Precast Plank Grout

[FootNMouth]

Please see the photo from the pre-pour and out typical detail below. We had specified to use core plug to keep the grout from penetrating into the cores. The contractor did not order these in time and is now proposing to use masonite board as shown in the picture below.

We believe there is an issue that the masonite is wavy and secured to the precast planks. Has anyone experienced this and do you see any other issues with their proposed procedure?

 

[JedClampett]

Maybe I'm missing something, but my short answer to

do you see any other issues with their proposed procedure?

is Heck Yes!
The purpose of the grout is to tie together the planks and anchor the reinforcing, mostly for shear. I see no mechanism for transferring shear using the Masonite boards. I don't see any grout through the hollow core.
I'd have them remove the Masonite, drill access holes in the hollow core, fill the cells with a piece of something (a sponge; a wadded-up newspaper, something) 2'-0" in and install per the detail. There's a topping slab, so the holes will be eventually leveled off and not visible.

 

[lexpatrie]

I don't see the structural logic here - this feels like a diaphragm connection, for in-plane shear, but there's no grout in the left side (is the hatch missing?), otherwise, if the grout isn't missing on the left, what are these bars supposed to do anyway?

And shouldn't the planks to the left be secured into the beam somehow? Beyond say, friction on the bearing pad and whatever shear you get from the topping slab?

 

[dik]

as noted... bad idea.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[FootNMouth]

There is continuous grout and rebar in the keyways between adjacent panels. Panels are 4' wide. Below is plan view showing this grouted keyway.

We have directed them to remove the masonite board, our concern was how much grout will follow into the hollowcore voids. Our detail specified a plug to limit this penetration. Precaster is saying the plugs are not used and that at most the grout will infiltrate into the cores 6".

 

[jayrod12]

In the old days, the guys would just ball up the newspaper they had just finished reading to block the cores. I don't understand why it has to be a purpose built thing.

 

[lexpatrie]

So, in the second detail the two planks are parallel to each other, there's no rebar across the joint, and there's a rebar in the key way that's depicted graphically but not called out as anything specific. So the shear transfer is through the unreinforced topping, and/or the grout/concrete vertical interface. I'd concede this is pretty typical though I'm unaware of specific testing on the strength there, though the diaphragm stresses are probably fairly low like 25 plf along that joint.

I suppose the same is true of detail 15, except there's a rebar in the section and a lot of breaking pieces out of the precast that don't seem to have an explicit purpose. If there's 6" of grout in the cell, that's unlikely to be sufficient to develop a bar for shear friction, so why bother? What is detail 15 supposed to accomplish?