ecast Flooring and Pr

Transcription

1 Flooring and Precast

2 Maccaferri fibres: Make your Concrete Unique! What is fibre reinforced concrete? Steel fibres have been used to reinforce concrete for over 100 years since the first patent was applied for in Introducing fibres into the concrete provides new and improved mechanical properties; the fibres are distributed in three-dimensions throughout the concrete providing performance precisely where it is needed. In some applications, such as floor slabs, traditional steel reinforcement can be replaced entirely by steel fibres. Synthetic fibres are now being used within concrete, in order to offer other non-structural performance benefits. With over 30 years experience in the design and supply of fibre reinforcement, Maccaferri offers a wide range of Wirand fibres, both steel and polymer, designed to Make your Concrete Unique! 2

3 Effect on Concrete / Benefits Wirand fibre reinforcement enhances the performance of concrete; From brittle to ductile behaviour From compressive strength to flexural structural performance Enhanced structural and constructional benefits Fibres within the concrete act once cracks initiate, bridging the cracks and controlling their width. The stiffness and resistance to creep of the fibre, as well as the shear and flexural toughness performance provided by the fibre, are critical within reinforcement applications. Improvement Greater Ductility Flexural Toughness Post-crack residual strength Wirand Steel fibre Fibromac Micro Synthetic The improvement in performance of the concrete is dependent upon the physical characteristics and geometry of the steel fibre: High Young s Modulus of steel fibres (200,000 MPa) High tensile strength of steel fibres ( MPa) High strength at very low strain Negligible creep under load Anchorage mechanism (end hook shape) Dosage rate (kg/m 3 ) and fibres per unit weight Fibre length and diameter (Aspect Ratio) As the fibres are evenly distributed throughout the matrix, the resulting concrete possesses homogeneous 3-dimensional mechanical behaviour, right up to the edges of the slab and joints. Long-Term Benefits Crack width control Fatigue improvement Impact resistance Permeability Abrasion resistance Long term shrinkage Fire resistance Freeze-Thaw resistance Corrosion Resistance Early Age Benefits Reduced Early Plastic shrinkage cracking Reduced Early Plastic settlement cracking 3

4 Types of Fibres Steel fibres are used for structural reinforcement and crack width control Micro-synthetic fibres are used for controlling plastic shrinkage during setting and improved resistance to temperature. The selection of an appropriate fibre and its dosage is dependent upon the concrete class and the application. Combinations of different fibre types can be used within the concrete mix, each offering specific improvements. Effect of fibres on hardening concrete 0-48 hours: Young concrete 80% of the concrete setting occurs over this time. Fine-cracks due to shrinkage may start to occur as the concrete dries. Micro-synthetic fibres retain water on their vast specific surface. This slows down the rate of drying, maintaining the hydration of the matrix which reduces the risk of shrinkage cracking as the concrete sets. The smooth body of the steel Wirand fibres does not inhibit this necessary movement, reducing locked-in stresses within the concrete. Wirand Steel Fibres 0 Fibromac Synthetic Fibres 2 days 28 2 days 2-28 days: Maturing concrete The concrete has experienced the majority of movement and is now stabilising. The specially developed anchorage hooks on the Wirand fibres now engage with the hardening concrete. Cracks may develop from applied loads, or from the micro-cracks formed previously. Wirand steel fibres bridge the cracks and inhibit the crack opening. 4

5 Design Design parameters for each industrial flooring, pavement or precast application are unique. Maccaferri s design software PAVE, is used to design floor slabs and incorporates standard and latest methodologies including non-linear fracture mechanics, yield line theory (TR- 34/3, ACI 360 R-10) and elastic theory (Westergaard). This enables the optimization of designs with regard to concrete class and thickness, fibre dosages and on major projects, even fibre characteristics to save our clients time and money. Most national and international (e.g. FIB Model Code) design standards and guidelines do not allow synthetic fibres to be used as structural reinforcement for concrete, because their Young s Modulus is significantly affected by time and/or thermo-hygrometric phenomena. Micro-synthetic fibres enhance the fire resistance of concrete and are used in pre-cast elements potentially exposed to these conditions; e.g. tunnel segments. Successful construction Plastic membrane Maintains hydration of concrete / vapour barrier Allows slab to slip over ground 2. Fibre reinforced concrete placement Thickness & dosage defined in design Testing design = solution optimisation Maccaferri s technical teams work in partnership with clients, selecting fibres, optimising designs and advising on dosing equipment. Potential reduction in slab thickness Design note Design values, such as the R e,3 toughness factor and f R,3 residual flexural strengths, are used for the design of SFRC slabs. They characterise the flexural post-crack performance of the matrix and are determined through beam testing in accordance with international standards and guidelines. The obtained residual strength or the equivalent tensile strength are basic design values from where the direct tensile and shear characteristics for design are derived. 5

6 Flooring slabs Compared to traditional reinforcement, Wirand steel fibre reinforced concrete (SFRC) can; Reduce weak points in the slab Increase panel sizes by eliminating saw-cuts Reduce slab thickness Be quicker, safer and cheaper to install Replace traditional reinforcement Increase the daily construction output The cyclic loading of flooring slabs, particularly in heavy industrial applications, is demanding. The response of the concrete slab is dependent on the ductility or toughness of the concrete; as steel fibres have a high modulus of elasticity and do not creep over time, they substantially improve the elasto-plastic response of the slab. Jointless floors Maccaferri s Lodimac (LOng DIstance MACcaferri) system enables floor panels of up to 2,500m2 to be cast without saw-cut joints, greatly increasing design possibilities and flexibility of construction. Superflat floors Wirand SFRC slabs fully comply with the demands of high racking, narrow aisle loads and critical surface level tolerances as required by the manufacturers of racking systems and load-haul equipment manufacturers. KEY APPLICATIONS Logistics Centres / Warehouses Tilt-up construction Container & harbour terminals Residential slabs Airport slabs and runways Composite metal decks Concrete roads Slab on piles Floors with high thermal range Concrete repairs Tank farm slabs Foundations (strips/slabs) Commercial flooring White topping Parking areas & garages 6

