Either the wet-mix process or the dry-mix process may be used to produce shotcrete.
Dry mix process
Batching and Mixing
Aggregate and cementitious materials
shall be batched by mass. Equipment for batching by mass shall be
capable of the accuracy specified in ASTM C94. The mixing equipment
shall be capable of thoroughly mixing materials in sufficient quantity
to maintain placing continuity and be capable of discharging all mixed
material without any carryover from one batch to the next.
Delivery Equipment
The equipment shall be capable of
discharge the aggregate-cement mixture into the delivery hose and
delivering a continuous smooth stream of uniformly mixed material to the
discharge nozzle. The discharge nozzle shall be equipped with a
manually operated water injection system (water ring) for directing an
even distribution of water through the aggregate-cement mixture. The
water valve shall be capable of ready adjustment to vary the quantity of
water and shall be convenient to the nozzleman. The water pressure at
the discharge nozzle shall be sufficiently greater than the operation
air pressure to ensure that the water is completely mixed with the other
materials. If the line water is inadequate, a water pump shall be
introduced into the line. The water pressure shall be steady
(non-pulsating). 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.
Wet mix process
Batching and mixing
Batching and mixing shall be
accomplished in accordance with the applicable provisions of ASTM C94.
The mixing equipment shall be capable of thoroughly mixing the
specified materials in sufficient quantity to maintain continouous
placing. Ready-mix shotcrete complying with ASTM C94 may be used.
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.
