Flax fiber reinforced concrete a natura1 fiber fiber reinforced concrete-a natura1 fiber biocomposite

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  • Flax fiber reinforced concrete-a natura1 fiberbiocomposite for sustainable building materials

    J. E. FemandezBuilding Technology Progrum, Dept. of Architecture, Massachusetts Institute of Technology, USA.

    Abstract

    developing regions.for a class of concrete biocomposites for use in a variety of building types inespecially steel. For architectural applications, the results indicategood potentialoffers strategies that may lead to substantial savings in construction materials,strength of structural members composed of the flax fiber reinforced concretelength of 3cm for flax fiber in concrete. As a result, an increase in the shearcomposite. A theoretical analysisconfiied the empirical results of an optimumpotential to substantially increase the flexural toughness of the concretedecrease with others, results from the optimized formulation indicated thestrength was shown to increase with the inclusion of particular fiber lengths andincreased strength and toughness of the natural fiber-reinforced concrete.Whilemechanical laboratory testing yielded positive conclusions regarding thetoughness and crack management from the various samples. Results fromin concrete was sought in obtaining the highest possible ultimate strength,cured concrete. Specifically, an optimal ratio mix and fiber length of flax fiberswithin a concrete matrix is intended to augment the energy absorption of theindustrial capacity to process them. Generally, the inclusion of natural fibersregions with access to significant sources of cellulose fibers and small-scaleuse of natural fiber reinforced concretes (NFRCs) for buildings in developingconcrete (FFRC). The mechanical results are intended as a demonstrationof theThis paper presents the laboratory results o f an optimized flax fiber reinforcedpotential for architectural applications has not been adequately investigated.and inexpensive source of mechanically useful cellulose, the full extent of thepolymeric, earthen or otherwise. While natural fibers offer a widely availableand volume filler within the matrix of a composite material; cementitious,important use of the mechanical properties of natural fibers is tensile reinforcingarchitectural applications in structural and non-structural assemblies. OneFibers of many types, including some natural fibers, have been used widely for

    2002 WIT Press, Ashurst Lodge, Southampton, SO40 7AA, UK. All rights reserved.Web: www.witpress.com Email witpress@witpress.comPaper from: High Performance Structures and Composites , CA Brebbia and WP de Wilde (Editors).ISBN 1-85312-904-6

  • 194 High P e r j o m m ~ c eStmctur.es and Composites1 Introduction

    components [1][2][3][4][5].addressing the use of biomass as a source of raw materials for buildingThe work presented in this paper serves to augment the substantial literature

    stock to house growingurban populations.face substantial challengesin providing the necessary infrastructureand buildingquantities, the raw biomaterial. In addition, developing regions also continue toin this field are also those that have the capability to produce, in large enoughand productivity. It stands to reason that the regions of the world most interestedAfrica, have led t i s work during periods of greatest sustained research interestuniversities. Researchers in India and Latin America, and to a lesser extentdeveloping regions of the world, primarily in collaboration with Europeanwide-ranging work has occurred at research centers and universities inbeen an ongoing project for many decades [3]. Much of the most promising and

    The use of biologically derived materials in components for buildings has

    technologiesin a particular area, given a particular culture.valuable resource for evaluating what may be considered appropriatesubstantial experience with the materials at hand. This experience is often aespecially those derived of agricultural practices, brings with it the lessons ofembedded knowledge base of indigenous peoples. The use of natural materials,techniques of technology transfer for development that t i e advantage of the

    Furthermore, recent research [6] has indicated the value of investigating

    Fibers 1I I

    I l I ~ lNatural Man-madeI

    I I IAnimal MineralVegetable

    Figure 1: Fiber classification

    mix.which the fiber reinforcing serves to increase the overall toughness of the finalpolymeric composites. These composites are generally low-strength materials infibers produced by plants for tensile reinforcing in earthen, cementitious andfrom many different angles, the primary path of research has been the use ofWhile the potential of biomass in building components has been investigated

    paper and fabric coatings,not to mention ethanol as a petroleum fuel substitute.biomass such as starch-derivedplastics, biopolymers for secondary oil-recovery,[7]. Specialty products have been formulated from materials derived of plantmillion tons of waste biomass is generated each year in the United States aloneenergy production has been well documented. It has been estimated that 280

    In addition, the availability of biomass for use in large scale industrial and

    2002 WIT Press, Ashurst Lodge, Southampton, SO40 7AA, UK. All rights reserved.Web: www.witpress.com Email witpress@witpress.comPaper from: High Performance Structures and Composites , CA Brebbia and WP de Wilde (Editors).ISBN 1-85312-904-6

