. At three weeks, a heat wave (near 100F temperatures) re-activated them, and the surfaces were once again sticky in spots, shedding little tarry bits. At seven weeks, another heat wave (several days at 100F) did nothing. By seven weeks, they were as solid and tar-free as the asphalt they were laid on, despite the heat.
Second, this stuff varies from batch-to-batch. As you can see above, I laid mine down as a series of separate patches. I bought and laid the bags of QPR a few at a time, because that’s all I could handle. From one batch to the next, the QPR material differed in how “liquid-y/tarry” it was, in the final color once set, and to some degree, in the surface finish once set. I’m going to seal-coat this in the fall, so the color variations don’t much matter. But if you doing a big area, and are particular about how this looks, you might want to buy all you need, all at once, from a single batch or lot number.
But arguing against buying a whole lot at once, see the note below on how hard it may be to estimate what you need, if your driveway surface is as un-level and messed-up as this one was.
Big batch-to-batch variation could also explain part of the strong differences of opinion among on-line reviewers of QPR. In my case, if I’d stopped with my first first batch, I’d have said “QPR is a dandy product”, period. With the later batches, that has a huge qualification, that the “walk on it anywhere, any time” cure time is unknown. And all the hassle that can bring, during a hot spell.
Third, foot traffic across these patches makes a mess, due to the tiny little tarry stones that get tracked everywhere. It’s tough to state just how much of a pain those are. The get everywhere. The surface sheds those rocks for the first few days (again, Virginia, early summer), and then starts shedding again if it gets hot, for some weeks thereafter. So if this is going to be laid in place where people walk, either lay it in patches so that people can walk around the newest patches, or maybe lay plastic over it.
Fourth, the manufacturer says you can drive across these patches immediately. And … yeah, technically that’s true. If this were out in the middle of the street, and looks didn’t matter, I’d have no problem with that statement.
But I’d say that’s mistake, if you can avoid it, if you are picky about how the final product looks. In my experience, there’s a risk of marking the pavement surface slightly for the first couple of days, no matter how carefully you drive (i.e., don’t turn the wheels when stopped). And there’s a near-surety of picking up some of the tarry surface stones on your tires for the first few days. Better to stay off these patches as much as possible until they’ve had a few days to cure.
That said, laying down plastic, then thin ply, and driving over that, did seem to compact the surface finish better than I could do with just a tamper. So, drive over the plastic-and-ply protected surface to get the best flat-level surface on the patch. But don’t drive over the unprotected patch for a few days, if you can help it. If you have to, the patch will survive, but you’ll likely ding up the very top surface a bit.
QPR asphalt cold patch.
1: Why QPR.
QPR was a relatively cheap patching material that could be applied overtop the existing asphalt surface. I cannot over-emphasize how much labor that saves, relative to digging up all the alligatored asphalt that was deeply embedded in the clay soil of my driveway. And then applying a much thicker patch of some alternative material. If those patches will just stay stuck down, and don’t get popped up by freeze-thaw this winter, that labor savings alone will make it worthwhile to use QPR over other locally-available materials.
Of the cheap, asphalt-based patching compounds I could buy locally, one (Sackrete, at Home Depot) was for filling deep holes only. It should not be laid atop existing asphalt, per manufacturer’s directions. Using that would have meant digging up all that alligatored asphalt. All of which is firmly embedded in the underlying clay soil, because this broken-up section of driveway had originally been laid directly onto the dirt.
But QPR (Lowes), by contrast, can be laid directly over an existing asphalt surface. At least, that’s my takeaway from the manufacturer’s minimal instructions, and comments on the Lowes website and elsewhere. Obviously, that won’t work if the underlying asphalt itself is subject to movement. But as long as it’s firmly stuck in place, it should fine.
A completely different product, Aquaphalt, is a competitor to QPR that can also be laid directly over an existing asphalt surface. That’s a water-cured patching material that looks like asphalt, but isn’t. And while Aquaphalt appears to be a superior product in almost every way — particularly with a 15-minute cure time — it’s also between three and four times as expensive as QPR, per cubic foot. It also comes in plastic buckets, which then must be disposed of. (I used one bucket of Aquaphalt, on one particularly ugly stretch of pavement. I explain that below.)
2: I used a half-ton of material for this ~105 square foot patch.
Each bag of QPR weighs 50 pounds and costs about $20. Therefore, my 20 bags of QPR weighed half a ton, and cost a little under $400.
On net, for the area I patched, I got about five square feet of surface covered, per bag. But that’s clearly a function of how deep my patch is, on average.
