Removing Tar from Concrete Driveway

[Kilgore Trout]

So....

The previous owner of my house decided that what appears to be asphalt (bitumen or whatever you want to call it) would be a good substance to slather all over the cracks in my driveway. It looks like **** and over time, cracks have appeared in the tar, so it needs to be removed and replaced before we get the freeze thaw cycles of winter. I pried out all of the tar from the cracks. The cracks are no more than 3/4 of an inch wide (most are about 1/4).

I was planning on filling them with sand, foam backer rod, and then use sikaflex flex seal. However, I am having a hell of a time getting all of the tar off. The sikaflex states it shouldn't be used with bitumen containing materials - my guess is that it doesn't bond well. The tar is removed from the cracks, but there is still a bunch of tar (gobs in some places) on the surface of the concrete (1-2 inches on each side of the crack).

So I am looking for advice on how to remove it. Quite frankly I would like to use the sikaflex, since it looks way better and gets great reviews. But, I need some way to get rid of the tar... I want to slug the previous owner for globbing this crud on there in the first place.

I tried a wire wheel and a grinder - no good. Also tried my electric power washer - also no good...

 

[Cyberbear]

Depending on how thick the remaining tar is, you may try using dry ice to freeze the tar and then easily chip it off. If the tar has actually soaked into the concrete rather than laying on the surface, it may be a more difficult task to pull that tar out that penetrated the pores of your concrete. Hope this helps.

 

[Booth]

Are you sure its tar? Could it be rubber? We crack fill with hot rubber, but never on concrete.
Paul

 

[Platonic Solid]

I successfully used "Peelaway 7" to remove automotive undercoating and tar-paper glued to hardwood flooring (it's not advertised for either of these uses). Might be worth testing for your situation.

 

[magicrat]

Industrial power washer with hot water....Over 4400 psi......I think it will work....just a guess

 

[brownbagg]

wd 40

 

[Ben Buck]

 

[Kilgore Trout]

Well, I've definitely got WD 40. I'll give that a try.

Too dark to take pics now, but if it ever stops raining, I'll take some tomorrow.

I don't mind giving the industrial power washer a try as well. Looks like HD can rent me a 3500 PSI 3.5GPM gas power washer. Doesn't look like it is heated however. Think that would work?

 

[Kilgore Trout]

It might be rubberized crack filler as well... Now that I looked up some pictures of that on google, it could have been a horribly applied rubber crack filler.

Any thoughts on removing that stuff?

 

[CNGsaves]

Run a garden hose to the spigot on your hot water heater and use hot water with power washer.

It WILL come out . . . especially if you "pre treat" the spots with some solvent type stuff the night before.

WHERE are you at ?? Update GJ Profile with City / State / Country.

 

[Kilgore Trout]

Thinking about pre-treating with citristrip adhesive remover. Claims it will remove rubber and asphalt based adhesives. That plus the power washer might do it.

I'll post pics tomorrow. Still open to other suggestions.

 

[Seagoon]

If it is bitumen then it can be dissolved by any of its chemical group i.e. petrol(gas to you) diesel and the like. Not environmentally friendly but effective. Otherwise heat will soften it enough to be peeled off - pressure washer with heater, flame gun etc.
Personally I would probably use a garden hoe heated by a blow torch which would be tedious but effective, then diesel to remove the last traces.

 

[Platonic Solid]

It might be rubberized crack filler as well... Now that I looked up some pictures of that on google, it could have been a horribly applied rubber crack filler.

Any thoughts on removing that stuff?

Since "Peel Away 7" removed rubberized undercoating I still think it's worth a try.

Here's how it worked on the wheel wells of my 73 Mach1, though I think you'd have to put a much thicker layer on (say about 1/4").

And NO I don't have any affiliation with this product. I just did a lot of experimentation and found this to be the most effective, least damaging solution with the least effort.

 

[Kilgore Trout]

Well, it is STILL raining, so no pics today. I am open to trying Peel Away 7. The question is if I can find a distributor near me. According to their website, my local distributors only carry 5 gallon buckets (at $350). I'll try calling Sherwin Williams tomorrow to see if they have the 1 gallon ones, despite what the internet says.

 

[Platonic Solid]

Order the 16oz. sample size direct from the manufacturer for $9 before buying the gallon to find out if it works. I can get the gallon size at the local "True Value".

 

[Spareparts]

Brake-Kleen spray it thourghly cover with kitty litter spray it some more and let it dry for a couple of hours and sweep it up. Tried this on some roofing tar that was spilled on pourious concrete and it worked.

