TYPE FBS (Face Brick Standard) brick is forgeneral use in exposed masonry construction. Mostbricks are manufactured to meet the requirement ofType FBS.

TYPE FBX (Face Brick Extra) brick is forgeneral use in exposed masonry construction wherea higher degree of precision and a lower permissiblevariation in size than that permitted for Type FBSbrick is required.

TYPE FBA (Face Brick Architectural) brick ismanufactured and selected to produce characteristicarchitectural effects resulting from non-uniformity insize and texture of the individual units.

1.2.1.1.3 SOLID CLAY BRICK SIZES

There are no standard solid clay brick sizes andtherefore it is always necessary to check with thebrick manufacturer or supplier for the actual brickdimensions. As a guide some typical brick sizes areshown below:

Width Height Length

Standard Brick: 33/4" x 21/4" x 8"

Modular Brick: 35/8" x 21/4" x 75/8"

Oversize Brick: 3 x 25/8" x 95/8"

Norman Brick: 31/2" x 21/4" x 111/2"

Jumbo Brick: 3" x 31/2" x 111/2"

1.2.1.2 HOLLOW CLAY UNITS

A hollow clay masonry unit as specified in ASTMC652, and, as referenced in IBC Section 2103.2 andMSJC Specification Article 2.3 B, is a unit whose netcross-sectional area in any plane parallel to thebearing surface is less than 75% of its gross cross-sectional area measured in the same plane.Examples are shown in Figure 1.4. Hollow clay unitsare classified by Grade, Type and Class as outlinedbelow.

FIGURE 1.4 Hollow clay brick.

1.2.1.2.1 GRADES OF HOLLOW BRICK

Two grades of hollow brick are covered: GradeSW and Grade MW. These grades are similar to thegrades for solid brick.

1.2.1.2.2 TYPES OF HOLLOW BRICK

Four types of hollow brick are covered in ASTMC652.

TYPE HBS (Hollow Brick Standard) is forgeneral use in exposed exterior and interior masonrywalls and partitions where a wider color range and agreater variation in size than is permitted for TypeHBX hollow brick.

TYPE HBX (Hollow Brick Extra) is for generaluse in exposed exterior and interior masonry wallsand partitions where a high degree of mechanicalperfection, a narrow color range, and a minimalvariation in size is required.

TYPE HBA (Hollow Brick Architectural) ismanufactured and selected to produce characteristicarchitectural effects resulting from nonuniformity insize, color and texture of the individual units.

TYPE HBB (Hollow Brick Basic) is for generaluse in masonry walls and partitions where color andtexture are not a consideration, and where a greatervariation in size is permitted than is required by TypeHBX hollow brick.

1.2.1.2.3 CLASSES OF HOLLOW BRICK

Two classes of hollow brick are covered in ASTMC652:

Class H40V Hollow brick intended for usewhere void areas or hollow spaces are between 25%to 40% of the gross cross-sectional area of the unitmeasured in any plane parallel to the bearing surface.

Class H60V Hollow brick intended for usewhere larger void areas are desired than allowed forclass H40V brick. The sum of the void areas for classH60V must be greater than 40%, but not greater than60%, of the gross cross-sectional area of the unitmeasured in any plane parallel to the bearingsurface. The void spaces, the web thicknesses, andthe shell thicknesses must comply with the minimumrequirements contained in Table 1.2.

4 REINFORCED MASONRY ENGINEERING HANDBOOK

Solid shellhollow

brick units

Double shellhollow

brick units

Cored shellhollow

brick units

TABLE 1.2 Class H60V Hollow Brick MinimumThickness of Face Shells and Webs (ASTMC652, Table 1)

1.2.1.2.4 SIZES OF HOLLOW BRICK

Hollow clay brick, like solid brick, are available ina variety of sizes but are customarily manufactured innominal 4, 6 or 8 in. thicknesses. Actual thicknesses,however, are about 1/2 in. less than the nominalthicknesses (i.e., a 6 in. nominal hollow brick isactually about 51/2 in. thick.)

1.2.1.3 PHYSICAL REQUIREMENTS OF CLAYMASONRY UNITS

1.2.1.3.1 GENERAL

The physical requirements for each grade of solidand hollow brick are compressive strength, waterabsorption and the saturation coefficient as shown inTable 1.3. However, note that facing brick is onlyclassified into Grades SW and MW.

TABLE 1.3 Physical Requirements, Solid andHollow Bricks (ASTM C62, Table 1; ASTM C216,Table 1; ASTM C652, Table 2)

1. The saturation coefficient or C/B ratio, is the ratio of absorptionby 24-hour submersion in cold water to that after 5-hoursubmersion in boiling water.

2. Does not apply for ASTM C216 and C652.

1.2.1.3.2 WATER ABSORPTION AND SATURATIONCOEFFICIENT

The water absorption rate and saturationcoefficient (known as the C/B ratio) are indications ofthe freeze-thaw resistance of a brick. The values forGrade SW brick and Grade MW brick indicate thatthere are more voids or pores in Grade SW units whichallows water to expand as it transforms into ice.

1.2.1.3.3 TOLERANCES

Table 1.4 shows the allowable tolerances for facebrick and hollow clay brick according to ASTM C216and ASTM C652, respectively. Dimensionaltolerances for building brick conforming to ASTM C62are the same as for Type FBS. For tolerances ondistortion see ASTM C216 and C652.

TABLE 1.4 Dimensional Tolerances (ASTM C216,Table 3; ASTM C652, Table 3)

ASTM C67, Test Methods for Sampling andTesting Brick and Structural Clay Tile, includesmethods for measuring water absorption and thesaturation coefficient.

The saturation coefficient, commonly called theC/B (Cold/Boiling) ratio, is the percent absorption ofthe twenty-four hour cold water test divided by thepercent absorption of the five-hour boiling test.

The C/B ratio is based on the concept that only aportion of the pores will be filled during the cold watertest, and that all the pores which can possibly befilled will be filled during the boiling test.

1.2.1.3.4 INITIAL RATE OF ABSORPTION, I.R.A.

The initial rate of absorption (suction) of a brickhas an important effect on the bond between thebrick and the mortar. It is defined as the amount ofwater in grams per minute absorbed by 30 square

MATERIALS 5

NominalWidth of

Units (in.)

Face ShellThicknesses

Solid (in.)

Cored orDouble

Shell (in.)

End Shellsor End

Webs (in.)

3 and 468

1012

3/41

11/413/811/2

11/211/215/82

3/411

11/811/8

Des

igna

tion

MinimumCompressiveStrength for

Brick FlatwiseBased on

Gross Area(psi)

MaximumWater

Absorption by5 Hour Boiling

Percent

MaximumSaturation

Coefficient1

Aver

age

of5

Bric

ks

Indi

vidu

al

Aver

age

of5

Bric

ks

Indi

vidu

al

Aver

age

of5

Bric

ks

Indi

vidu

al

GradeSW

GradeMW

GradeNW2

3000

2500

1500

2500

2200

1250

17.0

22.0

no limit

20.0

25.0

no limit

0.78

0.88

no limit

0.80

0.90

no limit

SpecifiedDimension (in.)

Maximum PermissibleVariation from Specific

Dimensions,Plus or Minus (in.)

Type FBX;HBX

Type FBS;HBS & HBB

3 and underOver 3 to 4, incl.Over 4 to 6, incl.Over 6 to 8, incl.Over 8 to 12, incl.Over 12 to 16, incl.

1/163/321/85/327/329/32

3/321/83/161/45/163/8

inches of brick in one minute. Maximum bondstrength occurs when the suction of the brick at thetime of placement is between 5 and 20 grams ofwater per 30 square inches of brick when the surfacearea is immersed in 1/8 in. of water for one minute.

Note that there is no consistent relationshipbetween total absorption and suction or I.R.A. Somebricks with high absorption have low suction (I.R.A.)and vice versa. Suction of the brick while being laid isof primary importance and suction can be controlledat the jobsite by wetting.

Dry bricks and bricks with high suction rates tendto absorb large quantities of water from mortar whichoften results in poor bond adhesion. Therefore,wetting the dry bricks a few hours prior to laying isadvisable so the cores are moist while the surface isdry. Bricks in this condition, with a dry surface andwet core, are preferred since they tend to bond wellwith the mortar. Note that very wet or saturated bricksshould be avoided since they may not bond well tothe mortar. Saturated bricks move easily and do notstay in position (float), thus making bricklayingextremely difficult and slow.

To check the internal moisture condition of abrick, the bricklayer or inspector should occasionallybreak a brick and observe the interior dampnesscondition.

Brick properties often vary significantlydepending on the clay type and the manufacturer.Consultation with the local brick manufacturer isadvisable for specific information on the intendedbrick for a project.

1.2.2 CONCRETE MASONRY

Concrete masonry units for load bearing systemsmay be either concrete brick as specified by ASTMC55, Specification for Concrete Brick or hollow loadbearing concrete masonry units as specified byASTM C90, Specification for Loadbearing ConcreteMasonry Units. Likewise, these units are referencedin IBC Section 2103.1 and in MSJC SpecificationArticle 2.3 A.

Concrete brick and hollow units are primarilymade from portland cement, water and suitableaggregates with or without the inclusion of othermaterials.

Concrete brick and hollow units may be madefrom lightweight or normal weight aggregates or both.

1.2.2.1 CONCRETE BRICK

Concrete brick are typically solid units used forspecial purposes. Some applications include top orbearing course of load bearing masonry walls,exterior walls of masonry fireplaces and catch basinor manhole construction. ASTM C55 provides theproperty requirements for concrete brick. Note thatcomponent units normally conform to therequirements of ASTM C55.

Unlike masonry units specified under ASTM C90,concrete brick maintain the Grade N and Grade Sdesignation requirements. Concrete brick must alsowithstand higher compression capacity as outlined inthe following sections.

1.2.2.1.1 PHYSICAL PROPERTY REQUIREMENTS

The strength and absorption requirements forconcrete brick are given in Table 1.5.

