soft cold patch?

[Nate Nagel]

Hi all,

what could possibly have gone wrong? this past weekend I patched a couple spots in my driveway with Sakrete brand cold patch, exactly per directions - one "hole" was actually just an asphalt skin that had peeled up, a couple other spots I needed to dig away all the old rotten asphalt all the way to the base, in those cases I dug all the base up, screened the gravel out, made a new gravel base, and finished with about

1.5" to 2" of cold patch (deeper than the asphalt that was there before!) I used it exactly per directions, squared the edges of all holes, never put it down less than 1" or more than 4" thick, tamped it by hand with a 8" square steel tamper until it wouldn't compress down any more. After a day or so it was mostly hard so I figured all was good. Today I came home from work and it is SOFT! Not sure why, except it was up to about 80 degrees, but it is cool and rainy now. It still won't tamp down any more, but if I just touch it with my hand and push laterally, it moves like there's next to no adhesion at all. What the heck do I do now? I was hoping that I could seal the driveway later this summer, but if these patches don't work, what's the point?

nate

[Toller]

[Jim Yanik]

Nate Nagel wrote in news: [e-mail]:

You might try putting a steel plate or thick plywood sheet over the patch and driving your car or truck(heavier the better) over it to compress the patch.You'll get more pressure that way.

It's probably soft because the volatiles in the material BELOW the surface have not dissipated yet,and the 80 degF heat causes more volatiles to evaporate and soften the surface material.

[Jim Yanik]

"Toller" wrote in news:47M2i.8608$ [e-mail]:

Or maybe they have a website with a FAQ.

the Internet is a GREAT resource.

[Nate Nagel]

ACtually, no, I tried that. I mean, they do have a website with a FAQ but nothing that addresses any non-concrete products.

nate

[Clark]

Jim Yanik wrote in news:Xns9932CE8061A20jyanikkuanet@

64.209.0.87: [snip]

Just how much pressure do you think a car or truck tire exerts?

[snip]

[Noozer]

1/4 of the vehicles weight?

[mm]

About 30 pounds per square inch, although here it was recommended to put a plate or plywood sheet over the patch, so the weight would be spread out more.

I have no idea how much hand tamping does, but it's spread out too to

8 inches square, he said.

We have a lot of holes in our n'hood too. Does this cold patch work pretty well most of the time. I saw a car recommended for when one has no tamper. Is that good enough or, when I pull away, will the black stuff go up on my fender and stick there?

[Clark]

"Noozer" wrote in news:rAP2i.187977$DE1.44985@pd7urf2no:

While that does describe the total force one might expect, it does not describe the pressure which is force divided by area.

The pressure exerted by the tire on the road has to equal or be less than the air pressure in the tire. Any other condition would be a bad day (flat tire).

[Clark]

mm wrote in news: [e-mail]:

Yup, about the tire pressure and that is the key. The weight of the vehicle is less of a concern than the tire pressure. Although a heavier vehicle would give a larger contact area for a given tire pressure.

I don't know what hand tamping yields but I'm sure their are tables somewhere. Is there a civil engineer in the room?

I hate it when that happens...

[Joseph Meehan]

Clark wrote: ..

Well, not exactly. Let's say you have 40 psi in the typical car tyre. Making that 100 psi (if the tyre does not pop) and you would likely have very little difference in contact area because the tyre shape is determined by the tyre pressure and the tyre construction. Even with no pressure in the tyre there will be pressure on the surface. So while pressure is part of the game, it is not the only and maybe not even the principle player.

The standard method is to place a board or steel plate over the patch and drive a car or truck over it. In that case tyre pressure makes zero difference

[Clark]

"Joseph Meehan" wrote in news:464c4438$0$5750$ [e-mail]:

Well Joseph, I disagree. If we have 40 psi in a car tire and a 500 lb load then we will have approximately 500/40 = 12.5 square inches of contact area. If the tire pressure is increased to 100 psi then there will be approximately 5 square inches of contact area. Rubber deformation is not accounted for in these calculations and that is why the number is approximate. Of course rubber carries very little of the load.

Now a reduction in contact area of 60% may not be much to you but to me it is significant. Air pressure is the significant factor in assessing the pressure exerted by a tire on the ground. If it wasn't the significant factor then some other component would have to carry the weight of the car. What do you propose that component to be? The tire sidewall?

[Jim Yanik]

"Noozer" wrote in news:rAP2i.187977$DE1.44985@pd7urf2no:

a lot more than what a person can put on the patch,even with a tamper.

More if it's a front wheel drive auto,they generally have a 60-40 weight distibution.

It's simply a version of a steamroller.

[Jim Yanik]

"Joseph Meehan" wrote in news:464c4438$0$5750$ [e-mail]:

a FWD auto usually has approximately 60-40 weight distribution,front to rear. that's 1800 lbs for the front wheels,divide by two,and you get 900 lbs pressure on the plate.Since you slightly crowned the cold patch,all that pressure is compressing it. The plate is to give an even distribution of pressure on the patch,since the tire contact patch will deflect with the uneven surface of the patch.

And you can leave that pressure ON the patch as long as you want,while a tamper gives only a brief pressure.

[Jim Yanik]

Jim Yanik wrote in news:Xns99336FB7EBBBjyanikkuanet@64.209.0.87:

I forgot to type;

For a 3000 lb auto,

[Nate Nagel]

Well, it's still soft... it's definitely the sun doing it. It's *way* soft today, with the sun shining on the stuff, while yesterday it was only "kinda" soft... Sakrete has not responded to my inquiry. Any ideas what to do now? This is the only brand of cold patch I've been able to find locally. It's been a full week since applying the patch.

thanks,

nate

[Kris]

I had the same problem with a product from quickcrete. I ended up calling and asking why there product was doing this? They told me it still had moister in it And throwing dry sand on it would draw out the moister! Then I had to wait 28 days before putting a sealer on it. Did you ever fix what was wrong?

[N8N]

sold the house a few years ago, so I can't give a long term report. But th e patches did eventually firm up. Company never did reply to my inquiry bu t after a long time they did set and we were able to seal the driveway so i t looked pretty good. Not as good as a proper mill and repave, but good en ough that it didn't look as awful as it did when we first moved in, which w as the goal.

[Patch man]

replying to N8N, Patch man wrote: Very simple. It needs curing time. 30 to 90 days.

[DerbyDad03]

It's been 3,347 days since Nate posted his question. If it's not cured by now, he's got a problem.