 

[Kilgore Trout]

OK, so here are some pics. One where I cleaned out the crack, the others to see the starting point. You can clearly see the gobs of **** around the crack.

 

[Spareparts]

I have got a Landa 4000psi washer with hot water, will almost blow steam, that would clean it, maybe rent one. But if you can don't use the straight tip on it, it will cut the concrete. One of my guys cut the toe off of his rubber boot with it, luckily he had a size 8 foot in a size 12 boot.

 

[Kilgore Trout]

Well, I tried brake-kleen. Helped a little bit and would probably work eventually if I kept spraying, grinding, spraying grinding, etc. I don't mind spending half a day on this, but this method would literally take days. I tried goo-off as well. Similar results.

I ordered some peel away 7. Maybe it will work better. Otherwise, I am looking at renting a 3500 PSI power washer from HD.

 

[NUTTSGT]

That kinda looks like roof cement to me. I think I might try a rag and some gasoline. . . .no smoking while you try it.

 

[Kilgore Trout]

Well I certainly have gasoline..

I can give that a try too, though I am starting to think it is going to require something harsher...

 

[NUTTSGT]

Just make sure to properly dispose of any gasoline soaked rags.

 

[stihlntime]

I would use kerosene. If it is tar it will dissolve it.

 

[NUTTSGT]

I would use kerosene. If it is tar it will dissolve it.

Probably a better suggestion as it won't evaporate as fast either making it a little bit safer to use.

 

[G_P]

Kero works wonders on tar. I picked up an old trowel at a yard sale that had been used to apply crack filler on an asphalt driveway. Stuck it in a jar of kero overnight and the gunk scraped right off.

 

[gungatim]

I would use kerosene. If it is tar it will dissolve it.

This. we use kerosene all the time to clean off tar from vehicles and the like. spray it and let it sit. a million times safer than using gasolene...and I would not expect brakleen to touch it, evaporates too fast...

 

[boobag]

i'd rent a powerful pressure washer. use a narrow tip.

using solvents will just be messy it seems.

 

[reader2580]

A really narrow tip on a pressure washer can eat away concrete so be careful.

 

[Kilgore Trout]

I've got a sample of peel-away 7 coming. If that doesn't work miracles, then high powered pressure washer rental is the next step.

 

[LS6 Tommy]

Virginia 10 degreaser. All the tar goes bye-bye!

Tommy

 

[crf731]

Have you tried one of these?

http://t.homedepot.com/p/RIDGID-4-in-Double-Row-Diamond-Cup-Wheel-HD-AWD40/202884364

 

[Kilgore Trout]

Well...

I tried Peel Away 7. It certainly ate away at some of the tar (after about 16 hours of contact time), but removing it all would take many many coats. Even in very thin areas, I was unable to remove it all with a wire brush after using the peel away.

I also rented the 3600 PSI power washer from HD. That didn't do it either. After an hour of trying, there were a few small areas that flaked off, but other areas looked exactly the same. It seemed that if it was going to come off, it came off almost immediately. I even tried 5 minutes on one small (10 square inches) area. No dice. Even the area that I treated with peel away didn't clean off.

Starting to think I may need a professional. I have heard that sandblasting might work. I could also try the diamond grinder, but given that the concrete is pretty rough (concrete mixed with some occasional pebbles) I have low hopes for that as well. Alternatively, I could try sealing it with the same **** that was used before. I imagine it would bind to the old sealer. It just looks like trash.

 

[Platonic Solid]

Sorry it didn't work for you, but it was worth a shot. Just for the heck of it, I'd rough it up with a wire brush - put a good thick 1/8"+ coat on - cover with the wax paper supplied with it and leave it alone for at least 24 hrs. (assuming you can leave the area undisturbed for that long).

 

[DenisG]

Another option might be sandblasting. (No solvents. I think that solvents will just dissolve the tar and soak into the concrete.)

 

[stihlntime]

Have you tried kerosene? It will dissolve tar almost immediately. I've used it to remove tar off of vehicle's many times.

 

[engineer2]

A concrete guy told me that strong solvents like gasoline will just make the tar soak into the concrete more. Don't know about kerosene. I would pressure wash and then sandblast.

 

[Garage Junkie]

This thread got me motivated to tackle the same thing at my house. Someone tried to crack seal with concrete with an asphalt sealer. Needless to say, it looks like hell. I have a 3500 psi pressure washer and it won't touch it. So today I tried diesel and heat. The diesel worked a little bit- perhaps if it had time to really soak it might do more. A plumbers torch worked great to get the bulk of it to scrape right off, but still leaves a mess behind. I only played with it for 30 minutes or so. Results are below: