TM 5-809-3/NAVFAC DM-2.9/AFM 88-3, Chap. 3
sure, possibly augmented by tapping, to force the
accordance with ASTM C 1019.
c. Requirements during construction. Masonry
mortar into intimate contact with the unit surface.
i. Construction factors effecting mortar. Proper
units and grout interact in the same manner as unit-
mixing is essential to obtain a uniform distribution
mortar interaction, that is, water is drawn from the
of materials and the desired workability and
grout into the masonry by suction. The final grout
strength properties. Retempering, that is, adding
strength is a function of water content after
water to mortar to restore workability as permitted
suction.
(1) Mixing grout. Because of better control,
by ASTM C 270 should be employed with extreme
caution because the water-cement ratio may be
grout should be batched and mixed in transit-mix
altered with attendant loss of strength.
trucks.
(2) Placing grout. Grout may be poured or
3-5. Grout. Grout, ASTM C 476, is a mixture of
pumped into grout spaces. Proper placement of
cementitious materials and aggregate to which
grout requires that it be sufficiently fluid to be
sufficient water has been added to permit the grout
pourable and to completely fill the grout space. The
to be readily poured into masonry grout spaces
suction of the masonry units, IRA, in the case of
without segregation of the materials. Grout is
clay masonry units, will influence the amount of
placed in the cavities formed by the masonry units.
water required in grout. Higher water content is
It bonds to the masonry units and to steel
required if masonry units have a high rate of
reinforcement, ties, and anchors to form a unified
absorption (suction) to reduce the tendency of
composite structure.
grout to adhere to the sides of the grout space
a. Grout type and materials. Grout is identified
while it is being poured and thus constrict the
as fine or coarse depending on the maximum size of
space. The converse is true if the units have low
the aggregate used. Fine or coarse grout should be
suction. A grouting admixture may be useful in
used in accordance with the guide specification.
retarding water loss from grout. The water content
b. Grout strength. Grout will have a minimum
may be lower for large grout spaces (4-inch least
compressive strength of 2000 pounds per square
dimension), than for small grout spaces (2-inch or
inch as measured by a uniaxial compressive test in
smaller least dimension). Slump, as measured by
3-6
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