sufficiently greater than the operating air pressure to ensure that the
water is completely mixed with the other materials. If the line water
pressure is inadequate, a water pump shall be introduced into the line.
The water pressure shall be steady (nonpulsating). The delivery equipment
shall be thoroughly cleaned at the end of each shift. Equipment parts,
especially the nozzle liner and water ring, shall be regularly inspected
and replaced as required.
3.1.2
Wet Mix Process
**************************************************************************
NOTE: Delete these four paragraphs if dry-mix
process is specified. See the appropriate DM to
select the proper air content.
**************************************************************************
3.1.2.1
Batching and Mixing
Batching and mixing shall be accomplished in accordance with the applicable
provisions of ASTM C 94/C 94M. If volumetric batching and mixing are used,
the materials shall be batched and mixed in accordance with the applicable
provisions of ASTM C 685/C 685M. The mixing equipment shall be capable of
thoroughly mixing the specified materials in sufficient quantity to
maintain continuous placing. Ready-mix shotcrete complying with ASTM C
94/C 94M may be used.
3.1.2.2
Delivery Equipment
The equipment shall be capable of delivering the premixed materials
accurately, uniformly, and continuously through the delivery hose.
Recommendations of the equipment manufacturer shall be followed on the type
and size of nozzle to be used and on cleaning, inspection, and maintenance
of the equipment.
3.1.2.3
Air Content
Air-entraining admixture shall be used in such proportion that the air
content of the shotcrete prior to gunning shall be [_____] plus or minus
() 1.0 percent as determined by ASTM C 231.
3.1.3
Air Supply
The Contractor shall provide a supply of clean, dry air adequate for
maintaining sufficient nozzle velocity for all parts of the work and, if
required, for simultaneous operation of a suitable blowpipe for clearing
away rebound.
3.2
PREPARATION OF SURFACES
3.2.1
Earth
Earth shall be compacted and trimmed to line and graded before placement of
shotcrete. Surfaces to receive shotcrete shall be dampened.
3.2.2
Existing Concrete
All unsound and loose materials shall be removed by sandblasting, grinding,
or high-pressure water jets before applying shotcrete. Any area to be
repaired shall be chipped off or scarified to remove offsets which would
SECTION 03371
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