The Concrete And Fibre Reinforcement Construction Essay

The cover And fictional character Reinforcement face EssayCHAPTER 1Wi skimpy the future(a) dissertation I aim to study the use of eccentric Reinforced concrete at heart the construction industry.Over the last decade, character strengthened concrete (FRC) has fix widely used in different structural and non-structural applications such as pavements, floors, overlays, industrial slabs and shotcrete linings etc where the study occupation is toughness and first crack in flexure. It is estimated that more than 150 000 metric tonnes of FRC has been used throughout this duration of time.Particular focus forget be made as to FRC in spite of appearance the construction industry whilst arduous to identify what the future hold for this composite fabric.The question will be posed at to what the superior general consensus is indoors the construction industry in regard to the use of fibre reinforcement indoors concrete.1.2 cover and Fibre Reinforcement cover is a tangible t hat is very strong in compression although is relatively weak in tension. To compensate for this imbalance in the concretes behavior, an appropriate reinforcement must be seal into the concrete to friend carry the tensile hitchs.Two underframes of reinforcement commonly used atomic number 18 mark Fabric (Rebar) reinforcement and Fibre reinforcement.Steel Fabric Rebar/Mesh has been used for more eld in the construction industry to reinforce concrete and is usually made of carbon firebrand which is incorporated with ridges to help provide a better bond and adhesion to the concrete. As the rate that both steel and concrete expand and contract is the identical this assists in eliminating either possible issues relating to any untimely signs of scissure in spite of appearance the concrete which could occur if the materials expanded and contracted contradictory to each other. This will assist in enhancing the general strengthen of the structure.Rebar comes in mingled len gths and thicknesses to accommodate different vitrines and sizes of jobs. These bars can be tied together to form a grid or c be on, this is extremely effective for larger projects or alternatively occupy can be delivered in a variety of standard sheet sizes to site.An exciting alternative point of intersection to the above which could be used would be that of fibre reinforcement.The idea of using a fibrous material to provide tensile strength to a material strong in compression but unannealed loses itself in the mists of time in ancient Egypt straw was added to clay mixtures in order to provide brick with deepen flexural resistance, thus providing better handling properties after the brick had dried in the sun.Fibre beef up concrete is a composite material which entails a cementitious hydrated paste which is mixed with small reinforced filaments for guinea pig glass, steel, polymer or carbon fibres which come in motley shapes and sizes.The multiple fibres restructure the cleverness inside the concrete, preventing the mathematical operation of formation and extension of cracks.This helps to increase the ductility within the concrete whilst sustaining the residual capability during the positioning snap bean periodThe fibres within the concrete literally bond the sides of a forming crack together at the same time as preventing any visual damage from becoming app arentAlthough FRC is an application that has been used extensively throughout Western Europe and beyond, its use within the UK has been somewhat restricted to the purpose of reinforcement within industrial floors as its main application.The absence of a recognizably accepted design standard whitethorn halt an influence on the situation although calls are currently world made for clear industrial guidelines to be certified.The concrete Society Technical Report 63 concentrates on any problematic issues and provides focussing for current and future design.All development and design aspects associated with fibre reinforcement are incorporated within the British Standard Institution.BS EN 14889, Fibres for concrete Part 1 Steel Fibres Definition, specifications and conformity.Part 2 Polymer Fibres Definition, specifications and conformity.1.3 AimThe main aim of the following theses is to investigate and evaluate the various properties and functions of Fibre Reinforced Concrete (FRC) throughout the construction industry whilst giving consideration as to what lies ahead for the future of FRC.1.4 ObjectivesTo provide a historic overview of Concrete and Fibre Reinforcement.To identify and analyze the various types of fibre products available for concrete reinforcement.To present possible concrete mix exploit enhancements associated with FRC.To explore the Construction oversight criteria within the industry in relation to the use of FRC.To highlight the future possibilities and potential that FRC has within the construction industry whilst seeking the views and opinion s of various construction professionals.1.5 Rationale for ResearchThere are three main reasons why this particular study has been chosen for this theses along with the required look for which has been carried