DIVISION 4 – MASONRY
SECTION 0420 00 – UNIT MASONRY (BLOCK)
Page 1 of 9
PART 1 - GENERAL
1.01 RELATED DOCUMENTS
1.Drawings and general provisions of Contract, including General and Supplementary Conditions and Division-l Specification sections, apply to work of this section.
1.02 DESCRIPTION OF WORK
1.Work includes providing: Block work.
1.03 QUALITY ASSURANCE
1.Variation from Plumb: For vertical lines and surfaces of columns, walls and arises do not exceed 1/4" in 10', or 3/8" in a story height not to exceed 20', nor 1/2" in 40' or more. For external corners, expansion joints, control joints and other conspicuous lines, do not exceed 1/4" in any story or 20' maximum, nor 1/2" in 40' or more.
2. Variation from Level: For lines of exposed lintels, sills, parapets, horizontal grooves and other conspicuous lines, do not exceed 1/4" in any bay or 20' maximum, nor 3/4" in 40' or more.
3. Variation of Linear Building Line: From position shown on plan and related portion of columns, walls and partitions, do not exceed 1/2" in any bay or 20' maximum, nor 3/4" in40' or more.
4. Variation in Cross-Sectional Dimensions: For columns and thickness of walls, from dimensions shown, do not exceed minus 1/4" nor plus 1/2".
5. Prior to installation of masonry work, erect sample wall representative of completed masonry work required for project with respect to qualities of appearance, materials and construction. Locate mock-ups on site in locations indicated or, if not indicated, as directed by Architect. Retain mock-ups during construction as standard for judging completed masonry work.
1.04 SUBMITTALS
1. Submit manufacturer's product data for each type of masonry unit, accessory, and other manufactured products, including certifications that each type complies with specified requirements.
2. Submit, for verification purposes, samples of each exposed masonry unit and colored masonry mortar, if any. Include in each set of samples the full range of exposed colors and textures to be expected in completed work.
1.05 JOB CONDITIONS
1. Do not apply uniform floor or roof loading for at least l2 hours after building masonry walls or columns.
2. Do not apply concentrated loads for at least 3 days after building masonry walls or columns.
3. Prevent mortar or soil from staining the face of masonry to be left exposed or painted. Remove immediately mortar in contact with such masonry. Protect base of walls from rain-splashed mud and mortar splatter by means of coverings spread on ground and over wall surface.
4. Protect sills, ledges and projections from droppings of mortar.
PART 2 - PRODUCTS
2.01 MASONRY UNITS, GENERAL
1.All masonry work shall conform to the Building Code Requirements for Masonry Structures (ACI 530/ASCE 5), and Specifications for Masonry Structures (ACI 530.1/ASCE 6) except as herein specified.
2. Obtain masonry units from one manufacturer, of uniform texture and color for each kind required, for each continuous area and visually related areas.
3. Provide units complying with standards referenced and requirements indicated.
2.02 CONCRETE MASONRY UNITS
1.Manufacturer's standard units with nominal face dimensions of 16" long x 8" x 8" (15-5/8" x 7-5/8" x 7-5/8" actual), unless otherwise indicated.
- Provide ground-faced block as manufactured by Cossitt Concrete Products, Inc. Block shall be in thicknesses as shown and in some cases shall have a ground face on both sides. Manufacturer shall include Addiment block plus W as an integral water repellent in the manufacturing process. Addiment Primer Seal WB shall be applied prior to shipment, and Addiment final seal shall be applied after the wall is erected. Colors shall be limited to two, from manufacturer’s standard colors (not including white and beige).
3. Special Shapes: Provide where required for lintels, corners, jambs, sash, control joints, headers, bonding and other special conditions.
4. Hollow Load-Bearing: ASTM C 90, grade N, Type I.
5. Weight Classification: Normal weight units unless otherwise indicated. (125 lbs. per cu. ft. or more, oven dry weight of concrete).
6. Cure units in a moisture-controlled atmosphere or in an autoclave at normal pressure and temperature to comply with ASTM C 90, Type I.
.1 Limit moisture absorption during delivery and until time of installation to the maximum percentage specified for Type I units for the average annual relative humidity as reported by the U.S. Weather Bureau Station nearest the project site to produce less than the maximum estimated linear shrinkage.
7. Cores of exterior block shall be filed with Korfil insulation.
2.03 MORTAR MATERIALS
1. Portland Cement: ASTM C 150, Type I. (ASTM C 150, Type III for cold weather grouting).
2. Hydraded Lime: ASTM C 207, Type S.
3. Aggregate for Mortar: ASTM C l44, except for joints less than 1/4" use aggregate graded with l00% passing the No. l6 sieve.
