Is a fair bit of concrete. Some very old, some new but rubbish. All heavily ingrained with black foundry soot. Some covered sporadically with self levelling compound (that didn’t) and some with several layers of various grades of epoxy floor paint.
How to deal with that, get it reasonably flat, level, and where it was weak, made strong. How to get rid of what appeared to be occasional steel joists burnt off at floor level, lower or out altogether. Just how?
Lots of research later, after considering options as – do it all at once, get someone in. Impossible, where does the stock go and the cost was horrendous. Dig it all out in sections and start again. Price and time = nope. Diamond floor leveller, that may work, but expensive on wearable parts. Machine hire very expensive given how long it would be needed (months)
A floor scrabbler, Hmm Interesting toy. Does the job, can be had second hand, just messy. Oh boy are they messy. Dust lie you cannot believe, naughty, nasty hi silica concrete dust. Even with industrial extraction and air filters – it pervaded everywhere.
We needed to remove between 5 & 10mm of the top layer.
This exposed steels (everywhere) and so many weak areas, patched areas, channels, internal railway tracks for the molten steel. real aaaargh moments. Lots of them.
First, under an old section of racking, a small hollow area showed up. That got bigger and exposed a steel I beam, followed by another, and another. The entire hole, when finally emptied took nigh on 3 tons of concrete to fill.
Concrete. Is just concrete yeah? Nope. I researched how to make it A) strong, and B) flow correctly. Found all the grades I could and settled on 1:1:2 and then add super plasticiser. Thats Cement:Sand:10mm gravel by the way.
Superplasticiser is pretty amazing stuff actually, and comes in liquid or powder forms. Concrete gets stronger the less water you add, but without water, how does it flow instead of just being a pile of un responsive sand and stone? Add the superplasticiser at the set rate (250ml : mix in my case) and something most odd occurs.In the mixer it is close to a dry mix, that would be impossible to work. Add the gunk, and 10 – 30 seconds later, what water is already in there is foced out and the entire mix turns to a very thin almost soup consistency, that flows like water. But the mix does not segregate out to be stones and sand and water, which would be disaster.
Science lesson over – Super plasticised cement became one very, very useful tool to have at hand – from filling holes, to casting continuous padstones for steel lintels, the concrete physically flowing the entire lenght on a steel beam without any issue.
Once the decision was made to get a scrabbler, and the associated hardware, we could begin in stages. Thankfully stages worked.
Not just any old floor levelling compound went down, but proper industrial stuff that could withstand forklift traffic, heavy machines and workshop hardware without any strain.
Rockbond Industrial floor screed does just that job :-
Once dry, a very strong, clean finish was needed, again that can handle warehous traffic. For that we decided on Britannia Floor paints two pack system. Worked rather well, and looks pretty good I think.
Ill add some images here, and add more later with little more explanation, probably.