out, these areA personal interest in the material of concrete along with its various functions and applications due to work experience gained in this field.An interest in modern fontistic innovations being made available to the construction market which will enhance the overall application of the material.An inhalant to investigate whilst enhancing my current knowledge on the theory of FRC1.6 methodologyDue to the nature of the topic to cumulate the aims and objectives previously make out for this thesis and to establish the direction for this piece of work information has been obtained from the following sources.Primary literary works Academic Research Journals (Refereed)Conferences / Seminars (Referred)Government PublicationsTechnical Report PapersSecondary Literatur e Construction JournalsConstruction TextbooksLibrary Search Indexes and AbstractsInternet / World Wide WebLibrary enumerationCase orbit A bailiwick study of fibre reinforcement with regard toConstruction Management criteria will also be analyzed via various site visits prior and during any works being carried out.This will provide a valuable insight as to how this product is perceived whilst strengthening the case for use in the future.Questionnaire Questionnaires will also be distributed to variousProfessional bodies influenced by the use of FRC within the construction industry.The methodology adopted is fully discussed afterwards in Chapter 4 along with the synopsis of the explore findings in Chapter 5.1.7 Chapter OverviewChapter 1 IntroductionProvide a brief introduction into the areas of study which has been identified by the author whilst outlining the main aims and objectives to be achieved in order to fulfill the research criteria.Chapter 2 Background for Study (Literatu re Search)A review of the relevant theory and recent / current publications associated with Fibre Reinforced Concrete will be used to obtain the requirement information required to establish the Aim and Objectives which admit been disposed(p) by the author.Chapter 3 Case StudyOn site Case Study (tbc)Chapter 4 MethodologyAn evaluation of the types of research and methodology methods carried out in order to achieve the aims and objectives previously stated.This will cite how and why the chosen research methods had been adopted.Chapter 5 Data Interpretation and AnalysisThis will consist of an analysis of the data and information generated from the questionnaire returns using relevant diagrams, tables and text to illustrate all findings.Chapter 6 Conclusions and RecommendationsAll findings from the research process will be compiled and it will be observed as to whether the main outlined objectives squander been realized.Recommendations will also be given on areas of further research to enhance the material within the theses.CHAPTER 2A REVIEW OF FIBRE REINFORCED CONCRETE2.1 History of Concrete and Fibre Reinforcement.The story of composite materials started in ancient Egypt over 2000 years ago with mud bricks, reinforced with straw fibres.(Crowther, 2009)Concrete is the second or so widely used material on earth after water (The Economist, 2006)Concrete is a building material composed of cement, aggregate sand and water, often with chemical admixtures and other materials (Stanley Bond, 1999).Its modern breeding spans less than 200 years with 1824 being the patent date associated with the first Portland cement, according to Binns (2002), which is unrivalled of the most important milestones in concretes history.Concrete is an ever present material and its versatility, comparative cheapness and energy efficiency abide ensured that it is of great and increasing importance for all types of construction throughout the world.Many structures have concrete as thei r principal material, albeit as a composite with steel to give either reinforced or prestressed concrete, even in those structures where other materials such as steel or timber form the principal structural elements, concrete will normally still have an important role, for example in the foundations.In its simplest form, concrete is a mixture of cement, water and aggregates in which the cement and water have combine to bind the aggregate particles together to form a monolithic whole. (Illston Domone, 2001)(Sutherland, 2009) explains that even though our knowledge and understand of the material is far from complete, and research continues, concrete has been successfully used in many cultures and in many civilisations.It is not just a modern material the oldest concrete discovered so far is in southern Israel, and dates from about 7000 BC. It was used for flooring, and consists of quicklime, made by burning limestone, mixed with water and stone which set into a hardened material.Fi bres mixed into the concrete can provide an alternative to the provision of conventional rebar or steel fabric mesh in some applications. The concept has been in existence for many years (the first patent was applied for in 1874) and it has been used in a range of applications amongst the first major uses was the patching of bomb craters in runways during World War 2. However, it was during the 1970s that commercial use of