4. Water: Clean and potable.
2.04 MASONRY ACCESSORIES
- Horizontal Joint Reinforcing and Ties for Masonry: Provide welded wire units prefabricated in straight lengths of not less than 10', with matching corner ("L") and intersecting ("T") units. Fabricate from cold-drawn steel wire complying with ASTM A 82, with deformed continuous side rods and plain cross rods, into units with widths of approximately 2" less than nominal width of walls and partitions as required to position side rods for full embedment in mortar with mortar coverage of not less than 5/8" on joint faces exposed to exterior and not less than 1/2" elsewhere. Provide the following type of joint reinforcing unless otherwise indicated.
.1 Truss type with diagonal cross rods spaced not more than 16" o.c.
2. Wire Sizes: Fabricate with 9-gauge side and cross rods, unless otherwise indicated.
3. Wire Finish: Provide manufacturer's standard mil galvanized finish except as otherwise indicated.
4. Provide concealed flashings shown to be built into masonry.
.1 Copper-Fabric Laminate: Copper bonded to asphalt impregnated cotton fabric both sides. Fabricate with 3 oz. copper.
5.Expansion Joints:
.1 Provide sash block and install extruded rubber control joint furnished under Section 07900.
6.Plastic Weepholes: Unless otherwise indicated, provide 1/4” round x 4” long medium density polyethelene plastic tubes to form weepholes.
7.Column Anchors: AA 401 continuous with Flexlok AA 400 anchors as manufactured by AA Wire Products of equivalent.
8.All reinforcing bars shall conform to ASTM A615, Grade 60.
2.05 MORTAR AND GROUT MIXES
1. Do not lower the freezing point of mortar by use of admixtures of anti-freeze agents.
.1 Do not use calcium chloride in mortar or grout.
2. Mortar for Unit Masonry: Comply with ASTM C270, Proportion Specification, for types of mortar required, unless otherwise indicated.
.1 Limit cementitious materials in mortar to Portland cement-lime. Use Type S mortar composed of one (1) part Portland cement, one-half (l/2) part lime or lime putty, and four (4) parts sand by volume for reinforced masonry and where indicated. Mortar to have an average compressive strength at 28 days of 1800 p.s.i.
3. Grout for Unit Masonry: Comply with ASTM C476 "Specifications for Mortar and Grout for Reinforced Masonry", unless otherwise indicated.
.1 Limit cementitious materials in mortar to Portland cement-lime. Fine and course grout should be composed of (1) part Portland cement, (1/10) part lime or lime putty, and (3) times the sum of the volumes for fine and (2) times the sum of the volumes added for course. Grout to produce 2500 PSI @ 28 days.
.2 Grout shall be placed in lifts not exceeding 5 feet in height.
PART 3 - EXECUTION
3.01 INSTALLATION - GENERAL
1. Build masonry construction to the full thickness shown, except, build single-wythe walls to the actual thickness of the masonry units, using units of nominal thickness shown or specified.
2. Build chases and recesses as shown and as required for the work of other trades. Provide not less than 8" of masonry between chase or recess and jamb of openings, and between adjacent chases and recesses.
3. Cut masonry units with motor-driven saw designed to cut masonry with clean sharp, unchipped edges. Cut units as required to provide pattern shown and to fit adjoining work neatly. Use full units without cutting wherever possible. Use dry cutting saws to cut concrete masonry units.
4. Lay exposed masonry in the bond pattern shown, or if not shown, lay in running bond vertical joint in each course centered on units in courses above and below. Lay concealed masonry with all units in a wythe bonded by lapping not less than 2". Bond and interlock each course of each wythe at corners, unless otherwise shown.
.1 Match coursing, bonding, color and texture of new masonry work with existing work where indicated.
5. Layout walls in advance for accurate spacing of surface bond patterns, with uniform joint widths and to properly locate openings, movement-type joints, returns and offsets. Avoid the use of less-than-half size units at corners, jambs and wherever possible at other locations.
6. Stopping and Resuming Work: Rack back 1/2-masonry unit length in each course; do not tooth. Clean exposed surfaces of set masonry, wet units lightly (if specified to be wetted), and remove loose masonry units and mortar prior to laying fresh masonry.
7. As the work progresses, build-in items specified under this and other sections of these specifications, including but not limited to hollow metal door frames, lintels, etc. Fill in solidly with masonry around built-in items.
.1 Fill space between hollow metal frames and masonry solidly with mortar.
.2 Where built-in items are to be embedded in cores of hollow masonry units, place a layer of metal lath in the joint below and rod mortar or grout into core.
.3 Fill CMU cores with grout 3 courses (24") under bearing plates, beams, lintels, posts and similar conditions unless otherwise indicated.
