BLASTING and its type

mainly for civil engineers

1. SHRI K J PLOYTECHNIC BHARUCH CIVIL DEPARTMENT 1

2. TOPIC BLASTING TYPES OF BLASTING FEATURES OF MAGAZINE BUILDING STORAGE OF EXPLOSIVE GUIDED BY : MISS KHYATI CHOWKSI 2

3. BLASTING DEFINITION- The process of breaking rocks into smaller pieces by use of explosives. TYPES OF BLASTING- Abrasive Blasting Rock Blasting 3

4. ABRASIVE BLASTING 4

5. Abrasive blasting is the operation of forcibly propelling a stream of abrasive material against a surface under high pressure to smooth a rough surface, roughen a smooth surface, shape a surface or remove surface contaminants. A pressurized fluid, typically compressed air, or a centrifugal wheel is used to propel the blasting material. The first abrasive blasting process was patented by Benjamin Chew Tilgham. 5

6. Several abrasive variants are: Most abrasive: Shot blasting, Sand blasting Moderately abrasive: Glass bead blasting Mild abrasive: Soda blasting Barely abrasive: Ice blasting Non abrasive: Dry-ice blasting 6

7. Types of Abrasive Blasting Wet abrasive blasting Wheel blasting Bead blasting Bristle blasting Micro-abrasive blasting Automated blasting Dry-ice blasting Hydro blasting 7

8. Sand Blasting Sand blasting is a general term used to describe the act of propelling very fine bits of material at high velocity to clean a surface. 8

9. Wet abrasive blasting : It is an alternative to sand blasting. Bead blasting : Process of removing surface deposits by applying fine glass beads at high pressure without damaging the surface. Used to clean calcium deposits from pool tiles. Used in auto body work to remove paint. 9

10. Wheel blasting : A wheel uses centrifugal forces to propel the abrasive against an object. It is also known as Airless blasting as no propellent (gas or liquid) is used. Hydro blasting : A highly pressurized stream of water is used to remove old paint,chemical or build up without damaging original surface. It is also known as Water blasting . 10

11. Micro-abrasive blasting : It is dry abrasive blasting process that uses small nozzles to deliver a fine stream of abrasive accurately to a small part or small area on a large part. Also known as Pencil blasting . Automated blasting : It is simply the automation of abrasive blasting process. Care is needed to isolate the blasting chamber from mechanical components that may be subjected to dust fouling. 11

12. Application of Abrasive Blasting Lettering & engraving on most of modern cemetry monuments. Used to produce 3D signage. Used to refurbish bldgs or works of art. Used for cleaning boat hulks as well as brick, stone & concrete work. Used for cleaning industrial as well as commercial structure. 12

13. ROCK BLASTING 13

14. Blasting is controlled by use of explosives & other methods such as gas pressure blasting pyrotechnics to break rock for excavation. It is practiced mostly in mining, quarrying & civil engg. such as dam or road construction. The result of rock blasting is also known as rock cut. 14

15. Explosives are used in rock blasting: High velocity explosives for hard rock. Low velocity explosives for soft rock. The mostly used explosives in mining today are ANFO based blends due to lower cost than dynamite. 15

16. PROCEDURE OF ROCK BLASTING No. of holes are drilled into rock which are filled with explosives. Detonating explosives causes rock to collapse. Rubble is removed & new tunnel surface is reinforced. Repeat this steps until desired excavation is complete. 16

17. PROCESS OF BLASTING 1.The blast holes are made and cleaned by using the tools. 2.The charge of explosive placed at the bottom. 3.Remaining portion is filled with clay and tamped. 4.Fuse is inserted, kept projecting 15-20 cm above the rock surface. 5. Thereafter free end of fuse is fired by detonator. 17

18. MAGAZINE BUILDING A specially constructed bldg used for storing explosive is called magazine bldg . 18

19. FEATURES OF MAGAZINE BUILDING Should be const. of bricks, stone or C.C. Should be properly ventilated. Walls,floors,roof & door-windows should be made of fire resisting material. Should be provided by a high barbed wire fencing on its boundary. Floor area should not be less than 9 sq m. Not more than 150kg of explosive or 50000 m of safety fuse should be stored in magazine bldg. 19

20. Imp. Points taken care in Magazine bldg : Should be const. away from residential bldg & important structure. Smoking should be prohibited within radius of 50m from bldg. A water tank of 15cm depth should be provided near the gate of magazine bldg. Person entering the bldg should dip there feet or shoes in water before entering. Nobody is allow to enter with bare feet or with nailed shoes. 20

21. EXPLOSIVES An explosive is a chemical compound that can decompose instantaneously & violently when initiated by energy in form of heat, impact or friction or by another detonation difficult conditions like densely packed holes under water & so on. The principle ingredients in explosive are fuels & oxidizers. 21

22. EXPLOSIVE USED IN BLASTING Dynamite Ammonium Nitrate Slurry ANFO RDX 22

23. Dynamite : Explosive used in blasting. Consists of 25% of sandy earth saturated with 75% of nitroglycerine. Very poisonous in nature & develop violent headaches through touch with skin. Ammonium Nitrate : Widely used in const. project for surface as well as underground explosive. Economical than dynamite. 23

24. Slurry : Generic term for both water gas & emulsion. Made of ammonium, calcium or sodium nitrate & a fuel sensitizer along with varying amt. of water. ANFO : ANFO= Ammonium Nitrate Fuel Oil Used extensively for const. blasting & represents about 80% of all explosive used in U.S. RDX : RDX=Rapid Detonating Explosive 24

25. STORAGE OF EXPLOSIVES “ High explosive such as blasting caps, detonating cord, boosts, etc must be stored in: Type 1: Permanent magazine Type 2:Mobile magazine Type 3:Magazine for attended storage “ 25

26. PRECAUTIONS FOR STORAGE OF EXPLOSIVE All laws in this respect should be rigidly followed. The floor,roof,walls,doors-windows of magazine bldg should be made of fire resisting material. The floor area of magazine bldg shall not be less than 9 sq m. Magazine bldg should be well ventilated. Boxes of explosive should not be opened in magazine bldg. 26

27. For opening the boxes of explosive, brass hammer should be used. Store house should be properly locked by an authorized person. The keys of magazine bldg should be kept with authorized person. Detonators should not be stored with other explosive. Don’t keep explosive where they are exposed to excessive heat, spark or impact. 27

28. 28 THANK YOU