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Aesthetic Design With Concrete Masonry

August 2018

INTRODUCTION

One aspect of concrete masonry that has kept it at the forefront of building materials is its ability to incorporate and reflect a broad spectrum of existing architectural styles, as well as providing the designer with the ability to develop and present unique aesthetic affects and techniques. When skillfully designed, simple materials can provide unparalleled aesthetic enhancement. Inventive patterns, color choices (unit and mortar), unit sizes, and surface finishes (split face and standard) can be used in various concrete masonry bond patterns to evoke a sense of strength, modernity, tradition, or even whimsy.

Within the confines of meeting applicable building codes and specifications, concrete masonry’s modular sizes and range of colors, textures and patterns provide ample opportunity to demonstrate a design technique or overcome design challenges. In addition to the architectural finish, concrete masonry can provide the wall’s structure, fire resistance, acoustic insulation, and energy envelope.

This TEK addresses the proper application of architectural enhancements in concrete masonry wall systems. Where appropriate, related TEK and other documents are referenced to provide further information and detail.

Communication With Clients

Common dilemmas faced by designers are a client’s changing expectations and responses to the project’s changing appearance over time and under varying conditions. As discussed below, there are some basic requirements relative to aesthetics, but these are far from comprehensive. It is important to realize that code requirements primarily govern structural performance, not aesthetics. For example, code required construction tolerances are designed to ensure that masonry units are placed such that the completed wall can act structurally as an integrated unit.

These requirements assume an understanding of the techniques unique to the nature of masonry. The design and construction team should establish and consistently support ground rules affecting aesthetic interpretations of a project. It is also important for the client to realize the aesthetic standard that the project is based on, and that unusually high aesthetic standards can be more costly. In addition, certain high-profile areas, such as a building entrance, may require a custom level of quality, commensurate with an additional cost for the defined area. Several state and local masonry associations have developed guidelines for defining aesthetic requirements, and these can be a good resource for clarifying a project’s aesthetic standards.

Sample panels are a good means to communicate the minimum contract-based aesthetic standard to all parties. The sample panel is typically constructed prior to the project, and in some cases a portion of the work can serve as the sample panel. The sample panel remains in place or at least available until the finished work has been accepted, since it serves as a comparison for the finished work. The sample panel should contain the full acceptable range of unit and mortar color, as well as the minimum expected level of workmanship. Cleaning procedures, as well as application of any coatings or sealants, should also be demonstrated on the sample panel. See TEK 08-04A, Cleaning Concrete Masonry, (ref. 1) for more information on cleaning.

CONSIDERATIONS FOR CHOOSING CONCRETE MASONRY UNITS

Architectural Concrete Masonry Units

One of the most significant architectural benefits of designing with concrete masonry is its versatility—the finished appearance of a concrete masonry wall can be varied with the unit size and shape, color of units and mortar, bond pattern, and surface finish of the units. The term “architectural concrete masonry units” typically is used to describe units displaying any one of several surface finishes that affect the color or texture of the unit, allowing the structural wall and finished surface to be installed in a single step. CMU-TEC-001-23, Concrete Masonry Unit Shapes, Sizes, Properties, and Specifications, (ref. 2) provides an overview of some of the more common architectural units, although local manufacturers should be consulted for final unit selection.

Architectural concrete masonry units are used for interior and exterior walls, partitions, terrace walls and other enclosures. Some units are available with the same treatment or pattern on both faces, to serve as both exterior and interior wall finish material, increasing both the economic and aesthetic advantages. Architectural units comply with the same performance-based quality standards as conventional concrete masonry, such as Standard Specification for Loadbearing Concrete Masonry Units, ASTM C90 (ref. 3). See Aesthetics in ASTM C90 (page 4) for more information.

Concrete Masonry Unit Color

Being produced from natural aggregates, concrete masonry has natural color variations from unit to unit. When a more monotone appearance is desired, there are various techniques that may be specified to increase the color uniformity in concrete masonry. Perhaps the best method is to specify the use of mineral pigments in the concrete mix, which are available in a wide range of colors. Pigments provide an integral color throughout the unit and minimize variations in color and texture found naturally in aggregate and sand deposits. Using several colors of integrally-colored concrete masonry units in the same wall is an effective technique for producing other visual impacts, such as two-tone banding or complementary color palates (see Figure 1).

Other methods are also used to improve color uniformity. One method is to specify the use of a post-applied stain, paint or coating on the units. With a paint or coating, the resulting film minimizes the texture of the masonry surface as well as the visual impact of the mortar joints. Paints and coatings for concrete masonry should be compatible with the masonry, and should in general allow for water vapor transmission. TEK 19-01, Water Repellents for Concrete Masonry Walls, (ref. 4) contains information on the applicability of different types of paints and coatings for concrete masonry walls.

A more laborious method to improve color uniformity is to arrange with the masonry contractor for a pre-sorting of on-site supplied block during certain stages of construction.

Interaction With Sunlight

Because it is produced from natural materials, concrete masonry walls often interact with changing sunlight in much the same way that natural stone does, appearing to change color as the light hits the wall at different angles. Figure 2 shows how even a conventional gray concrete masonry wall can interact with sunlight to present a range of color. This same attribute can be used to advantage with electric lighting, as well as on interior walls.

Fluted concrete masonry units provide a rich texture and tend to enhance the sound attenuating properties of concrete masonry.

The vertical flutes also provide an interesting interplay of light and shadow, which can be much more dramatic than smoothfaced units.

MORTAR JOINTS

While mortar generally comprises less than ten percent of a typical concrete masonry wall surface area, it can have a significant impact on the overall aesthetics of the completed structure. Mortar joint finishing, profiles and color can all impact the overall wall aesthetics. See also Concrete Masonry Handbook for Architects, Engineers, Builders (ref. 5) for information on mortar joints.

Mortar Joint Tooling

Tooling refers to finishing the mortar joints with a profiled tool that shapes and compacts the surface of the joint and provides a sharper, cleaner appearance for the wall. The surface shape of the tool determines the joint’s profile (discussed in more detail in the following section). Tooling mortar joints also helps seal the outer surface of the joint to the adjacent masonry unit, improving the joint’s weather resistance. For this reason, tooled joints that compact the mortar and do not create ledges to hold water are recommended for construction that will be exposed to weather.

Mortar joints should be tooled when the mortar is thumbprint hard (a clear thumbprint can be pressed into the mortar without leaving cement paste on the thumb). Tooling the joints before they reach this stage results in lighter colored joints, because more cement paste is brought to the surface of the joints. Joints tooled too early can also subsequently shrink away slightly from the adjacent concrete masonry unit. Tooling at the proper time allows this initial shrinkage to occur, then restores contact between the mortar and the unit producing a more weatherresistant joint. Conversely, later tooling can produce a darker joint. A consistent time of tooling will minimize variations in the final mortar color.

