Section 04230 REINFORCED HOLLOW UNIT MASONRY

Section 04230

_{REINFORCED HOLLOW UNIT MASONRY}

PART 1 - GENERAL

1.1 THE REQUIREMENT

A. The CONTRACTOR shall furnish all tools, equipment, materials, and supplies and shall perform all labor required to complete the reinforced hollow unit masonry work as indicated on the Drawings and specified herein.

1.2 RELATED WORK SPECIFIED ELSEWHERE

A. The requirements of the following sections and divisions apply to the Work of this section. Other sections and divisions of the Specifications, not referenced below, shall also apply to the extent required for proper performance of this Work.

1. Section 03200, Reinforcement Steel

2. Section 03300, Cast-in-Place Concrete

3. Section 03600, Grouts

4. Section 03360, Concrete Curing, Finishing and Dampproofing

5. Section 04155, Masonry Accessories

6. Section 04510, Masonry Cleaning

7. Section 07130, Concrete Sealer and Hardener

8. Section 09905, Architectural Paint Finishes

1.3 REFERENCE SPECIFICATIONS, CODES AND STANDARDS

A. All Work specified herein shall conform to or exceed the applicable requirements of the referenced portions of the following publications to the extent that the provisions thereof are not in conflict with other provisions of these Specifications.

B. Comply with the applicable provisions of the following codes, regulations and standards.

1. Codes and Regulations:

CCR California Code of Regulations, Title 24, Part 2, California Building Code (CBC), 2010 Edition

2. Industry Standards:

ASTM C 33 Standard Specification for Concrete Aggregates

ASTM C 90 Standard Specification for Load-Bearing

Concrete Masonry Units

ASTM C 140 Standard Test Methods for Sampling and Testing Concrete Masonry Units and Related Units

ASTM C 144 Standard Specification for Aggregate for

Masonry Mortar

ASTM C 150 Standard Specification for Portland Cement

ASTM C 207 Standard Specification for Hydrated Lime for

Masonry Purposes

ASTM C 331 Standard Specification for Lightweight

Aggregates for Concrete Masonry Units

ASTM C 404 Standard Specification for Aggregates for

Masonry Grout

ASTM C 476 Standard Specification for Grout for Masonry

ASTM C 595 Standard Specification for Blended Hydraulic

Cements

SSPWC Sections 202-2 “Green Book”, Standard Specifications for

Public Works Construction, Concrete Block

SSPWC Sections 303-4.1 “Green Book”, Standard Specifications for Public Works Construction, Concrete Block Masonry

C. Comply with the applicable reference Specifications as directed in the General

Requirements and the Additional General Requirements.

1.4 CONTRACTOR SUBMITTALS

A. Submittals shall be made in accordance with the General Requirements, Additional

General Requirements and as specified herein.

B. The following submittals and specific information shall be provided.

1. Manufacturer's Literature: Submit information illustrating the horizontal joint reinforcement and preformed control joint materials proposed for use.

2. Samples: Before starting Work, samples of blocks to be used shall be submitted to the ENGINEER for acceptance. Materials used on the project shall conform to accepted samples.

3. Sample Panel: Lay up a sample panel for each type of masonry at the site to show the accepted bond and method of finishing joints. Sample panels shall be at least 4 feet high and at least 4 feet long, and shall remain intact after the panel acceptance until acceptance of the permanent masonry work and then shall be removed by the CONTRACTOR. The accepted sample panels shall serve as a basis of color, texture, and workmanship for acceptance of the permanent construction. The sample panel shall demonstrate the ability to receive grout in certain cells in any sequence of placement and demonstrate that the materials will be restricted to the cells and bond beams intended to receive that material. The sample panel construction shall show all areas required to receive mortar. The sample panel shall demonstrate the proper use of running bond or stacked bond meeting the requirements hereinafter specified.

4. Manufacturer's Certificate: Provide manufacturer's certificate(s) for the masonry units specified herein.

1.5 QUALITY ASSURANCE A. General:

1. The CONTRACTOR shall hire an independent test laboratory to visit the jobsite to sample and test the masonry units, to make samples of grout and mortar, and to cure and test these samples as herein specified. A copy of all testing reports shall be furnished to the ENGINEER within 5 days of the tests.