TABLE 1.5 Strength and AbsorptionRequirements (ASTM C55, Table 1)

1.2.2.2 HOLLOW LOADBEARING CONCRETEMASONRY UNITS

As previously noted, the physical and propertyrequirements for concrete masonry units arecontained in ASTM C90. The designer mustunderstand that this material standard is verydynamic, that is, it is revised frequently. Often thestandard is updated 2 or 3 times a year.

The Grades (S and N) and Types (I and II) havebeen deleted in favor of the more rigorousrequirements. Consequently, it is no longerappropriate to specify a 'Grade N, Type I' unit. Gradedesignations were deleted in the early 1990's and thetype designation was withdrawn in the year 2000.

6 REINFORCED MASONRY ENGINEERING HANDBOOK

Compressive Strength,Min., for

Concrete Brick TestedFlatwise (psi)

Water Absorption Max.,(Avg. of 3 Brick) with Oven

Dry Weight of Concrete(lb/ft3)

Average Gross Area Weight Classification

Grade Avg. of3

ConcreteBrick

IndividualConcrete

Brick

Light-weightLessthan105

MediumWeightLess

than 125to 105

NormalWeight125 orMore

NS

35002500

30002000

1518

1315

1013

1.2.2.2.1 PHYSICAL PROPERTY REQUIREMENTS

ASTM C90 requires concrete masonry units tomeet the strength and moisture absorptionrequirements listed in Table 1.6.

TABLE 1.6 Strength and AbsorptionRequirements (ASTM C90 Table 2)

1. Higher compressive strengths may be specified where requiredby design. Consult with local suppliers to determine availabilityof units of higher compressive strength.

2. Note: To prevent water penetration, protective coating shouldbe applied on the exterior face of the basement walls and whenrequired on the face of exterior walls above grade.

The water absorption requirements are based onthree weight classifications for hollow concretemasonry units:

1. Normal weight units at least 125 pcf whendry.

2. Medium weight units ranging from at least105 to 125 pcf when dry.

3. Lightweight units weighing less than 105 pcfwhen dry.

1.2.2.2.2 CATEGORIES OF HOLLOW CONCRETE UNITS

There are two categories of hollow concretemasonry units:

Standard Units require that no overalldimension (width, height and length) differ by morethan 1/8 in. from the specified standard dimensions.

Particular Feature Units have dimensionsspecified in accordance with the following (localsuppliers should be consulted to determineachievable dimensional tolerances):

1. For molded face units, no overall dimension(width, height and length) may vary by morethan 1/8 in. from the specified standarddimension. Dimensions of molded features(ribs, scores, hex-shapes, pattern, etc.) mustbe within 1/16 in. of the specified standarddimensions and must be within 1/16 in. of thespecified placement on the unit.

2. For split-faced units, all non-split overalldimensions may differ by no more than 1/8 in.from the specified standard dimensions. Onsplit faces, overall dimensions will vary.

3. For slumped units, no overall heightdimension may differ by more than 1/8 in.from the specified standard dimension. Onslumped faces, overall dimensions will vary.

1.2.2.2.3 SIZES OF HOLLOW CONCRETE MASONRYUNITS

Concrete blocks have customarily beenmanufactured in modular nominal dimensions whichare multiples of 8 in. (i.e., standard block arenominally 8 in. high by 16 in. long), as shown by theexamples in Figure 1.5.

FIGURE 1.5 Typical nominal 8 in. concretemasonry units.

MATERIALS 7

CompressiveStrength1, Min. (psi)

Water Absorption, Max.2,(Avg. of 3 Units) with Oven

Dry Weight of Concrete(lb/cu. ft)

Average Net Area Weight Classification

Avg. of3 Units

IndividualUnit

Light-weight,

Less than105

MediumWeight,

105 to lessthan 125

NormalWeight125 ormore

1900 1700 18 15 13

8 x 8 x 16 Standard

8 x 8 x 16 Open End 8 x 8 x 16 Double Open End Bond Beam

8 x 8 x 8 Half 8 x 8 x 16 Lintel

8 x 8 x 16 Bond Beam 8 x 8 x 16 Open End Bond Beam

8 x 8 x 16 Grout Lock 8 Y-Block

The actual block dimensions, however, aretypically 3/8 in. less than the nominal dimensions toaccount for a standard thickness mortar joint.Accordingly, an 8 x 8 x 16 in. nominal block is actually75/8 x 75/8 x 155/8 inches.

Slumped block units are equal to the standardmanufacturer's dimensions plus 1/2 in. to account forthe thicker mortar joints used with these irregularunits. Note also that the nominal dimensions of non-modular size units usually exceed the standarddimensions by 1/8 to 1/4 inch.

Face-shell thicknesses and web thicknesses ofconcrete masonry units are required to conform tothe values listed in Table 1.7.

TABLE 1.7 Minimum Thickness of Face-Shellsand Webs (ASTM C90, Table 1)

1. Average of measurements on three units taken at the thinnestpoint, as prescribed in Test Methods ASTM C140

2. Sum of the measured thickness of all webs in the unit,multiplied by 12, and divided by the length of the unit. In thecase of open-ended units where the open-ended portion issolid grouted, the length of that open-ended portion shall bededucted from the overall length of the unit.

3. This face-shell thickness is applicable where allowable designload is reduced in proportion to the reduction in thicknessesshown, except that allowable design loads on solid-groutedunits shall not be reduced.

4. For solid grouted masonry construction, minimum face shellthickness shall be not less than 5/8 inches.

Special unit designs (often called face shell unitsor expandable units, see Figure 1.6) requiringcorrosion-resistant metal ties between face shellsmay be used for appropriate applications. Thissystem adds significant labor cost, but allows thedesigner to specify an unusual wall thickness andallows for different texture and color differences onopposite sides of the wall.

FIGURE 1.6 Expandable component masonrysystem.

1.2.2.3 MOISTURE CONTENT FOR CONCRETEBRICK AND HOLLOW MASONRY UNITS

The primary purpose of moisture-controlled unitswas to limit shrinkage of concrete block and concretebrick due to moisture loss. This limitation was basedon a table considering moisture content and region ofhumidity to determine the maximum linear shrinkagefor moisture controlled units only.

The requirement was simplified to require amaximum 0.065% maximum linear shrinkageregardless of the unit type (moisture-controlled ornonmoisture-controlled), region of humidity ormoisture content.

When considering the significance of moisturecontent, the application of use of the masonry unitsshould be evaluated. For fences, enclosures andretaining walls, minor cracking in walls may beacceptable since these applications typically do notrequire moisture resistance from one side of the wall tothe other.

Determining linear shrinkage should be based onthe moisture content of units when delivered to thejobsite. This implies that the masonry units might haveto be protected from the weather after manufactureand during storage. Masonry units manufactured in amoist, rainy area should be stored under cover afterthey have sufficiently cured. Masonry unitsmanufactured in a dry area could be stored outsideand the dry weather will continue the curing process.

8 REINFORCED MASONRY ENGINEERING HANDBOOK

NominalWidth,

(in.)

ActualWidth,

(in.)

Face-Shell1

ThicknessMin. (in.)

Web Thickness

Webs1Min.,(in.)

Equivalent WebThickness, (Min.

in./Lin Ft)1,2

468

10

12

35/855/875/895/8

115/8

3/414

11/4413/84

11/43,411/2

11/43,4

3/411

11/8

11/8

15/821/421/421/2

21/2

Horizontalsteel

Vertical steel

#9 gauge high-lift grout ties at eithertop or bottom of every head joint.For 8 by 24 units, this is one tieevery 1.33 sq. ft. of wall area.

Face shell units withfull head and bedmortar joints

Any width24 max.

Concrete block, if stored for a period of time, canachieve climatic balance and perform satisfactorilywith a minimum of shrinkage. Thus, concrete blockunits should be protected from the weather evenduring storage at the jobsite. Units not covered andexposed to rain or snow at the jobsite may not meetmoisture requirements until they dry. Concretemasonry units should be aged a sufficient period oftime to achieve a climatic moisture balance condition.This period of time is dependent on the materials, themoisture content, the density or permeability of theblock and the humidity of the area.

Construction methods have a significantinfluence on the performance of concrete masonryunits. As the wall is constructed, the units arerestrained by the mortar head joint and the adjacentunits. When fluid, high slump grout is pumped intothe cells, excess water is absorbed into the block,increasing its moisture content. The block mayexpand and, upon drying out, subsequently shrink.This condition is difficult to avoid since a highly fluidslump grout is necessary in reinforced masonrywalls.

Multi-story load-bearing masonry buildings havebeen constructed throughout the United States. Theyhave been built in high seismic areas and one exampleis the Queen's Surf in Long Beach, California, shownin Figure 1.7. This 16-story structure is built of primarilyconcrete masonry units.

FIGURE 1.7 Queens Surf in Long Beach.

1.3 MORTAR1.3.1 GENERAL

Mortar is a plastic mixture of materials used tobind masonry units into a structural mass. Mortar hasthe following purposes:

1. Serves as bedding or seating material for themasonry units.

2. Allows the units to be leveled and properlyplaced.

3. Bonds the units together.4. Provides compressive strength.5. Provides shear strength, particularly parallel

to the wall.6. Allows some movement and elasticity

between units.7. Seals irregularities of the masonry units.8. Can provide color to the wall by using color

additives.9. Can provide an architectural appearance by

using various types of joints, as shown inFigure 1.14.

Historically, mortar has been made from a varietyof materials. Plain mud, clay, earth with ashes, andsand with lime mortars have all been used. Modernmortar consists of cementitious materials and wellgraded sand.

1.3.2 TYPES OF MORTAR

The requirements for mortar are provided inASTM C270, Specification for Mortar for UnitMasonry, also referenced in IBC Section 2103.8 andin MSJC Specification Article 2.1 A.

There were originally five types of mortar whichwere designated as M, S, N, O, and K. The types canbe identified by every other letter of the wordMaSoNwOrK. Type K is no longer referenced in thecode or material standards.

1.3.2.1 SELECTION OF MORTAR TYPES

The performance of masonry is influenced byvarious mortar properties such as workability, waterretentivity, bond strength, durability, extensibility, andcompressive strength. Since these properties varywith mortar type, selection of the proper mortar typeis important for each particular application. Tables 1.8and 1.9 are general guides for the selection of mortartype. Selection of mortar type should also consider allapplicable building codes and engineering practicestandards.

