How do I correct a poorly laid top screed?

[Sixtus]

I paid a bricklayer to lay a dpc membrane then lay a top screed to my new workshop floor. The dimensions are 20 foot long x 10 foot wide x 2 inches thick.

He estimated I needed 16 bags of cement and 1 tonne of sand. When I came home, I discovered he had used all the sand but only two bags of cement. I calculated he had mixed the cement and sand ratio 1 cement to 9 sand. As it looked fairly hard, I stood some dexion shelving on it but when I went to load the dexion, it had started to sink into the floor unloaded. It had not sunk far, only a quarter of an inch, but when loaded there will be a lot of weight on the shelving.

I now have the problem of laying a proper top screed. Can I just re-lay another screed on top of the poor one or will I have to chop up the existing screed? Any advice very welcome.

 

[Joe Malone]

Sorry Sixtus but it will have to come up. If you try and lay anything over the top it will just debond.

 

[chessspy]

I'm with joe on this one.
At least it should break up easily enough, and you will probably have to relay the dpc if it gets cut.
It's too bad, did you pay him, /can you get your money back?

 

[roughcaster]

It'll have to come up. The whole screed is more or less sand. (2@25kg bags of cement, to 1 ton of sand) ...... 4 to 1 is a good floor screeding mix...... 4 of gritty/sharp sand, to 1 of portland cement.... Mixed semi dry.

Roughcaster.