I brought the 50-pound bags of QPR home six to eight at a time, in my hatchback, after lining the back with a plastic sheet.
And it’s a good thing I bought just a few at a time, because I waaaaay over-estimated the amount needed, when I first looked over this section of driveway. Raising the entire sunken driveway surface back to its original level would have taken about 60 bags of the stuff. So instead of raising it to be fully level, I just filled in the low spots (the puddles), and raised it as little as I could, beyond that.
I’d have had a mess on my hands if I’d stockpiled the full 60 bags that I thought I’d need, before I started.
3: Applied in manageable pieces
I put this down over several sessions, over the course of a week and a half.
Each session being maybe three or four bags’ worth of material, applied to one defined section of the driveway.
From start to finish, you:
- sweep the area to be patched,
- haul in a bag of QPR patch,
- Slit the bag bottom, dump the QPR.
- Rake it out/shape it at the edges.
- Haul/slit additional bags as needed.
- Tamp it.
- Tamp it some more.
- Run over it with your car, after covering in plastic and thin plywood.
Some days I went through that two or three times. Most days on which I worked on the driveway, I only did that once.
One full cycle, from sweeping to running it over, seemed to take me about two hours. But that includes some time pondering the situation, wondering what I should do next. Mostly, pondering whether I was maintaining enough slope for water to flow, with the help of a 4-foot level.
In my “puddles first” strategy, the goal was to cover the entire area and not end up with standing water anywhere, after a rain. With that as the goal, it was helpful to have some rain halfway through the patching, so that I could see what puddles remained after I’d filled in the biggest ones.
4: It makes a mess if there’s foot traffic.
At least it did, in my climate (Virginia, typical day in the mid-70s, sunny).
The freshly-laid patch has a tarry surface. It will be stickier or less sticky depending on temperature and age. Fresher and hotter mean tarrier. As long as the patch is still tarry — either because it’s fresh, or it’s a few days old and in the hot sunshine — if you walk on it, you will pick up and track around tiny little tar-covered rock chips. Which then stick to everything.
And that’s a pain in the ass.
5: The tarry top surface of my patches temporarily went away over the course of a week.
(I have now rewritten the intro to reflect what actually happened over the course of seven weeks.)
After a week, in my climate, I could walk cleanly across the patch and not pick up anything.
Before that point, though, in addition to shedding rock chips, the surface of the patch tends to pick up any stray organic matter (e.g., leaves, pine needles, wood chips) that will stick to the tar. I believe this stuff will mostly move along once the surface is no longer tarry. At any rate, the week-old patches were mostly clear of debris.
In principal, these were “ready for car traffic” almost immediately after they’d been fully tamped. But only in the sense that the car tire would not squish the patch, much. But you’d still be well-advised to wait until the next day before driving over these. I think my car treads lifted some surface stones off the patch, when I drove over the patch on the first day.
The upshot is that, as the manufacturer advertises, you can drive right over the patches on Day 1. Don’t stop and turn your wheels. But my take on it is that you shouldn’t drive on the fresh patches if you can avoid it. Your tire treads are going to pull some tarry stones off the top of the patch when you do that. Better to minimize that until the top surface of the patch has had a few days to cure.
The other interesting aspect of aging of the patch is the surface gets smoother over time. I guess it continues to flow a bit. But, for sure, the fresh patch (dark) has a much rougher surface texture than the week-old patch, despite being laid and tamped the same.
6: Pros and cons of doing this piecemeal.
Doing this piecemeal, as I did, has several advantages. First, I don’t think I could have done 20 bags of QPR in one day. Second, I would walk on the older (cured) patches, as I put in the newer (fresh) patches. And I could walk on them as a way to walk around that freshly-laid patching material. Third, the only way I could figure to end up with a reasonably level final product was to fill in the low spots — the puddles — first.
Arguing against this approach are the looks and the time. I believe that the entire patches surface will cure to roughly the same dry and densely-packed finish. But the joins between the individual “batches” of patching will probably remain visible no matter what. But in addition, each fresh patch extends the time during which you’re at risk for tracking tarred stone chips around. For example, I started this more than a week ago, and it’ll be a week from now before the most recent patching material will have a cured, non-tarry surface.
Conclusion
I’m not sure I’d do this again. And I’m not sure I wouldn’t, either.
For me, it boiled down to QPR being the easy and cheap solution. You can drive down to your local hardware store, pick it up by the bag, and (after some significant surface prep) spread over a badly damaged asphalt surface.
This, as opposed to (say) trying to get three bids from pros, to come out, tear that up, and re-lay that section of the driveway correctly. If I could get a pro around here interested in something that small.
