types of masonry units

The information is presented in terms of the current Australian /New Zealand standard AS/NZS 4455, Masonry Units, Pavers, Vertical support for the masonry veneer is typically provided at each floor line. Standard Specification for Loadbearing Concrete Masonry Units, ASTM C 90-00. Concrete masonry units should meet the requirements of ASTM C90. by Richard A. Weber, RA, PEWiss, Janney, Elstner Associates, Inc. Masonry has been used in building construction for thousands of years in construction. Conventional concrete masonry units are manufactured using a “no-slump” concrete mix, which holds its shape when removed from the manufacturing mold. Special admixtures and mortars are available for use with glazed units that provide better stain, bacteria, and water penetration resistance. This drainage cavity should remain open to allow water to freely drain. As with many construction products and systems, there are often regional differences in terminology for the same type of architectural concrete masonry units: ribbed and fluted, ground and burnished, etc. Although this horizontal reinforcement improves the strength of the masonry, particularly for horizontal spans, but also serves to control shrinkage cracking. ), Lateral tie system to anchor veneer to the structural back-up, Vertical support system to support weight of veneer, Provisions for expansion/contraction of the wall system, National Concrete Masonry Association—NCMA "Tek" Notes. In addition to forming the exterior cladding, masonry walls can serve as a portion of the structural framing for the building. The units are categorized based on the weight (lightweight, normal weight and heavyweight). Lateral support for the masonry veneer is required. Several different finishes can be formed on the exterior surface of the brick such as wire cut or sand finished, depending on the method used to form the brick into the desired shape. Walls utilizing a variety of split face units are shown in Figure 1. From schools to warehouses, many buildings have CMU walls. American Society for Testing and Materials, 1999. and at through wall flashings. Concrete block is made from Portland Cement, aggregates and water. These materials expand in warm temperatures and contract in cold temperatures. The finished look of the ground surface can be altered by changing aggregate type and proportions. End dams are required at terminations to prevent water from flowing laterally off the flashing and into the adjacent construction. Has a higher proportion of cement and subsequently can have increased shrinkage of the mortar. Admixtures can be used in the fabrication of concrete masonry units to reduce water penetration due to absorption into units themselves. Updated October 26, 2020 Mortar is the element that bonds bricks or other masonry units together and provides structural capacity to the wall or other structure. Chapter 8 Flashcards – Most Common Types Of Masonry Units So for large work of masonry like for load bearing walls these solid blocks are preferable. These movements, if not accommodated in the design of the masonry elements, can cause cracking, spalling, and displacements in the masonry. Some works for structures, some make barriers to boundaries to separate the property line and some make the wall of the house for structural use. In the first case, the net area, and corresponding section properties, will be larger than those published for non-ribbed units, although the effect of this increase is typically neglected in structural calculations. They are more commonly available in the Southwest United States where adobe is part of the architectural heritage. Variegated units provide color variations within each unit, producing a marbled effect. Since water penetration through the exterior wythe of masonry is to be expected, the reliance on a single wythe of masonry as the exterior wall system is typically not recommended. B. In concrete masonry it is common to lay the units with mortar only on the face shells (face shell bedding). Other appropriate bond patterns are included in Table 1. Slump units, on the other hand, are manufactured using a concrete mix that slumps within desired limits when removed from its mold (see Figure 2c). Contact NCMA staff for details. Split-faced units can also be manufactured with ribs or scores to provide strong vertical lines in the finished wall. Common masonry unit types include clay and concrete units, which may be solid or hollow, and glazed or unglazed. It can be used to form a durable cladding system and to achieve various aesthetic effects. Architectural units comply with the same quality standards as conventional concrete masonry, Standard Specification for Loadbearing Concrete Masonry Units, ASTM C90 (ref. The movement joints must also accommodate these movements. In summer months, the air space behind the brick veneer will typically contain air that is hot and humid relative to the interior. Masonry is generally used for the construction of foundations, walls, columns, and other similar structural components of buildings. Structural masonry walls are typically constructed using concrete masonry. National Concrete Masonry Association, 1997. when the units are solidly grouted. The ribs can be manufactured to project beyond the overall unit thickness (i.e., the unit thickness including ribs is thicker than a typical CMU), or with the rib projection