7 Installation & Dosage Fibres are one component of the concrete mix, and control of all the constituents and processes is important to obtain a perfect result. Using Maccaferri Wirand fibres is simple; Introduce fibres into the concrete mix Let the fibres distribute homogenously Mixing time typically 1 minute per cubic metre of concrete Include admixtures to optimise workability. For smaller and one-off projects, the fibres are conveniently delivered in pre-weighed packs for deployment directly into the concrete mixing truck at the project site. Placement & Compaction Once the appropriate fibre has been selected, traditional techniques and equipment are used for placing fibre reinforced concrete. Wirand SFRC can be poured directly from the truck mixer or can be pumped without problems. Compared to normal reinforced concrete, SFRC shows minimal difference in placement, workability or the compaction effort required. Conventional floor finishing techniques can then be used; hardeners, screeds or coatings. For larger projects, the rate of delivery and dispersal of fibres within the concrete matrix is important, because the cycles are short. Maccaferri s full range of DOSO fibre dosing systems has been developed to solve the specific problems of large slab flooring contractors and precast plants. These can be standalone, or fully integrated into the concrete batching plant with the support of our production specialists. Successful construction Flooring hardeners After power-floating, spray hardeners 4. Curing compounds added 5. Screeds / non-slip coatings placed if required 7

8 Precast products Maccaferri Wirand and Fibromac fibres offer significant advantages when used in precast concrete. Customising the fibre types and blend within the concrete mix to suit the concrete end-product, brings many benefits. It increases the durability, ductility, shear, impact resistance and fire resistance of the precast product. Other benefits are: Reduced complex reinforcement detailing Reduced damage during demoulding Reduced damage during handling and transportation Improved freeze-thaw / thermal resistance Reduced early-age cracking Earlier demoulding / shorter mould times More slender products using less concrete Wider range of uses of final product. The use of fibres in tunnelling is presented in Maccaferri s Tunnelling Works brochure. Downloadable from your local KEY APPLICATIONS Precast tunnel segments Pipes and water tanks Manhole components Jersey barriers Basement Walls Railway sleepers Complex shaped products Modular concrete elements Drain components Slender concrete products Prestressed/post tensioned beams 8

9 CE Marking and Product Quality Maccaferri s Wirand steel fibres are manufactured in ISO9001 certified facilities and also have EC Certificate of Conformity, meeting the requirements of EN :2006 for structural use in concrete mortar or grout. This is an important and independent certification of the quality and performance of fibres. The conformance test regime includes beam tests to determine the appropriate use of the fibres. It certifies that steel fibres provide the specified toughness performance to permit their use within structural applications. Reassuringly for clients, CE Marking requires fibre manufacturers to declare the appropriate use for their fibres on their product packaging. Accordingly, Wirand packaging states For Structural Use. Synthetic fibres are not CE Marked For structural use. Maccaferri carries out additional tests at renowned institutions to refine our products and knowledge. This capability is passed onto our clients through optimised and efficient solutions. Wirand Fibre Steel fibres for structural use in concrete, mortar and grout Wirand FF3 - C30/37-30 kg/m 3 Nominal Stress σn [MPa] CTOD m [mm] 9

10 Project examples Underfloor heating installation Laser levelling Container port Container terminal Housing development foundation slabs 10

11 Superflat floor for high-racking Fuel station forecourt Arena floor Airport taxiway Technical Data, Case Histories and Contact Details can be found at your local Superflat floor for high-racking 11

12 Officine Maccaferri Group Profile Founded in 1879, Officine Maccaferri soon became a technical reference in the design and development of solutions for erosion control and retaining structures. Since then, through technological innovation, geographical expansion and focussed diversification, Maccaferri now offers solutions at a global level for a wide range of civil and environmental engineering applications. Consultancy and Partnership Maccaferri s motto is Engineering a Better Solution ; We do not merely supply products, but work in partnership with our clients, offering technical expertise to deliver versatile, cost effective and environmentally sound solutions. We aim to build mutually beneficial relationships with clients through the quality of our service and solutions. Organisational Structure Officine Maccaferri is at the heart of the Maccaferri Industrial Group. Its continued growth is based upon long-held values of innovation, integrity, excellent service and respect for the environment. Maccaferri s vision is to become a leading international provider of advanced solutions to the civil engineering and construction market. Implementing a strategy of vertical integration, Maccaferri researches, manufactures, designs, supplies and constructs solutions within its target markets. The capability of the business continues to expand due to a strategic plan to open new markets and grow existing ones; Maccaferri now offers advanced engineered solutions from beach nourishment to reinforced soil structures and from rockfall mitigation to tunnelling systems. With over 2000 employees, 26 manufacturing facilities and local operations in 100 countries around the world, Maccaferri can truly claim to have a global presence with local focus. Bureau Veritas Certified Quality System Company with SINCERT s and UKAS s accreditation ANY REPRODUCTION, INCLUDING PHOTOCOPY, FILM AND MICROFILM, IS FORBIDDEN. ALL RIGHTS RESERVED WORLDWIDE. Officine Maccaferri S.p.A. Via J. F. Kennedy, Zola Predosa (Bologna) - Italy Phone Fax comes@maccaferri.com Officine Maccaferri S.p.A. - Bologna - Italy - Print: Litografia Zucchini - Project: graficamonti.com - Photo: Officine Maccaferri Archive 12