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Posted: Tue Oct 17, 2006 2:43 am
by beryl10
We just had the driveway paved at my mother's house, and I guess gambled a bit with a technique to change the look of the asphalt (I'm in the U.S., but I think what we call asphalt is what you call tarmac). The contractor suggested dusting the newly laid asphalt with cement dust to achieve a lighter, grey color. Being that my mother hates the black, and all other options we too expensive or not available - i.e., pavers, colored asphalt, tar and chip- we decided to try this out. Well, what a mistake that was! The result is horrible! It is very streaky and uneven, with thick patches that are completely solid. The texture of the asphalt is suppose to show through and in these areas it doesn't. And, its not even a nice color. We tried brushing it off with a broom (which is how they spread it around after dusting it on), and then hosing it off, partly to keep the dust down, but also to more easily remove the cement dust. Now the driveway is snow white in the areas where it was brushed, rather than the tan cement color. Its a total mess and very depressing. 
I wonder, does anyone know a way to remove cement from asphalt? They used Portland cement. I've read Portland cement doesn't dissolve in acid. But additionally, wouldn't dilute acid ruin the new asphalt? We called the contractor and he said he'd come over to look at it. We are thinking to ask him to split the cost with us to lay down another very thin layer of asphalt. I'm also wondering about this. How thin can a surface course be? I've read about SMA (stone matrix asphalt) being laid as thin as 6mm (~1/4in.). But, how about HMA (hot mix asphalt)? Also, any problem laying asphalt over patches of cement? What about driveway sealer? I know you're not suppose to apply it until 6 mo. to a year after paving, so I'm not really keen on that idea. Also, as it wears down, it would only expose the layers of cement, rather than at least allowing them to wear off, if they ever would.
All ideas and expertise is welcome. I'm desperate.
Posted: Tue Oct 17, 2006 2:13 pm
by TarmacLady
Yike. By flushing it with water, you've set the concrete.
Sealer has to wait until the asphalt has fully cured, and the bulk of the aromatics have evaporated, otherwise the sealer will come right back up (I'm in the US, by the way, and used to work for one of the larger sealer manufacturers) -- and sealer won't adhere very well to the cement, anyway -- and you're right -- as it wears down, the cement will just begin to show again.
Sealer will also give you a velvety black finish -- exactly what your mum doesn't like!
You could always test some dilute acid in a small corner to see if it works before bathing the entire drive in it -- it shouldn't affect the asphalt itself, as it's done all the time before resealing. BUT -- since I don't know where you are, and don't know the exact mix your contractor, I can't guarantee that!
You might also try a pressure washer (again, in a corner) to see if the cement can be dislodged -- but it may take out some of the asphalt at the same time.
Posted: Tue Oct 17, 2006 3:49 pm
by beryl10
We're located in the New York Metropolitan area. The aspahlt used was a mixture of 1/4" and 3/8" top modified mix.
When they applied this cement dusting, they had sprinkled the driveway with water. However, the water was very uneven on the driveway, hence the patches of very thick cement, which was what we were initially trying to scrub off with a brush, and then with the hose.
Where we were hosing and brushing it, it became so snowy white. I suppose we preferentially removed the darker particles, leaving behind the part of the cement that is so white in color (is that the gypsum?).
We're expecting alot of rain tonight, so it'll be interesting to see what happens. I wonder if the rain will do exactly what the hosing and brushing did.
Do you know anything about that colored sealer called AsphaColor? I've never seen it in this area. The company is in Arizona.
Posted: Tue Oct 17, 2006 6:54 pm
by bobbi o
if you use the contact section at streetprint.com,they should be able to point you in the direction of your local streetprint contractor who will be able to coat your driveway in any colour you want.
Posted: Thu Oct 19, 2006 2:30 am
by TarmacLady
sorry, beryl, I don't know AsphaColor -- but it looks like an *awesome* product -- I'd give them a call to see if they have a distributor in your area -- if not, it looks like they'd ship it.
You could also ask them their opinion about the cement fiasco -- they might have additional input.
Posted: Thu Oct 19, 2006 3:54 am
by beryl10
Thanks, thats a good idea. The AsphaColor does look like a really neat product. I don't know why I didn't look into that before trying out this cement dust idea. It was always in the back of my head as an option, but when the contractor suggested cement dust we just thought it would work out well and if we didn't love it, we could chip seal later, or apply a sealer (I forgot to consider whether that could be done over the cement). I never thought it would come out so awful. It's not even a question of personal taste. It just a mess. I don't think I will ever dislike a black driveway again!
I wonder how AsphaColor compares to what StreetPrint uses to color the asphalt. I'll have to ask about that.
I'm borrowing a pressure washer on friday, and will see how that goes. I have a feeling it will remove the lightly dusted areas easily. Not so sure about the thick splotches, but I have hope. I will use it on the lowest setting possible, b/c I am worried about ruining the asphalt. However, I have seen websites discussing pressure washing before applying sealer. So, maybe its ok.
Posted: Sun Oct 29, 2006 2:27 pm
by geoffdance
Hi Beryl,
good luck with the pressure washer, but beware using too much pressure - asphalt/ tarmac is relatively soft. I'd be surprised if brick acid doesn't shift it. Again, don't overdo the acid as it will also damage the tarmac. Scouring it with a wire brush while the acid is fizzing will help.
Regards colouring the blacktop - Sealmaster have a range of acrylic asphalt sealants in a range of colours. Check them out on www.sealmaster.net I'm using some of their products here in the UK and they seem pretty good. TarmacLady - any comments?
