GLASS FIBER REINFORCED CONCRETE

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History of GFRC
•Brought from England to the United States in 1970
•Formed by Stromberg
•First GFRC was used in USA
•Developed many techniques and technology used in GFRC
•In 1978 GFRC product was sold and installed on construction project in North America

About GFRC 
  • —Offers exciting properties.
  • —Allows designer the ability to achieve the durability of stone or concrete.
  • —Composed of glass fiber, cement and fine aggregate.
  • —Reduce water absorption .
  • —Non combustible.
  • —Variety of shape.
  • —Easily match to stone, lime stone and granite.
  • —Become extremely popular among the architecture design.

Manufacture of GFRC

Two types :-

A. Sprayed Method- 
B. Premix Vibration Method

Note:-     
  • For larger items-Sprayed method
  • For small items-Premix method
  • Sprayed GFRC stronger than premix vibration
  • Sprayed GFRC has lower water content than premix GFRC
                          

Typical Mix Design of Sprayed And Premix GFRC

                     Sprayed GFRC                               Premix GFRC     
Sand                       50Kg                                             50Kg
Cement                   50Kg                                             50Kg
Water                  15-17 Litre                                   17-18 Litre
Plasticizer                0.4                                                 0.6
Fibre                    4-6% By Weight                         2-3% By Weight

Sprayed GFRC

Steps of Sprayed GFRC

  • —Preparation of mixer in a high shear mixer
  • —Transferred the mix to a pump/spray unit
  • —Built up in thin layers
  • —Cover with polythene to prevent moisture loss until the next day
  • —Product is then remolded
  • —Curing for approximately for 7 days

Premix GFRC


Steps of premix GFRC

  • —Sand and cement are mixed dry and then water/ Admixture and polymer are added
  • —Poured into moulds ,vibrated using a vibrating table
  • —Covered with polythene sheet to prevent moisture loss
  • —Product is remolded the next day
  • —Products are cured under polythene sheets to maintain moist conditions for 7 days

Properties of GFRC

Property Value Range
Dry  density 1700-2250 kg/m3
Impact strength 1.1-2.5 N/mm2
Compressive strength 490-840 kg/cm2
Elastic modulus (1.0-2.5).104 Mpa
Strain to failure (600-1200).10-5
Shear strength 35-54 kg/cm2
Thermal conductivity 0.52-0.75 W/cm2.c
Coefficient of permeability 10-8 cm/sec
Fire endurance  Better than that of concrete
Combustible  Noncombustible(no flame propagation)

Stress – Strain Chart

Seismic Design of GFRC


In earthquake prone regions the use of GFRC offers several benefits

  • —Light in weight as compared to precast concrete
  • —Ability to flex without breaking
  • —Unlike rigid masonry on concrete GFRC can accept a considerable amount of bending force &shaking without breaking

Advantages of GFRC

  • —Versatility
  • —Light weight
  • —Corrosion and root proofing
  • —Incombustible
  • —Diversity of color
  • —Cost effective

Technological advantages over plain concrete

  • —Improve cracking resistance, impact ductility
  • —High load carrying capacity
  • —High tensile strength
  • —Minimize or entirely avoid steel rods
  • —Labor and energy saving in reinforcement installation
  • Durability for a long life 
  • Reduced transport costs 
  • Reduced cement and energy usage 

  • Uses of GFRC

  • Exterior Ornamentation
  • Interior Details
  • Landscape Furnishings
  • Manufacture of precast product for building
  • Architectural design 
  • Can be used in conjunction with reinforced concrete



—Versatility
—Light weight
—Corrosion and root proofing
—Incombustible
—Diversity of color
—Cost effective




—Region -1-Concrete & fiber both behave as elastic material
—End of region1
Region -2- Matrix cracks & load transferred from cracked surface to the glass fiber —process carried out continue through the cracks on tension side
—Region -3-Loading is carried by only fiber until failure

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