In Seismic Design Category (SDC) D and higher,both the IBC and MSJC Code require that mortarused in the lateral force-resisting system be Type Sor M. This requirement provides additional strength andbond in structures located in high seismic risk areas.

MATERIALS 9

TABLE 1.8 Mortar Types for Classes ofConstruction

TABLE 1.9 Guide for the Selection of MasonryMortars1 (ASTM C270, Table X1.1)

1. This table does not provide for many specialized mortar uses,such as chimney, reinforced masonry, and acid-resistantmortars.

2. Type O mortar is recommended for use where the masonry isunlikely to be frozen when saturated or unlikely to be subjectedto high winds or other significant lateral loads. Type N or Smortar should be used in other cases.

3. Masonry exposed to weather in a nominally horizontal surfaceis extremely vulnerable to weathering. Mortar for such masonryshould be selected with due caution.

Masonry cement is also restricted in SDC Dand higher. MSJC Code Section 1.14.6.6 gives thisSDC exclusion as shown;

MSJC Code Section 1.14.6.6 (SDC D)1.14.6.6 Material requirements Neither Type

N mortar nor masonry cement shall be used as part of thelateral force-resisting system.

1.3.2.2 SPECIFYING MORTAR

Mortar may be specified by either property orproportion specifications. Compliance verificationrequirements (submittals) for the specified mortar arestated in MSJC Specification Article 1.5 B.1.a:

MSJC Specification Article 1.5 B.1.a1.5 B. Submit the following:

1. Mix designs and test resultsa. One of the following for each mortar mix,

excluding thin-bed mortar for AAC:1) Mix designs indicating type and

proportions of ingredients in compliancewith the proportion specification ofASTM C270, or

2) Mix designs and mortar tests performedin accordance with the propertyspecification of ASTM C270.

1.3.2.2.1 PROPERTY SPECIFICATIONS

Property specifications are those in which theacceptability of the mortar is based on the propertiesof the ingredients and the properties of samples ofthe mortar (water retention, air content, andcompressive strength) mixed and tested in thelaboratory.

Property specifications as listed in Table 1.10 areused for research so that the physical characteristicsof a mortar can be determined and reproduced insubsequent tests. Note that ASTM C780 should onlybe used for quality control for field tested mortar.

Compressive strength is usually the only propertyor characteristic which a specifier who is not aresearcher would require. Most design situations canaccomplish the compressive strength determinationfor conformance the specified compressive strength,f'm, by the proportion procedure in ASTM C270.However, the property procedure in C270 providesfor compressive strength determination. Twomethods are used to determine the compressivestrength of mortar. The first method tests 2 in. cubesof mortar in compression after curing for 28 days. Thesecond method, based on ASTM C780, provides for2 in. cubes or cylinders to be tested as a comparativefield determination of the compressive strength.Overall, any testing that is done for field properties isto be done in accordance with ASTM C780, whereas

10 REINFORCED MASONRY ENGINEERING HANDBOOK

ASTMMortar TypeDesignation

Construction Suitability

M

Masonry subjected to high compressiveloads, severe frost action, or high lateralloads from earth pressures, hurricanewinds, or earthquakes. Structures below oragainst grade such as retaining walls, etc.

SStructures requiring high flexural bondstrength, and subject to compressive andlateral loads.

N

General use in above grade masonry.Residential basement construction,interior walls and partitions. Masonryveneer and non-structural masonrypartitions.

O

Non-load-bearing walls and partitions.Solid load bearing masonry with an actualcompressive strength not exceeding 100psi and not subject to weathering.

Location Building SegmentMortar Type

Rec. Alt.

Exterior,above grade

Load-bearing wallNon-load bearingwallParapet wall

NO2

N

S or MN or S

S

Exterior, at orbelow grade

Foundation wall,retaining wall,manholes, sewers,pavements, walksand patios

S3 M or N3

InteriorLoad-bearing wallNon-bearingpartitions

NO

S or MN

any testing to determine the mix properties forlaboratory or research purposes is done inaccordance with ASTM C270.

TABLE 1.10 Property Specifications for Mortar1(ASTM C270, Table 2)

Note: The property requirements of this table cannot be used as arequirement quality control of field prepared mortar, instead ASTMC780 should be used for this quality control.

1. Laboratory-prepared mortar only.2. When structural reinforcement is incorporated in cement-lime or

mortar cement mortar, the maximum air content shall be 12percent.

3. When structural reinforcement is incorporated in masonrycement mortar, the maximum air content shall be 18 percent.

Table 1.11 provides a comparison of theequivalent strength between cylinders and cubespecimens for three types of mortar.

TABLE 1.11 Compressive Strength of Mortar1 (psi)

1. Lesser periods of time for testing may be used provided therelation between early tested strength and the 28-day strengthof the mortar is established.

The field strength of mortar should be used onlyas a quality control test, rather than a quantificationevaluation. The in-place mortar strength can be muchhigher than the test values. Higher in-place strengthis a result of a lower cement-water ratio since theunits draw excess moisture from the mortar andlower height to thickness aspect ratio (1/4 to 5/8 in.high by 11/4 to 4 in. wide) mortar joints. Additionally,

the masonry units above and below the mortar joint,as well as the grout, confine the mortar so that the in-place mortar strength is much higher than thestrengths of the test specimens.

National Concrete Masonry Association's(NCMA) TEK 18-5 explains that mortar compressivestrength is often misinterpreted for several reasons.First, mortar compressive strength in the laboratory isnot indicative of the mortar in the masonry wall.Second, there are several different test methods fordetermining mortar compressive strength and whenmortar is correctly proportioned in accordance withASTM C270, compressive strength values are notgiven. Additionally, the water-cement ratio of mortarin the wall is more favorable than mortar cast in testcylinders and the aspect ratio of mortar in a testcylinder or mortar cube is greater than mortar in ajoint.

Figure 1.8 depicts compressive strengthimplications of laboratory mortar test specimenscompared to the mortar in a masonry wall. Thisinformation is contained in NCMA TEK 107 publishedin 1979 and shows that mortar in a 3/8 in. joint hassignificantly greater compressive strength thanmortar in a 1 in. cube or 2 in. test cylinder.

FIGURE 1.8 Effect of specimen thickness oncompressive strength.

Because the in-place mortar strength exceedsthe cube and cylinder test strengths, mortar willperform well even when tests on mortar are less thanthe specified strength of the mortar specimens.Additionally, because the in-place strength is quite

MATERIALS 11

Mortar Type

Avg.Comp.

Strengthat 28Days

min. (psi)

WaterRetention

min. %

AirContentmax. %

AggregateRatio

(Measured inDamp,Loose

Conditions)

Cement-Lime

MSNO

25001800750350

75757575

1212142142

Not lessthan 21/4and not

more than31/2 timesthe sum of

the separatevolume of

cementitiousmaterials

MortarCement

MSNO

25001800750350

75757575

1212142142

MasonryCement

MSNO

25001800750350

75757575

1818203203

MortarType

2-in. Diameter x 4-in.Height

Cylinder Specimen

2-in. CubeSpecimen

MSN

21001500625

25001800750

14,000

12,000

10,000

8,000

6,000

4,000

2,000Com

pres

sive

Str

engt

h

2 1

Mortar Joint Thickness (in.)

16,000

0.5

0

0.37

5

high, mortar performs well even when the specifiedcompressive strength of the entire masonryassemblage, f'm, is higher than the cylinder and cubestrengths.

1.3.2.2.2 PROPORTION SPECIFICATIONS

Proportion specifications limit the amount of theconstituent parts by volume. Water content, however,may be adjusted by the mason to provide properworkability under various field conditions. When theproportions of ingredients are not specified, theproportions by mortar type must be used as given inTable 1.12. Mortars other than those approved inTable 1.12 may be used when laboratory or field testsdemonstrate that the mortar, when combined with themasonry units, will satisfy the specified compressivestrength, f'm. However, if field tests are used forquality control, then ASTM C780 must be used, notASTM C270.

Common cement-lime mortar proportions byvolume are:

Type M mortar; 1 portland cement: 1/4 lime: 31/2 sandType S mortar; 1 portland cement: 1/2 lime: 41/2 sandType N mortar; 1 portland cement: 1 lime: 6 sandType O mortar; 1 portland cement: 2 lime: 9 sand

1.3.3 MORTAR MATERIALS

The principal mortar constituents are cement,lime, sand and water each making a uniquecontribution to a mortar's performance. Cementcontributes to mortar durability, high early strength

and high compressive strength. Lime contributes toworkability, water retentivity and elasticity. Bothcontribute to bond strength. Sand acts as a filler andcontributes to the strength. Water is the ingredientwhich creates a plastic, workable mortar and isrequired for the hydration of the cement.

1.3.3.1 CEMENTS

Three types of cement are now permitted to beused in mortar by the IBC and the MSJC Code:portland cement, masonry cement and mortarcement. Plastic cement, or plasterers cement is notacknowledged as an acceptable material andtherefore must not be used in mortar.

Masonry cement and mortar cement aredesignated as Types M, S and N, which is not thesame as the mortar type (M, S, N and O). In Table1.12, the M, S and N designation for masonry andmortar cements in the third row represents gray, purecement added to other materials to make mortar,whereas the M, S, N, and O designations in column2 signify the mortar type (already mixed) the masonuses to lay the unit.

1.3.3.1.1 PORTLAND CEMENT

The basic cementitious ingredient in most mortaris portland cement. This material must meet therequirements of ASTM C150 for Portland Cement. Inmortar, the type of portland cement is limited to TypeI, II, III or V. The use of air-entraining portland cement(Type IA, IIA or IIIA) is not recommended for masonrymortar because air entrainment can reduce the bondbetween mortar and the masonry units.