this material began to insert momentum particularly in Europe, Japan and throughout America. (Clark, 2007)Crowther (2009) reiterates that throughout the 1960s research by various scientists which included Romauldi and Mandel who were industrial scientists,In the 1960s, studies by industrial scientists Romauldi, Mandel and others, created the hypothetical and experimental foundations to help realise the development of a steel fibre product which could be used to as a means of reinforcing and strengthening concrete.In the early 1970s, James Romauldi who was initial ly involved in establishing the creation of the steel fibre patent the philosophy of steel fibre reinforced concrete, essentially inventing a new material for use within the construction industry.Throughout the 20th century the appliance of astopperos fibre cement was extremely common and extensively utilised whilst more recently it has continued with the use of highly developed carbon fibre substances which have previously been more associated within the specialised aerospace and automotive industries.Glass fibres were introduced and research continued into harnessing the properties of synthetic substance fibres such as polypropylene along with various other plastic materials.By 2000, the first macro fibre, concrete was ready for production from various suppliers. (Tarmac, 2009)Fibre reinforced concrete is employed around the world on major construction projects which involve infrastructure works, tunnel linings, marine environments, pre cast and insitu walling systems, low shopli fting thin screeds, sprayed concrete applications and significant reinforcement structures.Throughout the UK, its general application is in the use of large industrial concrete floors.Characteristics which are extremely beneficial following the installation of the floors is the ameliorate in bear on resistance, this helps play down any possible unnecessary damage where high volumes of belligerent traffic is expected.The table below common fig tree 2 clearly shows how concrete is affected by the addition of fibres in various application palmTable 1 Concrete improvement by fibresApplication fieldStrengthCracking stand firmClosure systemsTunnelsSole plates / cellar wallsSewer systems / pipesPrecast elementsToppings / wear layersRoads / airfield pavingIndustrial floorsFigure 12.2 Types of Fibre Products used For Concrete ReinforcementAlthough there are numerous fibre products on the market the most commonly used fibre types are shown and discussed below giving information on the p roducer of the fibre, its properties, fibre content in appliance along with the effects of the fibre type within the concrete matrix.2.2.1 Steel FibresConcrete containing steel fibres has been shown to have substantially improved resistance to impact and greater ductility of failure in compression, flexure and torsion.(ACI Special publication sp-44)(Bentur Mindess, 1990) claim that it was throughout the early 1900s that steel fibres were first introduced into being mixed with concrete to provide the required reinforcement.The early design of steel fibres was relatively simple and consisted of a rather plain round and smooth design which was cut to the necessary lengths.Only more recently has the introduction of pendant end, indented etched roughened surface, crimped and new polygonal depraved modern fibres have been introduced whilst the original smooth fibres have mainly disappeared.More up to date fibres which are available commercially are contrived from drawn stainless steel wire or by a melting and moulding process which produce fibres which have a crescent profile crossbreeding section.(Concrete Society TR 63, (2007)) points out that steel fibres are produced by various processes as discussed above and are supplied in many different shapes and sizes as is shown below in Figure 2. They may either be on-key or deformed, however most are round in cross section with diameters between 25 and 60 mm. Steel fibres have a tensile strength typically 2-3 times greater than that of conventional fabric reinforcement and a significantly greater surface area (for a given bundle of steel) to develop bond with the concrete matrix.Figure 2(Neville, 1995) points out that the configurations of fibres can be either straight, continuous-deformed, or end formed as shown previous. Initially, straight fibers were the only configuration of steel fibers available. After further probe it was quickly learned that there bonding potential was limited which restricted there ex pected role to the engineering properties of concrete.New products were developed to increase the bond between the fibre and concrete, the two best configurations which emerged were A hooked end, draw wire fibre and a continuously deformed, slit sheet steel fibre.It was ascertain that the continuous deformed, slit sheet steel fibre provided better micro macro cracking motion as well as flexural strength enhancement, whereas the end deformed, drawn wire steel fibre performed best post first crack.As a feature of steel fibre reinforcement concrete its improved ductility helps to greatly enhance the application where impact resistance is important.The characteristic of fatigue resistance within the concrete is highlighted a being increased by up to 70%.