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PPT ON SHOTCRETE TECHNOLGY BY MD AMANULLAH
1. DEEPSHIKHA KALA SANSTHAN GROUP OF
INSTITUTIONS JAIPUR
A PRESENTATION ON
CONCEPTS OF SHOTCRETE TECHNOLOGY
UNDER THE GUIDANCE
OF
• MD AMANULLAH
• B TECH (C.E)
• SEM-7TH
• ROLL NO-11EDGCE027
SUBMITTED BY-
MR. RAJEEV KUMAR
MR. JAMBU JAIN
Assistant professor
DKSGI JAIPUR
2. CONTENT
INTRODUCTION
DEFINITION OF SHOTCRETE
SHOTCRETE MATERIALS
EQUIPMENTS USED IN SHOTCRETE
SHOTCRETE VERSUS CONVENTIONAL CONCRETE
DRY PROCESSES
WET PROCESS
APPLICATIONS OF SHOTCRETE
ADVANTAGES
DISADVANTAGES
CONCLUSION
REFRENCES
3. 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 with this shotcrete technology.
Tunnel linings are also becoming easy technology.
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.
4. 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.
applied mixture of cement, aggregate, and water conveyed through a hose and projected at
high velocity onto the application 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.
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.
5. HISTORY
Shotcrete, then known as gunite (/ˈgənīt/), was invented in 1907 by
American taxidermi Akeley to repair the crumbling facade of the Field
Columbian Museum in Chicago (the old Palace of Fine Arts from the World's
Columbian Exposition. He used the method of blowing dry material out of a
hose with compressed air, injecting water at the nozzle as it was released.
In 1911, he was granted a patent for his inventions, the "cement gun", the
equipment used, and "gunite", the material that was produced.
There is no evidence that Akeley ever used sprayable concrete in his
taxidermy work, as is sometimes suggested. F. Trubee Davison covered this
and other Akeley inventions in a special issue of Natural History magazine[
Until the 1950s when the wet-mix process was devised, only the dry-mix
process was used. In the 1960s,
The alternative method for gunning by the dry method was devised with the
development of the rotary gun, with an open hopper that could be fed
continuously. Shotcrete is also a viable means and method for placing
structural concrete.
6. SHOTCRETE MATERIALS
(SAME AS CONCRETE)
• Portland Cement
• Water
• Sand
• Admixtures / Fibers
Difference : ???
• Applied via Compressed Air
8. EQUIPMENTS USED IN SHOTCRETE
Batching and mixing equipment
Admixture dispensers
Air COMPRESSOR
Nozzles
Shotcrete accelerator
Fig-1.1
Fig-1.2
Cskeda.en.alibaba.c
9. SHOTCRETE VERSUS CONVENTIONAL CONCRETE
Unlike conventional concrete, which is first placed and then compacted in second operati
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.
Shotcrete is not placed or contained by forms. It can be impacted onto any type or shape o
surface, including vertical or overhead areas.
10. WORKING OF DRY PROCESS PROCEEDS AS PER
THE FOLLOWING STEPS:
Step1: Pre blended, dry or semi-dampened materials are placed into
shotcrete equipment and metered into a hose.
Step2: Compressed air conveys materials at high velocity to the nozzle
where the water is added.
Step3: Then the material is consolidated on receiving surface by high
impact velocity
.
The dry process can be used for any shotcreting applications from the
smallest patching and sealing works to largest projects.
The maximum production achievable with dry process equipment ranges
from 10-12 yards per hour of dry mix depending on the conditions.
Most applications have production rates of 2-6 cubic yards per hour of
mix.
11. DEFINITIONOFWETMIXSHOTCRETE
Shotcrete in which all of the ingredients, except accelerator, are mixed before
introduction into the delivery hose.
http://www.zzkaishan.en.alibaba.com
Fig-1.4
12. SHOTCRETE (WET MIX)
Accelerator, if used, is added to the shotcrete mixture at the nozzle in
such a way that the quantity can be properly regulated and monitored.
http://www.concreteconstruction.net/images/Shotcrete%20Pu
mps%20and%20Related%20Equipment_tcm45-342547.
Fig-1.5
13. WORKING OF WET PROCESS PROCEEDS AS
PER THE FOLLOWING STEPS:
Step 1: Wet material is pumped to the nozzle where compressed air is
introduced to
Step2: All ingredients, including water, are thoroughly mixed and introduced
into the shotcrete equipment.
provide high velocity for placement and consolidation of the material onto the
receiving surface.
Step 3: Mostly wet-process shotcreting is done with premixed mortar or small
aggregate concrete.
The mix design and consistency of supply are very important in order to provide
a mix with the workability or plasticity to be pumped through a small-diameter
hose.
Sand gradation is same as for the dry process and for coarse aggregate mixes;
20-30 percent of 20mm aggregate is added. Cement content will vary according
to agg.
However, most mixes contain approximately 700 pounds or more of
cement.
14. APPLICATION OF SHOTCRETE
Support of underground openings in tunnel, mines, drainage adits and
exploratory audits.
Rock slope stabilization and support for excavated foundations, often in
conjuction with rock and soil anchor systems.
Channel linings, protection of bridge abutments and stabilization of debris-flow
prone creeks.
Rehabilitation of reinforced concrete structures such as bridges ,chemical
processing and handling plants.
Rehabilitation of deteriorated marine structures such as bulkheads, piers, sea
Fig-1.6 Fig-1.7
21. ADVANTAGES
Little or no framework is required.
Cost effective method for placing concrete.
Ideal for irregular surfaces application.
Allows for easier material handling in areas with difficult access.
Easy start up, shutdown and clean up.
An increase in load bearing capacity due to redistribution of
stresses.
Excellent corrosion resistance
23. DISADVANTAGES
Rain may wash out the cement leaving a sandy surface, or it may
saturate the shotcrete and cause sloughing or sagging
Strong wind will separate the material between the nozzle and
the point of deposit, reducing the strength
It requires skilled and experienced labours.
A greater degree of geotechnical knowledge is required
Improperly applied shotcrete may create conditions much worse
than the untreated condition
24. CONCLUSION
The use of Shotcrete to build new concrete structures as well as
to restore and repair existing structures is well known and
documented and it is perhaps the most diverse method available
for concrete construction.
The use of this innovative technology is increasing day by day and
procedures for its proper performance are well developed and
high quality work is regularly obtained.
Shotcrete is a viable option for doing superstructure repair
(unformed) and substructure repair (unformed) if done strictly
according to specifications and best practices.
It is a good substitute for the manual lay-up method for vertical
and overhead applications using rapid set mortar.
