Clay can be alkaline or acidic and more often alkaline. I think the problem is that the grain size of clay is so fine, < 2um and asphalt is porous. So I suspect the small particulates have leeched into the asphalt.
Clay is somewhat plastid in water, so water will not be a good solution. Perhaps you might try dehydrating the stain with a heat dryer and then attempt to use high pressure air to blow it out.
Other thought was some sort of oil mix to paint on the stain? It may not match so well if the asphalt is weathered, but over time I think it might blend.
It will fade naturally with time.
If someone is worried about a driveway being dirty why are they driving a vehicle on it?
Do they get out and wash the tires before they park the car?
What about grass clippings and bird poop?
My god! Someone should put a roof over it and walls around it to keep it out of the weather!
But wait, then the roof will get wet and birds will poop on it too. Oh no its a never ending OCD spiral! Help mee, Help meee!
Seriously its a driveway. They just get like that.
Darn right!
You dont see me worried about a dirty driveway.
If God didn't like dirt everywhere why did he build the planet out of it?
The as constructed example obviously shows clean and organized was far far down on the list as I see it!
So who am I to question or assume cleanliness was in his plan!
I clean when I am stressed. I also take medication for stress. When I start cleaning know it time to get back on the meds. My place maybe dirty but to me that just says the medication really does work!
If it's a freshly paved driveway I can understand their being some sore feelings, things like that are only new once. Then yer neighbor comes stomping over with clay on his boots and ruins the whole thing! =)
If God didn't like dirt everywhere why did he build the planet out of it?
The as constructed example obviously shows clean and organized was far far down on the list as I see it!
So who am I to question or assume cleanliness was in his plan!
That's a great idea Sceadwian. You can get different tips from 30 degree all the way to zero. That one will cut a brick in half.
I rent one every year for sidewalks, driveways, side of the house and vinyl fencing. I never realize how dirty my sidewalk is until I pressure wash it.
My house is cluttered but not dirty. The few things that have ever been in any pictures I have posted here are not as filthy as they look. The camera flash tends to make a little surface dust look worse on the pictures than it really is.
But no argument on the needing a good clean up though.
As far as my work spaces thats my way and I am happy with it as is.
If I couldn't find an advantage to working that way it would not be that way.
I am a stickler for work efficiency not organization!
I would begin by using CLR and a pressure washer. If that fails try muratic acid since it's an etchant. It's available at swimming pool chemical supply centers. Always try the solutions on small test areas first. As for a Karcher brand pressure washer, those are junk. I've gone through self-car washes that have more pressure than a Karcher!
Real pressure washers use gas engines and Comet, CAT, AR brand pumps.