Instant Concrete

Bought a bag of Hanson Instant Concrete t'other day to repair a step, it worked very well but left me a little confused.

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zoomed into B&Q, grabbed the first bag marked concrete & went. I expected it to be just a small bag of normal dry mix concrete, but it wasn't.

Very fine powder with what felt like 'flakes' of aggregate - certainly nothing like as large as pea shingle. I expected a mixture of cement, sand and a coarse aggregate. This felt more like post crete/fix.

The blurb on the bag claims its stronger than normal concrete, but I though concrete gained much of it strength from the aggregate?

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concrete experts out there?

Reply to
The Medway Handyman
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It may contain fibrous binders. Many modern mixes do, and make very strong results. Not sure what the specs mean about Chromium though.

R.

Reply to
TheOldFellow

Most of the "patch and repair" ones, certainly. I've spent much of the last year filling the parts of my big sheds that weren't sufficiently shed-like with quick tubfuls of Wickes own brand.

Strong, but the surface has poor wear resistance. If you're patching steps, they need epoxy floor paint or similar on top of them, otherwise the wear from normal traffic is ridiculous.

Not just any chromium, but chromium VI or hexavalent chromium (the nasty one). The precursor rocks contain chromium, cement burning turns this to the VI form. In the USA this is seen as a low-risk wide-effect risk for cancer (Erin Brockovich), in Europe it's mostly seen as an acute problem with allergic dermatitis for those handling it - there's a 2005 EU directive about it. In Scandinavia they add ferrous sulfate to control it.

Reply to
Andy Dingley

It consists of:

"Dry pre-blended cementitious material to BS 5838 Part 2, containing, Portland cement and graded sharp sand."

Nothing fancy then, and it contains no coarse aggregate at all. It is hardly a "concrete" mix, not by any accepted definition of the term.

Still, that doesn't mean that it would not work. The key is to control the water content, keeping it close to the absolute minimum required to hydrate the cement.

Reply to
Bruce

Thats what confused me.

Went back to the same site today, its as hard as a rock.

Reply to
The Medway Handyman

It works extremely well. Good enough so that any professional posing as DIYer can achieve acceptable results that a customer will pay for.

Reply to
Steve Firth

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