How long for commercial concrete to cure

How long does it take for commercial concrete to be ready for pressure washing?
Is 8 GPM @ 4000 psi too much on 1-2 year old commercial concrete?

What about 6 month old commercial concrete?
 

Nick L

New member
Test. I would be extra cautious with the new concrete. We have a account that we first started when it was poured a little over a year ago. First few cleanings we just soft washed, after 6 months I started testing with lower pressure and a surface cleaner. It seemed that the areas of concrete that did not get much sunlight did not do good while the concrete that got a lot of sunlight was stronger in the early months. I don't think there is a set age when concrete is ready for specific psi. Test it and see how it holds up.
 
Gonna be using some 40 degree tips on the 1-2 year old location. I'll go behind the dumpster or something first to do a test. I've never messed up concrete before. What exactly am I looking for?


Edit: just found out one of the locations had their grand opening in November 2012, so the concrete should be at least 2 years old.
 

Nick L

New member
Gonna be using some 40 degree tips on the 1-2 year old location. I'll go behind the dumpster or something first to do a test. I've never messed up concrete before. What exactly am I looking for?

Look at the color of the run off from the surface cleaner. If it's a milky color look close at the test section to insure there are no surface cleaner swirls etched into concrete and the cream is intact and looks uniform. That milk color run off will dry white so, if the run off goes over the lot you need to rinse that as well. Low pressure and test.
 

Christopher

Moderator
Concrete cures for over 30 years getting harder and harder.

I would not ever use more than 3000psi on concrete but after testing all the time, most concrete cannot handle over 2000 to 2500psi or the creme comes off, too many concrete contractors taking shortcuts and delivering weak pours to save them some time and dollars.
 
Thanks guys.
I think mine has a height adjustment.
I hate 4000 psi.
I wish I had known the things I knew now, when I bought these machines.
Gonna jack this sucker up and do some tests.
Hopefully it holds up bc I'm in no mood to soft wash this whole thing.
It's a decent sized lot.
Anyways, thanks for the advice again guys
 

Jesse Vincent

New member
My pump is rated for 4 gpm 4000 psi. My machine says it's 4.8 gpm 3000 psi. When I ordered a new pump I found out that hydrotek had special permission to over rev the pump to achieve 4.8 gpm and 3000 psi. So maybe you could change the pulley on the pump or motor and maybe get more gpm and less psi, or maybe use larger nozzles to adjust the psi. That's just what I experienced with my pump yours may be different.
 
Hmm, sounds interesting. Wish I were mechanically inclined enough to know about all that. Might give Russ a shout. The oversized nozzles is also a good idea, but I'd love to have 4.8 @ 3000 without having to buy a new pump!
 

nibbsy

New member
While Christopher is correct, “Concrete cures for over 30 years”, effectively concrete is cured after 90 days.

I find it hard to understand the issue with the removal of cream from commercial grade concrete, 5000 – 8000 psi (34-55 MPa).
If it were an issue, then I would suspect the costumer did not get the concrete grade that they paid for.

Jeremy, a 4000psi machine will do everything that a 3000psi can do but a 3000psi machine will never clean to the same level or rate as a 4000psi machine. (given the same GPM)
If you want to lower the pressure of your machine, just increase the tips size that you are using.
 

nibbsy

New member
Having said what did below, I hit some soft concrete last night. I suppose you can never be too careful.


While Christopher is correct, “Concrete cures for over 30 years”, effectively concrete is cured after 90 days.

I find it hard to understand the issue with the removal of cream from commercial grade concrete, 5000 – 8000 psi (34-55 MPa).
If it were an issue, then I would suspect the costumer did not get the concrete grade that they paid for.

Jeremy, a 4000psi machine will do everything that a 3000psi can do but a 3000psi machine will never clean to the same level or rate as a 4000psi machine. (given the same GPM)
If you want to lower the pressure of your machine, just increase the tips size that you are using.
 
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