WORLD LEADERS IN FIBRE REINFORCING - Sika … OF CONCRETE - FIBRE INTERACTION Plain concrete is a non-homogeneous mixture of cement, water, coarse aggregates, fine …

WORLD LEADERS IN FIBRE REINFORCING

FIBRE REINFORCINGSIKA RADMIX2

WORLD LEADERS IN FIBRE REINFORCING

Sika Radmix combines comprehensive research into the latest reinforcing fibre technology from Australia, Europe, Korea, China and the USA with in-house development of fibre design and production technology. This investment has placed Sika Radmix as one of the world’s most efficient and technologically advanced synthetic and steel fibre manufacturers.

As a result, new types of fibres for different applications have been produced from synthetic, wire and slit sheet. Sika Radmix stands as one of the few companies, world wide, to provide a complete range of fibres and technical expertise at competitive prices.

Sika Radmix’s philosophy of fibre design has at its core the focus of maximum user friendliness in all stages of construction, including construction technology effects and cost effectiveness.

This focus compliments a “fracture mechanics” approach to ductility and crack propagation in FRC in the recommendation of fibre specification for a particular end use. An in-house computer-aided design service provides the interface with Consulting Engineers and also the Design and Construction Industry.

A commitment to, and investment in research has led the expertise developed by Sika Radmix being sort after by engineers and construction companies around the globe.

Fibres are playing an increasing role as the reinforcing medium of choice for concrete construction. Fibre Reinforced Concrete (FRC) uses have now expanded beyond pavement applications, into areas where the reinforcing specification has historically been bars or fabric.

With developments in fibre technology, FRC performance characteristics include significant ductile and structural behaviour and enhanced tensile, shear and flexural strengths.

Compared to conventional reinforced concrete, FRC exhibits greater crack resistance, durability, fatigue life, resistance to impact and gauging, shrinkage stresses, thermal shock and seismic ductility characteristics.

Comprehensive research into FRC has placed Sika Radmix in a position as one of the world’s most efficient and technologically advanced steel and synthetic suppliers and manufacterers. Focusing on innovation and flexibility in the development of fibres, Sika Radmix is able to provide the optimum fibre type for a variety of applications.

With over 25 years of experience and training in construction technology, the engineers at Sika Radmix continue to provide the most appropriate solution to concrete reinforcing.

MECHANISM OF CONCRETE - FIBRE INTERACTIONPlain concrete is a non-homogeneous mixture of cement, water, coarse aggregates, fine aggregates and admixtures. The hydration reaction between the cement and water results in a net shrinkage in the hardened cement paste. The function of the coarse aggregate is a duality of economically reducing the volume of the cement paste, and to provide a restraint mechanism against the autogenous (hydration) shrinkage.

Hsu, Slate, Sturman & Winter in their paper “Microcracking of Plain Concrete and the Shape of the Stress- Strain Curve” [Journal of the ACI Feb 1963 pp209] showed that there are incipient microcracks at the surface of the larger coarse aggregate particles. These cracks exist in a zero load condition.

As concrete is stressed due to various loading conditions, including fatigue, the microcracks are propagated along the faces of the aggregate and under appropriate conditions propagate through the concrete matrix to adjacent coarse aggregate particles. These cracks exist in a zero load condition.

As the matrix consists of cement paste and the finer aggregate, it is the matrix into which the steel fibres are mixed and are ‘randomly’ aligned, though modified by the relative positioning of the larger aggregate.

The matrix thus becomes a composite mixture, reinforced by the fibres. The fibres change the tensile stress level required for a crack to initiate through it, depending on the number and effectiveness of the fibres in the crack tip zone.

FIBRE REINFORCINGSIKA RADMIX 3

RADMIX FIBRE APPLICATIONS Pavements

Shotcrete

Precast Products

Bored Compression Piers

Toppings & Decking Systems

Refractory Applications

Explosion Resistant Structures

Chemical Containing Facilities

Mine Blocks

Tilt Panels

FIBRE REINFORCEMENT OF SHOTCRETEReinforcement is added to shotcrete in order to give some pseudo-ductility as well as post-crack load-bearing capacity, especially in high deformation applications, such as those encountered in the mining industry. Welded wire mesh has been used to reinforce Shotcrete, but stiffness compatibility and placement difficulties has meant that a continuous metallic reinforcement has been dropped in favour of discreet fibres that cross incipient cracks to add toughness and ductility.

PROPERTIES OF SIKA RADMIX FIBRE REINFORCED CONCRETEThe capacity of Sika Radmix fibres to uniformly transfer loads throughout a matrix is a representation of the ductility that can be achieved with SFRC compared to plain concrete. The brittleness of plain concrete is therefore eliminated.

Depending on the specification of the concrete and the dosage rate of Sika Radmix fibres, the various physical properties of concrete may be modified by the following degree, as shown in Table 3.1.