For the cleanest result, horizontal mortar joints should be tooled before vertical joints. For white and light-colored mortar, Plexiglas jointers can be used to avoid staining the joints during tooling. After all joints are tooled, any mortar burrs on the wall should be trimmed off with a trowel or other tool (a tool such as a plastic loop is easier to use on a split face wall than a trowel, for example). As a final step the joints are dressed using a brush, a piece of burlap, or similar material.

Mortar Joint Profiles

Traditional mortar joint profiles are illustrated in Figure 3. For walls not exposed to weather, the joint profile selection can be based on aesthetics and economics (as some joint profiles are more labor intensive to produce). For exterior exposures, however, the mortar joint profile can impact the wall’s weather resistance, as discussed above.

Unless otherwise specified, mortar joints should be tooled to a concave profile when the mortar is thumbprint hard (refs. 6, 7). For walls exposed to weather, concave joints (Figure 3a) improve water penetration resistance by directing water away from the wall surface. In addition, because of the shape of the tool, the mortar is compacted against the concrete masonry unit to seal the joint. V-shaped joints (Figure 3b) result in sharper shadow lines than concave joints.

Grapevine and weather joints (Figures 3c, 3d) provide a water shedding profile, but do not result in the same surface compaction as concave or V-shaped joints. Both are used in interior walls to provide strong horizontal lines.

Beaded joints (Figure 3e) are formed by tooling the extruded mortar into a protruding bead shape. Care must be taken to obtain a straight line with the bead. Although technically a tooled joint, the beaded tooler does not produce the same mortar surface compaction as a concave or V-shaped tool. In addition, the protruding bead can allow water, ice or snow to collect. Therefore, beaded joints are not recommended for weather-exposed construction.

Flush joints (Figure 3f) are typically specified when a wall will be plastered. Excess mortar is simply struck off the face of the wall with the trowel, then dressed with a brush or other tool.

Squeezed or extruded joints (Figure 3g) are made using excess mortar that is squeezed out as units are laid. They may be specified for interior walls.

Struck joints (Figure 3h) provide a strong horizontal line, similar to weather joints, however because the shape provides a ledge for rain, ice or snow, they are not recommended for walls that will be exposed to weather. Raked joints (Figure 3i) provide a dramatic contrast between the units and mortar joints. They are formed using a joint raker, which removes the mortar to a maximum depth of 1/2 in. (13 mm). With raked joints, small imperfections on unit edges can be more noticeable, because the mortar is not compacted against the unit (the compaction tends to fill in small surface irregularities along the unit edge). The resulting joint is not weather-resistant, and may not leave enough mortar cover over horizontal joint reinforcement (joint reinforcement is required to have 5/8 in. (16 mm) mortar cover in walls exposed to weather or earth (refs. 6, 7)). A better option for exterior surfaces is to specify an integrally colored mortar to provide the visual contrast.

Mortar Joint Color

Choosing a specific mortar color allows additional creativity by specifying integral color to either provide a visual contrast or to match the unit color, as shown in Figure 4. Note that using a mortar color that matches the surrounding units minimizes the effects of minor mortar staining; i.e., with a contrasting mortar color, greater care should be used to remove mortar droppings and splatters from the masonry units.

Because foreign material in mortar sand can affect the mortar quality, as well as appearance, ASTM C144, Standard Specification for Aggregate for Masonry Mortar (ref. 8), limits deleterious substances in aggregates for masonry mortars. Sand can also affect mortar color: sands from different natural sources may have different hues. Therefore, all of the sand for a particular project should come from the same source. Silica sand, which is more expensive than typical masonry sand, is often specified for white mortar. Consistent batching and mixing procedures also help produce uniform mortar color from batch to batch. See TEK 03-08A, Concrete Masonry Construction (ref. 9), for further information.

Using a consistent amount of mix water is important to maintain color uniformity for all mortars and especially when using integrally colored mortar. Changing the amount of water can significantly change the resulting mortar color intensity. For this reason there are special methods and equipment, such as shading materials and equipment from direct sunlight, the use of cooled water, and the use of damp, loose sand piles to reduce excessive retempering. Mortar that is too stiff or older than 2 1/2 hours after initial mixing is to be discarded.

EXPECTATIONS FOR UNITS AND CONSTRUCTION

Aesthetics in ASTM C90

ASTM C90 provides minimum requirements for concrete masonry units that assure properties necessary for quality performance. The specification includes requirements for materials, as well as dimensional and physical requirements such as minimum compressive strength, maximum water absorption, maximum dimensional tolerances, and maximum linear drying shrinkage. It also includes finish and appearance criteria for concrete masonry units.

It should be noted that the requirements in ASTM C90 are intended to address the performance of the masonry units when installed, not the aesthetics of the units nor of the constructed masonry. The time for product inspection is before placement. As such, the finish and appearance criteria, for example, prohibits defects that would impair the strength or permanence of the construction, but permit minor cracks or chips incidental to usual manufacturing, shipping and handling methods.

Qualities that are not included in C90 include color, surface texture, surface features such as scores or flutes, density choice, water repellency, fire resistance rating, thermal properties and acoustic properties. If required, these properties must be addressed in project contract documents. ASTM C90 does, however, include acceptance criteria for unit color and surface texture: namely, that the finished unit surfaces that will be exposed in the final structure conform to an approved sample of at least four units. The sample should represent the range of color and texture permitted on the job. As a practical matter, color and texture should be expected to vary somewhat due to the nature of the material.

The ASTM C90 specification is described in more detail in CMU-TEC 001-23, (ref. 2).

Considerations for Integrally Colored Smooth-Faced Units

Integrally-colored concrete masonry units are available in a wide variety of colors and shades. The mineral oxide pigments are evenly dispersed throughout the concrete mix, producing a low-maintenance enhancement that lasts the life of the structure.

During unit manufacture, the integrally-colored concrete mix is placed into a steel mold, which is stripped off while the concrete is still plastic. This stripping of the mold draws moisture and coloring pigment to the unit surface, which impacts the surface appearance. On split-faced or ground-faced units, this surface is either ground away or not exposed (in the case of split-faced units). Because the formed surface is the final exposed surface on smooth-faced units, however, these units will have a wider color variation than is seen with split-faced or ground-faced units. Understanding this color variation will help avoid possible disappointment that the finished wall does not have the color uniformity of a painted or stained wall.