12 REINFORCED MASONRY ENGINEERING HANDBOOK

TABLE 1.12 Mortar Proportions for Unit Masonry (IBC Table 2103.8(1), ASTM C270, Table 1)

Mortar Type

PROPORTIONS BY VOLUME (Cementitious Materials)Aggregate Measured

in a Damp, LooseCondition

PortlandCement orBlendedCement

Masonry Cement Mortar CementHydrated Limeor Lime PuttyM S N M S N

Cement-lime

MSNO

1111

1/4over 1/4 to 1/2over 1/2 to 11/4

over 11/4 to 21/2

Not less than 21/4 andnot more than 3 times the

sum of the separatevolumes of cementitious

materials

Mortarcement

MMSSNO

1

1/2

1

1

1111

Masonrycement

MMSSNO

1

1/2

1

1

1111

Portland cement is the primary adhesive materialand, based on the water cement ratio, can producehigh strength mortar. Hydrated lime is used inconjunction with portland cement to provide thedesired strength, workability and board life (board lifeis defined as the period of time during which mortaris still plastic and workable).

1.3.3.1.2 MASONRY CEMENT

Masonry cement is a proprietary blend ofportland cement and plasticizers such as ground inertfillers and other additives for workability. Masonrycement must meet the requirements of ASTM C91Masonry Cement and is available for Types M, S, Nand O mortar.

There are three types of masonry cement:

1. Type N contains the cementitious materialsused in the proportions called for in ASTMC270. Type N masonry cement may also beused in combination with portland cement orblended hydraulic cement to prepare Type Sor Type M mortar.

2. Type S contains the cementitious materialsused in the proportions called for in ASTMC270.

3. Type M contains the cementitious materialsused in the proportions called for in ASTMC270.

The use of masonry cement for mortar for thelateral force-resisting system is prohibited in SeismicDesign Categories D and higher.

1.3.3.1.3 MORTAR CEMENT

Mortar cement is also a portland cement basedmaterial which meets the requirements of ASTMC1329, Mortar Cement. Mortar cement may be usedfor mortar in all seismic design categories.

There are three types of mortar cement:

1. Type N contains the cementitious materialsused in the proportions called for in ASTMC270. Type N mortar cement may also beused in combination with portland cement orblended hydraulic cement to prepare Type Sor Type M mortars.

2. Type S contains the cementitious materialsused in the proportions called for in ASTMC270.

3. Type M contains the cementitious materialsused in the proportions called for in ASTMC270.

Unlike masonry cement, mortar cement can beused in high seismic applications. Mortar cement hashistorically had more uniform properties thanmasonry cement, and ASTM C1329 also requires alower air content for mortar cement as well as testingof the flexural bond strength of the mortar. Thesedifferences give building officials the confidence topermit the use of masonry cement for significantlateral load-resisting systems.

FLEXURAL BOND STRENGTH OF MORTAR AND MASONRYASSEMBLAGE

The flexural bond strength of mortar cement isbased on a laboratory evaluation of a standardizedtest apparatus, as prescribed in ASTM C1072. Thetest apparatus consists of a metal frame used tosupport a specimen as shown in Figure 1.9. Thesupport system must be adjustable to support prismsof various heights (See ASTM C1072 for additionalinformation on this test).

FIGURE 1.9 Bond wrench test apparatus.

1.3.3.2 HYDRATED LIME

Hydrated lime is manufactured from calcininglimestone (calcium carbonate with the water ofcrystallization, CaCO3H20). The high heat generatedin the kiln drives off the water of crystallization, H20,and the carbon dioxide, CO2, resulting in quicklime,CaO.

MATERIALS 13

Bearing plate

Eccentric load

Clampingbolts

Ball bearing

Loading arm bracketTest specimenUpper clamping bracketLower clamping bracketCompression memberStyrofoamAdjustable prismbase support

Ball bearing

The quicklime can then be slaked by placing it inwater thus making hydrated lime, lime putty or slakedlime Ca(OH)2. The hydrated lime is then dried andground, producing a white pulverized hydrated limewhich is sacked and used in mortar.

Hydrated lime can be used without delay makingit more convenient to use than quicklime.

Hydrated lime is required to meet ASTM C207,Specification for Hydrated Lime for MasonryPurposes, and is available in the following fourTypes, S, SA, N and NA. Of these, only Type Shydrated lime is suitable for masonry mortar. Type Sand N hydrated limes contain no air entrainingadmixtures. However, Types NA and SA limes mayprovide more entrained air in the mortar than allowed.Additionally, unhydrated oxides are not controlled inType N or NA limes thus making only Type Shydrated lime suitable for masonry mortar.

When used in mortar, lime in mortar providescementitious properties and is not considered to bean admixture.

Used in mortar lime:

1. Improves the plasticity or workability of themortar.

2. Improves the water tightness of the wall.

3. Improves the water retentivity or board life ofthe mortar.

Figure 1.10 shows the relationship betweenvarious proportions of cement and lime versus mortarstrength and water retentivity.

FIGURE 1.10 Relation between mortarcomposition, compressive strength, and waterretentivity.

1.3.3.3 MORTAR SAND

For masonry mortar, sand aggregate is requiredto meet ASTM C144, Specification for Aggregate forMasonry Mortar.

Sand gradation is most often specified or definedby referring to a standard sieve analysis. For mortar,sand is graded within the limits given in Table 1.13.

TABLE 1.13 Sand for Masonry Mortar (ASTMC144, Section 4.1)

Sand should be free of significant amounts ofdeleterious substances and organic impurities.ASTM C144 provides guidelines on determining if anaggregate has excessive impurities.

Concrete sand should not be used in mortarbecause the maximum grain size is too large.Additionally, the fine particles which are needed inmasonry sand have often been washed out ofconcrete sand thus creating a harsh, coarse sandunsuitable for mortar. Mortar sand needs at least 5%fines which pass the 200 sieve to aid plasticity,workability and water retention of mortar.

Sand used in preparing mortar can be eithernatural or manufactured. Manufactured sand isobtained by crushing stone, gravel or air-cooledblast-furnace slag. It is characterized by sharp andangular particles producing mortars with workabilityproperties different than mortars made with naturalsand which generally have round, smooth particles.

Mortar sand, like all mortar ingredients, should bestored in a level, dry, clean place. Ideally, it should belocated near the mixer so it can be measured andadded with minimum handling and can be kept fromcontamination by harmful substances. Pre-blendedmortar shipped in sacks or bulk silos circumvents theneed for jobsite protection of exposed materials.

14 REINFORCED MASONRY ENGINEERING HANDBOOK

5000

4000

3000

2000

1000 CompressivestrengthWater retentivity

100C0L

80C20L

60C40L

40C60L

20C80L

0C100L

Com

pres

sive

stre

ngth

(A

ge 2

8 da

ys) p

si 878685848382

8180

797877

7675

Wat

er re

tent

ivity

inde

x

Proportion of Cement (%) (C): Lime (L) in mortar (C + L):Sand: 1:3 by volume

Sieve SizePercent Passing

NaturalSand

ManufacturedSand

No. 4No. 8No. 16No. 30No. 50No. 100No. 200

10095 to 10070 to 10040 to 7510 to 352 to 150 to 5

10095 to 10070 to 10040 to 7520 to 4010 to 250 to 10

1.3.3.4 WATER

Water must be clean and free of deleteriousamounts of acids, alkalies or organic materials. Watercontaining soluble salts such as potassium andsodium sulfates should be avoided since these saltscan contribute to efflorescence. Also, water shouldnot be high in chloride ion content since that highcontent can contribute to potential rusting ofreinforcement. A practical guide is to limit the chlorideion content in mortar or grout to the prescribed limitsgiven for concrete in Table 4.4.1 of ACI 318.Alternately, epoxy- or zinc-coated reinforcement maybe used for corrosion protection.

1.3.3.5 ADMIXTURES

There are numerous admixtures which may beadded to mortar to affect its properties. One of these,called a retarding set admixture, delays the set andstiffening of mortar. In fact, the set may be delayed for36 hours or more if desired.

There are also admixtures used to replace lime.These may be an air entraining chemical or apulverized fire clay or bentonite clay to provideworkability. Care should be taken with theseadmixtures since the bond between the mortar andthe masonry units may be reduced. Use of a limesubstitute may be considered when hydrated lime isnot available.

The use of any admixtures must be approved bythe architect or engineer and should be acceptable tothe building official. Admixtures high in chloride ioncontribution should be avoided, unless epoxy- orzinc-coated reinforcement is used.

1.3.3.6 COLOR

Mortar colors are generally mineral oxides orcarbon black. Iron oxide is used for red, yellow, andbrown colors; chromium oxide for green, and cobaltoxide for blue colors. Commercially prepared colors formortars also offer a wide variety of colors and shades.

The amount of color additive depends on thecolor and intensity desired. Typically the amount ofcolor additive ranges from 0.5% to 7.0% for themineral oxides with a maximum of 2% for carbonblack when using portland cement. MSJCSpecification Article 2.6 A.2 further limits the amountof color additive that can be used with masonry ormortar cement. These percentages are based on theweight of cement content and the maximumpercentages are far greater than the normal amountsof color additives generally required.

Mixing time of the mortar should be long enoughfor a uniform, even color to be obtained and shouldbe the same length of time for every mortar batch.Additionally the mixing sequence should be the samefor each batch.

Retempering of colored mortar must be kept to aminimum to reduce the variations in color of themortar. For best results, mortar should not beretempered at all.

Finally, the source, manufacturer and amount ofeach ingredient should remain the same for allcolored mortar on a project to obtain the same colorthroughout. Prepackaged mineral color additives thatcan be added to the mix based on full sacks ofportland cement generally provide a consistentmortar color. Pre-blended mortars are extremelyprecise with material proportioning.

1.3.4 MIXING

1.3.4.1 MSJC SPECIFICATION FOR MIXING

Article 2.6 A provides the mortar mixingrequirements as shown:

MSJC Specification Article 2.62.6 Mixing

2.6 A. Mortar1. Mix cementitious materials and aggregates

between 3 and 5 min. in a mechanical batchmixer with a sufficient amount of water toproduce a workable consistency. Unlessacceptable, do not hand mix mortar.Maintain workability of mortar by remixingor retempering. Discard mortar which hasbegun to stiffen or is not used within 21/2 hrafter initial mixing.