2. After delivery to the jobsite, the masonry units will be sampled and tested in accordance with ASTM C 140. Masonry construction shall not proceed until test results are known and the masonry units are certified by an accepted testing agency as complying with ASTM C 90 and this Specification.

3. Grout and mortar samples for strength testing shall be taken at the beginning of the masonry work and thereafter at the discretion of the ENGINEER. The samples shall be taken as hereinafter specified.

a. Field Compressive Test Specimen for Grout: On a flat nonabsorbent base, form a space approximately 3 inches x 3 inches x 6 inches high (i.e., twice as high as it is wide) using masonry units having the same moisture conditions as those being laid. Line the space with a permeable paper or porous separator so that water may pass through the liner into the masonry units. Thoroughly mix or agitate grout to obtain a fully representative mix and place into molds in two layers, and puddle each layer with a 1-inch x 2-inch puddling stick to eliminate air bubbles. Level off and immediately cover molds and keep them damp until taken to the laboratory. After 48 hours to set, carefully remove masonry units and transport and place grout samples in a fog room until tested.

b. Field Compressive Test Specimen for Mortar: Spread mortar on the masonry units 1/2 inch to 5/8 inch thick, and allow to stand for 1 minute. Then, remove mortar and place in a 2-inch x 4-inch cylinder in two layers, compressing the mortar into the cylinder using a flat-end stick or fingers. Lightly tap mold on opposite sides, level off and immediately cover molds and keep them damp until taken to the laboratory. After 48 hours to set, have the laboratory remove molds and place them in the fog room until tested in the damp condition.

c. Requirements:

1) Each such mortar test specimen shall exhibit a minimum ultimate compressive strength of 1,800 pounds per square inch.

2) Each such grout test specimen shall exhibit a minimum ultimate compressive strength of 2,000 pounds per square inch.

PART 2 - PRODUCTS

2.1 MASONRY UNITS A. General:

1. Units shall be of size shown. Provide or cut special shapes for corners, jambs, lintels, and other areas shown or required. Special units shall match color and texture of standard units. Where masonry units are placed so that the end of a unit is exposed, such as at a corner or intersection, the end of that block shall have a surface to match the color or texture of the sides of the other units.

2. Units shall be sound, dry, clean, and free of cracks and shall have reached the specified moisture content and compressive strength prior to placing in the structure.

3. Vertical cells to be grouted in all units covered under this Specification shall have vertical alignment sufficient to maintain a clear, unobstructed continuous vertical cell measuring not less than 2 inches by 3 inches.

4. The color of the units shall be gray and the surface texture shall be smooth on all exposed surfaces.

B. Hollow Concrete Units (CMU):

1. Hollow concrete masonry units (CMU) shall be Grade N Type I in accordance with ASTM C 90.

2. Tests for conforming to the above Specifications shall be made in accordance with ASTM C 140.

3. Blocks shall have dense faces suitable for painting.

4. The manufacturer shall certify that the masonry units meet all requirements of ASTM C 90 including the moisture content and linear shrinkage requirements for humid conditions.

2.2 CEMENT

A. Portland Cement: All cement to be used or furnished shall be Type II low alkali Portland cement conforming to ASTM C 150, or Type IP (MS) Portland-pozzolan cement conforming to ASTM C 595, unless otherwise specified. Either cement shall conform to the low alkali requirements of Table IA of ASTM C 150. Type IP (MS) cement shall contain no more than 20 percent pozzolan, which shall be interground with the clinker.

B. The CONTRACTOR shall furnish a Certificate of Compliance signed by the manufacturer identifying the cement and stating that the cement complies with these requirements. Supporting test data shall be furnished when requested by the ENGINEER.

C. Whenever suitable facilities accepted by the ENGINEER are available for handling and weighing bulk cement, such facilities shall be used. Otherwise, the cement shall be delivered in original unopened sacks that have been filled by the manufacturer. They shall be plainly marked with the manufacturer's name or brand, cement type and weight.

D. Cement shall be stored in such a manner as to permit ready access for the purpose of inspection and sampling, and suitably protected against contamination or moisture. Should any cement delivered show evidence of contamination or be otherwise unsuitable, the ENGINEER may reject it and require that it be removed from the site.

E. All Portland cement used in concrete for any individual structure shall be of the same brand and type unless otherwise accepted by the ENGINEER.

