Strength and Workability

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    STRENGTH AND WORKABILITY

    CHARACTERISTICS OF FLY ASH

    BASED GLASS FIBRE REINFORCED

    HIGH-PERFORMANCE-CONCRETE

    Dr.H.Sudarsana Rao

    PROFESSOR OF CIVIL ENGINEERING

    JNTUA COLLEGE OF ENGINEERING

    ANANTAPUR-515002

    HANCHATE123@YAHOO.CO.IN

    SRI. H. M. SOMASEKHARAIAH

    RESEARCH SCHOLAR

    J.N.T. UNIVERSITY

    ANANTAPUR - 515002

    SSSKAR07@GMAIL.COM

    DR.VAISHALI. G.GHORPADE

    ASSOCIATE PROFESSOR IN CIVIL ENGINEERING DEPT.

    JNTUA COLLEGE OF ENGINEERING

    ANANTAPUR-515002

    GHORPADE_VAISHALI@YAHOO.CO.IN

    Dr.H.Sudarsana Rao et al. / International Journal of Engineering Science and Technology (IJEST)

    ISSN : 0975-5462 Vol. 3 No. 8 August 2011 6266

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    Abstract

    To increase the applications of Glass Fibre Reinforced High-Performance-Concrete (GFRHPC) in India, greaterunder standing of GFRHPC produced with locally available materials and indigenously produced mineral

    admixtures is essential. In the present investigation, GFRHPC has been produced with locally available

    aggregates and fly ash as the mineral admixture. Various fly ash based GFRHPC mixes were designed byabsolute volume method. Cubes of 150X150X150 mm size and cylinders of 150X300mm were cast and cured

    for 28 days and then tested for compressive and tensile strengths to asses the strength characteristics ofGFRHPC. Workability has been measured by conducting compaction factor test on fresh GFRHPC mixes. Theexperimental results indicate that fly ash can be successfully utilized in producing good quality Glass Fibre

    Reinforced High-Performance-Concrete. The various results which indicate the effect of fly ash and glass fibres

    on the strength and workability characteristics of high-performance-concrete are presented in this paper to drawuseful conclusions.

    Keywords: Fly ash, High Performance Concrete, Glass fibres

    1. INTRODUCTION

    The set back in the health of newly constructed concrete structures promoted the most directed and

    unquestionable evidence of the last two/three decades on the service life performance of our construction and

    the resulting challenge that confronts us is the alarming and unacceptable rate at which our infrastructuresystems all over the world are suffering from deterioration when exposed to real environments. When thegeneral performance concrete is substantially higher than that of normal type concrete, such concrete is regarded

    as High Performance Concrete (HPC). Concrete may be regarded has high performance for several different

    reasons: High strength, High workability, High durability-and perhaps also improved visual appearance. HPC

    produced with the use of glass fibres is known as Glass Fibre Reinforced High Performance Concrete(GFRHPC). In India the applications of GFRHPC are very limited due to the lack of mix proportions, and

    proper understanding of its behavior. There are no specified codes and provisions for usage of GFRHPC.

    Fly ash is the finely divided mineral residue resulting from the combustion of ground or powdered coalin electric generating plant (ASTM C 618). Fly ash consists of inorganic matter present in the coal that has been

    fused during coal combustion. This material is solidified while suspended in the exhaust gases and is collected

    from the exhaust gases by electrostatic precipitators. Since the particles solidify while suspended in the exhaust

    gases, fly ash particles are generally spherical in shape. Fly ash particles those are collected in electrostaticprecipitators are usually silt size (0.074 - 0.005 mm). Due to its pozzolanic nature, FA is a beneficial mineral

    admixture for concrete. It influences many properties of concrete in both fresh and hardened state. Moreover,

    utilization of waste materials in cement and concrete industry reduces the environmental problems of power

    plants and decreases electric costs. Utilization also reduces the amount of solid waste, greenhouse gas emissions

    associated with Portland clinker production, and conserves existing natural resources.Hassan et al. [2000] presented the influence of two mineral admixtures, silica fume and fly ash on the

    properties of super-plasticized high-performance concrete. The results indicated that usage of the mineral

    admixtures improved the properties of high performance concrete. Gopalakrishna et al. [2001] presented theperformance of HPC mixes having different replacement levels of cement with low calcium fly ash (class F) and

    reported a compressive strength of 80 MPa with 25 % replacement of cement with fly ash and also concluded

    that fly ash concretes have superior durability properties. Long et al. [2002] presented studies on very high

    performance concretes with ultra fine powders such as pulverized fly ash (PFA), pulverized granulated blastfurnace slag (PS) and silica fume (SF) and reported that the use of ultra fine powders improved the relative

    density of compound pastes with low w/b ratios. Goh et al. [2003] carried out laboratory tests to characterize the

    properties of municipal fly ash as a blended cement material and reported that higher mortar strength than that

    of control mortar cubes was achieved by replacement of OPC with municipal fly ash up to 10%. Uzal and

