Anchorage: Is grouting under pole base plates recommended?

Grouting is not recommended by most pole manufacturers. Opinions on whether or not grout should be used with double-nut-moment joints differ. In a properly designed joint, all loads are resisted in the anchor rods. Due to the greater stiffness of the anchor rods compared to the grout, and the tendency of the grout, even for so-called "non-shrink grouts", to shrink, though perhaps imperceptibly, below the bottom of the base plate, little load transfer to the grout is likely even if assumed so in design. Grout, if well installed, may pick up loads due to very high or unexpected load cases. Proper grout installation is difficult when base plates tend to be rings, as with large light poles. A means must be provided to restrict grout flow inside the base ring while fully filling beneath it. For these reasons, and several listed below, grouting of double-nut-moment joints is generally not recommended: It may crack, retain moisture, and then promote corrosion. It makes it impossible to inspect and retighten bottom nuts if necessary. In order to place the grout after the base plate is in place, the standoff distance between the top of concrete and the bottom of the leveling nut may exceed the recommended distance equal to the anchor rod diameter. Where base plates are not grouted, a stainless steel wire mesh should be placed around the base plate to eliminate debris from accumulating beneath the base plate and keep animals out and protect electrical wires if present.

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