Grout Mix for Pump Primer

[Galambos]

I have a new slab on metal deck on top of an existing building.

My contractor is requesting to use a grout mix as a pump primer and to leave it in the slab.

The grout mix is of the same compressive strength as my slab on metal deck mix.

To me, this seems REALLY far fetched. Has anyone had a similar request?

 

[Ron]

Tell him to waste it. You'll get differential shrinkage between the grout mix and the deck mix. He shouldn't need much for priming anyway.

 

[Zambo]

I agree with Ron, it should be pumped through the pipes and then be discharged as waste.

I doubt it will be the same compressive strength as the concrete.

 

[beton1]

As a alternate, they now use a pail of lubricant. Grout can be used (usually they order a cubic metre or yard) which should be wasted or thoroughly mixed with concrete (doubtful).

 

[HSIII]

Commonly, whatever is used to prime the pump is wasted. The grout that they use is usually so heavily watered down that it will never meet the "strength" of a good grout mix.

I've seen it attempted to be mixed in with the concrete once, with abysmal results.

Also, usually concrete pumps up here carry their own dry slurry mixed with water off of the concrete truck or their own truck for slicking (is that even a word?) the line and it's discharged somewhere on site (NOT in the forms).

 

[doka1]

The lubricant doesnt really work for a slab because likely you will be using a considerable length of hose. Lubricants like "slick willy" are only really sufficient the lubricate the pipes in the boom. We mix some grout out of type s mortar mix but dont leave in in the slab mainly because the slab will take forever to set in that area.

Yeah the discharge of the slick pack is a slimy mess, never placed in the forms.