1. Purpose
1.1 This specification defines for the contractor the minimum requirements for furnishing and erecting masonry work.
2. scope
2.1 The contractor shall provide all labor, materials, tools, and equipment and shall perform all operations required to furnish and erect all concrete masonry units and lintels according to the contract drawings and this specification.
2.2 The contractor shall install all items to be built into the masonry (such as loose lintels, frames, switch boxes, wood blocking, sleeves, inserts, anchors, reinforcing mesh, wall ties, and wall flashing), and the contractor shall construct all recesses in the masonry as required for all trades.
3. RELATED DOCUMENTS
3.1 American Society for Testing and Materials (ASTM)
A 153/A 153M Specification for Zinc Coating (Hot-Dip) on Iron and Steel Hardware
A 615/A 615M Specification for Deformed and Plain Carbon Steel Bars for Concrete Reinforcement
A 951/A 951M Specification for Steel Wire for Masonry Joint Reinforcement
C 90 Specification for Load-Bearing Concrete Masonry Units
C 91/C 91M Specification for Masonry Cement
C 144 Specification for Aggregate for Masonry Mortar
C 150/C 150M Specification for Portland Cement
C 206 Specification for Finishing Hydrated Lime
C 270 Specification for Mortar for Unit Masonry
4. MATERIALS
4.1 General
4.1.1 Material shall be free from defects impairing strength, durability, and appearance. Material shall be protected from damage at the shop, in transit to job, and at the job site until erected in place, inspected, and accepted by the Air Products representative.
4.2 Concrete Masonry Units
4.2.1 Concrete masonry units shall be lightweight, insulative units of nominal 16-inch length, to the width shown on the drawings, and shall have a minimum face shell thickness of 1 1/2 inches and a minimum web thickness of 1 inch. Concrete masonry units shall be precise in form and dimension, shall conform to the requirements of ASTM C 90, shall be Ashler Grade A, and shall be free from iron and other substances that will stain the paint. Exposed surfaces shall be uniform and shall have a fine to medium texture.
4.2.2 Concrete masonry units shall be constructed of lightweight aggregate and shall be moist steam cured in curing rooms in which the temperature is maintained at 190°F under saturated humidity conditions. Units of bituminous or anthracite under aggregate shall not be used. Standard units of the Concrete Masonry Institute (CMI) shall be used for items such as jambs and pilasters.
4.3 Mortar Materials
4.3.1 Cement for mortar and grout shall be Portland cement and conform to ASTM C 150.
4.3.2 Masonry cement shall be “Brixment” as manufactured by the ESSROC Cement Corporation or approved equal. It shall conform to ASTM C 91.
4.3.3 Lime shall be double-hydrated and shall conform to ASTM C 206.
4.3.4 Sand shall be clean bar sand. It shall be well graded with not more than 5% retained in a Number 8 sieve, between 30% and 60% passing a Number 30 sieve, between 10% and 30% passing a Number 50 sieve, and not more than 10% passing a Number 100 sieve. It shall conform to ASTM C 144.
4.3.5 Water shall be clean, free of deleterious amounts of acids, alkalies, or organic materials.
4.4 Mortar shall conform to ASTM C 270. Proportions by volume shall be one part Portland cement, three parts sand, and one-fourth part lime.
4.5 Grout, as required to fill hollow cores of concrete masonry units, shall have a fluid consistency for pouring without segregations. For walls of nominal thickness less than 8 inches, grout shall have the same proportions as specified for mortar. For walls of nominal thickness of 8 inches or more (where the least clear dimension of the spaces to be filled is at least 4 inches), a concrete mix of one part Portland cement, two parts sand, and two parts 3/8-inch pea-gravel shall be used. When the least dimension of the grout space is 5 inches or more, 3/4-inch gravel concrete shall be used.
4.6 Precast Concrete Lintels
4.6.1 Precast concrete shall be a mixture of Portland cement, well-graded sand, and coarse aggregate (not exceeding 1/2 inch in size) in such proportions to produce a concrete with an ultimate strength at 28 days of not less than 3750 pounds per square inch. The concrete shall be reinforced as required by the span and the load.
4.6.2 The precast concrete shall be well cured for at least two weeks after manufacture and shall be protected from freezing or rapid drying.