Construction Tolerances

The International Building Code and Specification for Masonry Structures (refs. 6, 7) contain site tolerances for masonry construction which allow for deviations in the construction. The permissible tolerances are intended to ensure that misalignment of units or structural elements does not impede the structural performance of the wall. Although the tolerances are not intended for the purpose of producing an aesthetically pleasing wall, these tolerances are generally adequate for most aesthetic applications as well. If tighter tolerances are desired, they must be specified in the project documents.

As an example, unless otherwise specified, the actual location of a masonry element is required to be within a certain tolerance of where the element is shown on the construction drawings: + 1/2 in. in 20 ft, + 3/4 in. max (+ 13 mm in 6.2 m, + 19 mm max). More precise placement dimensions can be specified, typically at a higher cost.

Tolerances apply to: plumb, alignment, levelness and dimensions of constructed masonry elements, location of elements, levelness of bed joints, mortar joint thickness, and width of collar joints, grout spaces and cavities. A full discussion of code-required masonry construction tolerances is presented in TEK 03-08A, Concrete Masonry Construction (ref 9).

MODULAR COORDINATION

Concrete masonry structures can be constructed using virtually any layout dimension. However, for maximum construction efficiency, economy, and aesthetic benefit, concrete masonry elements should be designed and constructed with modular coordination in mind. Modular coordination is the practice of laying out and dimensioning structures to standard lengths and heights to accommodate modularly-sized building materials.

Standard concrete masonry modules are typically 8 in. (203 mm) vertically and horizontally, but may also include 4-in. (102 mm) modules for some applications. These modules provide the best overall design flexibility and coordination with other building products such as windows and doors. Designing a concrete masonry building to a 4- or 8-in. (102- or 203-mm) module will minimize the number of units that need to be cut, providing a more harmonious looking masonry structure. TEK 05-12, Modular Layout of Concrete Masonry (ref. 10) provides details of modular wall layouts and openings.

CONTROL JOINTS

Control joints, a type of movement joint, are one method used to relieve horizontal tensile stresses due to shrinkage of concrete products and materials. They are essentially vertical planes of weakness built into the wall to reduce restraint and permit longitudinal movement due to anticipated shrinkage. When control joints are required, concrete masonry requires only vertical control joints. When materials with different movement properties are used in the same wythe (such as clay masonry and concrete masonry), this movement difference needs to be accommodated, and may require horizontal movement joints as well (see the Banding section, below). Recommendations for band in a split-faced wall (see Figure 5); with different unit sizes, such as the use of a 4-in. (102-mm) high band in a wall of 8-in. (203-mm) units; or with a combination of these techniques. Combining masonry units of different size, color and finish provides a virtually limitless palette.

The use of concrete masonry bands in clay brick veneer has also become very popular. The architectural effect is very pleasing; however, proper detailing must be provided to accommodate the different movement properties of the two materials to prevent racking. The detail shown in Figure 6 has demonstrated good performance in many areas of the United States and is the preferred detail, as it is economical and maintenance free. Horizontal joint reinforcement is placed in the mortar joints above and below the band, as well as in the band itself if it is more than two courses high. In addition, lateral support (wall ties) are provided within 12 in. (305 mm) of the top and bottom of the band and the band itself must contain at least one row of ties. Some designers prefer placing joint reinforcement in every bed joint of the concrete masonry band. In this case, a tie which accommodates both the tie and reinforcement in the same joint (such as seismic clips) should be used. Another, but less recommended, option is to use horizontal slip planes between clay masonry and the concrete masonry band (see TEK 05-02A, Clay and Concrete Masonry Banding Details, Reference 12).

The maximum spacing of expansion joints in the clay masonry wall should be reduced to no more than 20 ft (6.1 m) when concrete masonry banding is used. When the clay masonry expansion joint spacing exceeds 20 ft (6.1 m), an additional control joint should be placed near mid-panel in the concrete masonry band, although the joint reinforcement should not be cut in this location. At locations control joint spacing, locations and construction details can be found in CMU-TEC-009-23, Crack Control Strategies for Concrete Masonry Construction (ref. 11).

Aesthetically, control joints typically appear as continuous vertical lines in the field of the masonry walls, and perhaps at other areas of stress concentration, such as adjacent to openings, at changes in wall height, etc. Several strategies can be used to make control joints less noticeable. Perhaps the simplest approach is to align the control joint with another architectural feature, such as a pilaster or recess in the wall. In this case, the vertical shadow line provided by the architectural feature provides an inconspicuous control joint location.

BANDING

Concrete masonry banding is successfully used in many architectural applications. Banding can be accomplished with different colors of block; with different textures, for example a smooth-faced of expansion joints in the clay masonry, joints should be continued through the concrete masonry band and the joint reinforcement cut at these locations. TEK 05-02A provides a fuller discussion and additional details for combining these two materials, including details for incorporating clay masonry bands into concrete masonry walls.

LIGHTING DESIGN CONSIDERATIONS FOR CONCRETE MASONRY WALLS

Masonry has historically been associated with diffuse illumination located on or recessed into ceilings, as step (walkway) fixtures located below the waist, or generally placed at a distance from the masonry wall assembly. Diffuse lighting does not concentrate a focused beam but rather spreads the light to provide soft illumination. Although this is sometimes accomplished using an array of many individual light sources at a distance, it is more typically accomplished with fixtures and devices made for this purpose. When wall-mounted light sources are necessary, there are specialized fixtures adapted for masonry that internally refract, reflect, deflect, partially block, diffuse, and/or shade light from directly impinging on the wall surface. Often, the fixture includes additional light diffusers facing away from the wall surface to assist in softly lighting the adjacent area. No noticeable shadows are cast onto the wall, because the shadow is intentionally located away from the wall surface, thus masonry aesthetics are enhanced with a lower lighting intensity and more graceful illumination. These concepts are illustrated in Figure 7.

Non-diffuse light shining onto a concrete masonry wall from a surface mounted light fixture or sconce can sometimes cast unwanted long shadows, giving the erroneous visual appearance of unacceptably poor materials or workmanship (see Figure 7). With non-diffuse light, glossy surface treatments and coatings could also inadvertently magnify this problem. Well-designed diffuse light can eliminate such concerns.

Certain concrete masonry units, such as ground face (also called honed or burnished), can be highly reflective. Figure 8 shows a residential project using a custom-fabricated white ground face block. The designer used a complementary balance of several lighting fixtures with what might have otherwise been a challenging masonry reflective finish. The harmonious use of interior lighting combined with exterior overhead (recessed trim) and step lighting is an effective way of solving this challenge.

