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Recron 3S Fibre Reinforced Concrete 

            Normal reinforcing steel is designed to take account of all tensile and bending stresses as well as temperature related stresses in concrete structures. The design parameters are well established in the Indian Standard Code I.S. 456 and are minimum structural requirement for design and construction. These required steel are termed for this paper as primary steel. Use of secondary reinforcements does not alter the requirements of "Primary Steel".

         But structural reinforcement does not provide its benefits until concrete hardens. Hence secondary reinforcement in form of fibre reinforcement should be added to concrete. Unlike structure reinforcement, synthetic fibres provides benefits while concrete is still in plastic stage. They enhance some of the properties of hardened  concrete also. Hence it is proved that by addition of small quantities of evenly distributed secondary fibre reinforcement improves the static and dynamic properties of concrete. Fibre Reinforced Concrete provides three dimensional random reinforcement in the entire mass of the concrete. The properties which fibres induce is totally intrinsic to the type and number of fibres being administered with concrete i.e. each type of fibre will induce different kinds of characteristics into the concrete mass. As a whole Fibre Reinforced Concrete has greater resistance to Drying Shrinkage Cracking, Compressive Strength, Tensile & Flexural Strength, Abrasion and Impact Resistance and Water Permeability /Penetration. 

Recron 3S Polyester Construction Fibres 

              Recron 3S is a triangular polyester fibre in cross section with cut length of 6mm & 12mm which is being widely used in the Indian Construction industry market. It is much cheaper than any other imported construction fibres. At the specified dosage of 0.25% by wt of cement there are million of fibres which form a mesh in the concrete. the spacing is approx less than 1mm between any two fibre filament in any coordinate of the matrix. Recron 3S FRC exhibits the following improvements in properties over any other same mix design control concrete.

·                     Drying Shrinkage ( Reduces by 80%-100% )

·                     Water Permeability / Penetration ( Reduces of 40% to 50% )

·                     Compressive Strength ( Increases by 10% to 20% )

·                      Flexural Strengths ( Increases from 8% to 22% )

·                     Tensile Strengths ( Increases by min of 6% - 10% )

·                     Abrasions Resistance ( Increases by 20% to 40% )

·                     Impact Resistance ( Increases by 80% to 120% )  

Also improves Resistance of Structures to Earthquake 

Application Areas of FRC with specific reference to maximum technical benefit and cost implications as mentioned below. 

i)        Water Retaining Structures-Overhead/Underground Water Tanks & ESR

ii)         Roof Slab and Thin Section Concrete eg. Screed Concrete

iii)        Basement & Retaining Walls

iv)        Industrial Flooring, Rigid, Pavements, Taxiways, Aprons, Platforms

v)       Machine Foundations & Shotcreting

vi)        External & internal Plaster. 

Shrinkage Cracks

            Concrete will crack. The use of FRC prevents the formation of micro cracks and further propagation of micro cracks into macro cracks at higher alternate stress cycles. The huge number of uniformly dispersed fibres controls the bleeding/segregation and hence plastic settlement cracks of concrete. Hence it results in lesser honeycombing and improved homogeneity. 

            These fibres with high tensile strength bridge the cracks even after opening up by being present through the crack plane. Cracking leads to interstices and fissures through which water permeates or seep and cause distress to the reinforcement by oxidation in the form of rust and spelling thereafter. Since the use of FRC reduces water penetration and permeability by more than 50% w.r.t control according to IS 2645 stipulations it can also be used as waterproofing admixture. However the basic attributes of FRC are reduction in shrinkage cracks and improvement in elastic properties of concrete. 

Compressive Strength

             The intricate matrix formed by huge number of fibres increase the compressive strength of a desired mix of concrete. Fibres impart ductility/  tensile strength to concrete and thereby resist the shear failure mechanism. It has also been noticed that FRC requires much more time to fail than control concrete. This makes it an effective tool to use in earthquake prone zone. 

Flexural Strength / Tensile Strength

              Addition of fibres produce non linear curve after first crack and reaches its peak at the ultimate strength of maximum sustainable static load. Factors affecting flexural strength are fibre type and fibre volume. Polymeric fibres having relatively low modulii of elasticity, slightly reduce the initial stiffness and ultimate strength but their better extensibility results in a appreciable post-peak performance and toughness and are more effective in limiting the size of the cracks and arresting the micro cracks.

Abrasion / Impact Resistance Approvals

Recron 3S FRC has been approved by various Government, Semi-Government,Private and Industrial Projects. it has been approved by

i)        Airport Authority of India

ii)          Military Engineer Services

iii)          State PWD Schedule of Rates ( Maharastra, Gujurat,Rajasthan, J&K,Punjab,Tamil Nadu, KarnatakaWest Bengal & Assam )

    It has been also been used in major industrial and private project referred by structural consultants. the approval has been awarded after extensive field trials by all these authorities.

      It has been supported by in depth details testing of the Recron 3S on all parameters at many institutes including IIT Chennai & Guahati,CRRI Delhi,REC Surat,GERI Ahmadabad, National Test House Kolkata, Airport Authority Delhi, REC Coimbatore,AI Futtain Bodycote Dubai etc.

STM Codal provision for usage of FRC exist for past few decades in various applications. 

Dosage

weigh batched @ 0.25% by wt of cement used i.e.. 125 grams/50 kgs bag of cement for concrete.

FT 2024 ( 12 mm fibre cut length ) - For Concrete applications

FT 2424 ( 12 mm fibre cut length ) - For Concrete Applications in RMC/Batching Plants

FT 2012 ( 06 mm fibre cut length ) - For Plaster Applications

FT 2010 ( 4.8 mm fibre cut length ) - For Plaster Applications

the quantity fibre to be used will depend on the grade of concrete and quantum of cement used. 

Standard Packing

25 gms    Packet to be mixed with a bag of Cement.

00 gms    Packet to be mixed with a bag of Cement in case of FT 2010 ( 4.8 mm )

50 gms    Water Soluble Packet for RMC/Batching Plant applications. 

Price

 CT 2024 ( 12 mm fibre cut length ) - Rs 30.00 / 125 gms packet OR Rs 240/Kg

CT 2012 ( 06 mm fibre cut length ) - Rs 30.00 / 125 gms packet OR Rs 240/Kg

CT 2010 ( 4.8 mm fibre cut length ) - Rs 27.00 / 100 gms packet

Above Price are MRP of the product.

Mixing

       The Recron 3S fibre pouch is to be mixed in full/half bucket of water and then added to revolving drum of the empty mixer. Thereafter normal procedure of adding aggregates, sand, cement and balance quantity of water is to be done. The mixture should be properly mixed by giving adequate no.s of revolutions to the drum of the mixer. the uniformly dispersed fibre like hairs can be immediately seen once mortar mixture is taken out.