PHYSICAL PROPERTIES MODIFIED BY SIKA RADMIX FIBRES

PHYSICAL PROPERTY BENEFICIAL EFFECT

Modulus of Rupture 1 to 2 x plain concrete

Shear Strength 1.25 to 2 x plain concrete

Torsional Strength 1.25 to 2 x plain concrete

Impact Energy Absorption 2 to 15 x plain concrete

Fatigue Resistance 1.2 to 2 x plain concrete

Cavitation & Erosion Resistance 1 to 1.4 x plain concrete

Restrained Shrinkage Cracks Reduced Crack Widths

Corrosion ResistanceNo Cathodic Corrosion Observed

FRACTURE MECHANICS VS. CRACK MANAGEMENTThe approach by Sika Radmix to the dispersion of propagating cracks in the matrix as described above, leads to a fundamental differing of philosophy of SFRC behaviour relative to some other fibre purveyors. It is more appropriate to adopt the ‘fracture mechanics’ approach of the fibre matrix, acting as a composite material, being able to withstand higher tensile stresses before gross crack initiation, rather than one which relies on ‘bridged’ macro cracks (crack management).

This ‘crack management’ approach has as its basis that the developed stress in the unbonded fibre allows the concrete element to continue to take load at high deflection. This approach includes the consideration of the global performance in the constant deflection rate flexural beam or ‘toughness’ test up to 3mm deflection over a 450mm span, irrespective of the formation of cracks which may be more than the durability limiting crack width of 0.1mm.

ADVANTAGES OF FIBRES IN CONCRETEAs the crack tip progresses through the matrix, as discussed above, the width of the propagating crack increases. For fibres passing through and resisting the microcrack widening, the development of the required stress in the fibre is provided by both;

• Surface bond effects between the cement paste and the fibre; and

• Mechanical anchorage mechanisms due to fibre shape, which enhance the effect of surface bond or act as an alternative should stress levels in the matrix exceed the surface bond effects, which have been estimated to be in the order of 3 MPa.

Fibre manufacturers have addressed the challenges presented by straight fibres through providing various mechanical anchorages in the fibre shape. These can be classified into two distinct types: continuously deformed and end-anchored.

These fibres, under the developing stress from the propagating microcrack, progressively loose surface bond dependant on the effectiveness of the end anchorage. They then bridge the developed crack over the length of the debonded fibre. The published literature by the purveyors of this type of fibre shows diagrams of the bridged crack with the stressed fibre.

When the stress in the concrete exceeds this ‘balanced’ macro crack condition the end anchorage is lost and the deformed ends either slide through the void cast into the cement paste in a straightening mode, or alternatively slip by local crushing the matrix as the end pulls through. The purveyors of these end anchorage fibres define that this is a preferred failure mechanism. The fibre stress at which fibre pull-out occurs, relative to the tensile capacity of the fibre is not defined.


SIKA RADMIX RAD48S (STRUCTURAL SYNTHETIC) FIBRE

PRODUCT DESCRIPTION

Macro Structural Synthetic Polypropylene Fibre, minimum tensile strength 550 MPa. These fibres show very defined ductile behaviour characteristics. Performance levels are excellent in ground slabs, pre-cast products and highly corrosive environments.

PRODUCT CODE RAD48S

PERFORMANCECHARACTERISTICS

Width = 1.2855mm Length = 48mm Thickness = 0.3325mmHigher Re3 values are achieved in slabs on grade when using this fibre.

PROFILE


PRODUCT DESCRIPTION

Macro Structural Synthetic Polypropylene Fibre. General purpose synthetic fibre.

PRODUCT CODE RAD55S


Width = 1.4820mm Length = 55mm Thickness = 0.4611mmSuitable for all types of concrete reinforcing.

PROFILE


PRODUCT DESCRIPTION

Macro Structural Synthetic Polypropylene Fibre.

PRODUCT CODE RAD65S


Width = 1.6825mm Length = 65mm Thickness = 0.4822mmGenerates a very high energy absorption rate in the concrete when used in shotcrete enabling the matrix to provide greater flexural toughness.

PROFILE

The Sika Radmix macro synthetic structural fibre has been embraced by and readily accepted in the shotcrete and engineering industries, as the end users recognise the benefits of replacing reo-bar and mesh with synthetic fibre. Structural synthetitic fibre SikaRAD””s series is superior to conventional reinforcement in shotcrete plus giving high Re3 values, while creating cost savings.

Sika Radmix has uniquely packaged it’s synthetic fibres in 5kg water-soluble packaging. The fibres are placed in the concrete mix. The packs then dissolve within seconds, leaving the fibres to disperse evenly throughout the matrix. Since the packages are light they are safe to handle.

