A machine base plate is only as good as the grout beneath it. The grout layer is what transfers static weight, dynamic vibration and bolt pre-load from the equipment into the concrete foundation, then into the ground. Get it right and you lock in alignment, damp vibration and extend bearing and seal life. Get it wrong, through voids, bleeding, shrinkage cracks or a poor bond, and you invite soft-foot, loosening anchor bolts, fretting and premature failure of expensive rotating equipment. This guide explains how to grout machine base plates correctly, whatever the brand of grout you use. You will learn how to choose between non-shrink cementitious grout and high-strength epoxy grout, how to prepare the concrete and the underside of the base plate, how to build watertight formwork with a head box, and how to place the grout in a single direction so it flows without trapping air. We also cover curing, common mistakes that quietly destroy a good grout job, and when to bring in a specialist applicator. Throughout, we map the decision to product families across Fosroc, Sika, MC-Bauchemie, Master Builders Solutions, STP, UltraTech and Dr. Fixit, all of which Space Arc Engineering supplies and can apply.

Why correct base plate grouting matters (and how it fails)

The grout under a base plate has one job: maintain full, intimate, void-free contact between the underside of the plate and the foundation throughout the life of the machine. That continuous contact is what lets the foundation absorb vibration and hold the equipment in alignment. Most field failures trace back to a handful of root causes. Ordinary sand-cement mortar shrinks as it cures and pulls away from the plate, leaving a gap. A grout mixed too wet bleeds, segregates and leaves a weak, chalky layer right at the critical bearing interface. Air gets trapped because the grout was placed from both sides at once, or poked and rodded under the plate where it could not escape. Anchor bolts loosen as the unsupported plate flexes under load, then alignment drifts and bearings and seals wear out. The fix is to use a purpose-made non-shrink grout, place it correctly so it fills completely, and protect it while it gains strength. The sections below walk through each step.

Cementitious vs epoxy grout: choosing the right type

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.

Brand and product options across the seven manufacturers

Across the manufacturers Space Arc Engineering supplies, the same two families recur. For non-shrink cementitious grouts, common choices include Fosroc Conbextra (the GP / GP2 general-purpose and higher-flow grades), Sika SikaGrout, MC-Bauchemie Emcekrete, Master Builders Solutions MasterFlow (e.g. the 928 family) and UltraTech POWERGROUT (NS-type flowable grades), with STP and Dr. Fixit also offering non-shrink grouting compounds for general base plate and pocket grouting. For high-strength epoxy grouts used under heavy dynamic equipment, the established options include Fosroc Conbextra EP / Concresive epoxy systems, Sika Icosit KC and epoxy SikaGrout grades, and Master Builders Solutions MasterFlow epoxy grouts (such as the 648 family), with epoxy anchoring and grouting products available across STP and Dr. Fixit ranges too. Exact grade selection depends on pour thickness, flow distance, temperature and load, and the published values differ between products, so always size the grade against the project and refer to the current Technical Data Sheet (TDS) for compressive strength, flow, layer thickness limits and yield. As an authorized distributor and applicator for all seven brands, Space Arc can supply the matched grade plus primers, expansion-joint material and formwork advice.

Step 1 to 3: surface preparation, formwork and mixing

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.

Step 4 to 5: placing the grout and curing

Pour from one side only. Place the grout continuously from a single side or end and let it flow under the plate to the far side, so it pushes the air ahead of it rather than trapping it. Maintain a head of grout in the head box so flow does not stall; for long plates this pressure head is what carries the grout the full distance. Do not place from opposite sides at once, and do not poke, rod or vibrate the grout in a way that causes bleeding or segregation, gentle persuasion with a strap or chain is fine for cementitious flowable grout, but the material should largely move under its own weight. Fill until grout shows continuously at the far edge and the plate is fully bedded. Trim back the surplus to a neat shoulder, leaving non-load-bearing shoulders where expansion joints can later be cut. Curing: cementitious grout must be kept moist immediately after placing, with wet hessian and polythene or a curing compound, for the period the TDS specifies, to develop strength and avoid plastic and drying shrinkage cracks. Epoxy grout is not water cured but is temperature sensitive, keep surfaces within the specified temperature band before, during and after placing, and protect from rain until set. Only load or re-shim the machine once the grout has reached the strength stated for that grade.

Common mistakes and when to call a professional applicator

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 seven 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.

Related: Browse all Grouts & Anchors products and brands available from Space Arc Engineering.

Frequently Asked Questions

Cementitious or epoxy grout: which should I use for a machine base plate?

Match the grout to the duty. Use a non-shrink cementitious grout for general base plates carrying static or light-to-moderate dynamic load, for high service temperatures, and where budget matters, it flows well and tolerates damp concrete. Use a high-strength epoxy grout for heavy vibration, impact or reciprocating equipment, very thin precision pours, and where oil or chemical exposure is expected. Epoxy gives higher strength and near-zero creep but costs more and needs dry, temperature-controlled conditions. When in doubt, size it against the equipment load and refer to the product TDS.

Why should I never use ordinary sand-cement mortar under a base plate?

Plain sand-cement mortar shrinks as it cures and pulls away from the underside of the plate, leaving voids. Those voids destroy the intimate contact needed to transfer load and damp vibration, so anchor bolts loosen, the plate flexes, and alignment drifts. Purpose-made non-shrink grouts use controlled expansion and low water demand to stay in full contact with the plate, which is exactly what a machine foundation needs.

How do I avoid trapping air voids when grouting?

Pour from one side or end only and let the grout flow under the plate to the far side so it pushes air ahead of it. Use a head box to maintain pressure head, keep the pour continuous, and stop only when grout appears continuously at the far edge. Do not pour from two sides at once and do not over-rod or vibrate flowable grout, which causes bleeding and segregation. Build the formwork to let air escape.

How long before I can run the machine after grouting?

Wait until the grout has reached the strength the manufacturer specifies for that grade, not just until it feels hard. Cementitious grouts need a moist-curing period first to develop strength and avoid shrinkage cracking; epoxy grouts need to be kept within their temperature window while they set. Loading or re-shimming too early can crack the grout or lose alignment. Always follow the curing and strength-gain guidance on the relevant TDS.

What does machine base plate grouting cost in India?

Cost depends mainly on grout type, volume (pour area times thickness), and whether you self-perform or use an applicator. Non-shrink cementitious grouts are the most economical per bag and suit most jobs; high-strength epoxy grouts cost several times more per litre but are essential for heavy dynamic duties. Budget separately for surface preparation, formwork, primers, expansion-joint material and curing. For an accurate, project-specific quotation on supply and application, contact Space Arc Engineering with your pour dimensions and equipment details.

Do I need expansion joints in the grout?

For most cementitious pours on small to medium plates, expansion joints are not required. For larger pours, and particularly for epoxy grout, expansion joints are commonly placed in the non-load-bearing shoulders to control thermal movement and prevent edge cracking. The joint should be detailed so it bonds to the grout and does not create a path for oil or water to reach the concrete. Ask Space Arc for joint detailing guidance for your grade and layout.

Which grout products can Space Arc Engineering supply and apply?

Space Arc Engineering is an Authorized Distributor and Applicator for Fosroc, Sika, MC-Bauchemie, Master Builders Solutions, STP, UltraTech and Dr. Fixit, so we can supply the right cementitious or epoxy grout grade for your equipment, plus primers, expansion-joint material and trained applicator support including method statements and on-site supervision. For product selection, pricing or to book an applicator, call +91 9999155255 or email info@space-arc.com with your equipment data sheet and foundation details.

Need help selecting the right product?

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