included in the overall unit thickness. What Types and Sizes of Concrete Masonry Units are Available? This consists of building a concrete masonry wall with cables within the cells, similar to a pre-stressed concrete element. ASTM C90 prescribes minimum faceshell thickness requirements for all loadbearing concrete masonry units, but also contains a variance for split face units where up to 10% of a split faceshell can be less than the minimum specified thickness, but not less than ¾ (19 mm). Masonry walls can be single or multi-wythe. In addition, the unit to which the facing is applied must comply with ASTM C90 when used in loadbearing applications. Concrete masonry units are manufactured from very dry, stiff concrete mixtures. These changes have also led to excellent quality control and uniformity of units. During cold temperatures, masonry will be cool, particularly in shaded exposures. The standard for clay masonry units is ASTM C216 (Standard Specification for Facing Brick (Solid Masonry Units Made from Clay or Shale). Concrete Masonry Units Concrete Masonry Units are one of the most versatile products in the construction industry. This is typically provided by an interior wall. © 2020 National Institute of Building Sciences. Clay brick masonry should include solid (full) head and bed joints. The ribs may have either a rectangular or circular profile, and may be either smooth or split for added texture. This is accomplished by omitting the mortar between the top course of masonry and the underside of the support. Which Type Of Masonry Structure Is The Best? A soft split unit is produced using a special mold which textures the face of the unit as it is removed from the mold. American Society for Testing and Materials, 2000. This is the most common masonry mortar used in non-structural applications in new construction. NW (negligible weathering) units should only be used in interior conditions where the interior air is conditioned and there is no exposure to moisture. The units described herein are some of the more common architectural concrete masonry units. Where restrictions in the cavity exist, flashings are recommended to collect water and drain it to the exterior. What is not so commonly known are the varying characteristics of different types of materials. In concrete structures, creep of the concrete frame should also be accommodated. This 10% limit does not apply, however, in. Units may also be available with 2, 3, 5, or 7 vertical scores. In this standard, and in building specifications, clay units are categorized by grade (NW, MW or SW) and type (FBA, FBS and FBX). Mortar (Type K)… The (Type K) Mortar cannot be found listed under the ASTM C 270 anymore, although it will still be use in projects that have a pre-historic preservation need. Full bedding of concrete masonry units is typically only performed where a portion of the cells will be filled with grout. Types of Masonry Wall Several different types of masonry units are commonly used. In this fashion, the wall acts similar to a reinforced concrete element. Table 1 is a general guide for selection of mortar type. Disclaimer, Unified Facilities Guide Specifications (UFGS), Exterior Insulation and Finish System (EIFS), American National Standards Institute (ANSI), Unified Facility Guide Specifications (UFGS), DRAFT Federal Guide for Green Construction Specifications, CMHC Best Practice Guide—Brick Veneer Steel Stud, National Concrete Masonry Association (NCMA), Masonry Contractors Association of America (MCAA). The mortar is retempered (additional water added to the mix) periodically to maintain workability. Consult a local manufacturer for final unit selection. The use of white cement results in more vibrant colors, but also increases cost. CSE block 235 x 235 x 140 Solid plain Stretcher. However, the admixture must also be mixed into the mortar in order to achieve proper bond. However, manufacturers may carry additional products not listed here, and conversely, not all products listed will be available in all locations. The “no-slump” or “low-slump” material is placed into molds, vibrated and compacte… Note that varying bond patterns can impact how the wall responds to structural loads (see ref. Guidelines for control joint placement are provided in National Concrete Masonry Association (NCMA) Tek Note 10-A. The recommended cavity width behind the masonry veneer is 2 inches minimum. brick, stone, concrete block etc. The most common masonry types and uses in new construction are as follows: Mortar proportions and mixing requirements are outlined in ASTM C270 and in the appropriate Technical Notes published by the Brick Institute of America (BIA). The horizontal joints between units are called bed joints while the vertical joints are called head joints. Depending on the size and spacing of the reinforcement, the spacing of control joints will vary. Type N—Used in general masonry walls above grade. Where grouting is performed, mortar should be kept from falling into the cells since this will form a weak plane in the grout. The final unit color varies with the amount and type of pigment used, cement color, aggregate color, and the amount of water used in the mix (a wetter mix will generally produce lighter and brighter colors). These walls directly transfer loads… If structural masonry walls are to serve as the exterior walls, a second wythe of masonry is typically recommended. Masonry