Hey guys I was at a job the other day day and the customer asked me to test clean his concrete patio. Its at a wedding place and they are pressurewashing it every week but it takes them hours because they have to go over and over it because they get lots of streaking. I cleaned 3 squares for them, 1 with just water and a hard surface wand, 1 I pre sprayed, and 1 I presprayed and ran over it with a crb with medium brushes on it. They opted to go with the just water cleaning so I went back and cleaned it yesterday. I still just used water but I used my spinner instead of the hard surface wand. I cleaned in both directions plus at the end I quickly went back over it all with the hard surface wand. This is what it looked like when it dried, I go back in the morning to redo it all but any suggestions are appreciated.
Concrete
- Thread starter jwfoulk12
- Start date
Old Coastie
Supportive Member
If that is stamped concrete or mortered blocks, it looks as if the patio has been washed to the point of removing cement and exposing aggregate. That always occurs unevenly.
It always looks streaky because of the uneven texture.
My suggestion is to explain that due to weekly pressure washings, they have simply altered the surface. You could use a post-clean spray of bleach with a slug of detergent (for wetting and foam to see how it is covering) and then let it dry. It will look bright and nice. Subsequent washings should be lower pressure and detergent, just to remove soil without disrupting the cement.
You could also propose an external sealant be applied, although that can lead to problems later if bloom occurs underneath.
It always looks streaky because of the uneven texture.
My suggestion is to explain that due to weekly pressure washings, they have simply altered the surface. You could use a post-clean spray of bleach with a slug of detergent (for wetting and foam to see how it is covering) and then let it dry. It will look bright and nice. Subsequent washings should be lower pressure and detergent, just to remove soil without disrupting the cement.
You could also propose an external sealant be applied, although that can lead to problems later if bloom occurs underneath.
It was poured with the aggregate puposefully exposed to give it a little more texture. Something in what I did caused this checkerboard pattern though and I'm not sure what. Will a detergent and crb with stiff brushes help me out here?
dgardner
Moderator
Looks a lot like the rebar pattern showing through. It never looked like this prior to your cleaning?
If you run your hand over the surface can you feel a depression over the pattern marks or is it only visible?
If you run your hand over the surface can you feel a depression over the pattern marks or is it only visible?
It didn't look like this prior to cleaning and didn't look like this after my test cleaning but i had only used a hard surface wand at 1200 psi. When I did the cleaning I used my spinner and went back and forth over it and then side to side using only water. These are just pics that they have sent me. I have yet to see it in person. Its raining here today and you can't see it in the rain.
Russ T.
Supportive Member
Was it still damp, or might it go away as it dries?
It does look like the rebar pattern.
I can't imagine how you would cause that pattern with a cleaning
It does look like the rebar pattern.
I can't imagine how you would cause that pattern with a cleaning
dgardner
Moderator
Agreed.
That was apparantly how it dried but im not sure. Its still rainy and dreary out today but they have a wedding this weekend so I'm gonna go back and redo it this morning. The plan is to prespray with flex and hit it with the crb with black brushes, then rinse with the hard surface wand.
Old Coastie
Supportive Member
I really do not think you caused it or can scrub it out (unless it is partially caused by rust.)
There are solvent-based sealers that penetrate and last for years. A good buff-colored driveway sealant would work wonders.
There are solvent-based sealers that penetrate and last for years. A good buff-colored driveway sealant would work wonders.
Goomer
Member
Streaking from P'washong is a result of poor/erratic lance technique/control, and possibly too narrow of a tip (degree) and or too high pressure for the application.
NO WAY you caused such a perfectly spaced pattern, but likely just exposed it.
You need to inquire about the history of the patio, specifically, what was on top of it previously?
Did they have paving stones or some type of other flooring surface ON TOP of the concrete for an extended period of time??
You need to get them to fess up in regards to what they had over it previously and nip any blame on you in the bud.
With concrete being porous, any discoloration that does not respond to p'washing is most likely deeper beyond the surface and set into the pores.
Just like dealing with porous grout stains, an acid (Muriatic) may work by etching a thin layer away, but of course will only fully correct the issue if the discoloration is only within the thin, acid removable top layer, and not deeper.
Be VERY careful with Muriatic acid if you have never handled it before, and read and follow the directions VERY carefully.
Test first and guarantee nothing.
NO WAY you caused such a perfectly spaced pattern, but likely just exposed it.
