workability at as low a slump as possible.
3.2
INSTALLATION
3.2.1
Underbed Placement
Surfaces of concrete subfloor shall be cleaned and saturated with water in
accordance with NTMA Info Guide. Do not treat concrete substrate to
receive bonded terrazzo with curing agent or additives which would preclude
bonding. Excess water shall be removed from the subfloor before slushing
and brooming with neat cement paste. The underbed shall be placed on the
concrete subfloor and shall be screeded to an elevation 13 mm 1/2 inch
below the finished floor. Divider strips shall be installed in the
semiplastic underbed. The underbed shall be firmly troweled along the
edges to insure positive anchorage of the divider strips. Control joint
strips shall be installed over subfloor expansion joints and shall extend
the full depth of the underbed.
3.2.2
Setting Divider Strips
Set in accordance with layout indicated while underbed is still plastic.
Set strips to straight lines and to the proper level to ensure that tops of
strips will show uniformly after completing grinding and finishing
operations. Fit joints and intersections tight. Where divisions in field
work are not shown, divide field work into squares or rectangles of uniform
size and not more than 1800 mm 6 feet on a side. Divide borders by strips
to coincide with the layout of division strips in the field of floors.
Place edging strips at doorways between terrazzo and other types of
flooring and along the edges of terrazzo borders adjoining other types of
floor finishes or floor coverings. Place expansion strips over control
joints, construction joints, and expansion joints.
3.2.3
Placing Terrazzo Topping
The underbed shall be slushed and broomed in accordance with NTMA Info Guide
with neat cement paste of the same color as required for the topping. The
topping shall be placed in panels formed by divider strips and shall be
troweled level with the top of the strips. The troweled surface shall be
seeded with chips in the same color proportions as contained in the
terrazzo mix, troweled and rolled with heavy rollers until excess water has
been extracted. The terrazzo shall be troweled to a uniform surface
disclosing the lines of the divider strips.
3.2.4
Curing
The terrazzo shall be cured until the topping develops sufficient strength
to prevent lifting or pulling of terrazzo chips during grinding. Keep the
completed terrazzo continuously moist and free of traffic during the curing
period. Cure by covering with a liquid membrane-forming compound, sheet
materials, wet sand, or sprinkling with water.
3.2.5
Finishing
[Finishing shall be in accordance with NTMA Info Guide.] [After curing the
grout coat for a minimum of 72 hours, grind the floor using a No. 80 or
finer grit stone. In the latter stages of grinding, use grit stones or
other abrasive in the grinding machine of a grain or fineness that will
give the surface a honed finish. Grind and rub by hand small areas,
inaccessible portions, and corners that cannot be reached by the grinding
SECTION 09410
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