  • High P e r f i m m n c e Stmctures und Composites 195

    I Renewable Resources l

    materialsCompositeand filmsBiopolymersadhesivesIndustrialdetergentsSoaps andvarnishesPaints anddyesPigments andand inksSoybeanoils LiquidSolid

    MethanolBagasseEthanolLigninFuel OilCoke

    Gas I%wsMethane IHydrogen 1

    Figure 2: Current bio-based products

    chemicalsAgriculturalsurfactantsIndustrialacidsAcetic and fattySpecialty chemicalsPhenols and fiu-fwalOxy-fuel additivesActivated carbon

    2 Mechanical properties of flax fiber reinforced concretem0

    crack inhibitor in a cementitious composite.natural fibers in terms o f tensile strength, a property critical to the behavior of afibers because of their lesser tensile strengths. Note that flax rates highest amongalso clear that natural fibers may not be used as a simple substitute for syntheticproperties for use as structural reinforcement in an archtectural composite. It ismodulus that a number of natural fibers possess reasonably good mechanicalglass, aramide and carbon fibers. It is clear from the results for Young'sTable 1 [l] lists various properties for a number of natural fibers as well as

    2002 WIT Press, Ashurst Lodge, Southampton, SO40 7AA, UK. All rights reserved.Web: www.witpress.com Email witpress@witpress.comPaper from: High Performance Structures and Composites , CA Brebbia and WP de Wilde (Editors).ISBN 1-85312-904-6

  • 196 High Performance Structures and CompositesTable 1: Various properties of selected natural and synthetic fibers

    7.0-8.0(MP4 (GP4

    C/.) strength ModulusFiber Density Elongation Tensile Youngs

    (&m3)

    Cotton 1.5-1.6 287-597 5.5-12.6

    kraftSoft wood 1.5(cord)Viscose 11.4Coir 1.2 30.0Sisal 1.5RamieHempF l a x l.5 2.7-3.2Jute 1.3 1.5-1.8

    1.6

    2.0-2.53.6-3.8

    593175511-635400-938690345-1035393-773

    1000

    27.626.5

    11.04.0-6.09.4-22.061.4-128

    40.0

    (standard)Carbon 1.4(normal)Aramide 1.4S-glass 2.5E-glass 2.5

    3.3-3.7 3000-3150 63.0-67.02.82.5

    1.4-1.8

    2000-3500 70.04570 86.0

    4000 230.0-240.0

    the economic costs associated.various positive attributes to the task of tensile reinforcing that stand to temperoverall importance of the fiber as a tensile reinforcing agent. Natural fibers bringthat of e-glass. However, this fact alone should not affect consideration of theflax fiber rates among the more expensive of the natural fibers, often exceedinghandling indicate good possibilities for their use in composites. In terms of cost,

    These mechanical properties, along with relatively low cost and ease of

    biocomposite material technologies.processes. Natural fibers from plant material are the primary source for newprimary material or secondary by-product of well-established agricultural

    1.Natural fibers are found globally and often commonly harvested as either a

    and maturation of the plant is restricted to the soil in which it is planted.biodegradable. In addition, the environmental impact during seeding, growing

    2. Natural fibers, as the product of natural processes, are renewable [l] and often

    in the atmosphere [ 1][7].fixed thereby contributing a net zero sum gain to the overall amount of carbondecomposition is returned to the environment from which it was originally

    3. Natural fibers fix and retain carbon. The CO2 released during combustion or

    This widespread familiarity in cultivation, harvesting, processing andand social history within developing and predominantly agricultural regions.

    4.Natural fibers are a group of materials with a long economic, technological

    2002 WIT Press, Ashurst Lodge, Southampton, SO40 7AA, UK. All rights reserved.Web: www.witpress.com Email witpress@witpress.comPaper from: High Performance Structures and Composites , CA Brebbia and WP de Wilde (Editors).ISBN 1-85312-904-6

  • and vernacular expertise [61.technologies utilizing natural fibers can build upon this existing knowledgevarious products for thousands of years. Any development of contemporaryviable sustainable production processes. Certain fibers have been in use formanipulationof natural fibers is an important component in the formulationof

    High Pe$omance S t rwtwes and Composites 197

    recycling [7].biodegradable and may therefore re-enter the organic material cycle throughprocessing required - relative to synthetic fibers. In addition, natural fibers are