What kind of material is normally used for machine foundation isolation?
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  1. #1
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    Default What kind of material is normally used for machine foundation isolation?

    The foundation drawing for a new machine purchase specifies 100mm "Styrofoam" all around the slab to isolate from any vibration in the existing floor.

    This is a Japanese machine and the English translation on this drawing is good but you can still tell that it's translated.

    To me, styrofoam is polystyrene. Does that seem likely?

    Contractor that quoted for pouring the found said they would probably use Kingspan, but asked how we would cap it on the surface.

    Any insights?

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    In the US the styrofoam is about as common as dirt. And you are correct, it is polystyrene.

    Per google search: Styrofoam is a trademarked brand of closed-cell extruded polystyrene foam (XPS), commonly called "Blue Board" manufactured as foam continuous building insulation board used in walls, roofs, and foundations as thermal insulation and water barrier.

    As to how to cap it, that is an excellent question. Many solvents will instantly dissolve styrofoam so it should be sealed well at the top in case of some eventual spill.

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    Quote Originally Posted by gregormarwick View Post
    The foundation drawing for a new machine purchase specifies 100mm "Styrofoam" all around the slab to isolate from any vibration in the existing floor.

    This is a Japanese machine and the English translation on this drawing is good but you can still tell that it's translated.

    To me, styrofoam is polystyrene. Does that seem likely?

    Contractor that quoted for pouring the found said they would probably use Kingspan, but asked how we would cap it on the surface.

    Any insights?
    It is used on an isolated foundation.
    Under as well as along the sides ?

    There are different densities IIRC 1 lb. and 2 lb.

    As it comes up the sides (probably dirt) you stop it at the existing concrete floor, there is a thick (1/2") felt product, that gets nailed to the saw cut.
    On top of it (IIRC comes as one) a block off strip, maybe 1/2" sq. (commonly called a zip strip)

    After pouring, pull off/out that strip, and use Sika flowable caulking to seal the joint.

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    For the foundation under my 300 ton Bliss I used 1/2" thick pressed rubber barn mats.

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    I put my air compressor on some old tire tread found by the side of the road. Avoid the ones with sharp wires sticking out.
    Bill D.

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    Kingspan make a number of products, but their wall panels are rigid polyurethane or phenolic foam. they won't recover as well from long term movement and vibration as foundation type polystyrene/Styrofoam.

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    Pink Panther Foam. Buy at Home Depot.

    https://www.homedepot.com/p/Owens-Co...-45W/100320352

    That is the reason they spec 2" thick. What we do then to gap the area from the new machine pad to the existing floor is the contractor will have a 2" wide steel plate fabricated up with rods that then gets poured in with the concrete. This covers the 2" wide gap on the top of the concrete.

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    Many bugs chew right through the plain old white polystyrene.
    They make more bug resistant stuff.

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    I use asphalt impregnated fiber board covering the face of the concrete. I have used it all the way to the bottom of the hole on a balance machine. I have seen 2" polystyrene specified for the sides and bottom of a foundation for some machines but that seems like overkill. there are products on the market that are specially designed for this use and are very expensive as well. The manufacturer claims that it will not compress over time. I don't know about that, gravity is relentless. There are lots of variables to consider but sometimes the manufacturer gets extreme. 4" sounds extreme. You will want some type of bond breaker between the isolation material and the sealant, backer rod usually suffices. I like to seal with a semi-rigid epoxy but time sometimes dictates a regular self leveling poly-urethane joint sealer. A joint that wide will need some kind of protective cover.

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    I'd put in exactly what the manufacturer says, strictly to make sure you don't have a problem. 4" may sound like a lot but it likely has to do with how much motion can be absorbed without crushing that does not spring back. Like reinforced concrete. You need enough steel that the total stretch under maximum load is less than 2% or so, otherwise the concrete spalls off the steel. If you see a parking lot light foundation all cracked up it you are looking at one that doesn't have enough vertical steel rebar reinforcement.

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    Thanks for the replies so far. This is somewhat outside my sphere of experience so not really in a position to respond, but I am reading and absorbing each post.

    More information:

    200mm gravel / hardcore
    200mm subslab on top of that
    main slab and styrofoam sides sit on top of the subslab, 600mm deep.
    Drawing specifies strength of 20.6MPa after 28 days.

    Styrofoam is around the sides only, no horizontal layers anywhere.

    Machine is 19Te, and the base casting footprint is about 4m x 2m on 15 levelling / dry anchor points. Point loading is 27KPa according to the drawing.

    The found is specified at 5m x 3m, but we are making it 1m larger in each direction to accommodate final positioning.

    The foundation drawing does not specify reinforcement, but we have agreed with the contractor to have one sheet of mesh in the subslab and two in the main slab.