3.02 MORTAR BEDDING AND JOINTING
1. Lay solid concrete masonry units with completely filled bed, head and collar joints: butter ends with sufficient mortar to fill head joints and shove into place. Do not slush head joints.
2. Lay hollow concrete masonry units with full mortar coverage on horizontal and vertical face shells. Bed webs in mortar in starting course on footings and foundation walls and in all courses of piers, columns and pilasters, and where adjacent to cells or cavities to be reinforced or to be filled with concrete or grout. For starting courses on footings where cells are not grouted, spread out full mortar bed including areas under cells.
3. Maintain joint widths shown, except for minor variations required to maintain bond alignment. If not otherwise indicated, lay walls with 3/8" joints. Cut joints flush for masonry walls which are to be concealed or to be covered by other materials. Tool exposed joints slightly concave using a jointer larger than joint thickness. Rake out mortar in preparation for application of caulking or sealants where shown.
4. Remove masonry units disturbed after laying; clean and relay in fresh mortar. Do not pound corners at jambs to fit stretcher units which have been set in position. If adjustments are required, remove units, clean off mortar, and reset in fresh mortar.
3.03REINFORCED STRUCTURAL MASONRY
1.All masonry shall be placed in running bond unless otherwise noted.
2.Horizontal and vertical reinforcing shall be placed in the walls in accordance with the drawings and manufacturer's recommendations.
3.All masonry mortar shall be placed within one (1) hour after initial mixing. Tempering of mortar shall not be allowed.
4.Grouting of solid masonry walls shall conform to one of the two following
methods:
.1Low Lift Grouting:Maximum height = 5’-0”
Clean outs are not required
Lift shall stop 1-1/2” below top of
block
.2High Lift Grouting:Maximum height = 12’-0” using
secession of 4’ lifts
Clean outs are required at the bottom,
located 8” o.c.
Grout shall be pumped and vibrated.
5.No backfilling of below grade walls shall take place without provisions for adequate bracing.
3.04 HORIZONTAL JOINT REINFORCING
1. Provide continuous horizontal joint reinforcing as shown and specified. Fully embed longitudinal side rods in mortar for their entire length with a minimum cover of 5/8" on exterior side of walls and 1/2" at other locations. Lap reinforcement a minimum of 6". Do not bridge control and expansion joints with reinforcing, unless otherwise indicated. Provide continuity at corners and wall intersections by use of prefabricated "L" and "T" sections. Cut and bend units as directed by manufacturer for continuity at returns, offsets, column fireproofing, pipe enclosures and other special conditions.
2. Space continuous horizontal reinforcing as follows:
.1For single-wythe walls, space reinforcing at l6" o.c. vertically, unless otherwise indicated.
.2 For parapets, space reinforcing at 8” o.c. vertically, unless otherwise indicated.
3. Reinforce masonry openings greater than 1'-0" wide, with horizontal joint reinforcing placed in 2 horizontal joints approximately 8" apart, both immediately above lintels and below sills. Extend reinforcing a minimum of 2'-0" beyond jambs of the opening, bridging control joints where provided.
3.05 ANCHORING MASONRY WORK
1. Provide anchoring devices of the type indicated. If not indicated, provide standard type for facing and back-up involved. Anchor masonry to structural members where masonry abuts or faces such members to comply with the following:
.1 Provide an open space not less than l" in width between masonry and structural member, unless otherwise shown. Keep open space free of mortar or other rigid materials.
.2Anchor masonry to structural members with metal ties embedded in masonry joints and attached to structure. Provide anchors with flexible tie sections, unless otherwise indicated.
3.06 LINTELS
1. Install loose lintels of steel and other materials where shown.
2. Provide minimum bearing of 8" at each jamb, unless otherwise indicated.
3.07 CONTROL AND EXPANSION JOINTS
1. Provide vertical expansion, control and isolation joints in masonry where shown, but in no case in excess of 40 feet horizontally. Build-in related masonry accessory items as the masonry work progresses.
.1Build flanges of expansion joints into masonry. Seal joints below grade and at junctures with horizontal expansion joints, if any.
3.08 REPAIR, POINTING AND CLEANING
1. Remove and replace masonry units which are loose, chipped, broken, stained or otherwise damaged, or if units do not match adjoining units as intended. Provide new units to match adjoining units and install in fresh mortar or grout, pointed to eliminate evidence of replacement.
2.During the tooling of joints, enlarge any voids or holes, except weep holes, and completely fill with mortar. Point-up all joints at corners, copings and adjacent work to provide a neat, uniform appearance, properly prepared for application of caulking or sealant compounds.
3.Clean exposed concrete masonry units by dry brushing at the end of each day’s work and after final pointing to remove mortar spots and droppings. Comply with recommendations in NCMA TEK Bulletin No. 28.
END OF SECTION
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