2. Limit the maximum percentage of mineraloxide or carbon black job-site pigments byweight of cement as follows:a. Pigmented portland cement-lime mortar

1) Mineral oxide pigment 10 percent2) Carbon black pigment 2 percent

b. Pigmented mortar cement mortar1) Mineral oxide pigment 5 percent2) Carbon black pigment 1 percent

c. Pigmented masonry cement mortar1) Mineral oxide pigment 5 percent2) Carbon black pigment 1 percent

3. Do not use admixtures containing more than0.2 percent chloride ions.

4. Glass unit masonry Reduce the amount ofwater to account for the lack of absorption.Do not retemper mortar after initial set.Discard unused mortar within 11/2 hr afterinitial mixing.

MATERIALS 15

For thin-bed mortar used with AAC, the MSJCCode specifies the following:

MSJC Specification Article 2.6 C2.6 C. Thin-bed mortar for AAC Mix thin-bedmortar for AAC masonry as specified by the thin-bedmortar manufacturer.

1.3.4.2 MEASUREMENT OF MORTARMATERIALS

The method of measuring materials for mortarmust be such that the specified proportions of themortar materials are controlled and accuratelymaintained. A reasonable method to control themortar proportions is to use full sacks of cement ineach batch and to use measuring boxes for theproper amounts of lime and sand. Dry preblendedmixes are also available.

1.3.4.3 JOBSITE MIXED MORTAR

Mortar mixing is best accomplished in a paddletype mixer. About one-half of the water and onequarter of the sand are put into the operating mixerfirst, then the cement, lime, color (if any), and theremaining water and sand. All materials should mixfor three to five minutes in a mechanical mixer withthe amount of water required to provide the desiredworkability. Dry mixes for mortar which are blended ina factory should be mixed at the jobsite in amechanical mixer until workable, but not more thanfive minutes.

Figure 1.11, shows a paddle mixer with astationary drum. The blades rotate through the mortarmaterials for thorough mixing.

FIGURE 1.11 Plaster or paddle mortar mixer.

A drum or barrel mixer, shown in Figure 1.12rotates the drum in which the materials are placed.The materials are carried to the top of the rotationand then the material drops down to achieve mixing.

FIGURE 1.12 Drum or barrel concrete mixer.

1.3.4.4 PRE-BLENDED MORTAR

Mortar can also be factory preblended and storedat the jobsite in sacks or silos. Some silo systemsintroduce water to the dry mortar mix in an augerscrew at the base of the silo, while other silo systemsdischarge the dry mortar mix directly into aconventional mixer.

FIGURE 1.13 Silo mixing system.

16 REINFORCED MASONRY ENGINEERING HANDBOOK

Pre-blended dry mortar is also available in sacks,which may be beneficial in keeping project debris ata minimum. This packaging method can be especiallyuseful in limited working areas, such as parkinggarages.

When factory blended mortar is used,manufacturers certification of the type of mortar isrecommended.

1.3.4.5 EXTENDED LIFE MORTAR

ASTM C1142, Specification for Extended LifeMortar for Unit Masonry, covers the requirements forthis material. Extended life mortar consists ofcementitious materials, aggregate, water and anadmixture for set-control which are measured andmixed at a central location, using weight or volumecontrol equipment. This mortar is delivered to aconstruction site and is usable for a period in excessof 21/2 hours.

There are four types of extended life mortar, RM,RS, RN, and RO. These types of mortar can bemanufactured with one of the four mortarformulations: portland cement, portland cement-lime,masonry cement, or masonry cement with portlandcement. Table 1.14 shows these propertyspecification requirements.

TABLE 1.14 Property Specification Requirements(ASTM C1142, Table 1)

1. Twenty-eight days old from date of casting. The strengthvalues as shown are the standard values. Intermediate valuesmay be specified in accordance with project requirements.

2. When structural reinforcement is incorporated in mortar, themaximum air content shall be 12%, or bond strength test datashall be provided to justify higher air content.

Extended life mortar is selected by type and thelength of workable time required. The consistencybased on the mason's use should be specified.Otherwise, the extended life mortar is required tohave a cone penetration consistency of 55 5 mm asmeasured by ASTM C780, Test Method forPreconstruction and Construction Evaluation ofMortars for Plain and Reinforced Unit Masonry.

Pre-blended mortars that meet the above criteriaare popular for many jobs. These pre-blendedmortars are especially popular on smaller jobs whereeconomy of control is not available.

1.3.4.6 RETEMPERING

Mortar may be retempered, preferably limited toone time, with water when needed to maintainworkability. This should be done on wet mortarboards by forming a basin or hollow in the mortar,adding water, and then reworking the mortar into thewater. Splashing water over the top of the mortar isnot permissible.

Harsh mortar that has begun to stiffen or hardendue to hydration, should be discarded. Mortar shouldbe used within two-and-one-half hours after the initialwater has been added to the dry ingredients at thejobsite. Retempering color mortar should be avoidedto limit color variations.

1.3.5 TYPES OF MORTAR JOINTS

Nine examples of commonly used mortar jointsare illustrated in Figure 1.14. Each joint provides adifferent architectural appearance to the wall.However, because some joints provide poor weatherresistance, care must be taken in the selection of theproper type of mortar joint. Joints with ledges such asweather, squeezed, raked and struck joints tend toperform poorly in exterior applications and allowmoisture penetration. Concave tooled joints arerecommended for exterior applications since thetooling compacts the mortar tightly preventingmoisture penetration.

MATERIALS 17

MortarType

Avg1CompressiveStrength at 28

days, min.(psi)

WaterRetentionmin. (%)

AirContent2,max. (%)

RMRSRNRO

Cubes25001800750350

75757575

18181818

a) Concave Joint It is the most common joint used.The tooling works the mortar tight into the joint,compressing the mortar producing a weather joint.The joint emphasizes the masonry unit pattern andconceals small irregularities in laying the unit.

b) "V" Joint Tooling works the mortar tight andprovides a weather joint. However, the notch of the9 can be a point of discontinuity and cracks maydevelop which allow water migration. This jointemphasizes the masonry unit pattern and concealssmall irregularities in laying, while providing a line incenter of mortar joint.

c) Weather Joint The purpose is to emphasizehorizontal joints. This type of joint is a marginallyacceptable weather-type joint. The reason for this isthe top ledge of the joint acts as drip ledge. If the jointis not properly tooled, the surface tension of waterwill allow water to pool at the drip ledge and the watercan migrate back into the mortar.

d) Flush Joint This joint is used where the wall isto be plastered. Special care is required to make thejoint weatherproof. Mortar joint must be compressedto assure intimate contact with the masonry unit. Notrecommended for exposed exterior use.

e) Squeezed Joint This type of joint provides for arustic, high texture appearance. Satisfactory forinterior use and exterior fences. Not recommendedfor exterior building walls, since no weatherresistance is created because the mortar is notcompressed back into the joint. Also the top ledgeallows for pooling of the water.

f) Beaded Joint This is a special effect, poorexterior weather joint due to exposed ledge and is notrecommended.

g) Raked Joint This joint type strongly emphasizesthe units. Poor weather joint and not recommended ifexposed to weather unless tooled at bottom of mortarjoint. Pooling of water can occur at the top ledge(surface tension properties of water) and the bottomledge.

h) Struck Joint This joint type is used to emphasizehorizontal lines. Poor weather joint, therefore notrecommended as water will penetrate on lower ledge.

i) Grapevine Joint This joint shows a horizontalindentation. Same limitations as flush joint.

FIGURE 1.14 Mortar joint types.

18 REINFORCED MASONRY ENGINEERING HANDBOOK

1.4 GROUT1.4.1 GENERAL

Grout is a mixture of portland cement, sand, peagravel and water mixed to fluid consistency so that itwill have a slump of 8 to 11 inches. Grout is placed inthe cells of hollow masonry units or between thewythes of solid units to bind the reinforcing steel andthe masonry into a structural system. Additionally,grout provides:

1. More cross-sectional area allowing a groutedwall to support greater vertical and lateralshear forces than a non-grouted wall.

2. Added sound transmission resistance thusreducing the sound passing through the wall.

3. Increased fire resistance and an improved firerating of the wall.

4. Improved energy storage capabilities of a wall.

5. Greater weight thus improving the overturningresistance of retaining walls.

Requirements for grout are given in ASTM C476,Specification for Grout for Masonry. An example ofgrouting a hollow unit wall is shown in Figure 1.15.

FIGURE 1.15 Grouting of hollow unit blockwall.

1.4.2 TYPES OF GROUTThe IBC and MSJC Code identify two types of

grout for masonry construction: fine grout and coarsegrout. As their names imply, these two types of groutsdiffer primarily in the maximum allowable size ofaggregates. The fineness or coarseness of the groutis selected based on the size of grout space and theheight of the grout pour. Table 1.15, Grout SpaceRequirements, provides the maximum grout pourheight based on cell or cavity size and grout type.

TABLE 1.15 Grout Space Requirements (MSJCCode Table 1.16.1, MSJC Specification Table 7)

1. Fine and course grouts are defined in ASTM C476.2. For grouting between masonry wythes.3. Grout space dimension is the clear dimension between any

masonry protrusions and shall be increased by the diametersof the horizontal bars within the cross section of the groutspace.

4. Area of vertical reinforcement shall not exceed 6 percent of thearea of the grout space

5. Minimum grout space dimension for AAC masonry units shallbe 3-in. x 3-in. or a 3-in. diameter cell.

1.4.2.1 FINE GROUT

Fine grout can be used where the grout space issmall, narrow, or congested with reinforcing steel.When fine grout is used, there must be a clearanceof 1/4 in. or more between the reinforcing steel andthe masonry unit.

Typical proportions by volume for fine grout are:

1 part portland cement 21/4 to 3 parts sand Water for a slump of 8 to 11 in. Also, up to 1/10 part of hydrated lime or lime

putty can be used

1.4.2.2 COARSE GROUT

Coarse grout may be used where the groutspace for the grouted cavity of a double-wythemasonry construction is at least 11/2 inches in widthhorizontally, or where the minimum block celldimension is 11/2 x 3 inches.