2.3 LIME

A. Lime putty shall be made from Type S hydrated lime and shall conform to

ASTM C 207. Lime shall be kept dry.

2.4 AGGREGATES

A. Hollow Concrete Units: Aggregates for hollow concrete units shall conform to ASTM C 33 and ASTM C 331 or shall be blended from aggregates conforming to these Specifications. Use the same type or types of aggregate throughout the project unless otherwise indicated or written permission is received from the ENGINEER. Aggregates used for the project shall produce concrete with a dry density of 105 to 125 lbs. per cubic foot, normal weight.

_{B. Mortar: Aggregate for mortar shall conform to ASTM C 144.}

C. Grout: Aggregate for grout shall conform to ASTM C 404.

_{2.5 WATER}

A. Water used for concrete shall not contain deleterious substances. Water shall not contain an amount of impurities that will cause a change in the time of setting of Portland cement of more than 25 percent nor a reduction in relative mortar strength at 7 and 28 days of more than 10 percent compared to results obtained with distilled water.

B. In conventionally reinforced concrete work, water shall not contain more than

1,000 ppm of chlorides calculated as Cl or more than 1,000 ppm of sulfates calculated as

SO₄.

2.6 MORTAR

A. Mortar shall be freshly prepared and uniformly mixed in the ratio portioned by a loose volume of 1 part Portland cement and 2-1/2 to 3 parts sand to which 1/4 to 1/2 part, maximum, lime putty or hydrated lime has been added. Mortar shall attain a minimum compressive strength of 1,800 pounds per inch in 28 days. Test results verifying the compressive strength shall be submitted to the ENGINEER.

2.7 MORTAR ADMIXTURE

A. Water repellent admixture shall be added to all mortar in the quantity recommended by the manufacturer. Water repellent admixture shall be Hydrophobe 31, manufactured by W. R. Grace and Company; Sika Red Label, manufactured by Sika Chemical Corporation; Omicron Mortar Proofing, Master Builders Corporation; Or Equal.

B. Inert coloring pigments may be added, but shall not to exceed 6 percent by weight of the cement. Color shall be as selected by ENGINEER.

C. Quantity of admixture per mortar batch shall be in accordance with manufacturer's recommendations.

2.8 GROUT

A. Conform to ASTM C 476 except as hereinafter specified.

B. General: Grout shall be sufficiently fluid to ensure complete filling of all sections of masonry requiring grout, but not so thin as to allow separation of aggregate.

C. Proportions:

1. Grout for pumping shall be of fluid consistency and shall have not less than seven sacks of cement in each cubic yard of grout. The mix design shall be subject to ENGINEER’s acceptance.

2. Fluid consistency shall mean a fluid suitable for pouring without segregation.

3. Grout for use in spaces less than 4 inches clear in any dimension, grout proportioned by volume shall be 1 part Portland cement and 2-1/4 to 3 parts sand. For spaces 4 inches or larger in all horizontal directions, grout shall be 1 part Portland cement, 2 to 3 parts sand and 1-1/4 to 2 parts No. 4 concrete aggregate.

D. Grout Admixture: Grout admixture shall be Sika Grout Aid, Type II, manufactured by Sika Chemical Corporation; Grout Aid GA-II, manufactured by Concrete Emulsions; Or Equal. Amount of admixture and method of introducing admixture shall be in accordance with manufacturer's recommendations.

E. Compressive Strength: The average 28-day compressive strength of the grout samples for each grout pour tested shall not be less than 2,000 pounds per inch. Test results verifying the compressive strength shall be submitted to the ENGINEER.

2.9 HORIZONTAL JOINT REINFORCEMENT

A. Two parallel No. 9 wires, uncoated, weld connected to No. 9 perpendicular cross wire at 15 inches on center. Special manufactured corner and wall intersection pieces shall be used at these locations. Horizontal joint reinforcement shall be ladder-type masonry wall reinforcement, manufactured by Dur-O-Wall National, Inc., Cedar Rapids, IA; AA Wire Products Company, Chicago, IL; Or Equal.

2.10 PREFORMED CONTROL JOINT

A. Joint material shall be a solid rubber extrusion such as regular Rapid Control Joint, manufactured by Dur-O-Wall National Company, Cedar Rapids, IA; Sonneborn Control Joint, manufactured by Sonneborn-Contech Company, Oakland, CA; Or Equal.