REFERENCES

Cleaning Concrete Masonry, TEK 08-04A. Concrete Masonry & Hardscapes Association, 2005.
Concrete Masonry Unit Shapes, Sizes, Properties, and Specifications, CMU-TEC-001-23, Concrete Masonry &
Hardscapes Association, 2023.
Standard Specification for Loadbearing Concrete Masonry Units, ASTM C90-09. ASTM International, 2009.
Water Repellents for Concrete Masonry Walls, TEK 19-01.
Concrete Masonry & Hardscapes Association, 2006.
J. A. Farney, Melander, J. M., and Panarese, W. C., Concrete Masonry Handbook for Architects, Engineers, Builders, Sixth Edition, Engineering Bulletin 008. Portland Cement Association, 2008.
International Building Code, International Code Council, 2009.
Specification for Masonry Structures, TMS 602/ACI 530.1/ASCE 6. Reported by the Masonry Standards Joint Committee, 2008.
Standard Specification for Aggregate for Masonry Mortar, ASTM C144-04. ASTM International, 2004.
Concrete Masonry Construction, TEK 03-08A. Concrete Masonry & Hardscapes Association, 2001.
Modular Layout of Concrete Masonry, TEK 05-12. Concrete Masonry & Hardscapes Association, 2008.
Crack Control Strategies for Concrete Masonry Construction, CMU-TEC-009-23, Concrete Masonry & Hardscapes Association, 2023.
Clay and Concrete Masonry Banding Details, TEK 05-02A.
Concrete Masonry & Hardscapes Association, 2002.

Modular Layout of Concrete Masonry

August 2018

INTRODUCTION

Although concrete masonry structures can be constructed using virtually any layout dimension, for maximum construction efficiency and economy, concrete masonry elements should be designed and constructed with modular coordination in mind. Modular coordination is the practice of laying out and dimensioning structures and elements to standard lengths and heights to accommodate modular-sized building materials. When modular coordination is not considered during the design phase, jobsite decisions must be made—often in haste and at a cost. This TEK provides recommendations for planning masonry construction to minimize cutting of masonry units or using nonstandard unit sizes.

When a project does require non-modular layout, further design and construction issues need to be addressed, including:

Placement of vertical reinforcement—In construction containing vertical reinforcing steel, the laying of units in other than running (half) bond or stack bond interrupts the vertical alignment of unit cells. As a result, reinforcement placement and adequate consolidation of grout becomes difficult, and partial grouting of walls is virtually impossible.

Interruption of bond pattern—In addition to the aesthetic impact a change in bond pattern can create, building codes often contain different design assumptions for masonry constructed in running bond versus other bond patterns. Walls incorporating more than a single bond pattern may present a unique design situation.

Locating control joints—In running bond, control joint construction can be accomplished using only full and half-size units. Similarly, stack bond construction only requires full-size units when control joints are properly spaced and detailed. However, with other bond patterns units may need to be cut if specially dimensioned units are not used or are not available.

MODULAR WALL ELEVATIONS

MODULAR WALL OPENINGS

The rough opening dimensions illustrated in Figure 1 apply to the layout and construction of the masonry. To allow for fastening windows and doors to the masonry, however, the nominal heights and widths of these elements are slightly less.

For conventional construction methods, the widths of masonry openings for doors and windows should generally be 4 in. (102 mm) larger than the door or window width. This allows for 2 in. (51 mm) on each side of the opening for framing. The heights of masonry openings to accommodate windows are typically 8 in. (203 mm) greater than the window height. This opening size allows for 2 in. (51 mm) above and below for framing and 4 in. (102 mm) for installation of a sill at the bottom of the window. Masonry openings for doors are commonly either 2 or 4 in. (51 or 102 mm) greater than the door height, allowing for the door framing as well as the use of a standard sized door.

Thus, door and window widths of 28, 36, 44, and 52 in. (711, 914, 1,118 and 1,321 mm) (and so on in 8 in. (203 mm) increments) do not require the masonry to be cut. Modular window heights are any multiple of 8 in. (203 mm), with a masonry window opening 8 in. (203 mm) greater than the height of the window if a 4-in. (102 mm) sill will be used. Similarly, door heights 2 in. (51 mm) less than any even multiple of eight can be installed without the need for cutting the masonry. For the commonly available 84-in. (2,134 mm) high door, a 4-in. (102 mm) door buck can be placed at the top of the opening. In addition, precast lintels are available in some areas containing a 2 in. (51 mm) notch to accommodate 80-in. (2,032 mm) doors.

Hollow metal frames for doors should be ordered and delivered
for the masonry before the other door frames in the project are scheduled for delivery. For economy, the frames should be set before the walls are built. If the walls are built before the frame are set, additional costs are incurred to set special knock down door frames and attachments.

MODULAR WALL SECTIONS

For door and window openings, the module size for bond patterns and layout are nominal dimensions. Actual dimensions of concrete masonry units are typically 3/8 in. (9.5 mm) less than nominal dimensions, so that the 4 or 8-in. (102 or 203 mm) module is maintained with 3/8 in. (9.5 mm) mortar joints. Where mortar joint thicknesses differ from 3/8 in. (9.5 mm) (as may be specified for aesthetic purposes or with brick construction), special consideration is required to maintain modular design. Figure 3 illustrates this concept.

Typically, concrete masonry units have nominal face dimensions of (height by length) 8 by 16 in. (203 by 406 mm), and are available in nominal widths ranging from 4 in. to 16 in. (102 to 406 mm) in 2-in. (51 mm) increments. In addition to these standard sizes, other unit widths, heights and lengths may be available from concrete masonry producers. The designer should always check local availability of specialty units prior to design.

Incorporating brick into a project, either as a structural component or as a veneer, can present unique modular coordination considerations in addition to those present with single wythe construction. Brick most commonly have a nominal width of 4 in. (102 mm), length varying from 8 to 16 in. (203 to 406 mm) and height from 2 1/2 to 6 in. (64 to 152 mm). The specified dimensions of modular concrete and clay brick are typically 3 5/8 by 2 1/4 by 7 5/8 in. (92 by 57 by 194 mm), but may be available in a wide range of dimensions.

Because of their unique dimensions, concrete and clay brick are usually laid with bed joints that are slightly larger (or sometimes smaller depending upon the actual size of the brick) than the standard 3/8 in. (9.5 mm) mortar joint thickness. For example, common modular brick are laid with a 5/12 in. (11 mm) thick bed joint, thereby providing a constructed height of 2 2/3 in. (68 mm) for one brick and one mortar joint. (Note that a 5/12 in. (11 mm) thick bed joint is within allowable mortar joint tolerances (refs. 1, 2).) The result is that three courses of brick (including the mortar joints) equals one 8-in. (203 mm) high module, thereby maintaining modular coordination (see Figure 3).

