Concrete Shed Base - Urgent Advice

[planemad]

Hi

I had a concrete shed base done on Tuesday.
I have taken a look today, the concrete seems hard when you tap it but the surface is very powdery and I can scratch away the concrete.

What has gone wrong?

The bloke who done it said he used 12-13 shovels of ballast to half a bag of cement.

 

[^woody^]

Nothing. Just not trowled or tamped enough

 

[planemad]

Nothing. Just not trowled or tamped enough

Thank You. what shall I do then just leave it? will it be weak? with it get harder over time?

It was only laid on Tues and its rained a few times since.

 

[cmother1]

This happens if the mix is a bit wet and the fine particles in it float to the top when it's being tamped. It will get harder with time. Just try not to gouge it for now.
You might not build a dam on the Zambesi with a mix like that but it sounds OK for a shed base.

 

[^woody^]

It wont be weak and the slab will continue to harden, but the surface will probably remain "dusty" now.

See what its like in a weeks time

You can get proprietary concrete sealing solutions to stop this, or paint it with a suitable flooring paint

 

[Thermo]

or paint it with a suitable flooring paint

oh god JohnD has got to you hasnt he, youll be posting pictures of painted concrete next!

 

[^woody^]

You can't beat a nice red or grey painted floor. Proper workshop it is then