The first real decision is grout chemistry. Non-shrink cementitious grouts are blends of cement, graded fillers and additives that give controlled expansion in the plastic state so the grout stays in contact with the plate without shrinking. They flow well, tolerate damp concrete, handle high service temperatures and are economical, which makes them the default for the large majority of base plates carrying static or light-to-moderate dynamic loads, structural columns, anchor pockets and general machine bases. Epoxy grouts are resin-and-hardener systems filled with aggregate. They deliver very high compressive strength, near-zero creep, excellent edge-lift resistance and good chemical resistance, so they are specified for heavy dynamic and impact loading such as large reciprocating compressors, big pumps and crushers, for thin precision pours, and where oil, fuel or chemical attack is expected. Epoxy costs more, must be placed on dry surfaces and is sensitive to temperature, so it is reserved for duties that genuinely need it. When you are unsure, match the grout to the load: vibration, impact or chemicals point to epoxy; everything else usually points to a quality cementitious grout. Space Arc Engineering can review the equipment data sheet and foundation drawing and recommend the right grade.

Preparation decides the bond, so do not rush it. Concrete: the foundation should have gained adequate strength and be roughened to expose sound aggregate, with all laitance, oil, curing compound and loose material removed by chipping or grit blasting to give a coarse mechanical key. Remove any defective top layer down to sound concrete. Base plate underside: clean it back to a sound surface, removing oil, grease and loose rust or coating so the grout can bond; for epoxy, exposing bright metal improves adhesion. Moisture: for cementitious grout, pre-soak the concrete so it is saturated surface dry (damp but with no standing water) to stop the dry substrate sucking water from the grout. For epoxy grout the opposite applies, all surfaces must be clean and dry. Formwork: build it watertight, stiff and tight to the foundation, with a clear gap around the plate for flow and air escape. On the pour side, fit a head box (a tall reservoir) so you can maintain pressure head and drive the grout across. Mixing: use the manufacturer’s stated water dosage for cementitious grout, the lowest that gives the required flow, and never over-water to make it easier; for epoxy, mix the full kit at the correct resin-to-hardener-to-aggregate ratio. Use a forced-action or slow-speed mixer, and only mix what you can place within the working time.

The mistakes that ruin grout jobs are predictable: using ordinary sand-cement instead of a non-shrink grout; over-watering cementitious grout, which causes bleeding and a weak interface; pouring from both sides and trapping air; skipping surface roughening so the bond fails; placing epoxy on damp concrete; grouting outside the temperature window; and loading the machine before the grout has cured. Detailing matters too, omitting expansion joints in long epoxy pours, or leaving load-bearing shoulders where they should be relieved, can lead to edge cracking. Call in a professional applicator when the equipment is critical or high-value (turbines, compressors, large pumps), when pours are deep, very long or congested with bolts, when an epoxy precision pour or resin injection of existing voids is required, or when site temperatures are extreme. Space Arc Engineering supplies the matched grout, primers and expansion-joint material from all nine brands and provides trained applicator support, including method statements, on-site supervision and full installation. Getting the chemistry, placement and curing right the first time is far cheaper than re-grouting a machine that has lost its alignment.