‘Bajaj Fibre Tuff’ - Macro Synthetic Fibre For Shotcrete
Bajaj Reinforcement LLP
Bajaj Fibre Tuff is easily available in India as it is produced in India itself. It can be used effectively in concrete mix for high rise building foundation, shotcrete, beams, columns, slabs along with steel rebars to obtain enhanced seismic performance in comparison to the ordinary RCC. Bajaj Fibre Tuff PP fibres are used in bulk in concrete construction for infrastructure projects and precast concrete. It has been tested for all its major properties as per its standard and approved by Indian engineers, consultant and authorities for use in their projects.
In addition, we introduce ourselves as manufacturers of Bajaj Fibre Tuff Macro Structural Synthetic Fibres for shotcrete/sprayed concrete. Sprayed concrete is a mixture of cement aggregate and water, projected pneumatically from a nozzle into a place to produce a dense homogeneous mass. It normally incorporates admixture or fibres, or a combination of them. Fibre-reinforced concrete has greater ductility and toughness characteristics, which allow it to deform under tensile stress, as well as greater energy absorption capacity despite cracking, which gives the structure enhanced seismic performance and serviceability.
The European specifications (EFNARC) for sprayed concrete indicate the use of different fibre types, based on the performance requirements of fibre reinforced sprayed concrete. The EFNARC also state the requirements of final product and one of the requirement is the toughness of the material either specified by residual strength (beam test) class or energy absorption (plate test) class, amongst other tests such as compressive, strength flexural strength, modulus of elasticity, bond strength, etc.
Bajaj Fibre Tuff Polypropylene macro fibre manufactured by M/s Bajaj Reinforcement LLP, Nagpur, a company manufacturing premium quality macro and micro fibrillated polypropylene fibre, being used across India in various infrastructure projects, were tested for their suitability in sprayed concrete by conducting energy absorption test on square panel as per European Standard EN 14488-5.
The tests were conducted at IIT Hyderabad and at RVNL Rishikesh-Karnaprayag Rail Project, Uttarakhand, amongst testing done at other institutes.
- Testing at IIT Hyderabad:
- The tests were conducted as per EN 14488-5 and displacement controlled machine at a constant rate of (1 ± 0.1) mm/min at centre of panel as
Fig. 1: Test Setup Showing the Loading Arrangement
The dose of macro synthetic fibre was 5 kg/m3 and 7 kg/m3, respectively. Three samples of each were tested, and load and deflection were continuously recorded throughout the test (Fig. 2 and Fig. 3).
Energy deflection curves were plotted from which the conservative estimate of energy absorption capacity between 0 mm and 25 mm deflection were 595 J and 800 J, respectively (Fig. 4 and Fig. 5).
Fig. 4: Energy-Deflection Curves for Panels With 7 kg/m3 Fibres
Note: Conservative estimate of the energy absorption capacity between 0 mm and 25 mm deflection, is 800 J.
Fig. 5: Energy-Deflection Curves for Panels with 5 kg/m3 Fibres
Note: Conservative estimate of the energy absorption capacity between 0 mm and 25 mm deflection, is 595 J.
- Testing at RVNL, Uttarakhand:
The polypropylene fibre reinforced shotcrete (PFRS) mix M35 grade with UltraTech OPC 53 Grade Cement sample was tested for compressive strength, core test and energy absorption capacity. The fibre dosage was 6.5 kg/m3. The average value of energy absorption (Joule)
was found to be 781 J. The energy deflection curves were recorded throughout the test and cracking pattern noted is shown in Fig. 6.
Fig. 6: Load vs. Displacement Curve and Cracking Pattern of Panel
The energy absorption by polypropylene macro fibre manufactured by M/s Bajaj Reinforcement (LLP), Nagpur for various doses as found from the above testing’s are:
As per EFNARC, the toughness classification based on energy absorption in Joule for deflection up to 25 mm is classified into the three classes and accordingly, the fibre tested not only fulfils, but exceeds the requirement of class ‘b’, i.e., energy absorption of 700 J for 6.5 kg/m3 and 7 kg/m3 dosages.
Hence, the ‘Bajaj fibre’ can be very well used in sprayed concrete having inherent properties of non-corrosiveness and at the same time, fulfil the requirements of strength, toughness and durability.
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