Bendable concrete also known as Engineered Cementitious Composites abbreviated as ECC belongs to the class of ultra-ductile fiber reinforced cementitious composites, characterized by high ductility and tight crack control width. This material is capable of exhibiting considerably good flexibility. An ECC has a strain capacity of near about 3% and thus acts more like a ductile metal. A bendable concrete is reinforced with micromechanically designed polymer fibres and also some amount of steel fibres as per requirement.
Conventional concretes are almost unbendable and have a strain capacity of only 0.1% making them highly brittle and rigid. This lack of bendability is a major cause of failure under strain and has been a pushing factor in the development of an elegant material namely, bendable concrete also known as Engineered Cementitious Composites abbreviated as ECC.
A bendable concrete is reinforced with micromechanically designed polymer fibres. ECC is made from the same basic ingredients as conventional concrete but with the addition of High-Range Water Reducing (HRWR) agent to impart good workability. Coarse aggregates are not used in ECCs. The content of finer materials in ECC is relatively high. Cementitious materials, such as fly ash, silica fume, blast furnace slag, silica fume, etc. may be used in addition to cement to increase the plasticity index of the mix. Additionally, ECC uses low amounts, typically 2% by volume, of short, discontinuous fibres. ECC incorporates super fine silica sand and tiny Polyvinyl Alcohol-fibres covered with a very thin (nanometer thick), slick coating (thermoplastic/teflon/antifriction type coating). This surface coating allows the fibre to begin slipping when they are over loaded so that they do not fracture, this prevents large cracks. Thus an ECC deforms much more than a normal concrete but without fracturing.
ECC has proved to be 50 times more flexible than traditional concrete, and 40 times lighter, which could even influence design choices in skyscrapers.
The excellent energy absorbing properties of ECC make it especially suitable for critical elements in seismic zones.
Conventional concretes are almost unbendable and have a strain capacity of only 0.1% making them highly brittle and rigid. This lack of bendability is a major cause of failure under strain and has been a pushing factor in the development of an elegant material namely, bendable concrete also known as Engineered Cementitious Composites abbreviated as ECC.
A bendable concrete is reinforced with micromechanically designed polymer fibres. ECC is made from the same basic ingredients as conventional concrete but with the addition of High-Range Water Reducing (HRWR) agent to impart good workability. Coarse aggregates are not used in ECCs. The content of finer materials in ECC is relatively high. Cementitious materials, such as fly ash, silica fume, blast furnace slag, silica fume, etc. may be used in addition to cement to increase the plasticity index of the mix. Additionally, ECC uses low amounts, typically 2% by volume, of short, discontinuous fibres. ECC incorporates super fine silica sand and tiny Polyvinyl Alcohol-fibres covered with a very thin (nanometer thick), slick coating (thermoplastic/teflon/antifriction type coating). This surface coating allows the fibre to begin slipping when they are over loaded so that they do not fracture, this prevents large cracks. Thus an ECC deforms much more than a normal concrete but without fracturing.
ECC has proved to be 50 times more flexible than traditional concrete, and 40 times lighter, which could even influence design choices in skyscrapers.
The excellent energy absorbing properties of ECC make it especially suitable for critical elements in seismic zones.
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