Downloaded 139 times
More Related Content
Similar to Shotcrete concrete
Shotcrete concrete
- 1. TECHNICAL SEMINAR ON SHOTCRETE CONCRETE S.SRINIVAS REDDY 14H51A01A4
- 2. DEFINITION • Shotcrete, guniteor 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, thenknown 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 hasproved 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 DRYPROCESS : • 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 WETPROCESS : • 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.
- 14. CONCULSION : • Theuse 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.