Grout under baseplate
Grout under baseplate
(OP)
Other then providing a level surface for the column to sit on, is there any other reason to have non-shrink grout under the column base plate?
When was the last time you drove down the highway without seeing a commercial truck hauling goods?
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RE: Grout under baseplate
If you have large loads the grout should give you a better feeling about the load being applied evenly to the top of foundation or pier. By sloping out from the base plate you can get a little more bearing area on your pier. The grout allows a little play in the as-cast foundation height as gives you space for leveling. On exterior base plates the grout keeps water from sitting in the plate/pier joint.
Not really compelling arguments for sure. I'd need to scour AISC to see if grout is actually required.
RE: Grout under baseplate
In addition if the anchor bolts were cast with sleeves to allow some movement the grouting of the sleeves can be carried out at the same time as the underside of the baseplate. Some corrosion reistance is provided for the bolts.
RE: Grout under baseplate
Theoretically, the concrete would be perfectly flat, dead-nuts level left and right and fore-and-aft (or north-south-east-west for you civil-type readers out there), and the concrete would be clean and dust free machined to a perfectly flat match with the bottom of the plate - which would of course - also be perfectly falt and dead-nuts level north-south and east-west.
Theoretically, the bolts would be perfectly vertical and always at the right length and exactly at the right spacing ....
Ain't gonna happen. Heck perfect baseplates on perfect concrete surfaces don't even happen underneath the highly machined baseplates of turbine and generator casings.
So, in the real world, you gotta play some games and use some approximations. Over the years, people have found that getting everything as close as possible in making the column and then welding on baseplates; then pouring and leveling the concrete pads, floors, and foundations; then allowing the bolts/studs to protrude "too far" above the top of the baseplate allows room for grout to be jammed in under the baseplate above and around the bolts. The column is leveled using the bolts and a set of nuts under and over the plate, NOT by bolting the baseplate tightly down to the uneven floor or concrete pad.
Hopefully - and usually it really does happens - the grout is stuffed far enough under the plate and with enough pressure so enough grout connects top-of-concrete and bottom-of-baseplate to carry the load. If it doesn't carry the load, you find out when the column collapses years later. Or hours later.
[My opinion? There's got to be a better and cheaper way than having a guy push grout around to a 45 degree slope with a trowel and a piece of cardboard and plywood. And there for sure has to be a better and faster and cheaper way of pouring grout in pump baseplates (other than through too-little-pour holes!) ]
RE: Grout under baseplate
BA
RE: Grout under baseplate
Try building a form around the column and pouring premixed pourable grout from one side. When it builds up to the same level on the other side, it's full.
RE: Grout under baseplate
RE: Grout under baseplate
You have mentioned that before on another thread. I have never seen that technique used. Is it common in your area? Do you use leveling nuts under the 1/4" plate?
BA
RE: Grout under baseplate
They can be lifted after grouting to verify that the entire baseplate is bearing on a flat surface.
Dik
RE: Grout under baseplate
I honestly do not know if it is used commonly in my area.
And, yes, I use leveling nuts under the plate. The field guys love it. They set and level the plate to the correct elevation and, if they choose and are careful enough, they can lift the plate to place the grout and set the plate back into the grout and let it spread under the plate.
All I know is it has provided nearly 100% mistake free foundation construction for me and has helped eliminate excessively large base plate holes (that drives me nuts). I tend to think the base plate hole sizes given by AISC are ridiculous.
Once the column is in place, that's it, she's done.
The only concern I have ever had with the method was compressive loads on the anchor rods b/c of the leveling nuts.
RE: Grout under baseplate
BA
RE: Grout under baseplate
Dik
RE: Grout under baseplate
BA
RE: Grout under baseplate
And I have another question: What is the importance of non-metallic grout (which I have always seen to be non-shrink too). What do they mean by non-metallic?
RE: Grout under baseplate
BA
RE: Grout under baseplate
RE: Grout under baseplate
ht
Personally, I have never used metallic grout, so cannot confirm or dispute any of the claims made.
BA
RE: Grout under baseplate
Any chance you could provide a rough drawing or schematic of your leveling plate method? I having trouble picturing what your describing in your post.
RE: Grout under baseplate
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)