Sectionals Micro Fiber

Fiber reinforced concrete

Historical perspective

The concept of using fibers as reinforcement is not new. Fibers have been used as reinforcement since ancient times. Historically, horsehair was used in mortar and straw in mud bricks. In the early 1900s, asbestos fibers were used in concrete, and in the 1950s the concept of composite materials came into being and fiber reinforced concrete was one of the topics of interest. There was a need to find a replacement for the asbestos used in concrete and other building materials once the health risks associated with the substance were discovered. By the 1960s, steel, glass (GFRC), and synthetic fibers such as polypropylene fibers were used in concrete, and research into new fiber reinforced concretes continues today.

Effect of fibers in concrete

Fibers are usually used in concrete to control plastic shrinkage cracking and drying shrinkage cracking. They also lower the permeability of concrete and thus reduce bleeding of water. Some types of fibers produce greater impact, abrasion and shatter resistance in concrete. Generally fibers do not increase the flexural strength of concrete, so it can not replace moment resisting or structural steel reinforcement. Some fibers reduce the strength of concrete. The amount of fibres added to a concrete mix is measured as a percentage of the total volume of the composite (concrete and fibres) termed volume fraction (Vf). Vf typically ranges from 0.1 to 3%. Aspect ratio (l/d) is calculated by dividing fibre length (l) by its diameter (d). Fibres with a non-circular cross section use an equivalent diameter for the calculation of aspect ratio. If the modulus of elasticity of the fibre is higher than the matrix (concrete or mortar binder), they help to carry the load by increasing the tensile strength of the material. Increase in the aspect ratio of the fibre usually segments the flexural strength and toughness of the matrix. However, fibres which are too long tend to “ball” in the mix and create workability problems.

Some recent research[where?] indicated that using fibers in concrete has limited effect on the impact resistance of concrete materials[1 & 2]. This finding is very important since traditionally people think the ductility increases when concrete reinforced with fibers. The results also pointed out that the micro fibers is better in impact resistance compared with the longer fibers.

The High Speed 1 tunnel linings incorporated concrete containing 1 kg/m of polypropylene fibres, of diameter 18 & 32 m, giving the benefits noted below.

Benefits

Polypropylene fibres can:

Improve mix cohesion, improving pumpability over long distances

Improve freeze-thaw resistance

Improve resistance to explosive spalling in case of a severe fire

Improve impact resistance

Increase resistance to plastic

Some developments in fiber reinforced concrete

The newly developed FRC named Engineered Cementitious Composite (ECC) is 500 times more resistant to cracking and 40 percent lighter than traditional concrete.[citation needed] ECC can sustain strain-hardening up to several percent strain, resulting in a material ductility of at least two orders of magnitude higher when compared to normal concrete or standard fiber reinforced concrete. ECC also has unique cracking behavior. When loaded to beyond the elastic range, ECC maintains crack width to below 100 m, even when deformed to several percent tensile strains.

Recent studies performed on a high-performance fiber-reinforced concrete in a bridge deck found that adding fibers provided residual strength and controlled cracking. There were fewer and narrower cracks in the FRC even though the FRC had more shrinkage than the control. Residual strength is directly proportional to the fiber content.

A new kind of natural fiber reinforced concrete (NFRC) made of cellulose fibers processed from genetically modified slash pine trees is giving good results[citation needed]. The cellulose fibers are longer and greater in diameter than other timber sources. Some studies were performed using waste carpet fibers in concrete as an environmentally friendly use of recycled carpet waste. A carpet typically consists of two layers of backing (usually fabric from polypropylene tape yarns), joined by CaCO3 filled styrene-butadiene latex rubber (SBR), and face fibers (majority being nylon 6 and nylon 66 textured yarns). Such nylon and polypropylene fibers can be used for concrete reinforcement.

For statical calculations there is a new modelling in the book: B.Wietek, Stahlfaserbeton, edited by Vieweg + Teubner, 2008, ISBN 978-3-8348-0592-8.

See also

Reinforced concrete

Glass-reinforced plastic

Fibre-reinforced plastic

References

^ a b

[dead link]

Related article and publications

STEEL FIBER PRODUCS FOR FLOORING AND SHOTCRETING

Steel fibre reinforced Concrete FAQ

Categories: Composite materials | Concrete | Glass applications | Building materialsHidden categories: Articles needing additional references from September 2009 | All articles needing additional references | Vague or ambiguous geographic scope | All articles with unsourced statements | Articles with unsourced statements from October 2009 | All articles with dead external links | Articles with dead external links from January 2010
About the Author

I am a professional editor from
China Suppliers
, and my work is to promote a free online trade platform.
http://www.frbiz.com/ contain a great deal of information about

folding chair in bag
,
propane camping stoves

welcome to visit!

3 PC Hazelnut Microfiber Sectional Sofa

Bobkona Manhattan Reversible Microfiber 3-Piece Sectional Sofa Set, Navy Blue $714.00 You will receive a total of 1 chaise, a 2-seat sofa and 1 cocktail ottoman. Chaise Dimension: 65″W x 30″D x 35″H 2-Seat Sofa Dimension: 53″W x 34″D x 35″H Cocktail Ottoman Dimension: 32″W x 24″D x 19″H Finish: Navy Material: Microfiber Plush 3 pcs Sectional Sofa Set with Ottoman and Accent Pillows in Navy This sectional sofa set is designed in contemporary style with 2 free accent pillows. …

Cue Silk Micro Fiber Towel $11.95 Cue Silk Micro Fiber Towel

Aramith Micro Fiber Cleaning Cloth $9.83 Aramith Micro Fiber Cleaning Cloth

Eggplant Micro Fiber Corner Chair $305 Eggplant Micro Fiber Corner Chair

Swobbit Chenille Micro Fiber Mitt $16.99 SWOBBIT MICRO FIBER WASH MITT CHENILLE

Glee – Season 1 Volume 1 – Road to Sectionals $23.99 Glee – Season 1 Volume 1 – Road to Sectionals

Chenille Micro Fiber Mitt $10.94 Chenille Micro Fiber Mitt Chenille Micro Fiber MittSW61865 Thousands of tiny micro fibers 1/100th the width of a human hair clean without smearing or streaking. Super-soft chenille micro fiber strands gently wash paint, fiberglass, windows and enclosures. Holds plenty of soap and water. Lined for your comfort. Mitt measures 9″ x 11″. Elastic Cuff.

Micro Fiber Pants $12.99 Silky Scrubs – Elastic waist pant with tie front. 2 side pockets. Polyester micro-fiber feels like silk. 29″ inseam.