Using hydrocloric acid to mouldy clean pavers

[advancebooking]

We have old cement pavers outside our shop and during the rain its really slippery and dangerous to walk on.

 

Years ago back home I remember using pool chlorine on the steps which cleaned all mould and made them look new again. I visited a pool shop who had liquid chlorine but when telling them I wanted to use it on concrete pavers they talked me out of it and sold me hydrochloric acid. Now I have a big 25l drum of it and unsure if I should use it or not and go back and swap it for chlorine which is effectively bleach....

 

What do you think? If acid is the best option how am I supposed to pour it out of the large 25l drum without spilling it on myself. If I were to pour it on the pavers and then scrub it using a long handle device, should I then rinse with a hose?

 

thanks

[Fruit Trader]

Hydrochloric acid will attack cement and is good for a one time application to remove cement stains.  Pressure washing is safer on cement pavers and chlorine to kill mould.

 

Down on the farm, a leaking container of fuming hydrochloric acid punched a hole clean through a concrete slab.

[wayned]

I use Vixol bathroom cleaner, purple bottle in the cleaning locutions department in the market, and a long handle wire brush.  It's actually 10% HCL. You have to be very careful when working with HCL, and never try to dilute it by adding water to the acid, always add the acid to the water.  If you add water to the acid the mixture will become very hot and could boil violently and splash out of the container.  I'd take the acid back and use Vixol which is already premixed.

[advancebooking]

7 minutes ago, wayned said:

I use Vixol bathroom cleaner, purple bottle in the cleaning locutions department in the market, and a long handle wire brush.  It's actually 10% HCL. You have to be very careful when working with HCL, and never try to dilute it by adding water to the acid, always add the acid to the water.  If you add water to the acid the mixture will become very hot and could boil violently and splash out of the container.  I'd take the acid back and use Vixol which is already premixed.

I think I will take this advice and return it. Im worried about using the acid...

[watcharacters]

10 minutes ago, advancebooking said:

I think I will take this advice and return it. Im worried about using the acid...

 

That's a wise decision, IMHO.

 

[Snow Leopard]

Ask for chlorine salt instead. Its not difficult to handle. Rubber gloves, goggles and mask. 

[jvs]

like you already mentioned use common bleach,spray it on lightly ,leave for a few minutes and a brush and garden hose will clean it.

The acid will also kill anything that is green and can harm you also.

 

[cooked]

By mould I take it you mean algae? Algae prefer an acid environment, so using acid is just going to increase the speed with which the algae recolonise.

1. Pressure clean

2. Apply bleach

3. Pressure spray again.

 

[moe666]

You would need to dilute the acid, breathing the fumes is a danger in its self. Even the chlorine is not 100 percent safe fumes, splash on your self. Pressure washer lot safer

Edited July 15, 2019 by moe666

[Lacessit]

Algae and mould will come back unless it is poisoned as well. Hydrochloric acid will attack the cement grout between and under the tiles.

Chlorine works best on bacteria in water. It's not so effective with biomass.

I've found the best solution to mould is 5% copper sulphate in water, sprayed on and left overnight. Then clean with liquid detergent, pressure spray with water.

[mahjongguy]

Hydrochloric acid (aka muriatic acid) is definitely overkill. We use ordinary household bleach on the shady areas of the driveway. Let it sit briefly and scrub it off with a long-handled brush. Rinse with the garden hose. Use eye protection and wear old clothing.

 

Pressure washers are effective but if used with any chemical that will get vaporized and easily get into your eyes and lungs. So will the mold.

[eyecatcher]

HCL is used in the building industry for cleaning cement, mortar stains off brickwork and really cleaning up that concrete wrap around your shovel.

it is of course diluted HCL.

Always handy to have for domestic purposes like getting rid of that tile grout mark you never got around to cleaning but for organic growrths and mildews, a stiff brush and bleach is your game here.

[eyecatcher]

On a different point, that of chlorine salts.

We had a period where a couple of the local dogs thought my drive entrance was the latest "hong nam"

 

After catapulting "hin" at them, hosepiping them and introducing them to the wife they continued to create a hazard.

Wifes friend suggested i mix chlorine in a bucket with water (yes i was almost gassed just like when you go for a piss after the wife has poured bleach in) and chuck it across the entrance.

Useless it was, it was such a performance that after three nights i gave up and reverted back to catapults at 30m

Thought i would just rule chlorine out fwiw...

[tutsiwarrior]

HCl is a deadly corrosive and the fumes alone are enough to kill a man...on industrial applications where I've been (chemical cleaning for high pressure carbon steel pipe) they won't let the stuff on the site unless it's handled by folks that know what they're doing and special attention is given to the passivation and disposal of the waste...there are specialised outfits that handle all of it...

 

if yer just wanting to clean some concrete there has to be a better way...sounds like some somchai saw yew comin' when he had some shit that he couldn't unload...

 

 

[lemonjelly]

Just sluice it down with a cupful of household bleach to a bucket of water once a month, it’s usually sufficient 

[advancebooking]

4 hours ago, tutsiwarrior said:

HCl is a deadly corrosive and the fumes alone are enough to kill a man...on industrial applications where I've been (chemical cleaning for high pressure carbon steel pipe) they won't let the stuff on the site unless it's handled by folks that know what they're doing and special attention is given to the passivation and disposal of the waste...there are specialised outfits that handle all of it...

 

if yer just wanting to clean some concrete there has to be a better way...sounds like some somchai saw yew comin' when he had some shit that he couldn't unload...

 

 

im taking it back today to swap for chlorine. its worked for me before

 

[dzodun]

In this whole sequence I did not see one reference to the fact that muriatic acid is

commonly used to etch old concrete before painting. You will find instructions on any can of paint that can be applied to concrete to first "etch" the surface with a mild solution of muriatic acid before painting. This is because the surface of bare concrete constantly "hydrates" over time. As it absorbs water the surface is gradually decomposing. This decomposition must be removed so the new paint will have a solid substrate to bind to. Frequently an older, generally exterior, surface must first have algae and mildew removed with a bleach solution as mentioned above before "etching". After each step the surface should be neutralized with copious amounts of water. Before painting the substrate should be allowed to dry thoroughly.