PART 3 - EXECUTION

3.1 GENERAL

A. All Work shall be performed in a workmanlike manner and in full compliance with the applicable building ordinances.

B. The foundation on which a masonry wall is to be built shall have a clean, smooth surface with aggregate exposed. Sandblasting shall be done if the surface has laitance or other foreign material lodged in the pores of the foundation surface.

C. All masonry walls shall be laid true, level, and plumb in accordance with Subsection 3.4 and the Drawings.

D. Masonry units shall be cured and dry, and surfaces shall be clean when laid in the walls.

E. During construction, all partially laid walls, as well as units in storage shall be protected from moisture. All concrete blocks units and any partially laid walls that become wet during the construction shall be permitted to dry for at least 1 week, or longer if required by weather conditions, before recommencing Work.

F. Proper masonry units shall be used to provide for all windows, doors, bond beams, lintels, pilasters, etc. with a minimum of unit cutting. Where masonry unit cutting is necessary, all cuts shall be neat and regular, and edges exposed in the finished Work shall be cut with a power-driven abrasive saw.

G. Where no bond pattern is shown, the wall shall be laid up in straight uniform course with regular running bond with alternate header joints in vertical alignment.

H. Intersecting masonry walls and partitions shall be bonded by the use of 1/4 inch minimum-diameter steel ties at 24 inches on centers (maximum).

I. Where stack bond is indicated on the Drawings, accepted metal ties shall be provided horizontally at 24 inches on centers (maximum).

J. Mortar joints shall be straight, clean, and uniform in thickness. Unless otherwise specified or detailed on the Drawings, horizontal and vertical joints shall be approximately

3/8 inch thick with full mortar coverage on the face shells and on the webs surrounding cells to be filled. Units shall be laid with "push joints." No slushing or grouting of a joint will be permitted, nor shall a joint be made by working in mortar after the units have been laid.

K. Exposed walls shall have joints tooled with a round bar (or V-shaped bar) to produce a dense, slightly concave surface well bonded to the block at the edges. Tooling shall be done when the mortar is partially set but still sufficiently plastic to bond. All tooling shall be done with a tool that compacts the mortar, pressing the excess mortar out of the joint rather than dragging it out.

L. If it is necessary to move a block so as to open a joint, the block shall be removed from the wall, cleaned, and set in fresh mortar.

3.2 WEATHER CONDITIONS

A. Protect the tops of walls at all times. Cover the tops of walls with waterproof paper when rain is imminent and Work is discontinued.

B. Protect masonry construction from loss of moisture during the curing period when ambient air temperature of 90 degrees F (37 degrees C) or greater exists and when relative humidity is less than 50 percent. Use light fog spray nozzles to cure the mortar when these conditions exist. Provide a demonstration of the fog spray nozzles prior to starting the Work.

3.3 BONDING WALL UNITS A. Foundation:

1. The foundation shall be prepared for the initial mortar placement by one of the following methods:

a. Sandblasting the foundation and reinforcing dowels after the concrete has fully cured to remove all laitance and spillage and to expose sound aggregate.

b. Water blasting the foundation and reinforcing dowels after the concrete has partially cured to remove all laitance and spillage and to expose sound aggregate.

c. Green cutting fresh concrete with high-pressure water and hand tools to remove all laitance and spillage from the foundation and the reinforcing dowels and to expose sound aggregate.

2. The foundation shall be cleaned of all loose material prior to the initial mortar placement.

B. Corners: Corners shall have a standard masonry bond for overlapping units and shall be grouted solid. Reinforcement shall be as shown.

C. Intersections: Intersecting walls shall be bonded with reinforcement as shown. The abutting wall shall not have a masonry bond with the straight wall.

3.4 LAYING REINFORCED MASONRY UNITS A. General:

1. Masonry construction shall conform to the applicable sections of the California Building Code, latest edition, and as supplemented by these Specifications. Do not start laying masonry units if the foundation horizontal or vertical alignment does not satisfy the tolerance specified in Section 03300, Cast-In-Place Concrete.