You need to inquire about the history of the patio, specifically, what was on top of it previously?
Did they have paving stones or some type of other flooring surface ON TOP of the concrete for an extended period of time??
You need to get them to fess up in regards to what they had over it previously and nip any blame on you in the bud.
With concrete being porous, any discoloration that does not respond to p'washing is most likely deeper beyond the surface and set into the pores.
Just like dealing with porous grout stains, an acid (Muriatic) may work by etching a thin layer away, but of course will only fully correct the issue if the discoloration is only within the thin, acid removable top layer, and not deeper.
Be VERY careful with Muriatic acid if you have never handled it before, and read and follow the directions VERY carefully.
Test first and guarantee nothing.
Russ T.
Supportive Member
Put some fans on that thing and let it DRY!
Rebar is showing through, it takes forever for it to dry. Especially since the surface has been compromised so many times by their pressure washing.
Rebar is showing through, it takes forever for it to dry. Especially since the surface has been compromised so many times by their pressure washing.
dealtimeman
Everyday is Saturday.
Read above post.
No way you caused this, if you did you would have just nailed a nitch market and many many people will want you to ghost patterns into their concrete like the one above.
That is almost a perfect grid, let it dry and I mean for a few days. And it should go away.
No way you caused this, if you did you would have just nailed a nitch market and many many people will want you to ghost patterns into their concrete like the one above.
That is almost a perfect grid, let it dry and I mean for a few days. And it should go away.
Goomer
Member
Rebar??
Kinda makes sense, but if that is the case, what went wrong?
Rebar way too shallow?
Never seen that before?
dgardner
Moderator
According to the info I was reading, either caused by rebar too shallow or stiff concrete along with lack of proper compaction (vibration) during the pour. Voids under the rebar cause settling and a tiny depression to form.
Never actually seen it myself either.
Never actually seen it myself either.
Russ T.
Supportive Member
Dan said it.
It just cured a little funny. It'll go away when dry. DON'T go throwing muriatic acid at it
I hate that he went back and cleaned that again
It just cured a little funny. It'll go away when dry. DON'T go throwing muriatic acid at it
I hate that he went back and cleaned that again
Goomer
Member
How does it only show when not fully dry??
Is it rust leaching through?
Is it rust leaching through?
Russ T.
Supportive Member
I'm not even sure but im absolutely convinced that is the rebar pattern
Russ T.
Supportive Member
The darker areas are the low spots. That's just my best guess
Goomer
Member
Interesting.....................Keep us updated Justin.
Ron K
Member
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- Jan 3, 2009
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- 2,371
Top picture right side edge squares look scalloped, not square shape as reBar would be.
Bob Hauser
Member
- Joined
- Nov 15, 2006
- Messages
- 46
in the first pic you can see crop circles at the edge of patio. you need to over lap more . using a 175 will help have fun
dealtimeman
Everyday is Saturday.
It looks like either moisture lines or exposures lines from extended contact to light or chems filtering thru some material laid in a grid formation.
Just like when you remove vct tile from concrete after many years. The grid will never go away.
Just like when you remove vct tile from concrete after many years. The grid will never go away.
dealtimeman
Everyday is Saturday.
How smooth is concrete
It has a rough texture from the aggregate but all in all it's fairly smooth. Idk why they would have never seen the lines before in all their pressure washing. The guy that owns this did all the concrete work and does some amazing work with stamped and decorative concrete. It's been pretty crappy out the last few days but is supposed to be nice most of next week. I want to figure this out and the best way to keep it clean as they are talking about having it done every week.
Old Coastie
Supportive Member
They'd do better spraying a non-acidic biocide every week (if that is even necessary). Pounding that surface 52 times a year is absurd.
Spurlington
Member
My first thought was rust bleeding through .. how about a good cleaning and a nice COLOR SEAL !!
FredC
Village Idiot
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FredC
Village Idiot
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Goomer
Member
If that's ghosting, then somebody is reeeaaaally fooking anal with laying rebar sooooo perfectly spaced across the entire pad.
I think there is more to the story you are not being told.
I think there is more to the story you are not being told.
FredC
Village Idiot
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- Jul 13, 2011
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thats not unusual........
plus you can get it like this:
http://www.homedepot.com/p/42-in-x-84-in-Sheared-Welded-Steel-Wire-06415/206514118
