I think I know the answer to this already but its worth a punt.

I laid a 4mx3m shed floor (clearly badly), with about 10 cm of hardcore and 7.5cm of cement, that whilst in the middle appears fine, on the outside has some very crumbly sections.

The floor doesn't need to last decades, it has a summerhouse(office) on it, so a few years use would be nice rather than it just collapsing when the winter arrives. Is there anything I can do to it to make it a bit more hardy in the short term other than knock it down and start again.?

crumbly floor

  • 2
    Looks to me like you better start again before you commit to putting a whole structure on top of that crumbly mess.
    – Michael Karas
    Jun 18, 2013 at 1:09
  • As there is already a structure on top of the crumbly mess thats not the answer I was hoping for :) Although clearly there will be a bit of a strength issue, there's no legs in removing the crumbly bits and laying some more concrete with a bonding agent?
    – bugg_tb
    Jun 18, 2013 at 6:52
  • Oh well I've ordered some Ronafix and knocked out the loose bits, hopefully that'll give it a life span of more than a few weeks :)
    – bugg_tb
    Jun 18, 2013 at 8:25

2 Answers 2


Do you just want to consolidate the loose surface stones for walking/tool storage?

If so, a concrete resurfacing mix, spread with a floor squeegee, will make a nice, smooth surface.

Understand that the underlying loose mix won't support much more than foot traffic (people walking on it) and the resurfacer may crack if overloaded.

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  • Hi HerrBag, thanks for the answer, the cement is just a base on top I was going to put a lightweight floor that will be suppported by some loadbearers running across the inside of the base, this area appears pretty solid its just the outside areas where there's no room to walk anyway.
    – bugg_tb
    Jun 18, 2013 at 14:14

you can reinforce the bond in your aggregate with unwaxed polyester resin. just make sure you add acetone to the mix and use very little catalyst. that will make it dilute enough to wick into the existing substrate, and the slow cat will let it have time to get in there before it kicks. we use it quite often for reinforcement in places its too cost prohibitive to remove or replace rotten concrete. its costly, but it will work, and it will make the slab strong as hell. your going to need probably 20 gallons or so, but it will work.

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