How it works
A machine grout has one job: carry the static and dynamic loads of the equipment from the baseplate into the concrete, uniformly and without voids, for the life of the installation. Epoxy grout does this as a bonded structural layer. Resin and hardener cure by chemical reaction rather than hydration, so there is no mixing water to leave and shrinkage is minimal. The cured material is dense, resists oil and most process fluids, and bonds to both the prepared concrete and the blasted underside of the baseplate. Cementitious grout shrinks slightly, absorbs lubricant and has lower tensile and bond strength — adequate under static equipment, weak under vibration.
API 686, the Recommended Practice for machinery installation and installation design, covers grouting of rotating equipment and treats epoxy grout as the normal choice in process plants.
Where it is used
- Pump, motor and compressor baseplates, new or re-grouted after cementitious grout has failed
- Sole plates and chocks under large machines, including SAG and ball mill foundation repair, where the grout under the sole plates cracks or debonds under heavy cyclic load
- Anchor bolt pockets and local concrete rebuilds at foundation edges
- Heavy bearing plates and crane rails
Epoxy grout is not a leveling compound. In foundation leveling for machinery, the baseplate is set to level and elevation on leveling screws, jack bolts or shims first; the grout then fills the gap and locks that position in. Grouting a distorted baseplate preserves the distortion, and soft foot comes back.
How to choose and place it
There is no single best epoxy grout for machinery foundations; the right product is the one whose data sheet matches the job:
| Criterion | Why it matters |
|---|---|
| Pour depth range | Reaction heat limits the thickness of a single lift |
| Flowability | Long flow paths under large baseplates need a flowable grade |
| Placement temperature | Cold concrete slows cure and traps voids |
| Compressive and creep data at temperature | Hot equipment and sustained loads |
| Chemical resistance | Fluids that will leak onto the foundation |
Placement follows a fixed sequence: remove old grout and laitance back to sound, dry, oil-free concrete; blast the baseplate underside to bare metal; seal the forms and fit head boxes; mix complete units within the pot life; pour continuously from one side to push air ahead of the grout; cure to the manufacturer's schedule before torquing anchor bolts and doing final alignment. The pump foundation repair article covers diagnosis and repair options in detail.