[Renerabbitt]

As the title implies, last day of work and my apprentice when left on his own used a needle point nozzle on the company power washer and scribed lines into concrete slab on an outdoor patio.
I'm new to these forums, would appreciate any help to try and make this patio look presentable once more. The needle point scored and even exposed some of the aggregate in the pad
Rene

 

[svronthmve]

Welcome to CT!

Pics always help, but here's what I did.

You can try going back over the whole area with a fan nozzle on high pressure and holding it close (6-10" away) to clean away whatever is the surface. This may be time consuming depending on the area size. This worked well for me on flagstone one time.

Or you could try spraying on some Purple Power OR muriatic acid and quickly scrubbing and pressure washing again with a fan nozzle. (I'd test in a small area first to be sure it will work.) You may not want to do this if there is vegetation nearby. Speed is essential with this also. You don't want to leave either product on very long.

Neither of my suggestions will fix your exposed aggregate problem.

Depending on how deep, you may or may not be able to skim coat those areas. Quik-Crete makes a super high strength skim coat product. You'll have to assess whether to spot skim or coat the whole area for aesthetics/customer satisfaction.

Good luck & keep us updated. Oh, and head over to the intro section and tell us a bit about yourself!

 

[Everett Abrams]

Sounds like too much direct pressure and damage already done. Once this happens you are usually in repair mode. When using a pressure washer it needs to be understood that pressure does not clean. The proper way, no matter what the substrate, should be to apply the right cleaner or chem to a surface and allow the proper dwell time for the product to work. Then use the pressure washer with the least amount of pressure to "rinse" with. When using a pressure washer to clean with it should be used as a big rinsing tool. Before trying repair it might be a good idea to call a local contractor who pressure washes regularly and has a surfaces cleaner and chems, which helps avoid striping, and has experience in this type of damage and "evening" it out first. It happens more often than you think.

 

[Supahflid]

Sounds like too much direct pressure and damage already done. Once this happens you are usually in repair mode. When using a pressure washer it needs to be understood that pressure does not clean. The proper way, no matter what the substrate, should be to apply the right cleaner or chem to a surface and allow the proper dwell time for the product to work. Then use the pressure washer with the least amount of pressure to "rinse" with. When using a pressure washer to clean with it should be used as a big rinsing tool. Before trying repair it might be a good idea to call a local contractor who pressure washes regularly and has a surfaces cleaner and chems, which helps avoid striping, and has experience in this type of damage and "evening" it out first. It happens more often than you think.

Listen to this poster, OP. I would also add that you might be able to LIGHTLY grind or polish the concrete (as in a walk behind type not a hand held grinder and also by a contractor that performs this type of work) surface and take away enough of the concrete to eliminate the unsightly marks. Whatever you do, test a small area before going whole hog.

 

[Metro M & L]

You might also be able to grind out the lines with a rotobrush. If youre not familiar its basically a point nozzle that spins in a conical fan. Its a beast. Im pretty sure it would work in evening it out.

On a side note; take the point nozzle of the washer and throw it away or keep it in the truck.