Page 106 - Machinery Component Maintenance
P. 106
Machinery Foundations and Grouting 89
Figure 3-8. An oblique view of the foundation shoulder shown in Figure 3-7 after it has
been dressed and painted (Courtesy Adhesive Services Company).
Grouting of Oil-Degraded Concrete
In establishing guidelines for the use of epoxy materials on oil-satu-
rated concrete, the expected results should be compared with the proper-
ties of good concrete because these were the criteria invoked when the
installation was originally designed.
The compressive strength of good concrete will vary from 2500 to
7000 psi depending upon its cement content, curing conditions, etc. The
internal tensile strength should be about 8 to 10 percent of the compres-
sive strength or 200 to 700 psi. The tensile strength at the surface of
formed concrete may be as low as 75 psi and the surface of a steel-trow-
eled floor may be as low as 50-100 psi due to laitance on the surface.
Consequently, good surface preparation must be carried out before a sat-
isfactory bond of epoxy to concrete can be obtained.
Experience has definitely shown that the best method of preparing a
concrete surface for bonding is through mechanical scarification to re-
move surface laitance. This scarification can be accomplished by chip-