    Turanli [2003] presented studies on blended cements containing a high volume of natural pozzolan and theyreported that blended cements containing 55% natural pozzolan showed excellent ability to reduce the alkali-

    silica expansion. Isaia et al. [2003] presented the studies on physical and pozzolanic action of mineral additionson the mechanical strength of high performance concrete. Bhatty et al. [2006] presented utilization of discarded

    fly ash as a raw material in the production of Portland cement. Their studies revealed that using fly ash isbeneficial in cement plants and power plants. Jerath and Hanson [2007] presented the effects of fly ash

    replacement of Portland cement and the use of dense aggregate gradation on the durability of concrete mixturesin terms of permeability. They found that, by the use of dense graded aggregate and increasing the fly ash

    content from 35 to 40% the durability of concrete mixtures increased. They also observed the reduction in the

    charge passed, when conducted rapid chloride ion permeability tests thus indicating increase in durability. Wang

    Dr.H.Sudarsana Rao et al. / International Journal of Engineering Science and Technology (IJEST)

    ISSN : 0975-5462 Vol. 3 No. 8 August 2011 6267

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    and Li [2007] presented the mechanical performance of engineered cementitious composites incorporating high

    volume fly ash. In view of these results, it is proposed to study the effect of fly ash as a partial replacement tocement in the production of Glass Fibre Reinforced High Performance Concrete.

    2. Experimental Program

    In order to study the behavior of GFRHPC and also to understand the influence of mineral admixturelike fly ash, a total number of 16 mixes have been tried. In all the mixes the same type of aggregate i.e. crushed

    granite aggregate; river sand has been used. The proportion of cement, sand and aggregate has been maintained

    same for all mixes. These relative proportions have been obtained by absolute volume method. OrdinaryPortland cement of 53 Grade from a single batch has been used. The test program consisted of carrying out

    Compressive strength test on cubes and split tensile strength test on cylinders. The nomenclature of the mixes

    studied in this investigation is presented in Table 1 which is self explanatory.

    Table: 1 Nomenclature of Mixes Studied

    S.NoDesignation of

    mixMix Details No of cubes cast

    No of Cylinders

    cast

    1 R Reference Mix M20 6 6

    2 P A 0Reference HPC mix with0% glass fibre,

    0% Fly ash6 6

    3 P A 10

    HPC Mix with 0% glass fiber, 10% Fly

    ash 6 6

    4 P A 20HPC Mix with 0% glass fiber, 20% Fly

    ash6 6

    5 P A 30HPC Mix with 0% glass fiber, 30% Fly

    ash6 6

    6 GF B 0GFRHPC Mix with 0.5 % glass fiber,

    0% Fly ash6 6

    7 GF B 10GFRHPC Mix with 0.5 % glass fiber,

    10% Fly ash6 6

    8 GF B 20GFRHPC Mix with 0.5 % glass fiber,

    20% Fly ash6 6

    9 GF B 30GFRHPC Mix with 0.5 % glass fiber,

    30% Fly ash6 6

    10 GF C 0GFRHPC mix with 1% glass fibre, 0%

    Fly ash6 6

    11 GF C 10GFRHPC mix with 1% glass fibre, 10%

    Fly ash6 6

    12 GF C 20GFRHPC mix with 1% glass fibre, 20%

    Fly ash6 6

    13 GF C 30GFRHPC mix with 1% glass fibre, 30%

    Fly ash6 6

    14 GF D 0

    GFRHPC mix with 1.5% glass fibre,

    0% Fly ash 6 6

    15 GF D 10GFRHPC mix with 1.5% glass fibre,

    10% Fly ash6 6

    16 GF D 20GFRHPC mix with 1.5% glass fibre,

    20% Fly ash6 6

    17 GF D 30GFRHPC mix with 1.5% glass fibre,

    30% Fly ash6 6

    Dr.H.Sudarsana Rao et al. / International Journal of Engineering Science and Technology (IJEST)

    ISSN : 0975-5462 Vol. 3 No. 8 August 2011 6268

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    2.1 Materials

    2.1.1 CementOrdinary Portland cement of 53 grade conforming to ISI standards has been procured and the

    properties of the cement are presented in Table 2.

    Table. 2 Properties of Cement

    S.No. Test Experimental values

    Suggested values as per I.S

    Specification

    1 Fineness of Cement 4.52%

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    Cem-FIL fibers offer superior performance to standard fiber reinforcing with widely v