21-05-2012, 01:02 PM
CONCEPTS OF SHOTCRETE TECHNOLOGY
CONCEPTSOFSHOTCRETETECHNOLOGY.pdf (Size: 271.38 KB / Downloads: 425)
ABSTRACT:
Shotcrete is the sprayed concrete, which was first used in Pennsylvania, USA in
1907 by Dr.Aneley. The technology is improving giving us enhanced comforts and the
task is completed with a greater economy in terms of both time and investment. This
innovative technology of shotcrete was introduced to make the work easier and
immediate where any alterations are to be made or any architectural effects are to be
enhanced.
INTRODUCTION: -
Shortcreting has proved to be the best method for construction of curved surfaces.
Domes are now much easier to construct with the advent of shotcrete technology. Tunnel
linings are also becoming easy with this technology. Not only are these but there a wide
range of applications where this technology has been a leading one.
This technical paper includes the concept of shotcrete and how it differs from
conventional concrete. It also enumerates the different types of process involved in
shotcreting i.e. dry mix process and wet mix process. Advantages of shotcrete and its
applications in various fields like tunneling, canals, buildings etc. are specified in detail.
This paper presents an overview of shotcreteing technology along with its applications.
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DEFINITION OF SHOTCRETE:-
Shotcrete is a mortar or high performance concrete conveyed through a hose and
pneumatically projected at high velocity onto a backing surface. It is the force of this
spraying action that leads to compaction of the concrete or mortar which then forms
layers of concrete to the required thickness. Shotcreting has been an acceptable way of
placing cementitious material in a variety of applications.
Usually patented polypropylene fibers are included in the shotcrete which
increases the cohesive nature of the shotcrete through mechanically binding the
cementitious materials together. This mechanism reduces the rebound waste that occurs
through the shotcreting process and these fibers also resist plastic shrinkage and cracking
through their ability to enhance the early stage tensile strength of concrete.
Shotcrete also gives better surface finishes and reduces surface tearing on nonlinear
sections. Cementitious material containing the poly propylene fibers resist cycles
of freezing and thawing and also reduces the chances of water and chemical penetrations.
SHOTCRETE VERSUS CONVENTIONAL CONCRETE:-
Unlike conventional concrete, which is first placed and then compacted in the
second operation, shotcrete undergoes placement and compaction at the same time due to
the force with which it is projected from the nozzle.
Shotcrete is more dense, homogeneous, strong, and waterproof than is possible to
obtain by any other process. For most bridges original concrete will require additional
repair long before shotcrete needs repair and it suffers little detoriations.
Shotcrete is not placed or contained by forms. It can be impacted onto any type or
shape of surface, including vertical or overhead areas. It forms an excellent bond with the
substrate and can be given a variety of surface finishes.