Fiber reinforced concrete

PRESNTED BYYOGESH C. KOTIYALM.TECH FIRST YEAR

GUIEDED BYDr. S. K. MADAN

Introduction

Fiber Reinforced Concrete can be defined as a composite material consisting of mixtures of cement, mortar or concrete and discontinuous, discrete, uniformly dispersed suitable fibers. Continuous meshes, woven fabrics and long wires are not considered to be discrete fibers, Because of some workability and impact resistance demerits.

PropertiesThe newly developed FRC is 500 times more resistant to cracking and 40 percent lighter than traditional concrete.

FRC can sustain strain-hardening up to several percent strain, resulting increase in a material ductility when compared to normal concrete .

FRC also has unique cracking behaviour. When loaded to beyond the elastic range, FRC maintains crack width to below 100 µm, even when deformed to several percent tensile strains.

Material uses

Fibers include steel fibers, glass fibers, synthetic fibers and natural fibers. Within these different fibers the character of fiber reinforced concrete changes with varying concretes, fiber materials, distribution, orientation and densities.

Typical Proportions For FRC…

Ingredients ProportionsCement content 325 kg to 550 kg/m2W/C Ratio 0.4 to 0.6Sand/Total Aggregates 50-100%Max aggregate size 10 mmAir content 6-9%Fiber PercentageSteel 1percent for 78Kg/m3Glass 1% for25Kg/m3Nylon 1% for11Kg

applicationsFibre- reinforcement is mainly used in shotcrete, but can also be used in normal concrete. Fibre-reinforced normal concrete are mostly used for on-ground floors and pavements, but can be considered for a wide range of construction parts (beams, pillers, foundations etc) either alone or with hand-tied rebars

AdvantagesFibres are usually used in concrete to control cracking due to both plastic shrinkage and drying shrinkage.

They also reduce the permeability of concrete and thus reduce bleeding of water.

Some types of fibres produce greater impact, abrasion and shatter resistance in concrete.

Steel fibres can:

Improve structural strength.

Reduce steel reinforcement requirements

Improve ductility.

Reduce crack widths and control the crack width tightly thus improve durability.

Improve impact & abrasion resistance.

Improve freeze-thaw resistance.

Polypropylene and Nylon fibres can:

Improve mix cohesion, improving pumpability over long distances.

Improve freeze-thaw resistance.

Improve impact resistance.

Increase resistance to plastic shrinkage during curing.

pre cast FRC

Conclusion

Recent studies performed on a high-performance fibre-reinforced concrete found that adding fibres 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.

References• fiber reinforced concrete by joost c. walraver

• FRC by R. N. Swammy.

•Encyclopedia FRC.

•www.books.google.com

Thank you