It has been demonstrated in the round determinate panel (RDP) tests, that by using synthetic fibres at a dosage rate of only 5kg to 9kg per cubic metre of concrete is required to obtain higher energy absorption (measured in Joules) compared to a steel fibre dose rate of 30kg to 50kg.

STRUCTURAL SYNTHETIC FIBRE


SIKA RADMIX “HW” (HOOKED WIRE) FIBRE

PRODUCT DESCRIPTION

Hooked end hard-drawn wire fibres, conforming to the provisions of ASTM A820 Type 1 (Drawn Wire).

PRODUCT CODE RAD6560HW


Glue Hooked End FibreDiameter = 0.9mm Length = 60mm Aspect Ratio = 66.66mmTensile Strength = 1100 MPaIdeal for ground slabs, giving a high Re3 value.

PROFILE



Glue Hooked End FibreDiameter = 0.75mm Length = 60mm Aspect Ratio = 80mmTensile Strength = 1100 MPaIdeal for concrete slabs under constant loads.

PROFILE



Glue Hooked End FibreDiameter = 0.5mm Length = 37mm Aspect Ratio = 74mmTensile Strength = 1300 MPaIdeal for shot-crete.

PROFILE

PRODUCT CODE RADPAVE 35


Diameter = 0.85mm Length = 30mm Aspect Ratio = 35mmTensile Strength = 1100Ideal for medium and heavy industrial pavements with large bay sizes and high post loading conditions.

PROFILE

SIKA RADMIX “HW” (HOOKED WIRE) FIBRE - continued



Diameter = 0.75mm Length = 35mm Aspect Ratio = 46.6mmTensile Strength = 1100 MPaGeneral purpose fibre also suited for shot-crete.

PROFILE

SIKA RADMIX “FW” (FLATTENED WIRE) FIBRE

PRODUCT DESCRIPTION

Flattened hard-drawn wire fibres, conforming to the provisions of ASTM A820 Type 1 (Drawn Wire), minimum tensile strength 900 MPa.

Flattened Wire Fibres, due to the positive mechanical anchorage characteristics of the undulation and high tensile strength are specially suited to applications where the risk of stresses on the concrete exceeding its tensile strength is clearly defined. Post-crack performance (toughness) is excellent.

PRODUCT CODE RAD40FW


Diameter = 0.9mm Length = 40mm Aspect Ratio = 44.44mmExcellent fibre for ground slabs and pre-cast. Other sizes available on order.

PROFILE

WIRE FIBRE


RADMIX BOX DOWEL

BOX DOWEL SPACING FOR GROUND SLABS

INSTALLATION

RIBFLEX

SLAB THICKNESS (MM)

Dowel Type 125 150 175 200 225 250 Plus

BD16 650 650 550 450 350 N/A

D20 N/A N/A 600 600 450 400

Step OneNail the Dowel Box on the inside of the formwork at a height that is central to the slab thickness.

Step TwoThe concrete is then poured between formwork, encasing the dowel boxes.

Step ThreeFormwork is then stripped, leaving the front of the Dowel Box exposed, ready for the insertion of the dowel bars.

Step FourDowel bars are placed into the holes provided by the Dowel Box previously cast into the slab. Concrete is then poured for the new slab, incasing the protruding ends of the dowel bars.


BENEFITS

Greater load carrying capacity over slab joints

Ease of movement between slabs

Reduction of slab curling

Fast installation

Wider spacing between dowels

Cost saving

The Box Dowel provides a system (Ribflex) which while maintaining a level slab surface over joints, allows movement sideways plus back and forth when expansion and contraction occurs in the concrete.

Our most current general sales conditions shall apply. Please refer to the relevant data sheet prior to any use and processing.

SIKA AUSTRALIA55 Elizabeth StreetWetherill Park, NSW, 2164Australia

ContactPhone : 1300 22 33 48Fax: +61 2 9756 0502aus.sika.com

SIKA‘S FULL RANGE OF CONSTRUCTION SOLUTIONS

Roofing

Sarnafil®

Sikaplan®

SikaRoof® MTC®

Joint Sealing

Sikaflex®

Sikasil®

Grouting

Sikadur®

SikaGrout®

Waterproofing

Sikaplan®, Sikalastic®

Sika® & Tricosal® Water stopsSika® Injection Systems

Flooring

Sikafloor®

SikaBond®

Concrete Repair and Protection

Sika® MonoTop®

Sikagard®

Sikadur®

Structural Strengthening

Sika® CarboDur®

SikaWrap®

Sikadur®

Concrete Production

Sika® ViscoCrete®

Sika® Retarder®

Sika® SikaAer®

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Sika

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Coatings, Silanes & Siloxanes

Sikagard®

Ferrogard®

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WORLD LEADERS IN FIBRE REINFORCING - Sika … OF CONCRETE - FIBRE INTERACTION Plain concrete is a non-homogeneous mixture of cement, water, coarse aggregates, fine …