Although approved aggregates for grout (sandand pea gravel) are limited to a maximum size of 3/8in., a coarse grout using 3/4 in. aggregate may beused if the grout space is especially wide, (8 in. or

MATERIALS 19

GroutType1

MaximumGroutPour

Height,(ft)

MinimumWidth of

GroutSpace2,3

(in.)

MinimumGrout Space

Dimensions forGrouting Cells ofHollow Units,3,4,5

(in. x in.)

FineFineFineFine

1 51224

3/42

21/23

11/2 x 22 x 3

21/2 x 33 x 3

CoarseCoarseCoarseCoarse

151224

11/22

21/23

11/2 x 321/2 x 33 x 33 x 4

more horizontally). Larger size aggregates take upmore volume, thus requiring less cement for anequivalent strength mix that used smalleraggregates. Larger aggregates also reduce theshrinkage of the grout and allow the slump of grout tobe reduced to 7 or 8 in. for easier placement. Placinggrout with 3/4 in. aggregate typically requires aconcrete pump.

When coarse grout is made with pea gravel,there must be a minimum clearance of 1/2 in. betweenthe reinforcing steel and the masonry unit.Accordingly, if coarse grout is made using largersized aggregates, the clearance between thereinforcement and the masonry unit must beincreased to approximately 1/4 in. more than thelargest size aggregate.

The typical proportions by volume for coarsegrout are:

1 part portland cement 21/4 to 3 parts sand 1 to 2 parts pea gravel Water for a slump of 8 to 11 in. Also, up to 1/10 part of hydrated lime may be

used

Submittal requirements for grout are given inMSJC Specification Article 1.5 B.1.b as shown below:

MSJC Specification Article 1.5 B.1.b1.5 B. Submit the following:b. One of the following for each grout mix:

1) Mix designs indicating type and proportionsof the ingredients according to the proportionrequirements of ASTM C476, or

2) Mix designs and grout strength testperformed in accordance with ASTMC476.

Grout space requirements are given in MSJCCode Table 1.16.1 and MSJC Specification Table 7.The table is one of the duplicated items between theCode and Specification as the requirements apply toboth the designer and contractor.

Smaller grout spaces and higher grout lifts arepossible provided the contractor provides a groutdemonstration panel to show that an alternate systemcan effectively place grout in the wall and conform tocode requirements.

1.4.3 SLUMP OF GROUT

Water content of grout is adjusted to providefluidity (slump) allowing proper grout placement forvarious job conditions. The high slump allows grout toflow into openings and around steel reinforcement.Excess water in the grout is absorbed by themasonry units, reducing the apparently highwater/cement ratio. Additionally the moist masonryaids in curing the grout.

Fluidity is measured by a slump cone test, asshown in Figure 1.16. The test consists of a 12 in.cone with openings on both ends. The grout sampleis taken from the middle of a transit mixed load, notthe initial 10% discharge and not the last 10%discharge. The cone is placed on a flat horizontalsurface and is filled with grout, by placing the grout inthe top of the cone and rodding to consolidate. Thecone is then lifted straight up, and the grout is free toflow into a resting state. The difference in heightbetween the top of the cone and the top of the grout,with the cone removed, is the slump. Both types ofgrout, fine and coarse, must contain enough water toprovide a slump of 8 to 11 inches.

FIGURE 1.16 Slump cone and slump of grout.

1.4.4 PROPORTIONS

Grout ingredient proportions may be selectedfrom Table 1.16, Grout Proportions by Volume.Proportions of the grout ingredients may also bedetermined by laboratory testing or field experience,if a satisfactory history of the grout's performance isavailable. Note that any grout performance historymust be based on grout, mortar, and masonry units,which are similar to those intended for use on the

20 REINFORCED MASONRY ENGINEERING HANDBOOK

12 C

one

8 to

11

Slu

mp

new project. The use of 70% sand and 30% peagravel requires six sacks of portland cement percubic yard and results in a pumpable grout thatprovides the minimum strength of 2000 psi requiredby ASTM C476. Grout must have adequate strengthto satisfy f'm requirements and for sufficient bondingto the reinforcing steel and the masonry units.Without adequate bonding, stresses cannot properlytransfer between the various materials. Adequatestrength is also needed to assure that embeddedanchor bolts will be anchored securely.

Experience has shown that grout proportionsbased on Table 1.16 are successful for normal load-bearing concrete masonry construction.

TABLE 1.16 Grout Proportions by Volume (IBCTable 2103.12; ASTM C476, Table 1)

1.4.4.1 AGGREGATES FOR GROUT

Aggregates for grout should meet therequirements of ASTM C404, Specification forAggregates for Masonry Grout. Grading of theaggregate should be in accordance with Table 1.17,Grading Requirements.

1.4.5 MIXING

Grout prepared at the jobsite should be mixed fora minimum of five minutes in order to assurethorough blending of all ingredients. Enough watermust be used in the mixing process to achieve a highslump of 8 to 11 inches. Dry grout mixes which areblended at a factory should be mixed at the jobsite ina mechanical mixer for at least 5 minutes in order toobtain the desired consistency.

TABLE 1.17 Grading Requirements (ASTM C404,Table 1)

The MSJC Specification requires the following inArticle 2.6 B:

MSJC Specification Article 2.6 B2.6 B. Grout

1. Unless otherwise required, proportion and mixgrout in accordance with the requirements ofASTM C476.

2. Unless otherwise required, mix grout to aconsistency that has a slump between 8 and 11 in.(203 and 279 mm).

1.4.6 GROUT ADMIXTURES

Admixtures are any materials other than water,cement and aggregate which are added to the grout,either before or during mixing, in order to improve theproperties of the fresh or hardened grout or todecrease its cost.

The four most common types of grout admixturesare:

1. Shrinkage Compensating Admixtures Usedto counteract the loss of water and theshrinkage of the cement by creatingexpansive gases in the grout.

2. Plasticizer Admixtures Used to obtain thehigh slump required for grout without the useof excess water. By adding a plasticizer to a4 in. slump grout mix, an 8 to 11 in. slumpcan be achieved.

MATERIALS 21

Type

Parts byVolume ofPortland

Cement orBlendedCement

Parts byVolume ofHydratedLime or

Lime Putty

Aggregate Measured in aDamp, Loose Condition

Fine Coarse

FineGrout 1

1/10

21/43 timesthe sum of thevolumes of thecementitious

materials

CoarseGrout 1

1/10

21/43 timesthe sum of thevolumes of thecementitious

materials

2 times thesum of the

volumes of thecementitious

materials

Amounts Finer than Each Laboratory Sieve (SquareOpenings), Percent by Weight

SieveSize

Fine Aggregate Coarse Aggregate

SizeNo. 1

Size No. 2SizeNo. 8

SizeNo. 89Natural Manu-factured

1/2 in. 100 100

3/8 in. 100 85 to 100 90 to 100

No. 4 95 to 100 100 100 10 to 30 20 to 55

No. 8 80 to 100 95 to 100 95 to 100 0 to 10 5 to 30

No. 16 50 to 85 70 to 100 70 to 100 0 to 5 0 to 10

No. 30 25 to 60 40 to 75 40 to 75 0 to 5

No. 50 10 to 30 10 to 35 20 to 40

No. 100 2 to 10 2 to 15 10 to 25

No. 200 0 to 5 0 to 5 0 to 10

3. Cement Replacement Admixtures Used todecrease the amount of cement in the groutwithout adversely affecting the compressiveand bond strengths of the grout. Types C andF fly ash are by far the most common cementreplacement admixtures. Current practiceallows 15 to 20% of the portland cement byweight to be replaced with fly ash as long asthe strength characteristics are maintained.

4. Accelerator admixtures Used in coldweather construction to reduce the time thatthe wall must be protected from freezing.Accelerators decrease the setting time of thegrout and speeds strength gain. Acceleratorsalso increase the heat of hydrationpreventing the grout from freezing undermost circumstances.

Careful consideration must be given prior to theuse of all admixtures, since an admixture mayadversely affect certain grout properties whileimproving the intended properties. Admixturescontaining chloride and antifreeze liquids may not beused per ASTM C476 despite their benefits, sincechlorides cause corrosion of the reinforcing steel.Some admixtures can reduce the compressive andbond strengths of the grout.

Similarly, care should be taken when using two ormore admixtures in a grout batch since thecombination of admixtures often producesunexpected results. Under all circumstances,information regarding laboratory and fieldperformance of an admixture should be obtainedfrom the manufacturer prior to use in grout.Additionally, MSJC Specification Article 2.2 requiresapproval of all grout admixtures prior to use.

1.4.7 GROUT STRENGTHREQUIREMENTS

According to ASTM C476, the grout can bespecified either by proportions (shown in Table 1.16)or by compressive strength. When compressivestrength is specified, the slump is to be 8 to 11 in., asdetermined by ASTM C143, and the compressivestrength shall be a minimum of 2000 psi at 28 dayswhen sampled and tested in accordance with ASTMC1019.

The required minimum compressive strength of2000 psi is needed in order to achieve adequatebond of grout to the reinforcing steel, and to themasonry unit. This minimum value is satisfactory formasonry construction in which the specified design

strength, f'm, equals 1500 psi, and the masonry unithas a compressive strength of at least 1900 psi. Therecommended compressive strength of the grout inconcrete masonry construction is often taken as 1.25to 1.40 times the design strength of the masonryassemblage, f'm. An example is that 2000 psi grout isrequired for a masonry assemblage with a specifiedstrength, f'm, of 1500 psi; or a grout that is 1.33 timesthe specified strength. MSJC Specification Article 1.4B.2, however, requires that the grout compressivestrength equals or exceeds the specifiedcompressive strength, f'm, of masonry and that thegrout compressive strength be not less than 2000 psi.This applies to both clay and concrete masonry.

For Strength Design procedures, MSJC CodeSection 3.1.8.1.2 limits the specified strength of groutto 5,000 psi for concrete masonry and 6,000 psi forclay masonry. Actual grout strength should alwaysequal or exceed the design strength, and may behigher than these prescribed design limits.