2. The maximum permissible variation from plumb of the wall or of a line of joints in the wall shall be 1/16 inch per foot of height, and 1/4 inch in the total height of the wall. The maximum permissible variation from a horizontal line along the base of the wall or for lines of horizontal joints shall be 1/16 inch per block, 1/4 inch per 50 feet of wall with proportionately greater tolerance for longer walls up to 1/2 inch in the total length of wall. Interior surfaces shall be maintained in the plane described above and the dimension tolerances of the units shall be taken up on exterior surfaces.

3. Units with chipped edges or corners within permissible ASTM limits shall be placed in the wall such that the chipped area is not exposed to view.

B. Wall Units:

1. General:

a. If it is necessary to move a unit after it has been once set in place, the unit shall be removed from the wall, cleaned, and set in fresh mortar.

b. Toothing of masonry units will not be permitted unless acceptance is given by the ENGINEER.

c. All masonry work shall be protected from damage until Final Acceptance of the Work. Damaged units will not be accepted.

2. Running Bond: Unless otherwise shown, walls shall be laid up in straight, uniform courses using a running bond pattern. The running bond pattern shall guarantee continuous vertical cells meeting the requirements of this Specification with mortar joints as required to prevent the different materials such as grout or poured insulation from escaping from the cell being filled to adjacent cells where the material is not intended to be placed.

C. Special Shapes: Provide and place such special units as corner block, door jamb block, lintel block fillers, and similar blocks as may be required. Use the required shapes and sizes to work to corners and openings maintaining a proper bond throughout the wall.

3.5 BUILT-IN ITEMS

A. Door frames, windows, vents, and other items required to be built in the wall shall be in position and the wall constructed around them. Standard masonry anchors shall be used to secure the items to the wall. All spaces around the items shall be filled with mortar or grout.

3.6 EMBEDDED CONDUITS

A. Electrical, instrumentation, or water conduits shall not be placed in a cell containing reinforcement unless accepted by the ENGINEER.

3.7 MORTAR PREPARATION

A. Mortar shall be mixed by placing 1/2 the water and aggregate in the operating mixer. Add cement. Add the remaining aggregate and water, and mix for at least 2 minutes. Add lime and continue mixing as long as needed to secure a uniform mass, but no less than

3 minutes after the addition of lime. The addition of the admixture shall be timed in strict accordance with the manufacturer's instructions, and the procedure used for adding it to the mix shall provide good dispersion.

B. The mortar shall be machine mixed in accepted mixers. Mixer drums shall be kept clean and free of debris and dried mortar. The mortar shall be in place before the initial setting of the cement has taken place. Retempering of mortar in which the cement has started to set will not be permitted.

3.8 MORTAR JOINTS A. General:

1. Mortar joints shall be straight, clean, and uniform in thickness, and shall be tooled as shown on the Contract Documents. Where no joint detail is shown and the wall is not to be coated or painted, exposed walls shall have joints tooled with a round bar to produce a dense, slightly concave surface well bonded to the masonry units at the edges. Tooling shall be done when the mortar is partially set but still sufficiently plastic to bond. All tooling shall be done with a tool that compacts the mortar, pressing the excess mortar out of the joint rather than dragging it out. Where certain joints are to be concealed under paint, these joints shall be filled flush and then rubbed with burlap to produce a dense surface without sheen.

2. Horizontal and vertical mortar joints shall be straight, clean, and shall have a uniform thickness of 3/8 inch.

3. The horizontal and vertical mortar joints shall have full mortar coverage on the face shells.

4. Vertical head joints shall be buttered well on each unit for a width equal to the face shell of the unit, and these joints shall be shoved tightly so that the mortar bonds well to both units. Joints shall be solidly filled from the face of the block to at least the depth of the face shell, pointing where necessary to completely and compactly fill the joints. Furrowing of the mortar will not be permitted.

5. All excess mortar shall be removed from the grout space of the cells to be filled as the units are being laid.

B. Exposed Joints:

1. Joints that will be exposed to view after final construction shall be tooled unless otherwise noted or shown. Joints shall be cut flush and, as mortar takes its initial set, shall be tooled to provide a concave joint. Tooling shall be done when the mortar is partially set but still sufficiently plastic to bond. All tooling shall be done with a tool that compacts the mortar, pressing the excess mortar out rather than dragging it out. Joints that are not tight at the time of tooling shall be raked out, pointed, and then tooled.