Geoff
Posted: Sun Oct 29, 2006 11:55 pm
by beryl10
Hi,
Thanks for the reply geoffdance. This SealMaster loooks like an interesting product. I need to read the literature over, but it looks like its used on the East Coast, unlike the AsphaColor sealant. I was away and forgot to write a reply to TarmacLady with the info I got from the AsphaColor company. So, here's that reply. AsphaColor told me that their sealant color mix cannot be used in my area (NY) because it only mixes with an emulsion sealer and in NY we use a coal tar sealer. I haven't had the chance to carefully read about the Sealmaster product, but maybe that's an option for us.
As for the pressure washing, I did one quick test with a borrowed washer, and it did seem to remove the cement, at least where it isn't so thick. The washer I was able to borrow is not very powerful, so I had to focus the stream of water on one tiny spot. It would take forever that way. I will have to rent something with about 4000 psi and give that a try.
If I do damage the asphalt with the pressure washer, or acids, I am wondering if a sealer would be sufficient, or if the driveway would need another layer of asphalt? The contractor is willing to work on this with us and one suggestion is another 1/2 in. of apshalt. The other is sealer. If sealer would do the job, I'd probably prefer that, rather than raise the driveway another 1/2 inch. I may still look into the tar and chip (seal chip) for a gravel drive look.
Its unbelieveable how ugly the driveway looks now. Its totally discolored from leaves, dirt and uneven wearing off of the cement.
Posted: Mon Oct 30, 2006 9:01 pm
by Dave_L
Wouldn't it have been far less hassle to have left the tarmac surface for two to three years for it to fade naturally to light grey?
Posted: Mon Oct 30, 2006 9:56 pm
by beryl10
Absolutely! If I had been given the choice between "hassle" and wait 2-3 years for light grey, I would have waited. Faded grey asphalt would be a million times better than this even if it does take 2-3 years. All I can say is we certainly didn't think we were signing up for a hassle (I'm not a big fan of them), or a really hideous driveway. We simply assumed it would be nice, otherwise, why would he do it?
The real question is: why didn't we ask to see an example before saying yes?
Posted: Tue Oct 31, 2006 3:47 pm
by TarmacLady
Beryl, double-check your information -- there are *very* few coatings manufacturers still using coal-tar sealers. I know of SealMaster, but am not really familiar with their formulae, as they are strictly commercial, and my time was spent with retail/DIY suppliers.
Because of the new information that indicates that coal tar is a carcinogen (plus, it's just nasty stuff -- somewhat caustic and will cause skin reactions, among other things) -- most of the DIY manufacturers have switched to asphalt formulations.
I know that all three of the major manufacturers who sell through the retail DIY industry (Depot, Lowes, etc) are offering asphalt formulae -- a couple of the manufacturers have dropped coal-tar formulae completely, and now don't even have coal tar as a raw material.
Only way to be sure is to read the buckets -- drop me a message (either on this thread or send me a PM) if you want with what you are considering, and I'll have a look at the data sheets for you.
Posted: Tue Oct 31, 2006 4:32 pm
by beryl10
Thanks TarmacLady. Our paving contractor also does sealcoating, and I will ask him what type he uses, since he will probably do this for us at no charge next summer. If he doesn't use the asphalt emulsion type, I will get someone else to do it.
I prefer the asphalt emulsion types to the coal tar also because it seems to me that what we might wind up eroding and removing with the pressure washing, and/or acid treatments is the asphaltic binder, so with an asphalt emulsion sealcoat, the pavement will be restored. Plus, I read the coal tar doesn't fade as much as the apshalt type, so, aesthetically, I wouldn't want it.
Do you know anything about overlaying a driveway with a very thin course of asphalt? How thin can it be? Also, with an aphalt overlay, would we have to be concerned about getting the cement off first? This is another option the contractor presented, however, we haven't yet discussed who's paying for it.
Posted: Wed Nov 01, 2006 4:19 pm
by TarmacLady
Coal tar has been used for many years, as its corrosive properties make it act as a primer and sealer over the asphalt -- it's been used for decades, it's just that the manufacturers are now finding better ways to make asphalt (resins, gels, etc., etc., all boffin-type stuff)
We're starting to veer out of what I know best, but a coat of asphalt thick enough to cover the mess would also be thick enough to change the contour of your driveway -- I'm concerned it would cause ponding in places you wouldn't want it -- like in your mum's garage.
My only other idea would be to go crazy on the blobs and whatnot, *then* lay a thin overlay -- or patch the dug-out spots with an asphalt repair compound (there are some good ones out there) and recoat the whole lot.
The more you start doing to it, though, the more the cost begins to add up.
I'd still be sorely tempted to go the tinted sealer route -- it's easy to apply and reasonably low cost.
At this point in the year, I'd also make sure you put it off until spring -- asphalt sealers do *not* like cold weather nor cold surfaces, and if you have sealer that doesn't cure correctly, you'll make an absolute disaster of the mess you already have.
Letting it sit over the winter would also mean that it would be considered "cured" by spring, and you could reseal it with no issues.
I also just had a thought as I type this -- if you have even a reasonably snowy winter, the freeze-thaw cycles and the snow shovel/snow plow might just knock some more of the cement blobs off, too.
Posted: Tue Nov 21, 2006 6:55 pm
by Dave_L
beryl10 wrote:Do you know anything about overlaying a driveway with a very thin course of asphalt? How thin can it be?
No, I don't personally but there are plenty of rogues around are who do! Their motto? Lay it THIN!