Page 139 - Machinery Component Maintenance

122 Machinery Component Maintenance and Repair

method is often preferred because of better control of the mixing and less
tendency to over-mix. When using a motorized mixer, limit the mixer
blade speed to a maximum of 25 rpm. A mortar hoe used to mix grout is
shown in Figure 3-38, while a typical motorized mortar mixer is shown
in Figure 3-39.
Most grout manufacturers furnish epoxy-resin containers large enough
to hold both the “A” part (resin) and the “B” part (hardener), so use this
container for mixing. Add the hardener to the resin and mix by hand with
a paddle for 3 to 5 minutes (Figure 3-40). Mix slowly to prevent air en-
trainment, because this causes the grout to foam and have air bubbles. A
“jiffy mixer” (Figure 3-41) can be used with a variable-speed drill, be-
cause it is designed to mix without entraining air. A stopwatch should be
used to time the epoxy resin mixing and to record the total time required
for grout placement.
When the epoxy has been mixed, place it into a wheelbarrow or motor-
ized mixer and remove all the epoxy from the can. Use a putty knife to
remove the last drop. Slowly pour the aggregate into the epoxy to allow
the air trapped in the aggregate to escape. Approximately 1 gallon of air

Figure 3-38. One method of epoxy grout-mixing is by hand, using a wheelbarrow and mor-
tar hoe. Aggregate is slowly added to the liquid epoxy.