veneer consists of an exterior wythe of masonry that forms a cladding material only. WBDG is a gateway to up-to-date information on integrated 'whole building' design techniques and technologies. Masonry walls also typically increase the fire resistance of the wall system or structural elements. In addition, aggregate is not fractured in a soft split as it is in a conventional split face unit. Masonry is the building of structures from individual units, which are often laid in and bound together by mortar; the term masonry can also refer to the units themselves. See Appendices for climate-specific guidance regarding building enclosure design. This is due to the size of the cores and the difficulty in installing mortar in the webs between cores without allowing significant amounts of mortar to fill the cores. Concrete masonry units can be manufactured in different sizes and with a variety of face textures. Several different types of masonry units are commonly used. In depth guide to design of Masonry containing general guidance on masonry and key equations used in Eurocode 6 (Design of masonry structures) Where tight tolerances are required, Type FBX should be specified. Concrete masonry units come in a variety of sizes, shapes, and specialty forms making them a versatile building material. If single wythe exterior walls are to be installed, a barrier should be provided on the exterior surface, such as a fluid-applied, breathable masonry coating or over-cladding (EIFS, metal panels, stucco and similar) to prevent water penetration into the masonry. Split faced units have a natural stone-like texture produced by molding two units face-to-face, then mechanically splitting them apart after curing, creating a fractured surface. A masonry unit is brick, tile, stone, glass block, or concrete block, conforming to certain product standards of ASTM. with mortar in sequence to get uniform member or element of building. These flashings must be designed to be watertight, particularly at corners, laps, and terminations of the masonry. The ribs are molded into the unit using a special mold. Masonry is typically site constructed (laid) using manufactured masonry units and site mixed mortar. The concrete masonry can be reinforced both vertically and horizontally to achieve the required flexural resistance. Vertical reinforcement that is installed within the cells of the concrete masonry is generally grouted solid. Horizontal reinforcement is typically installed using prefabricated welded wires that are embedded in the bed joints. There are different mortar types depending on the required strength. Critical components in masonry veneers exposed to moisture include: Veneer walls are designed as "drainage walls" in respect to their resistance to water penetration. Burnt Clay Bricks is one of the robust categories of masonriesthat is extensively … The units can also be oriented in various ways to form varying aesthetic effects. In addition, Type K mortar is sometimes used, but … Masonry Mortar Types. The units can be made to various dimensions, but typically have face dimensions of 8 inches high by 16 inches wide (nominal). Slump unit widths may vary as much as 1 in. When properly constructed, masonry wall systems require relatively little maintenance as compared to other wall systems. Schools, factories and residential buildings all often rely on concrete blocks as the bones of a masonry structure. However, with ribbed units, it is difficult to properly tool the mortar due to the projections. The masonry units can be oriented in different positions to create different patterns on the exterior wall. This joint should be designed to accommodate the vertical expansion of the masonry, as well as structural deflections of the support. Because coarse aggregate is also fractured and exposed in this process, aggregate selection can alter the final appearance. This can be due to bond separations, voids, and cracks. Masonry provides a significant improvement in fire safety for building walls. The service life of the masonry can be 100 years or more, depending on the detailing and maintenance. The aggregates used in the concrete mix also impact the final appearance. Premixed mortars must be carefully reviewed to determine the actual components of the mix. The glazed facings must comply with ASTM C744 (ref. Mortars consisting of portland cement and lime as well as sand are most common. This is typically a concrete foundation or structural steel or concrete beam system. Clay masonry units are typically formed of soft clay extruded into the required shape in the manufacturing plant. Ground face units are often scored to achieve a scale other than the conventional 8 16 in. Rough textures, like those available with split face units, are often used in areas prone to graffiti, as the texture tends to discourage graffiti vandals. These systems can be effective in reducing the amount of water penetration into the masonry; however, they should not be relied upon to eliminate water penetration. It is also known as a concrete masonry unit (CMU). Both white and gray cements are available. Metal ties are required to provide the lateral attachment of the veneer to the backup wall. Concrete blocks are manufactured in required shape and sizes and these may be solid or hollow blocks. Concrete masonry units are typically made in forms to the desired shape and then pressure-cured in the manufacturing