2. Joints at split-face surfaces, interior and exterior, shall be raked and tooled.

C. Concealed Joints: Joints that are not exposed shall be struck flush with no further treatment required.

3.9 CONTROL JOINTS

A. Preformed Control Joints: The mortar shall be omitted from the vertical joints. Place the rubber control joint material as the wall is built. After the wall is grouted, cured, and cleaned, install the backing rod and flexible sealant. Place and tool sealant to match depth of typical joint.

3.10 REINFORCING A. General:

1. Reinforcing bars shall be straight except for bends around corners or where bends or hooks are detailed on the Contract Documents. Vertical bars shall be fixed in the position and at the interval shown on the Contract Documents at each end of the bar.

2. All steel reinforcing bars shall be as shown on the Drawings or as specified in

Section 03200, Reinforcement Steel of these Specifications.

3. Reinforcing steel shall be placed as indicated on the Drawings. Splices shall be lapped a distance sufficient to develop the yield stress in the bar, with a minimum requirement of 40 diameters. Dowels other than column dowels need to be lapped only 30 diameters. Column dowels shall lap 50 diameters.

4. Outside horizontal steel shall lap around corners 40 diameters and be carried through columns unless otherwise shown on the Drawings. Inside horizontal steel shall extend as far as possible and bend into corner core. A dowel shall be provided in the foundation for each vertical bar.

5. Where horizontal courses are to be filled, metal stops shall be used. Use of paper stops will not be permitted. All horizontal reinforcing steel shall be laid in a course of bond beam blocks filled with grout.

6. Vertical cores containing steel shall be filled solid with grout, and thoroughly rodded.

7. Where knockout blocks are used, steel shall be erected and wired in place before three courses have been laid. Vertical cores at steel locations shall be filled as construction progresses.

8. Where knockout blocks are not used, vertical cores at steel locations shall be filled in lifts of not more than 4 feet. The maximum height of pour shall be 8 feet. Cores shall be cleaned of debris and mortar and shall have reinforcing steel held straight and in place. If ordered by the ENGINEER, inspection and cleanout holes shall be provided at the bottom of each core to be filled.

9. Reinforcing steel shall be inspected prior to placing grout. B. Foundation Dowels:

1. The size, number, and location of the foundation dowels shall match the vertical wall reinforcing unless otherwise noted.

2. When a foundation dowel does not line up as intended, with a vertical core, it shall not be sloped more than 1 horizontal to 6 vertical to bring it into alignment.

3. Dowels shall be accurately placed to match reinforcing in filled cells.

C. Vertical Reinforcing: Vertical reinforcing steel shall be held in position near the ends of the bars by wire ties to dowels and/or by reinforcing positioners. The bars shall be held in position at intervals not exceeding 160 bar diameters by reinforcing positioners.

D. Horizontal Reinforcing: Horizontal bars shall be laid on the webs of bond beam units, and shall be placed as the wall is built.

3.11 GROUTING

A. Grout Preparation: Grout shall be mixed as specified hereinbefore for mortar preparation if onsite mixing is performed. Transit-mixed grout shall meet the requirements of ASTM C 476. The grout admixture shall be added at the site. In accordance with the specified grout admixture manufacturer's recommendations, the admixture shall be premixed with water and the resulting solution shall be added to the grout mix and thoroughly mixed. Do not exceed quantity of admixture recommended by the manufacturer.

B. General:

1. All debris and projecting mortar shall be cleaned out before pouring grout.

2. Grout pour shall be stopped 1-1/2 inches below the top of a course to form a key at pour joints.

3. Grout shall not be mixed, conveyed, or placed with equipment constructed of aluminum.

4. All vertical and horizontal reinforcement, ties, bolts, anchors, and other required embedments shall be secured in place, inspected, and accepted before grouting starts.

5. Grouting of beams over openings shall be done in one continuous operation.

6. Vertical cells to be filled shall have vertical alignment sufficient to maintain a clear, unobstructed, continuous vertical cell measuring not less than 2 inches by

3 inches.

7. Grout shall be poured as soon as possible after the mortar has cured to reduce shrinkage and cracking of the vertical joints. Immediately after the grouting has been completed, the scum and stains on the masonry shall be washed off using clean water and fiber brushes. Grout and mortar stains shall not be allowed to dry on the face of the exposed masonry.

