Cleaning concrete

[Grumpy John]

I've got some rust and tannin stains in the concrete apron in front of my garage and was wondering if hydrochloric acid is the right product to do the job.

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[tea lady]

Someone at Bunnings should know!:D

[dj_pnevans]

Should work give it a go.
David

[Ironwood]

When I'm using Hydrocloric acid to clean concrete, I dilute it 5:1 with water.

Maybe do the spots first, to try and remove the worst of it, then do the whole area to get an even look.

[Big Shed]

I have successfully removed rust stains from concrete using Oxalic Acid.

[HazzaB]

Hey there,

Wasn't there a post about flattening sharpening stones, someone said that it cleaned their concrete, get a few mates to come over and give the driveway a bit of a scruffin'

Otherwise the diluted Hydro acid, and yes I'd do the spots first, then make sure that you rinse it really well or you will be getting little white fluffy bits popping up for ages.

HazzaB

[michaelxslx]

Hey, perhaps this might help. There are a bunch of instructions and documentation re. concrete surface preparation. Perhaps something related to cleaning concrete as well?

Cheers.

http://www.polishedconcretemelbourne.com.au/surface-preparation/

[Grumpy John]

Thanks everyone for their input. I mixed up a batch of oxalic acid today at the recommended rate (250g/ltr water) and applied it with a stiff brush after using a pressure washer to remove excess grime. It didn't do too bad a job, got rid of the rust stain and most of the tannin stain. I might give it a go with hydrochloric acid in a week or so. One thing I found out is that although my pressure washer works on tank water with gravity feed it is nowhere near as powerful as when used with mains pressure. I may have to invest in a cheap pump if I'm going to use the pressure washer on a regular basis.

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