Bendable concrete

A power point presentation on the topic 'Bendable Concrete'.

1. DEPARTMENT OF CIVIL ENGINEERING BENDABLE CONCRETE PRESENTED BY : MUDASIR AHMAD DAR ENROLL : 4606 Bendable Concrete 1

2. Introduction Conventional concretes are almost unbendable. This lack of bendability is a major cause of failure under strain. It has been a pushing factor in the development of an elegant material namely, bendable concrete also known as Engineered Cementitious Composites (ECC.) C apable of exhibiting considerably enhanced flexibility. It is reinforced with micromechanically designed PVA fibres. ECC is made from the same basic ingredients as conventional concrete but with the addition of High-Range Water Reducing (HRWR) agent. However, coarse aggregates are not used in ECCs (hence it is a mortar rather than concrete). Bendable Concrete 2

3. Scope and Background Traditional concrete is considered to be a ceramic, brittle and rigid. It can suffer catastrophic failure when strained in an earthquake or by routine overuse. ECC acts more like metal than glass. It is studded with specially-coated reinforcing fibers that hold it together. ECC remains intact and safe to use at tensile strains up to 5%. Traditional concrete fractures and can’t carry a load at 0.01 % tensile strain. Bendable Concrete 3

4. Ingredients of ECC CEMENT SAND [FINE AGGREGATE SUPER PLASTICIZER FLY ASH PVA FIBRES WATER Bendable Concrete 4

5. Cement Cement used is Ordinary Portland cement 53 grade. Blast furnace slag may also be used in some cements and the cement is called Portland slag cement (PSC ). The color of the cement is due mainly to iron oxide. In the absence of impurities, the color would be white . Bendable Concrete 5

6. SAND [FINE AGGREGATE The fine silica sand is suitable for the flexible concrete which is used in the water treatment plant but if it is not available the normal sand can be used but it may effect the strength and flexibility of concrete. We can also add fly ash, silica fume, blast furnace slag to the concrete . Bendable Concrete 6

7. SUPER PLASTICIZER Super plasticizer used is Melamine Formaldehyde Sulphonate. H elp in dispersing the cement uniformly in the mix by their deflocculating action. Typically super plasticizer increase slump from say 5 cm to about 18-20 cm without addition of water. When used to achieve reduction in mixing water they can reduce water up to 15-20 %. Bendable Concrete 7

8. FLY ASH Fly ash used is pozzocrete dirk 60. S uccessful in reducing heat generation without loss of strength, increasing ultimate strength beyond 180 days, and providing additional fines for compaction . In proportioning mixes, for minimum paste volumes, one of principal function of a fly ash is to occupy void space which would otherwise be occupied by cement or water. Occupation of void space with water would obviously result in reduction in concrete strength. Bendable Concrete 8

9. PVA FIBRES R einforcing materials for cementitious Composites . High modulus of elasticity, durability, tensile strength and bonding strength with concrete matrix are some of its desirable properties. PVA fibre has high strength and modulus of elasticity (25 to 40GPa ). Fibre elongation is about 6-10%. The tensile strength of fiber is between 880MPa to 1600MPa. Bendable Concrete 9

10. WATER Water fit for drinking is generally considered fit for making concrete. Water should be free from acids, oils, alkalis, vegetables or other organic Impurities. Soft waters also produce weaker concrete. Water has two functions in a concrete mix. Firstly, it reacts chemically with the cement to form a cement paste in which the inert aggregates are held in suspension until the cement paste has hardened . Secondly, it serves as a vehicle or lubricant in the mixture of fine aggregates and cement. Bendable Concrete 10

11. Advantages of flexible concrete The flexible concrete has the ability to bend like a metal. It is more Stronger, more durable, and lasts longer than conventional concrete. It has a self-healing property that is it can heal itself by using carbon dioxide and rainwater. It is not brittle like a glass. It is more resistant to cracking. It does not emit that amount of harmful gases as compared to conventional concrete. The flexible concrete is approx. 20-40 percent lighter. The use of steel reinforcement is reduced and can be eliminated. It reduces the cost of the project. It can be used as precast concrete. Bendable Concrete 11

12. Disadvantages of flexible concrete It has a high initial cost as compared to conventional concrete. It requires skilled labor for its construction. It needs some special type of materials which can be difficult to find in some areas. Its quality depend upon the material used and the condition under which it is made. Its compressive strength can be lesser than the conventional concrete. Bendable Concrete 12

13. Uses of ECC Earthquake resistance building: The structure made with the flexible concrete can take more tensile stresses that it does not break down due to the vibration caused by the earthquake. In Japan a 60 floor is under construction which uses this concrete . Concrete canvas: The concrete canvas can also be made with the flexible concrete. The concrete canvas is stronger and durable than the normal canvas. It can be used in the military area . For roads & bridges: It can be used in roads and bridges. With the use of flexible concrete in roads and bridges there is no need of joints such as expansion joint, contraction joint as the concrete is itself have the ability to change its shape. Moreover the bridges and roads are more durable and has low repair cost. Bendable Concrete 13

14. Structure made with flexible concrete Bendable Concrete 14

15. Where was it first used? Mihara Bridge in Hokkaido, Japan in 2004. Cable stayed Bridge. Length : 1000 m ECC layer thickness : 38mm Weight reduction : 40% Cost reduction: 50% Expected service life: 100 years Bendable Concrete 15

16. conclusion ECC is the upcoming advancement in technology which will almost replace the Conventional Concrete in countries which are more prone to natural disaster. But in India it is still a new material and requires a proper research for its use in India. Bendable Concrete 16

17. THANK YOU Bendable Concrete 17