8. Vertical reinforcement may be placed initially and the wall built up around it, providing the reinforcing steel is first wire tied to the foundation dowels. Reinforcing positioners and/or accepted cross bracing shall be provided to secure the top of the steel in place. The vertical steel will not be permitted to be dropped in after the block is laid unless reinforcing positioners are provided in the course above the previously grouted course.

C. Grouting Requirements:

1. Solid Grouting Requirements: Walls that are to be solid grouted shall have vertical grout barriers spaced not more than 30 feet apart, and which extend the full height of the wall.

2. Partial Grouting Requirements:

a. Walls that do not require solid grouting shall have all cells containing reinforcing steel and others as shown filled with grout.

b. Cells to be filled shall be constructed to confine the grout within the cell. Tops of unfilled vertical cells under a bond beam shall be covered with metal lath to confine the grout fill to the bond beam section.

c. Grout pours shall be limited in height to mid-depth of the course above the horizontal bond beam, except at the top course.

D. Low-Lift Grouting Requirements:

1. Unless otherwise accepted by the ENGINEER prior to the start of the masonry work, all grouting shall be low-lift grouting.

2. When grouting is stopped for 1 hour or longer, horizontal construction joints shall be formed by stopping the pour of grout 1-1/2 inches below the top of the uppermost unit. Horizontal steel shall be fully embedded by grout in an uninterrupted pour.

3. Grout pour shall be limited to a maximum height of 4 feet. The wall shall not be constructed more than one course above the top of the grout pour prior to placing the grout.

4. The grout shall be thoroughly consolidated with an internal "pencil" type vibrator operating at 5,000 RPM, to consolidate and reduce the amount of air voids. After waiting sufficient time to permit the grout to become plastic, but before it has taken any set, the grout shall be reconsolidated. The waiting period will vary depending upon weather conditions and block absorption rates, but under "normal" weather conditions with average masonry units, the waiting period should be between 30 to

60 minutes.

E. High-Lift Grouting Requirements:

1. Walls built with open-end units as shown shall not be grouted using the high-lift method. Standard construction masonry may be high-lift grouted if accepted by the ENGINEER.

2. Cleanouts of sufficient size to permit cleaning of the cell, positioning of the reinforcing and inspection shall be provided at the bottom of every vertical cell containing reinforcing. The location of the cleanout shall be such that it is not exposed to view after final construction, unless otherwise accepted by the ENGINEER.

3. After the wall has been inspected and accepted and prior to grouting, all cleanouts shall be capped in a manner that will seal them from grout leakage and provide a flush finish.

4. Grout pours shall be limited to 12-foot heights, with lifts not exceeding 4 feet. Each lift shall be thoroughly consolidated with an internal "pencil" type vibrator. Succeeding lifts shall not be placed until the previous lift has become plastic. Succeeding lifts shall be vibrated into the previous lift.

5. The last grout pour on a wall shall be reconsolidated as specified for low-lift grouting.

3.12 CURING

A. Masonry and mortar joints shall be wetted frequently for at least 3 days to ensure proper curing of mortar.

3.13 CLEANING

A. Clean all surfaces of excess mortar, grout spillage, dirt, and other foreign substances.

B. Walls not requiring painting or sealing shall be cleaned such that there are no visible stains.

C. No construction supports shall be attached to the wall except where specifically permitted by the ENGINEER.

D. Concrete and grout spilled on the wall shall be washed off before it can set up. At the conclusion of the masonry work, the CONTRACTOR shall clean down all masonry walls, remove any scaffolding and equipment used in the Work, clean up all debris, refuse and surplus material, and remove it from the premises.

E. Surfaces requiring painting or sealing shall be prepared in accordance with Section

09905, Architectural Paint Finishes.

3.14 PROTECTION

A. At the end of each day's work, tops of walls shall be covered with building paper or by other means that will protect the walls from becoming excessively wet.

3.15 TEMPORARY BRACING

A. The CONTRACTOR shall adequately brace all walls until the walls and roof are completed. Bracing shall be sufficient to protect the walls against damage from the elements, including wind.

3.16 SEALING

A. All block walls, unless otherwise indicated, shall be sealed on the exterior with a water- repellent sealer as specified in Section 07130, Concrete Sealer and Hardener.