Screed Disaster

[John Smith Esq.]

Used Benfer 2-50fl on a new concrete floor primed with SBR. Greatest depth around 15mm. Builder who has used it is experienced and used the product before, albeit less depth. He measured out correct amount of water. Doors closed. Not particularly warm in the room. Anyway, he has run his spiked roller over it and it's made a right mess. It is as though it has gone off too quickly and not been wet enough when spikes went over. He says it was hard to work with. In thicker aras anyway.

It looks nothing like latex leveller I've seen and used before.

Thoughts?

Do we try to smooth out and then go over it again tomorrow or get the lot up and start again?

 

[yorksbuilder]

Sorry, he can't be that experienced if he lets SLC go off and then run a spiked roller over it.

1. Re screed the whole floor again if you have enough depth to play with
Or
2. Get him to grind it down, and redo

 

[John Smith Esq.]

Sorry, he can't be that experienced if he lets SLC go off and then run a spiked roller over it.

1. Re screed the whole floor again if you have enough depth to play with
Or
2. Get him to grind it down, and redo

Thanks.

I suggested just taking it up whilst it was still tacky. Better than trying to do it tomorrow when it is rock hard.

We will have to see tomorrow if it has actually worked or not as a surface. He sprayed water over it and smoothed it all out, mostly. There are bound to be some flakey bits on the surface by the looks of it in the parts he wasn't able to smooth over. And it is unclear whether it was too late by the time he attempted this in places.

If we do go over what's there with new screed, does it need to be primed again?

Also, is it easier to work with the latex stuff? I've never seen this happen before, having had the rest of the house self levelled.

 

[yorksbuilder]

Dont need to prime again if its a sound and dust free surface, but looking at the pic, and if you have spare primer then do.
The latex SLC is a bit more expensive and offers slightly better flexibility and adhesion, other than that is very similar to work with

 

[John Smith Esq.]

So basically, after the photos above, he sprayed water on it and smoothed off to get ride of big holes and spiked surface. I don't know how effectively this will have removed holes below surface. He has then poured again over the top of it all about an hour later. Today it looks like the attached.

It is impossible to speak to Benfer without contacting Italy. I called Mapei who do a similar product and they said you shouldn't add layers to screed until the first layer has fully cured (like 24 hours or more) and should use primer again.

Builder hasn't done this. Put down the first layer and run spikes through it after it has started curing, basically shredding it up. Then dampened this to smooth off with his glide tool. Unclear how it now is within the layer below the surface - could be a load of holes hidden below. Then poured a new layer an hour later, before first layer has cured and with no primer. And it still doesn't look great.

If it is structurally sound I'd just sand off and leave it. But presumably might not find out if it is dodgy until possibly after floors, skirting boards, etc have all gone over the top? So do we bite the bullet, take the lot up, try to remove primer, start all over again with Mapei, I help him do it, get it all levelled and spiked within half an hour.

 

[opps]

You seem to have posted the same question twice.

Perhaps ask the mods to merge them. It gets confusing other wise.

 

[accelerator]

Builder hasn't done this. Put down the first layer and run spikes through it after it has started curing, basically shredding it up. Then dampened this to smooth off with his glide tool. Unclear how it now is within the layer below the surface - could be a load of holes hidden below. Then poured a new layer an hour later, before first layer has cured and with no primer. And it still doesn't look great.

If it is structurally sound I'd just sand off and leave it. But presumably might not find out if it is dodgy until possibly after floors, skirting boards, etc have all gone over the top? So do we bite the bullet, take the lot up, try to remove primer, start all over again with Mapei, I help him do it, get it all levelled and spiked within half an hour.

I'm not a concrete expert, but the curing process depends on moisture content. I'd say there is the possibility that the first layer cures OK, even after another layer has been added. It seems like a huge amount of work to take the lot up, when it could be fine. I feel it's unlikely, if you're pouring layer upon layer, that there will be hidden holes in it. Personally then, I would be inclined to just carry on.