MODULAR BUILDING LAYOUTS AND HORIZONTAL COURSING

In addition to wall elevations, sections and openings, the overall plan dimensions of a structure also need to be considered, especially when using units having nominal widths other than 8 in. (203 mm).

Ideally, the nominal plan dimensions of masonry structures should be evenly divisible by 8 in. (203 mm). This allows constructing each course of a wall using only full-length or half length units, which in turn reduces labor and material costs. In addition, maintaining an 8-in. (203 mm) module over the length of a wall facilitates the turning of corners, whereby half of the units from one wall interlock with half of the units from the intersecting wall. As an alternative to cutting units or changing building dimensions, corner block can be used if available. These units are specifically manufactured to turn corners without interrupting bond patterns. Concrete Masonry Corner Details,TEK 05-09A (ref. 4) contains a variety of alternatives for efficiently constructing corners.

METRIC COORDINATION

One additional consideration for some projects is the use of standard sized (inch-pound) masonry units in a metric project. Similar to inch pound units, masonry units produced to metric dimensions are 10 mm (13/32 in.) less than the nominal dimensions to provide for the mortar joints. Thus, the nominal metric equivalent of an 8 by 8 by 16 in. unit is 200 by 200 by 400 mm (190 by 190 by 390 mm net unit dimensions). Since inch-pound dimensioned concrete masonry units are approximately 2% larger than hard metric units, complications can arise if they are incorporated into a structure designed on a 100 mm (3.9 in.) metric module, or vice versa.

REFERENCES

International Building Code. International Code Council,
2003 and 2006.
Specification for Masonry Structures, ACI 530.1-05/ASCE
6-05/TMS 602-05. Reported by the Masonry Standards
Joint Committee, 2005.
Building Code Requirements for Masonry Structures, ACI
530-05/ASCE 5-05/TMS 402-05. Reported by the Masonry
Standards Joint Committee, 2005.
Concrete Masonry Corner Details, TEK 05-09A, Concrete
Masonry & Hardscapes Association, 2004.

Concrete Masonry Corner Details

August 2018

INTRODUCTION

A building’s corners are typically constructed first, then the remaining wall section is filled in. Because they guide the construction of the rest of the wall, building the corners requires special care. It is essential that the corner be built as shown on the foundation or floor plan to maintain modular dimensions.

For maximum construction efficiency and economy, concrete masonry elements should be designed and constructed with modular coordination in mind. Corners, however, present unique situations, because the actual widths of standard units are 3 5/8, 5 5/8, 7 5/8, 9 5/8 and 11 5/8 in. (92, 143, 194, 244 and 295 mm). In order to maintain an 8-in. (203-mm) module, special corner details have been developed to accommodate most typical situations.

Figures 2 through 6 show how corners can be constructed to minimize cutting of units while maintaining modularity of the construction. Vertical steel, while not always required, is often used at corner intersections.

UNITS

Unlike stretcher units, units used in corner construction have square ends (see Figure 1). In addition, all-purpose or kerf units are available, with two closely spaced webs in the center that allow the unit to be easily split on the jobsite, facilitating corner construction. Other special units may also be available, such as bevelled-end units, forming a 45° angle with the face of the unit, which are used to form walls intersecting at 135° angles. Units in adjacent courses overlap to form a running bond pattern at the corner. Architectural units, such as those with split or scored faces, are often available with the architectural finish on two sides to accommodate corner construction.

Local manufacturers should be contacted for information on unit availability.

CODE PROVISIONS FOR INTERSECTING WALLS

Building Code Requirements for Masonry Structures (ref. 3) stipulates three options to transfer stresses from one wall to another at wall intersections, each requiring the masonry to be laid in running bond. These three options are via: running bond; steel connectors; and bond beams. Corner construction lends itself to providing shear transfer by relying on running bond.

Running bond (defined as the placement of masonry units such that head joints in successive courses are horizontally offset at least one quarter the unit length) ensures there is sufficient unit interlock at the corner to transfer shear. When any of these conditions are not met, the transfer of shear forces between walls is required to be prevented.

REFERENCES

Annotated Design and Construction Details for Concrete Masonry, CMU-MAN-001-03, Concrete Masonry & Hardscapes Association, 2003.
Reinforced Concrete Masonry Inspector’s Handbook, 4th edition. Masonry Institute of America, 2002.
Building Code Requirements for Masonry Structures, ACI 530 02/ASCE 5-02/TMS 402-02. Reported by the Masonry Standards Joint Committee, 2002.

Productivity and Modular Coordination in Concrete Masonry Construction

August 2018

INTRODUCTION

For masonry construction, productivity is typically thought of as the number of concrete masonry units placed per unit of time. This production rate is influenced by many factors, some of which can be controlled by the mason and others which are beyond the mason’s control.

PRODUCTIVITY RATES

Ideally, concrete masonry productivity rates should be compiled by masonry estimators, based on records of completed jobs. Published productivity rates, such as those shown in Figure 1 and Table 1, should be used as guidelines only.

The following sections discuss some of the various factors that can impact masonry productivity. In addition to these, productivity rates can vary with unit size and concrete density, mortar workability, masonry bond pattern, number and type of wall openings, amount of reinforcement and wall size.

As illustrated in Figure 1, concrete ma-primarily in running bond, other bond patterns often require more time to lay. For example, stack bond has been estimated to decrease productivity by about 8% over comparable running bond productivity rates (ref. 4).

Bond pattern can also affect productivity. Because masonry crews are accustomed to laying concrete masonry primarily in running bond, other bond patterns often require more time to lay. For example, stack bond has been estimated to decrease productivity by about 8% over comparable running bond productivity rates (ref. 4).

IMPACT OF QUALITY ON PRODUCTIVITY

The overall quality of the project can influence the masonry productivity. Quality construction includes:

pre-bid and pre-construction conferences,
proper design,
attention to planning and layout,
quality materials,
adequate jobsite and
proper installation.

A project with these ingredients will also be conducive to a very productive jobsite.

Pre-Bid and Pre-Construction Conferences

Pre-bid and pre-construction conferences should be held and attended by all parties involved in the masonry work including the owner’s representative, the architect/engineer, the contractor, the construction manager, the masonry material suppliers and the mason contractor. This facilitates good communication prior to the commencement of work and prior to the development of any misunderstandings. Clear communication minimizes delays due to factors such as lastminute changes and errors.