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    Quote Originally Posted by gregormarwick View Post
    Thanks for the replies so far. This is somewhat outside my sphere of experience so not really in a position to respond, but I am reading and absorbing each post.

    More information:

    200mm gravel / hardcore
    200mm subslab on top of that
    main slab and styrofoam sides sit on top of the subslab, 600mm deep.
    Drawing specifies strength of 20.6MPa after 28 days.

    Styrofoam is around the sides only, no horizontal layers anywhere.

    Machine is 19Te, and the base casting footprint is about 4m x 2m on 15 levelling / dry anchor points. Point loading is 27KPa according to the drawing.

    The found is specified at 5m x 3m, but we are making it 1m larger in each direction to accommodate final positioning.

    The foundation drawing does not specify reinforcement, but we have agreed with the contractor to have one sheet of mesh in the subslab and two in the main slab.
    Cork was the go-to for a LOONG time. But I'm with Gary on this one.

    Use EXACTLY what the machine-tool maker spec'ed - either write or email and ASK if there is any doubt so you have it in file. Same again, your "locals" recommend an IMPROVED implementation. As seems wise, BTW.

    Last thing you need is any excuse at all for Warranty or service hassle over relatively small money between one isolating material choice over some other choice.

    It sounds like overkill, BTW, but then again.. I've done installations IN Japan, and "Earthquake resistant" or at least "Earthquake tolerant" or "Earthquake SAFE", drives most everything they do. They have no other option.

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    Quote Originally Posted by gregormarwick View Post
    The foundation drawing does not specify reinforcement, but we have agreed with the contractor to have one sheet of mesh in the subslab and two in the main slab.
    I'd suggest contracting with a concrette structural engineer and designing a more robust foundation, with better reinforcement. The cost for the design and extra mesh or rebar is trivial compared to discovering that the mix used by your supplier was sub-par, or that the single or two layers of mesh lead to fracture after a year or two.

    If it were me, for a 600mm depth of pour I'd be using around five layers of mesh (every 100mm) as well as 12mm vertical rebars with bent ends for Z connection, perhaps on a 250mm pitch.

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    8" rat slab and then a 24" main slab? You'd better get someone to look at that and spec some more reinforcement in there, I don't think you'll like the cracks that show up. Are you going to saw cut it as well?

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    Could one of you explain to me what the exact purpose of the sub slab is? None of the machine founds that we've put in before have had such...

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    Quote Originally Posted by gregormarwick View Post
    Could one of you explain to me what the exact purpose of the sub slab is? None of the machine founds that we've put in before have had such...
    My sense is that the sub slab creates a slip plane so that the main slab can move within the constraints of the polystyrene sides effectively isolating the building sub grade from absorbing lateral vibrations.

    I would not saw cut the main 24” machine foundation . . . wire mesh plus rebar should be such that you have a high integrity monolithic block.

    Our foundations were specified at 3500 psi concrete. Every cylinder test result was 6000 psi or higher. In our shop we used a large aggregate concrete recommended by our structural engineer and saw cut . . . the floor is about a year old and so far moving 30,000 pound loads around with a forklift and no cracks

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    gregormarwick --

    I'll suggest taking a look at Unisorb Installation Technologies website: UNISORB(R) Installation Technologies | Official Website

    I've used their foundation hardware and leveling systems several times -- and have been very satisfied -- but no personal experience with their isolation materials.

    John

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    Thanks again all,

    Next question, what do you guys mean by "saw cut"?

    We will saw cut the hole in the existing floor, but I'm not sure what "saw cut" means in relation to the new slab...

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    Our colonial cousins tend to cut saw lines across slabs to give pre-made locations for cracks to form. Can be important in work with thin slabs and continental temperature variations. Not a thing to do for a machine foundation.

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    Quote Originally Posted by gregormarwick View Post
    Thanks again all,

    Next question, what do you guys mean by "saw cut"?

    We will saw cut the hole in the existing floor, but I'm not sure what "saw cut" means in relation to the new slab...
    In the USA concrete interior floor slabs are saw cut after the concrete has hardened but before full strength. Saw cutting is done in a pattern specified by the engineer to control cracking due to concrete shrinkage. Saw cut joints are filled with a caulking made for the purpose.

    The isolated slab is a different piece of concrete either on top of the floor slab if it is capable of supporting it or in an opening in the floor slab and bearing directly on a gravel sub base on engineered soil. Styrofoam goes between the isolated concrete and sub base weather it be ground or building structure.

    Styrofoam is a brand. You must use the correct density specified by the machine manufacture and engineer. You must also install it correctly. Each installation will have variables and that is what you need a structural engineer for.


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