4.6.3 The precast concrete shall not be set in place until aged for a minimum of three weeks.
4.6.4 The surface finish of all lintels shall match, as close as possible, that of the masonry units furnished for this job.
4.7 Masonry wall reinforcement shall be truss mesh Dur-O-Wal as manufactured by Hohmann & Barnard Company, or approved equal, and shall conform to all the material requirements and physical characteristics of the applicable ASTM standard.
4.8 Flashing. Through wall flashing above exterior door lintels shall be Nervastral Seal-Pruf H-D as manufactured by the Rubber & Plastics Compound Co., Inc., New York, NY, or approved equal.
4.9 Metal Reinforcement and Accessories
4.9.1 Deformed reinforcing bars shall conform to ASTM A 615/A 615M for deformed and plain billet-steel bars for concrete reinforcement.
4.9.2 Joint reinforcement shall be protected from corrosion by galvanizing and shall comply with ASTM A 951/A 951M.
4.9.3 Metal accessories for use in exterior wall construction or interior walls exposed to a mean relative humidity exceeding 75 percent shall be hot-dipped galvanized after fabrication with a minimum coating of 1.5 ounces per square foot according to ASTM A 153/A 153M.
5. WORKMANSHIP
5.1 The contractor shall employ only labor which has been qualified by training and experience to capably perform the specific activities required to accomplish the work in a satisfactory manner.
6. EQUIPMENT
6.1 The contractor shall provide and maintain all tools and equipment in first-class condition and in sufficient quantities to ensure successful performance and completion of the required work.
7. PROCEDURES
7.1 Precautions
7.1.1 Temperature. The contractor shall follow normal construction practices when the ambient temperature is above 40°F. When the ambient temperature is between 25° and 40°F, special steps must be taken. The contractor shall heat mortar materials to produce temperatures between 40° and 120°F at the time of mixing and shall maintain mortar temperature above freezing until used in the masonry. If the masonry units have a temperature below 20°F, they shall be heated to above 20°F. All visible ice shall be removed from units.
7.1.2 Handling and Storage. After delivery to the job site, all masonry units shall be immediately stacked, covered, and stored on platforms or in any other approved manner that will protect masonry units from contact with soil and weather exposure. During stacking and storing, the contractor shall exercise care in handling the masonry units to avoid chipping and breakage. The contractor shall locate the stacks in protected areas on the job site to avoid masonry units being damaged or being disturbed by other work.
7.1.3 Protection of Completed Work. When the mean daily temperature is above 40°F, only the top of unfinished masonry work needs to be covered to protect it from weather. However, when the mean daily temperature is between 25° and 40°F, completed masonry shall be covered with a weather-resistive membrane to protect it from rain or snow for 24 hours after construction.
7.2 Laying Concrete Masonry Units
7.2.1 The contractor shall lay concrete masonry units plumb, level, and true to line in full beds of mortar. Mortar joints shall be straight, clean, and uniform in thickness. The contractor shall use the proper block to provide for all windows, doors, bond beams, and lintels with a minimum of block cutting. Where block cutting is necessary, it shall be neat and regular. Special units, such as corner blocks and fillers, shall be used as might be required to form corners and to maintain a proper bond throughout the wall.
7.2.2 Horizontal and vertical mortar joints shall be 3/8 inch. Mortar joints shall be full on the face shells and on the webs surrounding the cells. Vertical head joints shall be butted to the thickness of the face shell, and the blocks shall be set tightly so that the mortar bonds well to both locks. The contractor shall fill joints solidly from the face of the block to the depth of the face block and shall point, where necessary, to completely and compactly fill the joints. Furrowing of mortar shall not be permitted.
7.2.3 All exposed joints shall be finished with a metal tool to form a concave joint. Joints shall be finished to produce a dense surface well bonded to the block at the edges and shall be tooled when the mortar is partially set, but still plastic. All hairline cracks and crevices shall be closed.
7.2.4 The contractor shall lay out all walls and partitions (before construction) locating all doors and openings. The final location of the openings shall be adjusted so that partial size units are kept to a minimum.
7.2.5 Joint reinforcement shall be placed in every bed joint throughout the wall, unless otherwise indicated on the contract drawings. Joint reinforcement shall be wide enough to bridge the air gap and shall be 2 inches less in width than the nominal thickness of the wall. The minimum mortar coverage on the exterior exposed face of the wall shall not be less than 3/4 inch. Reinforcement shall be lapped sufficiently at splices to ensure continuity. Corners shall be cut and bent as required.