Proper Design

Quality design means that the designer has:

designed and detailed a project that is constructible,
developed plans and specifications that are sufficient for construction and are complete with the proper code and standards referenced,
reviewed the plans, specifications and structural drawings to eliminate conflicting words and conflicting details,
included the input of a quality mason contractor, and
incorporated all masonry materials into CSI Division 4. (Often, some mason materials are found in division 7. If all of the mason’s work is placed into Division 4, it enhances communication with the masonry team and has a better chance of being properly incorporated into the job.) Similar to the pre-bid and pre construction conferences, a comprehensive set of plans and specifications will help enhance productivity because it will reduce or eliminate time spent correcting misunderstandings and errors.

A complete set of plans and specifications will include a copy of Building Code Requirements for Masonry Structures and Specification for Masonry Structures (refs. 1, 2), the national consensus standards for masonry design and construction. In addition, applicable ASTM standards should be included for specifying masonry materials.

Planning and Layout

Attention to planning of the building itself and of construction sequencing and scheduling can impact masonry productivity.

Concrete masonry structures can be constructed using virtually any layout dimension. However, for maximum construction efficiency and economy, concrete masonry elements should be designed and constructed with modular coordination in mind. Modular coordination is the practice of laying out and dimensioning structures to standard lengths and heights to accommodate modular sized building materials. Standard concrete masonry modules are typically 8 in. (203 mm) vertically and horizontally, but may also include 4in. (102 mm) modules for some applications. These modules provide the best overall design flexibility and coordination with other building products such as windows and doors. Typically, masonry opening widths for doors and windows should be 4 in. (102 mm) larger than the door or window width. This allows for 2 in. (51 mm) on each side of the opening for framing. Masonry opening heights for windows typically are 8 in. (203 mm) greater than the window height. This opening size allows for 2 in. (51 mm) above and below for framing and 4 in. (102 mm) for installing a sill at the bottom of the window. Masonry opening door heights are 2 in. (51 mm) greater than the door height, which leaves 2 in. (51 mm) for the door framing. Figure 2 illustrates these opening sizes.

Thus, door and window widths of 28 in., 36 in., 44 in., and 52 in. (711, 914, 1118 and 1,321 mm), and so on in 8 in. (203 mm) increments, are modular and would not require cutting of the masonry. Modular window heights are any multiple of 8 in. (203 mm), with a masonry window opening 8 in. (203 mm) greater than the height of the window if a 4 in. (102 mm) sill will be used. Similarly, a modular door height is 2 in. (51 mm) less than any multiple of eight. Thus, an 86 in. (2,184 mm) high door, which fits into an 88-in. (2,235 mm) high masonry opening, has a modular height.

Note that products are available in some locations to accommodate 6’ 8” (2,032 mm) doors in masonry walls without the need for cutting the masonry units. These include precast lintels with a 2 in. (51 mm) notch which provides the necessary 6’ 10” (2,083 mm) masonry opening to accommodate the door and frame. In other areas, door frames are available with a 4 in. (101.6 mm) header which would allow a 6’ 8” (2,032 mm) door to fit into 7’ 4” or 88 in. (2,235 mm) high masonry opening.

Nonmodular layouts may require additional considerations for items such as using nonstandard units or saw cutting masonry units and maintaining bond patterns. Additionally, other construction issues may arise, such as placement of jamb reinforcement and adequate grout consolidation within small core spaces. The end product typically is more difficult to construct, produces more waste and is more costly.

Similarly, coordinating the placement of pipes, ducts, chases and conduits to align them with hollow masonry cores can reduce the need to saw-cut masonry units.

Steel congestion in reinforced masonry can slow productivity. Placing too many reinforcing bars in too small a space makes it difficult to place the steel and to provide adequate grout coverage. Specification for Masonry Structures (ref. 3) requires 1/4 in. (6.4 mm) clear space between the reinforcing bar and the masonry for fine grout and 1/2 in. (13 mm) clear space for coarse grout.

Sample panels reduce misunderstandings and provide an objective indicator of the intended construction practices. They help ensure all parties understand the range of materials, methods and workmanship acceptable on the job. Sample panels are typically at least 4 ft by 4 ft (1.22 x 1.22 m) and should contain the full range of unit and mortar colors. Selecting units of all one shade for the sample panel will not accurately reflect the completed work. Instead, units should be randomly selected as they would in the project construction. Cleaning procedures, sealant application and all other procedures should be performed on the sample panel so that their acceptability can be judged as well. The sample panel should remain in place throughout construction as a point of reference.

For maximum productivity, timely delivery of the units, mortar, grout and other masonry materials will help expedite the job. In addition, schedule masonry work to avoid times of the year particularly subject to freezing temperatures or prolonged rains whenever possible. Although masonry construction can take place during hot, cold and wet weather conditions, special construction procedures may be warranted in some cases to ensure the masonry quality is not impacted by the weather. More detailed information on these construction procedures can be found in All-Weather Concrete Masonry Construction (ref. 4).

Quality Materials

Masonry materials have a successful history of meeting applicable specifications and project requirements. Ensuring that the materials used are as specified helps keep the masonry construction on track. ASTM standards for masonry units, for example, specify dimensional tolerances for the units. Units meeting the ASTM tolerances will be easier to place, and allow the mason to more easily maintain level and alignment. Similarly, units without excessive chippage (a characteristic also governed by ASTM standards) allow placement without the need for sorting the product for quality—an activity that reduces overall productivity.

Jobsite

A quality jobsite helps productivity by including ample space for the mason subcontractor to work and having easy access to the masonry supplies. This includes having:

undisturbed space for building the sample panel(s),
a defined and ample-sized area for materials and supplies, and
a defined and ample-sized area for sampling and testing procedures as required for the project.

Proper Installation

In addition to the factors cited above, quality installation requires:

an ample number of qualified craftsmen,
qualified and sufficient supervision, and
the right equipment for the job.

There have been some marvelous developments in products and equipment to assist masons and hence increase masonry productivity. For example, newer fork lifts often have increased capacity, a single boom which increases visibility, are more maneuverable, have higher load ratings and higher extensions. Other equipment advances that can enhance productivity include portable hand-held lasers that work in numerous directions simultaneously, electric portable winches and power (crank-up or hydraulic) scaffolding. Products that are easier for the mason to install, such as self-adhesive flashings and pre-formed flashing end dams, can also impact masonry productivity.

Choice of mortar can also impact productivity. Masonry and mortar cements provide more consistency because all of the cementitious ingredients are premixed. Premixed mortars, which include the sand mixed with the appropriate cement, are also available in silos or in mixers or blenders. Premixed mortars can improve mortar quality control and uniformity and can also increase productivity by eliminating the need for job site mixing.

In some cases, work by other trades can also impact masonry
productivity. For example, poured concrete foundations or footings which do not meet their tolerances may require the mason to saw-cut the first course of block, or take some other measure, to compensate.

