Common Pumping Mistakes
by Jim Elsey
March 21, 2017

3. Allow Cure Time

Curing time for grout, especially epoxy grout, depends on the ambient temperature. If the site is too hot or cold, steps must be taken to change or control the situation, such as temporary insulated shelters or shade from the sun and heat. Never let rain fall on equipment during this process.

Be aware that during the curing process, the grout can actually pull the base out of level as it shrinks. Continue to check for level during the curing process.

4. Secure Bolts

Most designs require the installation of anchor bolts in the foundation that will run up and through penetrations on the baseplate. This is a highly recommended step. Many believe it is to hold the base to the foundation, but the purpose is to pull the foundation, the grout and baseplate together to form one monolithic mass. Place some tension on the anchor bolts relative to the base when grouting to keep the base from floating.

Do not allow the grout to come in contact with the anchor bolts. Use a protective sleeve/tube with some clearance to allow for tolerances and ease of handling. A common tip is to fill the sleeves with dry sand to prevent the grout from entering that area. The sand can be topped off with caulking or tape.

5. Use Shims & Jack Screws

When I started in the business, we would use sets of wood or metal shims to level the base prior to grouting, leaving the shims in place. Experience has taught me it is prudent to remove the shims after the process because as the shims corrode or rot they will create other issues with the foundation-to-grout joint. If using shims, be sure to apply a coating (such as light grease) of some sort to ease removal.

After some time in the field, I learned to use leveling jack screws in lieu of shims. This technique allowed for more precise results. It was easy if the base manufacturer designed for the use of jack screws, but even when that was not the case, they were easy to adapt and install in the field. If using leveling jack screws, coat them with something (grease) to facilitate their removal. Also, put a piece of metal under the jack screw to prevent digging into the concrete because this makes the leveling procedure very tedious. Small metal plates, preferably stainless steel, can be placed under the jack screw’s nose. These plates are commonly referred to as “pucks.”

Once the jack screws are removed, fill the resultant voids with grout or liquid epoxy.

6. Choose Pour Method

Prior to the grouting process, decide whether to use the two-pour or one-pour method. I prefer the one-pour process, especially if using epoxy grout; it takes a little more preparation time because of the more sophisticated forms, but it will yield excellent results if done correctly.

Keep in mind that when pouring the grout into the forms, the displaced air needs somewhere to go, and that transverse base members and braces can sometimes prevent the proper installation and venting.

I have added (drilled) plenty of vent holes in the base to allow for the venting process.

Typically it is best to pour from one side to let the air escape from the other.

7. Pour Grout

The grout forms need to be strong and liquid tight (do not hesitate to caulk the joints). By comparison, the forms used to pour a patio or driveway are probably not strong enough for this application. Coat forms with something that will not adhere to the grout. A common practice is to use two to three layers of paste wax. Do not use oil because it can react with the grout substrate.

You will not have enough grout if you simply allow for the volume of the form. Prudence suggests you have 10 percent more grout than the form volume—and I guarantee there will
be spillage.

Pour the grout from a head box that is positioned at an elevation higher than the baseplate to provide a static head for the grout to flow.

Try to avoid pushing or rodding the grout into place because it creates air entrainment and voids. It is acceptable to pump the grout in place with different and specific appliances for that purpose. Never use a vibratory device unless specifically directed by the grout manufacturer.

For epoxy grouts, mix the liquid first (resin and catalyst) and then add the aggregate to the liquid mix—not the other way around.

This tip reminds me of my submarine days when the specific instructions were to shut the hatch and then dive the boat. The specific sequence is paramount.

References

“Grouting of Small Pump Baseplates? Is it Worth It?” TAMU Paper 2004 Pump Symposium, Roger L. Jones, Charles A. Lickteig, Jean J. Zoppe

“The Road to Reliable Pumps,” TAMU Paper 2007 Pump Symposium, Todd R. Monroe

“Pump Users Handbook, Life Extension,” Heinz P. Block & Allan R. Budris

To read other articles in the 'Common Pumping Mistakes' column, go here.

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