plant. © 2020 NATIONAL CONCRETE MASONRY ASSOCIATION. This effect is accomplished by using a unit mold with the desired offsets. The most frequent maintenance is the regular replacement of sealant in expansion joints, perimeter of openings (windows, doors, etc.) Typically, Grade SW (severe weathering) is recommended in most areas of the US. Mortar is classified by ASTM C 270 Standard Specification for Mortar for Unit Masonry. Kitchens and laboratories also benefit from the chemical and bacteria-resistant surface. This volumetric change in the unit results in an accumulated growth of the wall system that is irreversible. Brick Masonry. NCMA and the companies disseminating this technical information disclaim any and all responsibility and liability for the accuracy and the application of the information contained in this publication. Scored units reduce the perceived scale of the masonry while still allowing construction using full sized units. The units have the appearance of polished natural stone. Historically, units came from a variety of sources and included materials such as rock and stone, either natural or cut. Generally, mortars are mixed on site with water to achieve a wet fluid mix, with sufficient water for workability. Appropriate use and application of the concepts illustrated in these details will vary based on performance considerations and environmental conditions unique to each project and, therefore, do not represent the final opinion or recommendation of the author of each section or the committee members responsible for the development of the WBDG. Type N or S mortar should be used in other cases. Steel bars are placed in the cores with grout installed surrounding the bars. However, control joints are required in all concrete masonry walls. All rights reserved. To improve acoustical performance, concrete masonry is typically filled with insulation to eliminate the voids in the cores. An air space/drainage cavity should be installed behind the masonry veneer to allow water that penetrates the masonry to flow down to the base of the wall, where it can be directed to the exterior. Masonry can be defined as the construction of building units bonded together with mortar. Scored concrete masonry units are manufactured with one or more vertical scores on the face to simulate additional mortar joints in the wall. Masonry units covered by most standards include those made from normal and lightweight concretes, calcium silicate, natural stone, and fired clay. Units categorized as solid typically contain cores for handling and to allow more uniform firing. For example, units with two and five scores can be placed in either stack bond or in a one-third running bond to align scores in adjacent courses. Striation can be applied to scored and ribbed units as well (see Figure 3c). Water penetration can also occur, although typically to a lesser degree, due to absorption through the units and mortar. Striated units achieve an overall texture by means of small vertical grooves molded into the unit face. The cores provide continuous vertical voids that are often reinforced. The units are laid in mortar to various heights, with the strength of the assembly being achieved during curing of the mortar. 3). Some units are available with the same treatment or pattern on both faces, to serve as both exterior and interior finish wall material, increasing both the economic and aesthetic advantages. For this reason, expansion joints are required in clay masonry construction, particularly in areas exposed to the exterior in where the units will become wet. When building concrete masonry walls, mortar is typically placed to all outside edges of the masonry unit. A masonry veneer wall consists of masonry units, usually clay-based bricks, installed on one or both sides of a structurally independent wall usually constructed of wood or masonry. The type of unit depends on the required dimensional tolerances. The masonry absorbs heat and will radiate the heat to the surrounding components of the wall system. If you’re wondering what mortar types your masonry units need for … Types of hollow concrete block: Concrete stretcher block: They are much like concrete blocks used to assemble masonry units. Type FBA units are typically used to create a rustic appearance with a high dimensional tolerance. (See Figure 3 for examples). Due to their relatively low cost as wall material and their fire resistance, CMU walls are laid on many types of projects. The masonry grade depends on the required durability of the units. Today, units most commonly used are concrete block or clay brick, offering standardized sizes and mechanical properties. Concrete masonry walls are typically reinforced with joint reinforcement for shrinkage control. Concrete masonry is typically used for firewall construction. (203 x 203 mm) units laid in stack bond. They can provide the structural frame of a building and they can also serve as a strong backup system for many types of veneer systems. For this reason, the structural design should assume the actual width of slump units is 1 in. molded from clays, cut from stones, poured with concrete, each requires different processes. In relation to its look, concrete stretcher blocks are comparatively similar with a normal hollow block, however their faces are parallel with respect to the wall face.

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