technical seminar topic SHOTCRETE CONCRETE for CIVIL ENGINEERING people

1. TECHNICAL SEMINAR
ON
SHOTCRETE CONCRETE
S. SRINIVAS REDDY
14H51A01A4

2. DEFINITION
• Shotcrete, gunite or sprayed concrete is concrete or mortar conveyed
through a hose and pneumatically projected at high velocity onto a
surface, as a construction technique.

3. HISTORY
• Shotcrete, then known as gunite , was invented in 1907 by Carl Akeley to repair the crumbling
facade of the Field Columbian Museum in Chicago .
• He used the method of blowing dry material out of a hose with compressed air, injecting water at
the nozzle as it was released.
• The dry-mix process was used until the wet-mix process was devised in the 1950s. In the 1960s, an
alternative method for gunning dry material with a rotary gun appeared.
• The nozzle is controlled by hand on small jobs, such as a modest swimming pool. On larger work it
is attached to mechanical arms and operated by hand-held remote control.

4. INTRODUCTION:
• Shotcreting has proved to be the best method for construction of
curved surfaces like Domes, tunnels etc.
• The technology is improving giving us enhanced controls and tasks is
completed with a greater economy in terms of both time and
investment
• Shotcreting is done with a special unit, which consists of a mortar gun
or concrete sprayer and a compressor

5. CLASSIFICATION OF SHOTCRETE
• 1. DRY PROCESS
• 2. WET PROCESS

6. 1. DRY PROCESS
• Pre blended dry or semi dampened materials are placed into shotcrete equipment .
• The dry mix method involves placing the dry ingredients into a hopper and then conveying them
pneumatically through a hose to the nozzle.
• The nozzleman controls the addition of water at the nozzle.
• The water and the dry mixture is not completely mixed, but is completed as the mixture hits the
receiving surface.
• This requires a skilled nozzleman, especially in the case of thick or heavily reinforced sections.
• Then the materials is consolidated on receiving surface by high impact
• The maximum production achievable with dry process equipment ranges from 10-12 yards per
hour of dry mix depending on conditions at a velocity of 130-170 m per sec.

8. ADVANTAGES OF DRY PROCESS :
• Easy start up, shutdown and clean up.
• Control of materials is on site
• Nozzle man can be up to 1000ft horizontally or 500ft vertically from the gun
• water content can be adjusted instantaneously by the nozzleman, allowing more effective
placement in overhead and vertical applications without using accelerators.

9. WET PROCESS :
• All ingredients including water are thoroughly mixed and introduced into the shotcrete equipment
• Wet material is pumped to the nozzle where compressed air is introduced to provide high velocity
• Mostly wet process shotcreting is done with premixed mortar or small aggregate concrete

11. ADVANTAGES OF WET PROCESS :
• Little or no formwork is required
• Cost effective method for placing concrete
• Ideal for irregular surface applications
• Allows for easier materials handling in areas with difficult access

12. APPLICATIONS OF SHOTCRETE :
• Tunnel lining is made much easy by this process
• Shotcrete technology proved to be more efficient and easy for the
construction of domed roofs
• The greatest advantage of the wet-mix process is all the ingredients
are mixed with the water and larger volumes can be placed in less
time than the dry process.

13. TUNNEL LINING
DOME LINING

14. CONCULSION :
• The use of shotcrete to build new concrete structures as well as to restore 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
performing are well developed and high work is regularly obtained.

15. THANKYOU