Normally, grout is specified at 2,000 psiminimum. When grout is delivered to the wall bymeans of a mechanical grout pump, there is sufficientcement content to achieve this minimum strength.The grout hose would plug if there was insufficientcement in the mix. For higher grout strengthrequirements, the designer may require testing toverify the grout strength.

If grout tests are required, the following scheduleis suggested.

1. At the start of grouting operations, take onetest per day for the first three days. The testsshould consist of three specimens which aremade in accordance with ASTM C1019, TestMethod for Sampling and Testing Grout.

2. After the initial three tests, specimens forcontinuing quality control should be taken atleast once each week. Additionally,specimens may be taken more frequently forevery 25 cubic yards of grout, or for every2500 square feet of wall, whichever comesfirst.

1.4.8 TESTING GROUT STRENGTH

In order to determine the compressive strength ofgrout, specimens, as defined in ASTM C1019, aremade that will represent the hardened grout in thewall. The specimen is made in a mold consisting ofmasonry units identical to those being used inconstruction and at the same moisture condition as

22 REINFORCED MASONRY ENGINEERING HANDBOOK

those units being laid. The units are arranged to forma space approximately 3 to 4 in. square and twice ashigh as it is wide (Figures 1.17 and 1.18).

FIGURE 1.17 Typical arrangement for making agrout specimen with block.

FIGURE 1.18 Typical arrangement for making agrout specimen with brick.

To prevent the grout from bonding to the masonryunits, the space is lined with a permeable paper orporous separator, which still allows any excess waterto be absorbed into the units. A paper towel does anexcellent job.

The representative samples of the grout areplaced in the molds, puddled and kept damp, andundisturbed for at least 24 hours. After the groutspecimens have cured between 24 and 48 hours, thespecimens are taken to a laboratory where they areplaced in a fog room until tested.

1.4.9 METHODS OF GROUTINGMASONRY WALLS

There are several methods of grouting masonrywalls that will result in strong, homogeneous andsatisfactory walls. The method selected is influencedby the type of masonry, the area and length of wall,the equipment available, and the experience of thecontractor.

1.4.9.1 GROUT POUR AND LIFT

The total height of masonry to be grouted prior tothe erection of additional masonry is called a groutpour. Grout is placed in increments called lifts. A groutlift is the height of grout placed in a single continuousoperation prior to consolidation.

Though lifts may not exceed 5 ft in height, a groutpour may consist of several lifts. For example, if thewall is built 15 ft high, the total grout pour would bethe entire 15 ft. For this situation, the contractorwould place the grout in 3 lifts of 5 ft each. Alternately,a grout demonstration panel may be constructed toshow grouting procedures, including higher lifts,which deviate from the code prescribedrequirements. This provision is contained in MSJCSpecification Articles 1.6 E and 3.5 F.

MSJC Specification Articles 1.6 E and 3.5 F1.6 E. Grout demonstration panel Prior to

masonry construction, construct a grout demonstrationpanel if proposed grouting procedures, constructiontechniques, and grout space geometry do not conform tothe requirements of Articles 3.5 C, 3.5 D, and 3.5 E.

3.5 F. Alternate grout placement Place masonryunits and grout using construction procedures employedin the accepted grout demonstration panel.

Currently MSJC Code limits a grout pour to amaximum height of 24 ft. For those cases wheregrout demonstration panels are constructed, thearchitect/engineer (A/E) should establish criteria forthe panel to assure that the important elements of themasonry construction are represented in thedemonstration panel. The A/E should also establishinspection procedures to verify grout placementprocedures throughout the construction of theproject. These procedures may include either non-destructive or destructive evaluation to confirm thatadequate consolidation has been achieved.

MATERIALS 23

Tape

Line units with anabsorbent material

Grout testspecimen

Wooden block

Grout testspecimen Wooden block

Line unitswith anabsorbentmaterial

1.4.9.2 LOW LIFT AND HIGH LIFT GROUTING

Although the terms low lift and high lift groutingwere deleted from the recent code editions, theseterms are still commonly used when referring togrouting methods.

In general, low lift grouting may be used whenthe height of the grout pour is 5 ft or less. High liftgrouting may be used only when cleanout holes areprovided, and the height of the masonry wall prior togrouting exceeds 5 ft.

1.4.9.2.1 LOW LIFT GROUTING PROCEDURE

When the low lift grouting procedure is used,masonry walls may be built to a height of 5 feet.Because of this limited pour height which also allowsfor easy inspection of the walls, cleanout openingsare not required.

For multi-wythe masonry walls, the wythes needto be tied together with wire ties or joint reinforcementwhenever the grout pour height is more than 12 in. toprevent the wythes from bulging or blowing out(Figure 1.19). These ties should be spaced no morethan 24 in. on center horizontally and 16 in. maximumvertically for running bond. For stacked bondconstruction ties must be spaced no more than 12 in.on center vertically.

FIGURE 1.19 Ties for two wythe walls.

A single wythe wall consisting of hollow unitmasonry does not require ties since cross-webs andend shells connect the face shells and resist bulgingand blowouts.

Grout may not be placed until all the masonryunits, ties, reinforcing steel and embedded anchorbolts are in place up to the top of the grout pour. Oncethese are in place the wall may be fully grouted. Forgrout pours 12 in. high or less, the grout may be

consolidated by puddling with a stick such as a 1 x 2in. piece of wood. However, grout pours in excess of12 inches in height must be consolidated by meansof a mechanical vibrator. The grout must also bereconsolidated after the excess water is absorbed bythe units (usually after 3 to 5 minutes) to close anyvoids due to the water lost.

Masonry units, ties, reinforcing steel, and anchorbolts for the next pour may be placed once the grouthas been thoroughly reconsolidated.

Horizontal construction joints should be formedbetween grout pours by stopping the grout pour 11/2in. below the top of the masonry. Where bond beamsoccur, these joints may be reduced to 1/2 in. deep toallow sufficient grout above the horizontal reinforcingsteel.

At the top of the wall, the grout should be placedflush with the masonry units.

FIGURE 1.20 Low lift grouting, cleanouts notrequired.

24 REINFORCED MASONRY ENGINEERING HANDBOOK

t

t - 2

11/2 minimum

Delay approximately 3 to 5minutes allowing the water to beabsorbed by the masonry units,then consolidate the grout bymechanically vibrating.

Afte

r low

er s

ectio

n is

gro

uted

,la

y an

d gr

out n

ext 5w

all

Max

imum

hei

ght

of g

rout

pou

r is

5

There is a provision in MSJC Specification Article3.5 D allowing a single grout lift of up to 12 ft 8 in.provided all of the following items are met:

Masonry wall has cured for at least 4 hours At all times during placement the grout slump is

maintained between 10 and 11 inches.

No intermediate bond beams (horizontalreinforcement) are obstructing vertical groutplacement

1.4.9.2.2 HIGH LIFT GROUTING PROCEDURE

Grouting after a wall is constructed to its fullheight is often quite economical. This method allowsthe mason to continually lay masonry units withoutwaiting for the walls to be grouted. High lift groutingprocedures must be used when grout pours exceed 5feet. Currently the maximum pour height the MSJCCode and Specification allows is 24 feet.

Cleanout openings must be provided in wallswhich have a grouted pour height exceeding 5 ft, inaccordance to MSJC Specification Article 3.2 F.Cleanouts are usually located in the bottom course atevery vertical bar. However, in solid grouted walls,cleanouts must be provided at no more than 32 in. oncenter, even if the reinforcing steel is spaced at agreater spacing (Figure 1.21).

FIGURE 1.21 Maximum spacing of cleanoutholes.

The purpose of the cleanouts is to allow the groutspace to be cleaned prior to grouting. Cleanouts canalso be used to verify reinforcement placement andtying. Cleanouts can be achieved by removing theexposed face shell for units in hollow unit groutedmasonry, or removing individual units when groutingbetween wythes. The MSJC Specification Article 3.2F requires that the cleanouts have an openingsufficient in size to permit removal of debris, and thatthe minimum opening dimension shall be 3 inches.After cleaning, the cleanouts are closed with closuresbraced sufficiently to resist grout pressure.

MSJC Specification Article 3.2 F is shown below:

MSJC Specification Article 3.2 F3.2 F. Cleanouts Provide cleanouts in the bottom

course of masonry for each grout pour when the groutpour height exceeds 5 ft (1.52 m).

1. Construct cleanouts so that the space to begrouted can be cleaned and inspected. Insolid grouted masonry, space cleanoutshorizontally a maximum of 32 in. (813 mm)on center.

2. Construct cleanouts with an opening ofsufficient size to permit removal of debris.The minimum opening dimension shall be 3in. (76.2 mm).

3. After cleaning, close cleanouts with closuresbraced to resist grout pressure.

FIGURE 1.22 High lift grouting block wall.

MATERIALS 25

Cleanout openingat all verticalreinforcing bars

32 maximum spacing of cleanoutopenings for solid grouted walls

Stop grout pour11/2 below top ofmasonry unit -suggested if pouris delayed 1 houror more.

Cleanout opening.Remove face shellfrom cells. Sealprior to groutingbut afterinspection.

5m

ax.

5m

ax.

5m

ax.

If grout pour is 0 or lessthen it can beplaced in onelift

Delayapproximately3 to 5 minutesallowing thewater to beabsorbed bythe masonryunits, thenconsolidate bymechanicallyvibrating

Two wythe masonry walls must be tied togetherwith wire ties or joint reinforcement, as outlined in thelow lift grouting section to prevent blowouts andbulging (Figure 1.23).

FIGURE 1.23 High lift method of grouting 2wythe walls, with cleanout openings.

Grout lifts may be up to 5 ft high and must bemechanically consolidated. After a delay of typically 3to 5 minutes, the grout should be reconsolidated toclose any voids due to water loss.

Because of the fluidity of grout and the tendencyof the aggregate to segregate, control barriers can beplaced in multi-wythe walls to confine the flow ofgrout. These barriers, which are constructed withmasonry units laid in the grout space, must extendthe full height of the grout pour. Traditional spacing ofthese barriers has been no more than 30 ft on center.The full height of the wall between control barriersshould be grouted in one day.

