Self compacting concrete

[Nickfromwales]

41 minutes ago, Oz07 said:

I dont understand all the hate for self compacting here. Ive used it on every house I've built. Whether its ground bearing slab or being used as a "screed" ontop of b&b. Always had the wagon back right up to the house and pour it in. Rake it about, dapple bar and get the sealer sprayed on. Very flat and has always been level enough as I've always poured to the top of the blockwork at dpc level. Back in the lafarge days they sent a rep/concreter out inc in the price to help you with all the gear. Last lot I had needed to pay a guy to help who the concrete company reccomend. It certainly doesn't do the job for you but its a lot easier and better flowing than normal concrete. 

It's not hate.

 

It's a pragmatic discussion involving some strangers on the internet  

 

I just doubt it's necessary, and my advice not to DIY is caused by the shiver that goes down my spine when someone, as a complete novice, thinks that this product will in any way make this easy or 'lay itself'. 

 

Regular concrete and a dapple bar, a home-made one at that, will be all that's needed. (IMHO).

[Iceverge]

On 16/02/2026 at 17:48, lizzieuk1 said:

Does anyone know if there's any reason you can't  use self compacting concrete in an insulated raft? 

(Not talking about flow screed types)

 

I did a bit of reading.

 

It's apparently very sensitive to getting the slump exactly correct. Small variations of temp can make it difficult to work. 

 

Also because it's so runny you need to hermetically seal the EPS or you'll have leaks of watery cement paste and it'll make the concrete crumbly. 

 

Normal concrete seems a better fit. 

 

[Nickfromwales]

1 minute ago, Iceverge said:

 

I did a bit of reading.

 

It's apparently very sensitive to getting the slump exactly correct. Small variations of temp can make it difficult to work. 

 

Also because it's so runny you need to hermetically seal the EPS or you'll have leaks of watery cement paste and it'll make the concrete crumbly. 

 

Normal concrete seems a better fit. 

 

Even with normal concrete it can be a nightmare. Most are simply too keen to get the wagon emptied out, so the next one can back up and empty that too. No time for the slump to be properly checked unless you're ferocious in insisting this gets done for each wagon. And then, if it's not right, you need a plan B in place ready to effect.

[Iceverge]

 

 

I must admit it does look good.

 

Mentioning of twice the material price in some places though. @Oz07 any insight here?

 

@lizzieuk1 maybe if you had a sheet of polythene inside the EPS and really boulstered up the shuttering at the outside you could get the SE on board. From what I read it's every bit as strong as normal concrete. 

 

Self build is where we push the envelope after all!!

 

 

 

 

[Iceverge]

26 minutes ago, Nickfromwales said:

Most are simply too keen to get the wagon emptied out.

 

That's a mistake you make once.

 

After dealing with a load of concrete drying in the wrong place once you learn to be robust with the drivers re waiting times and putting down their phone and backing the lorry up a few more ft to exactly where you need it. 

[torre]

1 hour ago, Iceverge said:

very sensitive to getting the slump exactly correct

Starting with which way up you fill the cone!