Shotcrete is concrete projected through a hose at high velocity using compressed air. It was invented in 1910 by Carl Ethan Akeley to reproduce dinosaur fossils in concrete. Shotcrete is mainly used in underground construction and can be applied either dry or wet. It offers benefits over traditional cast-in-place concrete like speed of construction, ability to build complex shapes, cost-effectiveness, and suitability for areas with limited access. However, proper planning, supervision, and skilled application are needed for successful shotcrete projects.

1. Fellow Constructor S.a.r.l 2012-02-24
SHOTCRETE
By definition, shotcrete is concrete transported by means of air under pressure with high
velocity. The projected concrete was invented by American architect Carl Ethan Akeley in 1910.
He was authorized to realize, in concrete, the reproduction of a dinosaur. Akeley had the idea to
develop a “cement gun” machine allowing the spraying of mortar or concrete.
Shotcrete is mainly used in underground construction projects (road-rail tunnel, hydropower
plant, mines, parking, subway, metro, storage area etc.). In addition to that, shotcrete is an
economical tool to accomplish slope stability work, swimming pools, waterways, concrete
repairs, inner lining and architectural structures. The total volume of shotcrete worldwide applied
yearly is more than 12 million cubic meters.
Compared to normal concrete, shotcrete differs mainly from three points:
The maximal size of the aggregate used.
The way to place it.
The mixture of shotcrete can be
dry or wet.
Dry Mix - Pre-blended dry or damp
materials are placed into the delivery
equipment. Compressed air conveys
material through a hose at high velocity
to the nozzle, where water is added.
Material is consolidated on the receiving
surface by the high-impact velocity.
References available upon request

2. Fellow Constructor S.a.r.l 2012-02-24
Wet Mix - All ingredients, including
water, are thoroughly mixed and
introduced into the delivery
equipment. Wet material is pumped to
the nozzle, where compressed air is
added to provide high velocity for
placement and consolidation of the
material onto the receiving surface.
Shotcrete systems are strong, durable,
and resistant to disasters, fires, mold,
insects and vermin, and have low
permeability, good thermal mass, and create tight envelopes. Although the hardened properties
of shotcrete are similar to conventional cast-in-place concrete, the nature of the placement
process provides additional benefits, such as very fast erection, particularly on complex forms or
shapes, including curved walls and arches. Shotcrete is a cost effective building method due to
the speed of construction and minimal equipment requirements. It is favorable in cases where
formwork is costly or impractical (forms can be reduced or eliminated), access to the work area
is difficult, thin layers or variable thicknesses are required, or normal casting techniques cannot
be employed. Additional savings are possible because shotcrete requires only a small, portable
plant for manufacture and placement. Shotcreting operations can often be accomplished in areas
of limited access to make repairs to structures.
The success of shotcrete applications is conditioned by proper planning and supervision, in
addition to the skill and the continuous attention provided by the shotcrete applicator. The
following picture is an extreme example of shotcrete improperly applied to mesh reinforcement.
It shows build-up of shotcrete on the face of the mesh and shadowing and voids behind.
References available upon request