7.2.6 When filling hollow cores, the contractor shall clean out all debris and projecting mortar before pouring the grout. Vertical cells to be filled shall be aligned to maintain a continuous, unobstructed cell area not less than 2 x 3 inches. Fill all cells solid with grout and pour grout in lifts not exceeding 4 feet. Stop pours 1 1/2 inches below the top of a course to form a key at the pour joints.
7.2.7 No patched, chipped, cracked, broken, or otherwise defective units shall be set.
7.2.8 The contractor shall slush hollow metal door frames full of mortar as concrete masonry units are laid up.
7.2.9 Walls shall be laid in straight, uniform courses with regular running bond. Bond intersecting masonry walls by overlapping units in alternate courses. Bond partitions to exterior walls with steel ties at 16 inches on center maximum. Steel ties shall be 3.4 pounds per square foot metal lath anchored in mortar joints or 1/4 inch hooked bars anchored in filling cells. Anchoring of special conditions shall be as indicated on the drawings.
7.2.10 The contractor shall brace all openings and frames at openings, at least until mortar and grout about them are set.
7.2.11 Use of admixtures to lower the freezing point of the mortar is prohibited unless sanctioned by the Air Products representative, but at no time may the admixture used exceed 2% by weight of the Portland cement.
7.2.11.1 The Air Products representative has the exclusive right to stop masonry work when weather conditions are too severe to continue.
7.2.12 On completion, the contractor shall fill all holes and joints, remove loose mortar, cut out defective joints, and rejoint where necessary. Exposed masonry surfaces shall be thoroughly cleaned with a solution of 10% by volume of commercial muriatic acid applied with a stiff fiber brush. All surfaces shall be left free of mortar and other stains at the completion of work.
7.3 Installation of Precast Concrete Lintels
7.3.1 Precast lintels shall be set in a bed of mortar as specified for concrete masonry unit work. Installation shall comply with paragraph 7.2.
7.4 Bearing Walls
7.4.1 Intersecting bearing walls shall not be tied together in a masonry bond, except at corners. One wall shall terminate at the face of the other wall with a control joint at that point. For lateral support, bearing walls shall be tied together with a metal tie bar 1/4 inch thick, 1 1/4 inches wide, and 28 inches long with 2-inch right angle bends on each end. The bonds at the ends of the tie bar shall be embedded in cores filled with mortar or concrete. Pieces of metal lath shall be placed under the cores to support the concrete or mortar filling. The tie bars, for lateral support, shall be spaced at a maximum of 4 feet, 0 inches vertically.
7.4.2 If the control joint at the intersection of the bearing walls will be exposed to view, the mortar shall be raked out to a depth of 3/4 inch and sealed with a caulking compound.
7.5 Nonbearing Walls
7.5.1 When a nonbearing wall intersects with another wall, walls shall not be tied together in a masonry bond, except at corners. Strips of metal lath of 1/4-inch mesh, galvanized, hardware cloth shall be placed across the joint between the two walls. The metal strips shall be placed in alternate courses in the wall. When one wall is constructed first, the metal strips shall be built into the wall and later embedded in the mortar joint of the second wall.
7.5.2 Where the two walls meet, the vertical mortar joint shall be raked out to a depth of 3/4 inch (if it will be exposed to view in the finished building), and a caulking compound shall be packed into the recess.
8. PROTECTION OF EMBEDDED STEEL
8.1 The contractor shall provide and place embedded items in the masonry work, such as all necessary anchors, sleeves, inserts, and wall ties required for the installation and attachment of other work. Such miscellaneous items shall be set accurately to template, built into the masonry plumb, and so maintained during the work by securely wiring as necessary. Bolts shall project from the face of the masonry the distance called for on the drawing, or a sufficient distance to allow for the proper attachment. All threads shall be oiled and protected by waterproof caps.
8.1.1 The contractor shall provide such openings as are required for the passing of other work through masonry.
8.2 The contractor shall take care to keep the required items embedded in the masonry and shall provide the required openings in the masonry at the proper locations.
9. INSPECTION
9.1 General
9.1.1 All materials and workmanship shall be subject to inspection and examination by the Company representative at any location where fabrication and erection is performed. Any defective materials and/or workmanship shall be corrected to the satisfaction of the representative.