Concrete hasn't been cleaned in 23 years

So I have been gathering all my supplies and equipment to start cleaning concrete as a side gig. I have cleaned my own and my parents that gets washed off pretty regularly, but never power washed. That went pretty smooth and turned out well.

My grandparents asked me to do theirs, their concrete has not been washed at all in the 23 years that they have lived in the home. What SH mix ratio would you all recommend for this? All that I have available locally is 10%. I have a 4gpm machine and a 15" surface cleaner.

Thanks in advance.

You have the machine, the surface cleaner, and the SH - so in theory, you can get the job done just fine. But, what we don’t know are things such as:

  • what are you trying to remove from driveway
  • condition of driveway surface
  • slope/grade of driveway
  • where runoff will go
  • method of chemical application
  • surfactant

All things to consider when looking at a driveway, whether it is washed yearly or every few decades.

Regarding mix ratio, sometimes a “standard” housewash mix is sufficient, but sometimes you’ll want 2%, or even 3%. And there’s nothing stating you couldn’t apply 6% if that’s what you wanted to do…but it wouldn’t be very cost effective, the fumes would be overpowering, and there a good chance you could ruin some landscape. You can always take some SH, water, and surfactant and mix them in a spray bottle/pump sprayer and see how that works for you. Do different ratios of water to SH and see what you find to most effective for your job at hand. And, this is assuming that you are wanting to use SH to remove mildew. Oil stains, tire marks, rust stains, paint overspray, etc are not going to be phased by SH.

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Always post pictures. Including close ups and showing the surrounding areas.

Here are the before pics. I used 3% SH mix. Then hit it with the surface cleaner.

Here are the after pics. I think it turned out well.

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Looks good! Try the next one using just around a 1% mix and see what you think. For concrete, I’ve never needed more than that. I tried stronger mixes and all I really noticed was more suds since I use the same SH/surfactant mix, just different ratios when applying it. Didn’t seem to make washing any faster going stronger. Definitely not faster enough to justify using 2-3x more SH mix.

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Will do! Thanks for the advice!