Epoxy grout is widely regarded as the best option for machinery bases due to its outstanding strength, adhesion, durability, and ability to dampen vibrations—attributes essential for preserving stability and accuracy in heavy equipment. In this article, we explore the different kinds of cement and epoxy grouts to provide a deeper understanding, so keep reading. But we should not neglect the characteristics of cement grout types, because cement grout and epoxy grout are always offered to buyers together in the construction materials market. Therefore, in the rest of this article, we will examine their properties in a comprehensive manner.
Why grout matters for machinery bases
A machinery base must transfer loads uniformly from the machine to the foundation, resist movement from dynamic forces, maintain alignment over time, and protect against corrosion and chemical attack. The wrong grout can lead to uneven bearing, bolt loosening, increased vibration, premature wear of machine components, and expensive downtime. Selecting an appropriate grout and installing it properly are therefore critical to long-term machine performance.
Types of grouts used for machinery bases
Cementitious grouts
Ordinary cement grout
Cement grout is a conventional, economical choice made from Portland cement, sand, and water. It is easy to mix and place but has lower compressive strength, higher shrinkage, and greater permeability than epoxy grouts. It can be acceptable for static loads and less critical machinery if moisture and chemical exposure are controlled.
Non-shrink cementitious grouts
Non-shrink cementitious grout is Portland-cement–based formulations with additives (expanding agents and polymers) that reduce or eliminate shrinkage as they cure. They provide better bearing contact and fewer voids than plain cement grout. Strength is improved versus plain cement, but durability and chemical resistance still lag behind epoxies.
High-strength cementitious grouts
High-strength cementitious grout is Special blend mixes with silica fume, blended cements, or higher cement content produce greater compressive strength and lower permeability. They’re used where higher load capacity is needed but epoxy is not specified.
Advantages: lower material cost; simpler mixing and placement for large-volume pours. Limitations: greater shrinkage risk, lower tensile strength, poorer chemical resistance, and longer cure times.
Epoxy grouts
Two-component epoxies
The most common epoxy grouts are two-part systems (resin and hardener) that cure to a rigid, high-strength material. They typically provide excellent compressive and tensile strength, strong adhesion to steel and concrete, very low shrinkage, and good chemical and moisture resistance.
Thixotropic vs. flowable epoxies
Thixotropic (non-sagging) epoxies are used where grout must stay in place under vertical surfaces or where slight gaps exist. Flowable epoxies are low-viscosity and used to fill thin bedding gaps and ensure full contact under precision equipment.
Rapid-setting vs. normal-setting
ast-curing epoxy grouts allow earlier machine startup, which reduces downtime. Normal-setting epoxies provide more working time for complex alignments.
Advantages: high strength, minimal shrinkage, excellent adhesion, vibration-damping properties, and superior resistance to oils, coolants, and chemicals. Limitations: higher material cost, temperature- and humidity-sensitive curing, requirement for careful surface preparation, and sometimes more demanding mixing and placement procedures.
Polymer-modified cement grouts These blend cementitious systems with polymer additives (acrylics, styrene-butadiene, or other resins) to improve adhesion, reduce permeability, and lower shrinkage. They sit between plain cement and epoxy grouts in performance and cost and are chosen when better durability is needed than cement alone but epoxy is unnecessary or too costly.
Selecting the right grout
Consider the following factors:
- Load and function of the machine: High-precision or heavy dynamic machines (grinders, CNC, turbines, pumps) typically require epoxy grout for stability and vibration control.
- Gap thickness: Epoxy grouts perform well in thin bedding layers; for large pour volumes, cementitious grouts may be more practical.
- Environmental exposure: Chemical contact, moisture, and temperature extremes favor epoxy systems.
- Required cure time: If minimizing downtime is essential, fast-setting epoxies are attractive.
- Base material and condition: Concrete quality, presence of cracks, and steel baseplate condition influence grout choice and the need for remedial preparation.
- Cost constraints: Cementitious grouts are less expensive but may carry higher lifecycle costs due to maintenance and risk.
Surface preparation and installation best practices
- Cleanliness: Remove all oil, grease, laitance, loose concrete, rust, and coatings from the foundation and baseplate. Solvents, mechanical grinding, or abrasive blasting are commonly used.
- Moisture control: Epoxy grouts require dry, clean surfaces for best adhesion. Cementitious grouts may tolerate some moisture but perform better on sound, damp-cured concrete.
- Forming and shimming: Use rigid forms to contain the grout and install shim packs or leveling bolts to set precise elevation and alignment. Leave temporary jacking points if large overlay or lifting is required.
- Pre-wetting and priming: Cementitious grouts benefit from pre-wetting the concrete to prevent rapid water loss. Some epoxy systems require primers to improve bond.
- Mixing: Follow manufacturer instructions for mix ratios, mixing speed, and time. Epoxies need thorough, consistent mixing to ensure complete reaction.
- Pouring technique: Place grout from one side to avoid air entrapment and use vibration or tapping (if recommended) to eliminate voids. Keep baseplate properly supported to maintain alignment until the grout reaches sufficient strength.
- Curing: Respect recommended cure times and environmental conditions (temperature and humidity). For epoxies, elevated temperatures accelerate cure; for cementitious grouts, controlled moist curing improves strength and reduces shrinkage.
- Inspection: After cure, inspect for voids or incomplete bearing. Non-destructive testing or core sampling can verify grout integrity for critical installations.
Common problems and troubleshooting
- Voids under the baseplate: Often caused by improper pouring, insufficient flowability, or trapped air. Remedy with pressure-injection repair or partial teardown if necessary.
- Shrinkage and cracking: Occurs in plain cement grouts due to drying shrinkage. Use non-shrink or polymer-modified grouts to prevent this.
- Poor adhesion: Frequently due to contaminated surfaces or inadequate priming. Re-surface and prepare properly before re-grouting.
- Premature loading: Applying load before the grout reaches design strength can crush or deform the grout. Respect manufacturer strength curves.
- Chemical attack or softening: Use chemical-resistant epoxy grouts where exposure to oils, coolants, acids, or solvents is expected.
When to use epoxy grout
Choose epoxy grout when you need:
- Maximum load transfer and bearing contact with minimal voids.
- High resistance to dynamic loads, vibration damping, and precision alignment retention.
- Chemical and moisture resistance in hostile environments.
- Rapid return-to-service with fast-curing formulations.
Conclusion
Proper grout selection and installation are integral to the performance and longevity of machinery installations. While cementitious grouts remain useful for many general applications because of their cost-effectiveness, epoxy grouts provide superior mechanical properties, adhesion, and durability where precision, vibration control, and environmental resistance are required. Assess the machine’s operational demands, environmental conditions, and lifecycle costs to select the best grout system, and follow rigorous surface preparation and placement procedures to ensure a reliable machine foundation.