3.2.3 Dry-pack mortar—Dry-pack mortar consists of one
part cement, two and one-half to three parts sand or
prepackaged proprietary materials, and only enough water
so the mortar sticks together when molded into a ball by
slight pressure of the hands and does not exude water but
leave the hands damp. Curing is critical because of the low
initial water content of dry-pack mortar.
a) Advantages—Because of its low w/c, dry pack exhibits
very little shrinkage. Therefore, the repair remains tight and
is of good quality with respect to durability, strength, and
water tightness. If the patch should match the color of the
surrounding concrete, a blend of gray and white portland
cement may be used. Normally, about 1/3 white cement is
adequate, but the precise proportions can only be determined
by trial.
b) Limitations—Dry pack is not well suited for patching
shallow depressions or for patching areas requiring filling
behind exposed reinforcement, or for patching holes
extending entirely through concrete sections. Without
adequate curing, dry pack repairs are subject to failure.
c) Applications—Dry pack can be used for filling large or
small cavities, form tie holes, or any cavity that allows for
adequate compaction. Such repairs can be accomplished on
vertical and overhead surfaces without forms. Dry pack can
also be used for filling narrow slots cut for the repair of
dormant cracks; however, it is not recommended for filling
or repairing active cracks. Dry pack is commonly used at
load transfer points and contact areas.
d) Standards—Currently, there are no standards for drypack
mortar