Rebuilding a concrete step

[Andy Dingley]

The pair of steps up from the loading bay into the main workshop have long been broken. They're concrete and it seems that the top inch was poured separately, and is now breaking away. Like most of the ad hoc concrete work in this place, it's not well done. Clearly I need to re- pour a new top.

Any advice? I know nothing of concrete or wet trades stuff.

What sort of mix? There's a gallon of SBR additive here that I've been using to weatherproof where I've been grouting my outdoor crack repairs. Any use?

Any bonding additive? I'd expect to use PVA, but given that it's a thin layer on a step, do I need to do anything else? Drill and stud the underlying substrate?

Any advice on technique for step building?

Thanks

[Tabby]

PVA is not suitable.

NT

[therustyone]

Some American data on concrete repairs at

select RAP-7 =97 Spall Repair of Horizontal Concrete Surfaces

They suggest using a 100% cement slurry as a bonding agent after cleaning. I did this on a broken concrete driveway with no problems for 6 years.

rusty

[Nightjar]

I have always used epoxy cement for patch repairs on steps. It is not cheap, but it is permanent. A repair I did in the early 1980s still looks as good as when it was first done. It will also work at any thickness, right down to a feather edge.

Colin Bignell

[Andy Dingley]

Bit pricey for this. It's less of a patch repair, more a whole new top layer.

[Tim Watts]

Andy Dingley ( [e-mail]) wibbled on Sunday 06 March 2011 12:33:

OK - then as previosuly mentioned, SBR is your friend.

Remove loose material, then soak the top of the step in 1:4 diluted SBR:water - couple of times if very absobant.

Mix a string mortar, with SBR as per datasheet (I'll look it up if you can't find it, but google for cementone and everbuild sbr - both manufacturers had application datasheets for download.

In a small bowl mix a cement/SBR/water slurry and paint on the old step.

Apply mortar immediately while slurry is still wet and work in the usual way (I find a metal float works best).

Clean tools asap.

The various pretreatments will ensure a strong bond between new and old and there will be some depth to the bond thanks to the initial SBR priming. Once cured, the result will be extrememely water resistant and mechanically much stronger than you would expect of mortar. It will look similar, but possibly

*slightly* shinier than regular mortar.

You should be able to work a layer down to 1cm thick and still have good strength.

[Nightjar]

Have you considered stair tread covers instead? Quick to fit, long lasting and inherently slip resistant.

Bignell

[jgharston]

Any advice on repairing a doorstep made of this kind of stuff:

is broken in a similar way.

JGH

[ARWadsworth]

Did you pinch that from from my local bakers?

[robgraham]

33:

Tim - what's a 'string mortar'? Typo or something I've never heard of before?

Rob

[Gill Smith]

'strong'?

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