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Aggregates for Concrete and Road Construction Materials

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    Group 8 Do Quoc Toan

    Phu Xuan Thai Nguyen Cong Tan

    Nguyen Thanh Trung

    Timo Trautwein

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    Aggregates

    for MaterialsNaturalaggreg

    ates

    Manufactured

    aggregates

    Reused

    By-

    products

    Recycled

    aggregates

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    2.1. Foamed blastfurnace slag (FBS)

    2.2. Fly ashaggregates (FAA)

    2.3.Manufactured

    sand (MS)

    2.4. Polystyreneaggregate (PA)

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    Description Applications and limitations

    - A by-product of iron slag

    - Was produced fist in Germany

    - Not available in Australia

    - Used as aggregates in

    concrete block and in

    insulating concrete

    - Foamed slag (2000 kg/m3) =>

    concrete 30 Mpa- Production contributes less to

    the air pollution than the

    normal does

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    Description Applications and limitations

    - An industrial by-product

    (which is recognized as an

    environmental pollutant)

    - Several lightweight concreteaggregates can by product

    from fly ash

    - Small density: 1740-1840

    kg/m3 (contain fly ash)

    compared with 2400 kg/m3

    (natural aggregates)

    - Spend more cement to reach

    the same structure grade (25

    Mpa)

    - Elastic modulus: 14-17 Mpa

    compared with 28-30 Mpa

    - Pelletizing and firing fly ash at

    controlled temperature ->

    synthetic aggregate

    - Synthetic aggregate has

    specific gravity:+1.20-1.47

    +bulk density: 650-790 kg/m3

    +water absorption: 16-24.8%

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    Description Applications and limitations

    - A purpose-made crushed fine

    aggregate produced from a

    suitable source material

    - The research of CCAA: the

    specification of manufactured

    sands in term of density,grading, particle shape

    - The R&D project of RTA:

    specification for natural and

    manufactured sands for

    asphalt and concrete mixes

    - Concrete 1 (fine sand :

    manufactured sand = 1:1)

    more workable than Concrete

    2 (natural sand)

    - Manufactured sand can be

    used to replace a majorproportion of natural sand

    with no significant loss of

    performance

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    Description Applications and limitations

    - Used in combination with

    normal weight aggregates to

    produce lightweight concrete

    - Concrete using PA : 1600-2000

    kg/m3; higher elastic

    modulus; density and creep

    are inverse ratio

    A comprehensive range of

    engineering properties of

    concrete made with such

    aggregate and many examples oftheir applications in Australia

    have ben reported

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    1.Recycled concrete aggregate(RCA)

    2.Recycle concrete and mansonry(RCM)

    3.Reclaimed aggregate(RAP)

    4.Reclaimed asphalt pavement(RAP)

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    Description

    + RCA is produced by crushing sound,clean demolition waste of at least 955 by concreteweight and have total contaminant level typically lower than 1% of bulk mass.

    + Gravel,crushed stone,hydraulic-cement concrete or suitable combination for premixconcrete production.

    Application:

    + Replacement for virgin materials(up to 30% of coarse RCA) for non-strctural concrete.

    + Stabilization base and sub base. Advantages:

    + The same carbonation rate

    + Lower specific weight than control concrete

    + Save cement and natural material

    + Similar flexural strength

    Disadvantages:

    + Higher permeability ,water absorption, dry shrinkage and creep

    + Higher chloride ion absorption and gas permeability.

    + Lower compressive strength

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    Description

    + RCM is graded aggregatee conducted from sorted and clean waste concreteand masonry.

    + The material may contain small quantities of brick,gravel,crushed rock or otherforms of stony.

    Application:

    + Road sub-base applications. Advantages:

    + Lower specific weight than control concrete

    + Save cement and natural material

    Disadvantages:

    + Higher chloride more swelling and creep+Lower workability.

    + Lower compressive strength than RCA concrete.

    + Difficulty in controling water content because of high water absorption.

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    Description

    + Aggregates can be obtained by saparating aggregates from water-cement slurry.

    + Must be handled to avoid segregation.

    Application:

    + replacement in a new mix.(100% RA can be used for 32 Mpaconcrete)

    + Partial replacement for natural aggregate in HSC.

    Advantages:

    + Enhance the strength

    + Save cement and natural material

    Disadvantages:

    +Lower workability.

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    Description

    + RAP is reuse of old asfalt concretes as the aggregates base for newasphaltic concrete.

    Application and limitations:

    RTA QA Spec R116 Asphalt permits the use of up to 15% reclaimed asphaltpavement.

    Increases in recycled content will be considered when performance

    implications of the current amendment are demonstrated.


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