(Clark, 2007) explains that the addition of steel fibres as supplementary reinforcement in concrete minimise the possibility of spalling of the concrete surface due to any inclement temperatures or weather conditionsSome of the physic al characteristics of fibres directly affect key aspects of concrete performance while others are less important. The factors considered to have the strongest influence on the performance of the steel fibre in concrete areBond and Anchorage mechanisms (e.g. straight or deformed shape, end cones or hooked ends)Fibre length and diameter.Dosage used in concrete pours. (kg/m3)Fibre count (number of fibres per kg of fibre), which is a function of fibre size and dosage.Tensile StrengthElastic Modulus(Hannant, D 2002) outlines that fibre reinforcement in concrete act in various ways. Firstly they can remove the formation and development of cracks due to early age plastic settlement and drying shrinkage. Secondly, they may provide a degree of post cracking load carrying capacity.The mechanisms are as followsSteel fibres, being randomly distributed in the concrete, intercept micro cracks as they form, inhibiting the tendency for them to form into larger cracks.After cracking, the fibres sp anning the crack will provide a residual load carrying capacity. The capacity can be considerable, depending on dosage and the type of fibre used.Following a shrinkage case study carried out by Propex concrete systems the photos below evaluate the initial 24 hours of set time comparing a traditional reinforced slab with wire mesh against a fibre reinforced slab.The traditional (control) slab started to crack within 3 hours whilst the fibre reinforced slab continued to perform whilst maintaining its integrity, this is shown below in Figure 3.Cracks within the concrete which occur at an early stage will only bring out the reliability whilst preventing the concrete from ever attaining its maximum performance capability.Figure 3The explanation for this early age damage to the slab is relatively simple traditional mesh refrains from functioning until there is movement within the slab and the concrete cracks, for there to be any possibility of the fibre mesh to work the slab would have to be knowing ensuring that the mesh had been placed In the top third of the slab.As has been previously mentioned there are various shapes and sizes of steel fibres which are used two examples which are used within the construction of industrial floors are shown below in Figures 4 and 5.Figure 4 Figure 5Figure 4 shows foursome different shapes and sizes of fibre products which include smooth surface, indented etched, roughened surface and round with hooked ends which are the most commonly products used in regards to steel fabric reinforcement. Whereas Figure 5 gives a more in-depth comment on the bundled hooked end product.2.2.2 Synthetic FibresStraight or deformed pieces of extruded, orientated and cut polymer material, broadly polypropylene, that is suitable for mixing in concrete. Macro fibres have a diameter greater than 0.3mm micro fibres have a smaller diameter(ACIFC, 2007)(Concrete Societys TR66, 2007) considers that polymer fibres can be described and categorised into the followingMacro synthetic fibres which are generally greater than 0.3mm in diameter and are used where an increase in post cracking flexural strength is required. Macro synthetic fibres can be incorporated within the design of structural concrete.Micro Synthetic Fibres are relatively similar to the previously mention Macro synthetic fibres although they are smaller in size along with the inability to fulfil any structural role within any concrete design.Characteristics of this type of fibre include the ability to reduce the instance of plastic shrinkage cracking along with acting as an enhancement for freeze thaw resistance.ReferencesIllston, J.M. and Domone, P.L.J. (2001) Construction Materials There constitution and Behavior 3rd Edition. P91. Spon Press.Sutherland, M. (2009) Concrete Engineering International plenty 13 Number 2. Summer 2009. The Concrete SocietyRomtech. (2009) Technical Support Products accessed 30th October at http//www.rom.co.uk/products.aspxCrowther, D. ( 2009) Concrete for the Construction Industry Journal Volume 43 Number 3 April 2009. The Concrete Society.Clark, J. (2007) Technical Report No. 63 Guidance for The figure of Steel Fibre Reinforced Concrete. CamberleyHannant, D, Fibres in concrete A Perspective. Concrete, Vol. 36, No 8, September 2002, pp 40 43.Tarmac. (2009) Topforce Fibre Reinforced Concrete accessed 12 November at www.tarmaconline.com//0982%20Tarmac%20Fibre%20Reinforced%20Concrete%20Brochure.pdf.Propex. (2006) Propex Concrete Systems accessed 13 November at www.CS-500_Propex%20Concrete%20Systems%20Brochure_Jul%2006 (1).Pdf.Anon., (2006). Concrete Possibilities. Economist engine room Monthly. The Economist, 380 (23 September), p32.Anon., (1972). American Concrete Institute, an International Symposium Fibre Reinforced Concrete, Detroit ACI, 1974. (ACI Special Publication SP-44)