Phosphoric acid for etching concrete 1

[gelb993]

Is phosphoric acid as effective as muriatic acid for etching concrete? I am concerned about the fumes created with muriatic acid.

 

[unclesyd]

It is not as effective as HCl in cleaning concrete, but it is a lot less trouble to mess with for the reasons you state and a few others. Be reminded we have had some complaints on the odors generated from H3Po4 in an enclosed space. The vapors go pick up by central air due to an dumb operational error.

We use H3PO4 in lieu of HCl to clean concrete for the application of Vinyl Ester flooring coverings in open chemical process areas. A lot of reasoning is that there are many crevices where SS piping would be exposed to Chlorides. We also clean concrete with H3PO4 for the application of Furane Cement.

In enclosed areas we use H3PO4 for preparation of concrete for the application of Epoxy floor coverings.

 

[gelb993]

I would be using it for one of the applications you mentioned. "In enclosed areas we use H3PO4 for preparation of concrete for the application of Epoxy floor coverings."

I intend to use epoxy floor finish in my personal garage. I had the concrete power trowelled so it's rather smooth in a lot of places. I really just need to open the pores of the concrete.

While I can have the garage door opened I don't want the fumes to damage any electronics or fade any paint. For such an application would H3PO4 be sufficient?

Thanks

 

[unclesyd]

For most epoxy coatings H3PO4 is quite sufficient provided that you follow a few simple guide lines. If possible I would buy a proprietary H3PO4 concrete etcher as it has wetting and rinse agents incorporated in the mix.

Try a small spot near the door to see if your concrete has a sealer on it. If it has a sealer you may have to rent a machine to abrade the sealed surface. Check with the coatings manufacturer about this.

The one thing I've seen most is that people don't thoroughly rinse off the acid and let some of the acid dry on the concrete surface.

If you want to test the PH you can use some swimming pool test strips.

Here is some very good information about etching concrete for epoxy coatings.

http://www.epoxyproducts.com/acid.html

 

[gelb993]

My concrete is 6.5" to 7.5" thick, fiber reinforced over welded wire on 3" upper slab bolsters. The 7 day test showed 3860 psi and the 28 day test showed 4640 psi.

I did not left them us any curing compounds or sealers.

Final ph needs to be between 8-10.

Thanks again for advice.