machinery bases or where design requires precision
setting of plates or requires that bedding material
have high resistance to shear, impact, or vibration,
and where good damp packing is difficult or
impossible. When using nonshrink grout on important
structures, such as large machinery bases, the grout
should be required to meet ASTM C 1107, Grade A, B,
or C, grade or grades as selected by the designer.
This nonshrink grout must not be used for embedding
post-tensioned tendons or rock bolts. Edit
bracketed item as appropriate, and delete entire
paragraph if not needed.
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After being properly positioned, column base plates, bearing plates for
beams and similar structural members, and machinery and equipment base
plates shall be set to the proper line and elevation with damp-pack bedding
mortar, except where nonshrink grout is indicated. The thickness of the
mortar or grout shall be approximately 1/24 the width of the plate, but not
less than 20 mm 3/4 inch. Concrete and metal surfaces in contact with
grout shall be clean and free of oil and grease, and concrete surfaces in
contact with grout shall be damp and free of laitance when grout is placed.
Nonshrink grout shall be used for [_____].
3.16.1
Damp-Pack Bedding Mortar
Damp-pack bedding mortar shall consist of 1 part cement and 2-1/2 parts
fine aggregate having water content such that a mass of mortar tightly
squeezed in the hand will retain its shape but will crumble when disturbed.
The space between the top of the concrete and bottom of the bearing plate
or base shall be packed with the bedding mortar by tamping or ramming with
a bar or rod until it is completely filled.
3.16.2
Nonshrink Grout
Nonshrink grout shall be a ready-mixed material requiring only the addition
of water. Water content shall be the minimum that will provide a flowable
mixture and completely fill the space to be grouted without segregation,
bleeding, or reduction of strength.
3.16.2.1
Mixing and Placing of Nonshrink Grout
Mixing and placing shall be in conformance with the material manufacturer's
instructions and as specified therein. Ingredients shall be thoroughly
dry-mixed before adding water. After adding water, the batch shall be
mixed for 3 minutes. Batches shall be of size to allow continuous
placement of freshly mixed grout. Grout not used within 30 minutes after
mixing shall be discarded. The space between the top of the concrete or
machinery-bearing surface and the plate shall be filled solid with the
grout. Forms shall be of wood or other equally suitable material for
completely retaining the grout on all sides and on top and shall be removed
after the grout has set. The placed grout shall be carefully worked by
rodding or other means to eliminate voids; however, overworking and
breakdown of the initial set shall be avoided. Grout shall not be
retempered or subjected to vibration from any source. Where clearances are
unusually small, placement shall be under pressure with a grout pump.
Temperature of the grout, and of surfaces receiving the grout, shall be
maintained at 18 to 30 degrees C 65 to 85 degrees F until after setting.
SECTION 03300A
Page 63
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