Grouts for Turbomachinery

hen installing or resetting a piece of equipment, grouts play a crucial role in the long-term performance of the pump, motor, or other type of machinery. Improper grouting can cause premature failure of expensive equipment.

Grouts are generally divided into one of two types, cementitious based grouts or epoxy grouts. Cementitious grouts are used in applications where the loads are static. Equipment generally has vibrations and other non-static loads, so they require epoxy grouts. We will focus on epoxy grouts here.

Other than vibration, there are other reasons epoxy grouts are ideal for making equipment and its foundation function as one unit:

• Develop a greater bond to steel than cement-based grouts.
• Form a higher bond to concrete than the concrete’s tensile strength.
• Higher compressive strengths than the concrete they are attached to, generally within 24-48 hours.

• When properly mixed and applied, they provide a bearing area greater than 90%.
• They come prepacked so proper proportioning should always be correct.

• Accommodate many chemicals that would react with cement-based materials.

Epoxy grouts come in a number of “flavors” to meet different needs. Flowable grouts are made to flow at a rate that they can fill a void. This property is required for almost any project. All epoxy grouts are sensitive to temperature differences. Flow rates slow and cure times extend based on the ambient temperature. Note that grout should not be stored in the cold or hot just prior to installation as a temperature difference of as little as 10 degrees can make a significant difference.

Deep pour grouts are formulated to create less heat when setting so they can be applied in bigger lifts and deeper sections. There are also high-strength or extreme grouts that produce much higher ultimate strength when needed. Lastly, there are highly chemical-resistant grouts for use in the most demanding, harsh environments.

Installing grouts is straightforward. Concrete foundations or bases should be 28 days old so they have achieved strength and drying shrinkage has taken place. Surface preparation should conform to a surface profile of 5-7 according to ICRI (International Concrete Repair Institute) Guideline 310.2, exposing the coarse aggregate of the concrete. Clean any residue with a vacuum, pressure wash, vacuum the water, and let it dry completely.

Forms must be tight, and the metal surface being attached should receive a suitable primer. Once this is complete, mix the epoxy. If there is a significant amount of epoxy, care should be taken to have a mixing process in place so there is a constant stream of material available until the void is filled. Place the epoxy by pouring it through the openings in the base. This is an abbreviated set of instructions to understand the process. Confirm the process with your specific grout manufacturer.

GROUTING AND SAFETY
One aspect of grouting that is receiving more attention of late is how the choice of grouting material impacts personnel and plant safety. During the mixing of grout materials, a great deal of dust thrown in the air. This presents a hazard and adequate safety precautions must be followed.

In recent years, however, new epoxy grouts have been developed which create very little dust. This safety advancement is a boon for installers and anyone else in the proximity of the project. DL (dustless) technology grouts are the future of the grouting industry. With a greater emphasis in most plants and jobsites on safety, dust limiting grout is finding wider application within the turbomachinery industry. ■