At the bottom of the wall the grout space may becovered with a layer of loose sand during constructionto prevent mortar droppings from sticking to thefoundations. The mortar droppings and sand are thenremoved from the grout space by blowing it out,washing it out, or cleaning it out by hand.

Once the foundation has been cleaned andinspected, cleanout holes may be sealed with amasonry unit, a face shell, or a form board which isthen braced to resist the pressure of the pouredgrout.

1.4.9.3 CONSOLIDATION OF GROUT

Grout must be consolidated just like concrete.Consolidation eliminates voids and causes grout toflow around the reinforcement and into smallopenings or voids.

Consolidation may be performed using a puddlestick if the lifts are not higher than 12 inches. Liftsheights greater than 12 in. however, must beconsolidated by mechanical vibrators. As there isgenerally only a small volume of grout to beconsolidated in a cell or grout space, the mechanicalvibrator need only be used for a few seconds in anylocation. Excessive vibration increases the possibilityof blowing out face shells or dislodging masonryunits. Additionally, the grout must be reconsolidatedbefore plasticity of grout is lost.

1.4.10 SELF-CONSOLIDATING GROUT

A new product currently under development andlimited use is SelfConsolidating Grout. Self-consolidating grout has properties that can eliminatethe need to mechanically vibrate the grout, creating asavings in time, labor, and equipment. Also self-consolidating grout may allow higher lifts during thegrout pour. The efficiency of not consolidating andreconsolidating grout without compromisingstructural integrity makes masonry more economical.The fluidity of self-consolidating grout relies onplasticizing admixtures, but must be stable. Thismaterial is not measured in slump, but in spread asdepicted in Figure 1.24.

FIGURE 1.24 Self-consolidating grout spread.

26 REINFORCED MASONRY ENGINEERING HANDBOOK

Section AA

Wall tie #9 wire spaced:

Horizontally24 o.c. max.

Vertical forrunning bond16 o.c.

Vertical forstack bond12 o.c.

Cleanout opening. Seal prior togrouting but after inspection.

A A

5m

ax.

5m

ax.

Gro

ut in

5l

ifts

to to

p of

pou

r

Reconsolidate the grout after theexcess water has been absorbed intothe masonry units

1.4.11 GROUT DEMONSTRATIONPANELS

MSJC Specification Article 1.6 E now provides fora "grout demonstration panel" which allows thecontractor to build a panel to show that a higher groutpour height can be obtained and still yet provide forproper consolidation of the grout. With approval,some alternate methods may be possible.

1.4.12 GROUT FOR AAC MASONRY

Grout used for AAC masonry construction isprovided in the MSJC Specification Article 3.5 G, asfollows:

MSJC Specification Article 3.5 G3.5 G. Grout for AAC masonry Use grout

conforming to ASTM C476. Wet AAC masonrythoroughly before grouting to ensure that the groutflows to completely fill the space to be grouted. Groutslump shall be between 8 in. and 11 in. (203 and 279mm) when determined in accordance with ASTM C143.

1.5 REINFORCING STEEL1.5.1 GENERAL

Reinforcing steel in masonry has been usedextensively in the West Coast since the 1930's,revitalizing the masonry industry in earthquake proneareas. Reinforcing steel extends the characteristicsof ductility, toughness and energy absorption that isnecessary in structures subjected to the dynamicforces of earthquakes.

Reinforced masonry performs well because thematerials; steel, masonry, grout, and mortar, worktogether as a single structural unit. The temperaturecoefficient for steel, mortar, grout, and the masonryunits are very similar. This similarity of thermalcoefficients allows the different component materialsto act together through normal temperature ranges.Disruptive stresses, which would destroy the bondbetween these materials and prevent force transfer,are not created at the interface between the steel andthe grout.

Structures subjected to severe lateral dynamicloads such as earthquakes must be capable ofproviding the necessary strength or energy absorbingcapacity and ductility to withstand these forces.Reinforcing steel serves to resist shear and tensile

forces generated by the dynamic loads. It can alsoprovide sufficient ductility to the masonry structure sothat the structure can sustain load reversals beyondthe capability of plain, unreinforced masonry.

In order for the reinforcing steel to provideadequate ductility and strength, placement of thereinforcing steel is of prime importance in providing acontinuous load path throughout the structure. Theengineer must pay special attention to reinforcingsteel details to ensure continuity. The following itemsmust be provided:

1. The proper size and amount of reinforcementwhich complies with the limited minimum andmaximum percentages of reinforcement andother code requirements.

2. The minimum required reinforcementprotection (cover).

3. The proper spacing of longitudinal andtransversal reinforcement.

4. Sufficient anchorage of flexural and shearreinforcing bars.

5. Adequate lapping of the reinforcing bars.

6. Sufficient stirrups, ties, metal plates, spirals,etc., in order to provide confinement.

1.5.2 TYPES OF REINFORCEMENT

1.5.2.1 GENERAL REINFORCEMENT

MSJC Code Section 1.13.2 provides reinforcementthat is used in design of masonry structural systems.

MSJC Code Section 1.13.21.13.2 Size of reinforcement

1.13.2.1 The maximum size of reinforcementused in masonry shall be No. 11 (M #36).

1.13.2.2 The diameter of reinforcement shall notexceed one-half the least clear dimension of the cell, bondbeam, or collar joint in which it is placed. (See Section1.16.1).

1.13.2.3 Longitudinal and cross wires of jointreinforcement shall have a minimum wire size of W1.1(MW7) and a maximum wire size of one-half the jointthickness.

The Strength Design provisions of MSJC Codecontain further limitations on reinforcing steel.

MATERIALS 27

MSJC Code Section 3.3.3.13.3.3.1 Reinforcing bar size limitations

Reinforcing bars used in masonry shall not be larger thanNo. 9 (M#29). The nominal bar diameter shall not exceedone-eighth of the nominal member thickness and shall notexceed one-quarter of the least clear dimension of thecell, course, or collar joint in which the bar is placed. Thearea of reinforcing bars placed in a cell or in a course ofhollow unit construction shall not exceed 4 percent of thecell area.

1.5.2.2 REINFORCING BARS

For reinforced masonry construction, deformedbars range in size from a minimum #3 (3/8 in.diameter) to a maximum #11 (13/8 in. diameter),however, the upper limit for masonry designed byStrength Design is #9 (11/8 in. diameter). Also, thereinforcing steel or reinforcing wire used in masonrymust conform to ASTM A82, A185, A496, A497,A580, A615, A706, A767, A775, A951 or A996 whichspecify applicable physical characteristics.

ASTM A615 and A996 cover reinforcing steelmanufactured from billet, rail and axle steelrespectively. ASTM A706, A767 and A775 aregenerally not applicable since they cover low alloy,zinc-coated and epoxy-coated reinforcing steel whichare currently seldom used in masonry construction.

Reinforcing steel may be either Grade 40 (MetricGrade 300), with a minimum yield strength of 40,000psi or Grade 60 (Metric Grade 420) minimum yieldstrength of 60,000 psi. Grade 60 steel is furnished inall sizes, while Grade 40 steel bars are normally onlyavailable in #3, #4, #5 and #6 sizes. If Grade 40 steelis required, special provisions may be required toassure delivery. Good practice consists ofdetermining the grade of steel and sizes available inthe area where the project is to be built.

The identification marks are shown (Figure 1.25)in the following order:

1st Producing Mill (usually an initial). 2nd Bar Size Number. 3rd Type of reinforcement (Type S for New

Billet, A for Axle, I for Rail, W for LowAlloy).

4th Grade of reinforcement for Grade 60 steel(grade is shown as a marked 4 (MetricDesignation for Grade 420) or one (1)grade mark line. The grade mark line issmaller and between the two mainlongitudinal ribs which are on oppositesides of all U.S. made bars).

1. Bar identification marks may also be oriented to readhorizontally (at 90 to those illustrated above).

2. Grade mark lines must be continued at least five deformationspaces.

3. Grade mark numbers may be placed within separateconsecutive deformation spaces to read vertically orhorizontally.

4. #13 = 1/2 bar and #19 = 3/4 bar.

Note:Grade 520 (75) steel also available for masonry.Bar size markings are given in metric which is indicated onreinforcement supplied for masonry use.

FIGURE 1.25 Identification marks, line systemof grade marks.

28 REINFORCED MASONRY ENGINEERING HANDBOOK

Mainribs

Letter forproducingmill1

Bar size#134

Type steel(new billet)

Grademarkline2

H

13

S

H

13

S

Grade 300(Grade 40)

Grade 420(Grade 60)

Mainribs

Letter forproducingmill1

Bar size#194

Type steel(new billet)

Grademark3

H

19

S

H

19

S

4

Grade 300(Grade 40)

Grade 420(Grade 60)

Bar Size # (mm)3

(10)4

(13)5

(16)6

(19)7

(22)8

(25)9

(29)10

(32)11

(36)

1.5.2.3 JOINT REINFORCEMENT

When high strength steel wire fabricated inladder or truss type configurations is placed in thebed joints to reinforce the wall in the horizontaldirections, it is called joint reinforcement.

The most common uses of joint reinforcementare:

1. to control shrinkage cracking in concretemasonry walls.

2. to provide part or all of the minimum steelrequired.

3. to function as designed reinforcement thatresists forces in the masonry, such astension and shear.

4. to act as a continuous tie system for veneerand cavity walls.

Joint reinforcement must meet the requirementsof ASTM A951, Specification for Masonry JointReinforcements. Examples of joint reinforcement areshown in Figures 1.26 and 1.27. See Chapter 7 ofthis book for additional information on jointreinforcement.

FIGURE 1.26 Ladder type joint reinforcement.

FIGURE 1.27 Truss type joint reinforcement.

MATERIALS 29

1.6 QUESTIONS AND PROBLEMS1-1 What three ASTM specifications give the

requirements for unit clay masonry?

1-2 What is the range of firing temperatures for buildingbrick and for face brick?

1-3 State the three stages of fusing clay and describeeach stage.

1-4 What is the approximate time required for the firingof brick in a kiln?

1-5 What is the difference between a solid clay unit anda hollow clay unit? Can solid units have voids? If so,what is the maximum percentage