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Masonry Cement and Mortar

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1 Lecture #18 Masonry Cement and Mortar  
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    Lecture #18

    Masonry Cement and Mortar

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    MORTAR

    binder = mortar

    Masonry = mortar + masonry units

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    MORTAR

    definitions

    differences w/ other cementitious

    mixtures

    classes

    components

    types

    properties

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    MORTAR

    cementitious

    materials

    lime portland cement

    sand

    water

    used with individual

    masonry units

    bonding bedding / seating

    leveling

    sealing irregularities

    providing strength

    providing aesthetic qualities

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    MORTAR

    weak link in masonry

    construction

    thin layer stronger

    (compression) than thick

    layer

    lime added

    workability

    adhesive properties extensibility

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    GROUT cement

    fine and coarseaggregate

    sand

    water

    high slump

    no segregation

    used to bond two masonry

    wythes together (walls one unitthick)

    filling cores and voids

    binding reinforcing steel and

    wythes

    providing load carrying capability

    ASTM C476

    fine and coarse grouts fC - lessin non-absorbent molds

    match with masonry fC

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    Differences w/ other cementitious

    mixtures component materials

    mortar

    cement, lime, water, fine aggregate

    grout cement, water, fine aggregate, small-sized coarse aggregate

    portland cement concrete

    cement, water, fine aggregate, coarse aggregate

    proportions

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    Differences w/ other cementitious

    mixtures structural performance

    PCC is structural material, resists mainly compressive

    stresses

    mortar, grout are binders, develop strong & durablebond w/ masonry unit

    workability & placement methods

    PCC placed in non-absorbent forms, minimum water,

    w/c ratio very important to performance mortar, grout placed in absorptive forms, much more

    water, w/c ratio less important

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    Classes lime mortar

    lime, sand, water

    slow strength gain

    calcium carbonate

    formation seldom used in

    permanent construction

    cement/cement-lime mortar

    cement, lime, sand, water

    most common

    masonry cement mortar proprietary ingredients

    workable

    low bond strength, not

    durable - most commonly

    used but least desirable

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    Components portland cement

    durability high early strength

    high compressive

    strength

    bond strength

    sand

    filler strength

    lime

    workability water retentivity

    elasticity

    bond strength

    extensibility

    water

    flow required for hydration

    admixtures

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    Components

    portland cement Type I - general use when special properties not

    required

    Type II - when moderate sulfate resistance or moderate

    heat of hydration required Type III - when high early strength required

    Air entrained portland cements tend to reduce bond

    strengths

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    Components

    hydrated lime [Ca(OH)2] chalk or limestone (CaCO3) burned at 900

    0C in kiln to

    produce quicklime (CaO)

    water added to quicklime

    Types (ASTM C207)

    N - normal, unhydrated oxides & plasticity not controlled

    S - special, commonly used

    NA - normal air-entraining, not recommended SA - special air-entraining, not recommended

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    Components aggregates

    natural or manufactured gradation (ASTM C144)

    Amounts Finer than Each Laboratory sieve (Square Openings),

    Weight %

    Fine Aggregate Coarse Aggregate

    Mortar or Grout

    Sieve size

    GroutNatural Manufactured

    Size No. 8 Size No. 89

    -in (12.5-mm)

    3/8-in (9.5-mm)

    No. 4 (4.75-mm)No. 8 (2.36-mm)

    No. 16 (1.18-mm)

    No. 30 (600-m)

    No. 50 (300-m)

    No. 100 (150-m)

    No. 200 75- m

    100

    95 to 10080 to 100

    50 to 85

    25 to 60

    10 to 30

    2 to 10

    10095 to 100

    70 to 100

    40 to 75

    10 to 35

    2 to 15

    10095 to 100

    70 to 100

    40 to 75

    20 to 40

    10 to 25

    0 to 10

    100

    85 to 100

    10 to 300 to 10

    0 to 5

    100

    90 to 100

    20 to 555 to 30

    0 to 10

    0 to 5

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    Components

    water clean

    potable

    free of deleterious

    materials

    acids

    alkalies

    organic materials

    admixtures color

    workability

    reduced water

    penetration

    accelerated curing

    use w/ caution air-entraining

    chlorides

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    Types (MASONWORK) ASTM C270

    proportion specifications - RECOMMENDED

    property specifications

    established with laboratory testing, trial & error

    same letter designations, but

    Type N (proportion) = Type N (property)

