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Removing high pressure washer marks

The concrete drive for our new house was poured in May this year. The driveway has not yet been sealed.

In mid-November, bricklayers working on a house next door tracked a lot of heavy clay mud onto our driveway. By the time the bricklaying was finished the mud had dried and hardened.

The workers tried to remove it with water and a broom but that didn’t work. They then brought in a pressure washer and, using a narrow, high pressure spray, were able to remove the mud.

Unfortunately, when the driveway was dry we discovered that the spray had left marks all over the parts of the concrete that had been mud-covered---as though someone had used a stone to draw designs.

The man who poured the driveway has checked the marks. According to him there is no sign at all of spalling. He said that over time the rest of the topmost layer of the concrete will wear away and the markings will not be noticeable.

We would rather not live with unsightly markings until that happens and the bricklaying contractor is prepared to do what is necessary to bring the concrete back to its original state.

We have had a number of suggestions about how to remove the markings and would appreciate any comments or recommendations on them:

1. The man who poured the driveway suggested using a dilute solution of muriatic acid, saying that it would hasten the removal of the topmost layer of the concrete.
2. Someone suggested using a rotating fiber brush, working across the driveway to preserve the ‘brooming’ ridges.
3. Another person suggested using a darkish sealer (the markings are not very noticeable when the concrete is wet).
4. Yet another person suggested ‘painting’ the concrete with a thin mixture of water and cement to cover up the markings, and when dry, sealing it.

We live in Ontario Canada and winter has arrived so we will not be attempting any repairs until the spring.

In the meantime, we would really appreciate any advice.

Re: Removing high pressure washer marks

You might try a solution of Muriatic Acid which will etch the concrete and may camouflage the damage. This is powerful stuff so be sure to use rubber gloves, shoes and be careful of the fumes, etc. There are directions and precautions on the bottle.

Re: Removing high pressure washer marks

Well........this is what happens all too often when a pressure washer is put in the hands of a novice. And I will assume that these guys were novices with a PW in that they evidently didn't own one, but rather bought one. FWIW, I feel your pain...and can picture what it is that you're looking at now. Ugh.

Advice = 1 - no muriatic acid. This will degrade and destroy the surface of the concrete to some degree. I personally wouldn't do that. 2- "Painting" the surface with a thin layer of concrete? Laughable. This will create another & different problem - flaking layer of concrete. 3- Rotating brush........maybe, but big maybe. Won't likely do any real harm, but might not result in a visually uniform surface either (color-wise). 4- Sealer- another maybe. *Might* make it more visually uniform, but if it doesn't, then you're fighting thru that sealer in further attempts to achieve what needs to be done.

I guess I would wait to see what spring brings before doing anything...or getting indigestion over the current situation. Time heals all wounds......eventually. If things haven't evened out by then, I would likely mount a 15 or 20 degree nozzle on a PW and very methodically (and very slowly) PW the entire surface with that. This would be done with the nozzle approx. 6" from the surface. Might take more than one pass to get it uniform, but it can be done. The objective is to get the surface uniformly "clean", if you will. IOW, a uniform amount of dirt left lodged in the pores of the concrete everywhere....or no dirt anywhere. Either way, visual uniformity is the goal.

If the guys who did this had a little more patience (and experience) they would have simply soaked the dried dirt/clay with water and let it sit (keeping it wet, of course)...for an hour or two (or eight hours if necessary) and then washed the surface off with a 15 or 20 degree nozzle on a PW.....or even with a garden hose. Instead they tried to rush it and used a zero degree nozzle. Rarely does anything good come from this approach.

Re: Removing high pressure washer marks


Thanks so much for the help!!

What a wonderful website this is!


Re: Removing high pressure washer marks

My old boss is just the guy for you! Only thing is he lives and works in Texas power washing tractor and trailer fleets :(. He's been power washing for 35 years and he can get a bugged up, muddy, filmy tractor to sparkle in 4 mins. He designs his own machines, burners, soap and electronics that can call soap and rinse modes by two quick pulses with the trigger. The guy's a genius! So my best advice is to find someone in his league and have them blend it out like nothing happened. He would probably be using a unit similar to thisbut as far as how he would dial in his pressure, heat, tip, soap on the fly is beyond my scope :confused:.

Re: Removing high pressure washer marks

Thank you for your help!!!

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