cleaning concrete building

[soluble solutions]

We have been asked to give a bid on cleaning a 80 yr. old concrete building. I would post pics., but don't know how (tried). The building has dark, mold,mildew and other pollutants on it. It's not bad every where, but around window sills and door ways are the worst. What I want to know is what some of you more experienced guys are using to clean such surfaces. I'm concerned due to the fact that the public (people traffic) is involved and there is grass and decorative vegetation (landscaping) around building along with trees. What am I looking at chemical wise, or can I just remove with pressure and heat? I've read of people using both, but what is the most effective way that is going to get this building clean. If you guys utilize chemicals....what types? If anyone would like pics., I have several, but could probably just email them to you. Any advice would be great. I have about a week and a half to put together a proposal.

Also tried the search, but couldn't really find what I was looking for info. wise. We've done a lot of flat work, but not a lot of big concrete buildings.

Thanks, Steve

[814jeffw]

Pictures would be nice. But anyhow, if I were doing this I would use a basic mix of sodium hypochlorite and sodium hydroxide and maybe something added for a little cling on vertical surfaces. Those two products together make for a very good cleaner. Because of the vertical surfaces you may want to have 4%-6% chlorine hitting the wall. Not sure how you're applying so I can only give you what I'd do in a 35 gallon tank of final mix. I would add 12-15 gallons 12.5% Hypo and about 2 lbs. of the hydroxide. If you're not familiar with hydroxide you may want to use something like simple cherry, I just prefer the hydroxide. Just keep all the plants and surroundings wet.

Jeff

Jeff

[big mike]

Steve,
We've done several of these, and the cleaning method varies with each. Do a search on "tilt up concrete". I can't believe that the building is 80 yrs old? I didn't think they started using concrete for exterior walls til the 60's.

Anyway, check on EacoChem's site and look up Safe Restore. A 4:1 dilution has worked well for us in the past, but testing is paramount. I doubt that hypochlorite or hydroxide will do anything on that porous of a surface. Hydroxide works well on flat concrete for oil stains and such, but I think you'll need an acid to clean the building. Also, you describe the staining around the window and door areas, and that sounds very much like mineral deposit staining from aluminum window frames and/or caulking. Don't fool yourself, this requires careful consideration and testing before submitting a bid, and could be a very costly "restoration" job, not just a simple wash.

[soluble solutions]

Big Mike, you brought up a very important detail. yes, you would be right. The building is not actually concrete...it is cut stone. I was doing a lot of research yesterday evening and I guess I had concrete on the brain. This is a large cut stone building that resembles the look of concrete. I will be meeting with the general maintenance guy who cares for the grounds and will have to find out a little more information. Just took an initial look and walk around to see if we could attempt or not.

Steve

[814jeffw]

I'm sorry, I thought you were talking about removing heavy mold, in which case a combination of hypo and hydroxide is tough to beat. You wouldn't need acid to clean mold. And the hydroxide would also attack any type of airborne dirt. Works on other stuff than just flat work and oil stains.

Jeff

[Tracy Handl]

Strong products on some stones can actually create stains. Try to be as mild as effectivly will clean. Pre wet prior to applying any cleaners so the cleaner stays towards the surface and the water is sucked intothe pores makeing rinsing easier.