REFERENCES

Building Code Requirements for Masonry Structures, ACI 530-02/ASCE 5-02/TMS 402-02. Reported by the Masonry Standards Joint Committee, 2002.
Specification for Masonry Structures, ACI 530.1-02/ ASCE
6-02/TMS 602-02. Reported by the Masonry Standards Joint Committee, 2002.
All-Weather Concrete Masonry Construction, TEK 03-01C,
Concrete Masonry & Hardscapes Association, 2002.
Kolkoski, R. V. Masonry Estimating. Craftsman Book Company, 1988.
Research Investigation of Mason Productivity. Concrete Masonry & Hardscapes Association, 1989.

Considerations for Using Specialty Concrete Masonry Units

August 2018

INTRODUCTION

Concrete masonry is an extremely versatile building product in part because of the wide variety of aesthetic effects that can be achieved using concrete masonry units. Concrete masonry units are manufactured in different sizes, shapes, colors, and textures to achieve a number of finishes and functions. In addition, because of its modular nature, different concrete masonry units can be combined within the same wall to produce variations in texture, pattern, and color.

For the purposes of this TEK, “standard” concrete masonry units are considered to be two-core units (i.e., those with three cross webs), 8 in. (203 mm) high, 16 in. (406 mm) long and 4, 6, 8, 10 or 12 in. (102, 154, 203, 254 or 305 mm) wide. In addition, concrete brick is available in typical lengths of 8, 9, 12 and 16 in. (203, 229, 305 and 406 mm), nominal 4 in. (102 mm) width, and a wide range of heights.

In addition to these “standard” units, many additional units have been developed for a variety of specific purposes, such as aesthetics, ease of construction and improved thermal or acoustic performance. For the purposes of this TEK, units other than those described above as standard will be referred to as specialty units. Specialty units can include units of different sizes or different unit configurations. Units of specialty configuration which are used at discreet wall locations rather than to construct an entire wall, such as sash units, pilaster units, etc. are not discussed here, nor are proprietary units discussed in detail. See CMHA CMU-TEC-001-23 Concrete Masonry Unit Shapes, Sizes, Properties, and Specifications (ref. 1), for information on these units.

By definition, specialty units are not available from all concrete masonry manufacturers. In some cases, such as the A- and H-shaped units used for reinforced construction, the “specialty” is commonly available in certain geographic areas. In California, for example, A- and H-shaped units are considered to be standard units. Other unit configurations discussed below may be available across the country, but from a relatively small number of producers. For this reason, it is imperative that the designer communicate with local concrete masonry manufacturers to establish the availability of the units discussed in this TEK, as well as other specialty units that may be available. Local manufacturers can provide detailed information on specific products, or the feasibility of producing custom units.

Regardless of unit size or configuration, concrete masonry units are required to comply with Standard Specification for Loadbearing Concrete Masonry Units, ASTM C90 (ref. 2). See CMHA CMU-TEC-001-23, ASTM Specifications for Concrete Masonry Units (ref. 3), for more detailed information.

This TEK discusses the advantages of using specialty units, and some of the design and construction issues that may impact the use of these units

SPECIALTY UNIT SIZES

Concrete masonry units may be produced with widths, heights, and/or lengths other than the standard sizes listed above. Use of these units produces walls with a scale and aesthetic properties different from those built with standard-sized units. Construction productivity may be impacted by the size, weight and configuration of the units selected. Also, some of the special shapes and sizes may not be available, and may require modification on site by the contractor.

One of the most important construction consideration when using specialty-sized units is modular coordination. Modular coordination is the practice of laying out and dimensioning structures and elements to standard lengths and heights to accommodate proportioning and incorporating modular-sized building materials. Modular coordination helps maximize construction efficiency and economy by minimizing the number of units that must be cut to accommodate window and door openings, for example. See CMHA TEK 05-12, Modular Layout of Concrete Masonry (ref. 4) for information on modular coordination with standard-sized units.

In addition to the specialty height units and specialty length units discussed below, veneer units (typically 4 in. (102 mm) thick) may be available in various specialty sizes, up to 16 in. high by 24 in. long (406 x 610 mm).

Specialty Unit Heights

Although the most commonly available concrete masonry unit height is 8 in. (203 mm), concrete masonry units may be available in 4-in. (“half-high”) or 12-in. (102- and 305-mm) high units. Half-high units are gaining in popularity. They provide an aspect ratio similar to brick, but are hollow loadbearing units. See CMHA TEK 05-15, Details for Half-High Concrete Masonry Units (ref. 7) for more detailed information.

As long as the unit cross-section (i.e., face shell and web thicknesses) is the same as the corresponding 8-in. (203-mm) high unit, these specialty height units can be considered to be structurally equivalent to their corresponding 8-in. (203-mm) high unit.

Vertical modular coordination must be adjusted in some cases with these units. Using 4-in. (102-mm) high units provides some additional flexibility in placing wall openings, as the wall is built on a 4-in. (102-mm) vertical module rather than an 8-in. (203-mm) vertical module. With 12-in. high units, the wall height, door opening height and window opening height should ideally be a multiple of 12-in. (305-mm) to minimize cutting units on site (see Figure 1). Note that special door frames may need to be ordered to fit the masonry opening. See CMHA TEK 05-12 for further information.

Veneer anchor spacing requirements remain the same regardless of unit height. For units with a height greater than 8 in. (203 mm), these spacing requirements should be verified and the anchor spacing planned out prior to construction. As an example, consider 12-in. (305-mm) high veneer units installed over a concrete masonry backup wythe. The anchor spacing requirements are: maximum wall surface area supported of 2.67 ft2 (0.25 m2); maximum vertical anchor spacing of 18 in. (457 mm); and maximum horizontal anchor spacing or 32 in. (813 mm) (ref. 11). In this case, anchors need to be installed in every course to meet the requirement for a maximum vertical anchor spacing of 18 in. (457 mm). If the anchors are spaced horizontally at the maximum 32 in. (813 mm), the wall area supported is 2.67 ft2 (0.25 m2), so this veneer anchor spacing meets the code requirements. Veneer anchor spacing requirements are presented in detail in CMHA TEK 03-6C, Concrete Masonry Veneers (ref. 8).