    (proportion - higher compressive strength)

    Type M (paving brick)

    high strength general use

    below grade OR in contact w/ ground

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    Types (MASONWORK)

    Type S (structural masonry, reinforced brick) high strength

    reinforced masonry

    areas subject to high wind

    Type N (normal, common)

    high strength

    general use

    below grade OR in contact w/ ground

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    Types (MASONWORK)

    Type O (interior) low strength

    non-bearing applications

    not subject to severe weathering

    Type K (restoration)

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    Types (MASONWORK) Proportion Specifications

    Proportion by Volume (Cementitious Materials)

    Masonry CementMortar Type

    Portland

    Cement orBlended

    CementM S N

    Hydrated Limeor Lime Putty

    Aggregate Ratio

    (Measured inDamp, Loose

    Condition)

    Cement-Lime M 1

    S 1 Over to

    N 1 Over to 1

    O 1 Over 1 to 2

    Masonry Cement M 1 1

    M 1

    S 1

    S 1

    N 1

    O

    1

    Not less than

    2 and notmore than 3

    times the sum

    of the separate

    volumes ofCementitious

    materials.

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    Determine quantities and absolute volumes

    for an N Type Mortar

    Vsand = 1.0 ft3

    Vlime= 0.5 to 1.25 Vc Vsand=2.25 to 3 (Vc+Vl)

    1 ft3 of damp loose sand will yield 1 ft3 ofmortar. (due to bulking of wet sand)

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    Types (MASONWORK) Property Specificationsa

    Mortar Type

    Average

    Compressive

    Strength at 28 Days,

    Min. psi (MPa)

    Water Retention,

    min, %

    Air Content,

    max, %

    Aggregate Ratio

    (Measured in

    Damp, Loose

    Condition)

    Cement-Lime M 2500 (17.2) 75 12

    S 1800 (12.4) 75 12N 750 (5.2) 75 14

    b

    O 350 (2.4) 75 14b

    Masonry Cement M 2500 (17.2) 75 c

    S 1800 (12.4) 75 c

    N 750 (5.2) 75 c

    O 350 (2.4) 75

    c

    Not less than 2

    and not more

    than 3 times the

    sum of the

    separate volumes

    of cementitious

    materials

    aLaboratory prepared mortar onlyb When structural reinforcement is incorporated in cement-lime mortar,

    the maximum air content shall be 12%c When structural reinforcement is incorporated in masonry cement mortar,

    the maximum air content shall be 18%.

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    Selecting Mortar Types considerations

    structural

    requirements

    exposure

    wall type

    workability

    no single type for all

    purposes

    DO NOT change mortar

    types within samestructure

    uneconomical

    NEVER use mortar

    stronger in compression

    than required

    shrinkage, debonding

    uneconomical

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    Laboratory vs. Field Mortar

    CANNOT COMPARE

    field mortar

    more water required (lost in evaporation or to masonry unit)

    laboratory mortar

    less water, lower initial flow

    different curing conditions

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    Properties plastic properties

    influence hardened

    properties

    workability initial flow

    flow after suction

    water retentivity

    hardened properties

    determine performance

    bond strength

    durability extensibilty

    compressive strength

    other properties

    color

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    Workability easily spread

    adhere to vertical surface

    difficult to measure directly

    no standard test or quantitative measure

    indicators include flow, water retentivity, resistance

    to segregation

    affected by properties of components

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    Flow (ASTM C109) cone formed on flow table

    raised & dropped 25 times in 15 seconds

    flow = ratio of increase in diameter

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    Bond Strength most important physical property

    difficult to measure directly, simulate construction

    Bond Strength

    Max Bond

    cement: lime

    1:1 to 1:1/4Type S mortar

    Suction (IRA)

    Air Content

    Elapsed Time

    Mortar Flow

    Brick Texture rough Retempering

    Pressure

    Movement after set

    Water Retentivity

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    Other Hardened Properties

    durability

    not significant if

    properly prepared

    no air-entraining

    components

    extensibility

    max et at rupture

    elongation beforecracking

    lime contributes

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    Other Hardened Properties compressive strength

    f (cement content, w/c)

    cubes (ASTM C109)

    cylinders, briquettes

    Proportion fc

    Cement Lime Water Flow

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    Other Properties

    color colored aggregates - PREFERRED

    colored pigment


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