The physical labor wasn’t that big a deal as long as you can lift the 50-pound bags. I worked up a sweat tamping it, but I’m not even sore from doing that. (OTOH, I lift weights regularly.)
Sure, it sticks to your tools. And to your shoes. And anything else it comes in contact with. And it stinks faintly of asphalt, for some days afterward. All depending on the temperature. But, given that it basically is asphalt, none of that should be a huge surprise.
I have no idea how well it will last. For now, it all appears to be physically solid and well-attached. This, despite doing my best to apply it as thinly as I could, in some areas. And without the best surface prep in the world.
The individual pieces of the patch give it a little bit of a redneck look. But that should mostly go away as all the patches cure to the same shade and surface finish.
In any case, I have to leave it alone for a couple of months as it cures fully. So I get to look at that patch until August or so. At which point I’ll apply some modern miracle crack filler to any remaining cracks, then top coat the entire pavement.
That’s the plan, anyway.
Addendum: Plus one bucket of Aquaphalt.
I actually started by purchasing a bucket of Aquaphalt 4.0 (smaller stones). That, before I realized how much of this stuff I needed. And how much Aquaphalt would cost to do the entire job.
I ended up using the Aquaphalt on one section of pavement that had been heavily colonized by grasses. Unlike QPR and similar products, Aquaphalt cures by addition of water, and it cures fast (15 minutes) and hard. No tarry mess. I figured that if the grass should try to grow back (despite my heavily salting the area per Post #1973), Aquaphalt would stand a much better chance of keeping the buried grass roots from growing through the pavement than would the slow-to-cure QPR.
Edit 7/19/2024; And, so far, so good. Going on eight weeks later, and nothing is poking up through my asphalt patches. I’m guessing that spraying the alligatored asphalt with a strong salt-water solution, prior to patching, killed the roots of all the vegetation that was there, as intended (Post #1973).
As far as I can tell, other than the high price and the waste stream of plastic buckets, Aquaphalt is a superior product. It spreads and shapes almost as easily as QPR, and seems to stick to the pavement just as well. It cures in 15 minutes, as advertised. The surface finish of the Aquaphalt 4.0 is much finer than that of the QPR, owing mostly to the smaller average gravel size in the Aquaphalt 4.0. The sole downside I noted to Aquaphalt is that it didn’t flow/rake to the edges of the patch as easily as QPR, and I don’t think I was able to lay quite as thin a patch with Aquaphalt as I was with QPR.
Edit 6/5/2024: That’s not quite right. Aquaphalt’s main downside is that it “flows” less well than QPR, at least once you’re at the water-and-compact stage. I ended up leaving marks in the Aquaphalt in areas where the tamper did not hit squarely onto the surface of the Aquaphalt. At the time, I thought I had fixed that by tamping these areas flat. But, in fact, the Aquaphalt’s surface had so little “flow” at that point that it didn’t fill in the little low spots my mis-tamping had created.
But worse, the finer surface finish of Aquaphalt is much less forgiving than the coarser surface finish of QPR. Little imperfections that are lost in the background roughness of the QPR surface finish stand out in the Aquaphalt surface finish.
The moral of the story being that if you are not the best at leaving a smooth surface finish on materials like this, Aquaphalt may not be the better choice, relative to a tarry patch such as QPR. For the reasons described just above.
That’s a lesson that my driveway and I learned the hard way.
Looking on the bright side, the little dings in the Aquaphalt section get lost in the overall unevenness of the patch.
I guess that’s a bright side.
We’ll see how it looks with a seal coat.
Otherwise, if I didn’t care about the expense or the waste stream of big plastic buckets, think I’d do the whole thing in Aquaphalt. It’s as versatile as QPR (in that you can lay it over existing pavement), but lacking all the factors that make QPR a bit of a mess. You also avoid QPR’s months-long wait prior to seal-coating over the patch and roadway.
Edit 6/5/2024: But on a raggedy, roller-coaster asphalt surface such as my driveway, you aren’t going to end up with a beautiful finished surface of Aquaphalt as-seen-on-TV. If nothing else, there’s no flat reference surface to screed to. Unsurprisingly, the finished surface of my driveway — after QPR top coating — is not flat. Plus, making it flat (level) with the remaining sound driveway surface would have required laying down three times as much material as I actually used with a “puddles first” patch-application strategy. I’m pretty sure I’d have done Aquaphalt the same way — in a series of discrete patches — if only because it’s 50 pounds a bucket, and don’t think I could move 1.5 tons of that material in a day. Let alone get it laid, watered, and tamped.