Another consideration for units with a height exceeding 8 in. (203 mm) is the use of joint reinforcement. Joint reinforcement in concrete masonry can be used to provide crack control, horizontal reinforcement in low seismic categories, and bond for multiple wythes, corners and intersections. Most requirements and rules of thumb for joint reinforcement are based on a specific area of reinforcement per foot of wall height and assume an 8-in. (203-mm) modular unit height. These should be considered prior to construction for units with heights exceeding 8 in. (203 mm). For example, empirical concrete masonry crack control criteria calls for horizontal reinforcement of at least 0.025 in.2/ ft of wall height (52.9 mm2/m) between control joints. This corresponds to a maximum vertical spacing of 16 in. (406 mm) when 2-wire W1.7 (9 gage, MW11) joint reinforcement is used. When using 12-in. (305-mm) high units, the joint reinforcement of that size needs to be placed in every horizontal bed joint to meet this requirement. A better alternative is to use 2-wire W2.8 (3/16 in., MW18) joint reinforcement, with a maximum vertical spacing of 24 in. (610 mm), allowing the joint reinforcement to be placed every other course when using 12-in. (305-mm) high units. See CMHA CMU-TEC-009-23, Crack Control Strategies for Concrete Masonry Construction (ref. 6) for a discussion of joint reinforcement for crack control, and TEK 12-02B, Joint Reinforcement for Concrete Masonry (ref. 7), for an overview of code requirements for the use of joint reinforcement. Properties of wire for masonry (including steel cross-sectional area) can be found in Table 3 of CMHA TEK 12-04D, Steel Reinforcement for Concrete Masonry (ref. 8)

Figure 1—Vertical Modular Coordination: 12-in. (305-mm) Unit vs. Height 8-in. (203-mm) Unit Height

Specialty Unit Lengths

Specialty concrete masonry unit lengths include 18-in. and 24-in. (457- and 610-mm) long units. Concrete masonry units longer than 16 in. (406 mm) are produced with the same equivalent web thickness (i.e., the average web thickness per length of wall) as 16-in. (406-mm) long units, per ASTM C90. As such, these units can be considered to be structurally equivalent to a 16-in. (305-mm) long unit of the same width.

Horizontal modular coordination should be considered when using these units. For example, wall length and placement of wall openings should ideally be a multiple of the unit length, as shown in Figure 2.

Veneer anchor spacing and joint reinforcement considerations are the same as for standard-length units.

Figure 2—Horizontal Modular Coordination: 18-in. (457-mm) Unit Length vs. 16-in. (406-mm) Unit Length

Specialty Unit Widths

In addition to the standard unit widths of 4, 6, 8, 10, and 12 in. (102, 152, 203, 254, 305 mm), specialty widths may include 14 and 16 in. (356 and 406 mm). Because unit width does not affect modular coordination, layout considerations are generally the same as for walls constructed using standard concrete masonry units.

One construction issue that arises with different unit widths is corner details. CMHA TEK 05-09A, Concrete Masonry Corner Details (ref. 9), presents details to minimize cutting of units while maintaining modularity for 4, 6, 8, 10, and 12 in. (102, 152, 203, 254, 305 mm) wide units. Corner details for 14-in. (356-mm) wide units are similar to those for 12-in. (305 mm) wide units, using 8-in. (203-mm) wide units with 2 x 6 in. (51 x 152 mm) pieces of masonry to fill the gaps in the inside corners. Because 16 in. (406 mm) is a modular size, corner details for these units are similar to those for 8-in. (203-mm) wide units. A standard 8-in. (203-mm) wide unit is used in each course at the corner to maintain the running bond.

Structural considerations may differ, however, as both the section properties and wall weight varies with wall width. CMHA Tech Note CMU-TEC-002-23, Weights and Section Properties of Concrete Masonry Assemblies, (ref. 10) list these properties for 14 and 16 in. (356 and 406 mm) wide walls.

From a construction standpoint, the larger cores of 14- and 16-in. (356 and 406 mm) wide units accommodate more reinforcement or insulation, when used, and require more grout to fill reinforced cells.

SPECIALTY UNIT CONFIGURATIONS

Specialty unit configuration refers to units whose cross-section varies significantly from that of a standard two-core concrete masonry unit. In this case, structural properties may be different from standard units. Modular coordination is the same as for standard units, unless the specialty configuration is also produced in a specialty size.

A variety of concrete masonry units have been developed to address specific performance or construction criteria. For example, units developed for improved energy efficiency may have reduced web areas to reduce heat loss through the webs, a thickened interior face shell for increased thermal storage, and/or additional cavities within the unit to accommodate insulation. Acoustical concrete masonry units provide increased sound absorption and/or diffusion.

These units may have unique construction and/or structural considerations, depending on their configuration. The concrete masonry producer should be contacted for more detailed information on the specific unit under consideration.

Units to Facilitate Reinforced Construction

Concrete masonry unit shapes have been developed for a wide variety of applications. The shapes illustrated in Figure 3 have been developed specifically to accommodate vertical reinforcement. Bond beam and lintel units have also been developed to accommodate horizontal reinforcement.

Open-ended units allow concrete masonry units to be inserted around vertical reinforcing bars. This eliminates the need to lift units over the top of embedded vertical reinforcement, or to thread the reinforcement through the masonry cores after the wall is constructed.

Because all open cells of A- and H-shaped units are grouted and bond beam and lintel units are fully grouted, walls constructed with these units can use the same structural design parameters as for grouted standard units.

REFERENCES

CMHA CMU-TEC-001-23, Concrete Masonry Unit Shapes, Sizes, Properties, and Specifications, Concrete Masonry & Hardscapes Association, 2023.
Standard Specification for Loadbearing Concrete Masonry Units, ASTM C90-09. ASTM International, 2009.
Modular Layout of Concrete Masonry, CMHA TEK 05-12. Concrete Masonry & Hardscapes Association, 2008.
Details for Half-High Concrete Masonry Units, CMHA TEK 05-15. Concrete Masonry & Hardscapes Association,
Concrete Masonry Veneers, CMHA TEK 03-6C. Concrete Masonry & Hardscapes Association, 2012.
Crack Control Strategies for Concrete Masonry Construction, CMHA CMU-TEC-009-23, Concrete Masonry and Hardscapes Association, 2023.
Joint Reinforcement for Concrete Masonry, CMHA TEK 12-02B. Concrete Masonry & Hardscapes Association,
Steel Reinforcement for Concrete Masonry, CMHA TEK 12-04D. Concrete Masonry & Hardscapes Association,
Concrete Masonry Corner Details, CMHA TEK 05-09A. Concrete Masonry & Hardscapes Association, 2004.
Weights and Section Properties of Concrete Masonry Assemblies, CMU-TEC-002-23. Concrete Masonry & Hardscapes Association, 2023.
Building Code Requirements for Masonry Structures, TMS 402-08/ACI 530-08/ASCE 5-08. Reported by the Masonry Standards Joint Committee, 2008.