A07_03_20200821_SECTION 044300 - STONE MASONRY_0007.pdf

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STONE MASONRY

SECTION 044300 - STONE MASONRY – Revised 21 August 2020

PART 1 - GENERAL

1.1 RELATED DOCUMENTS

A. Drawings and general provisions of the Contract, including General and Supplementary Conditions and Division 01 Specification Sections, apply to this Section.

1.2 SUMMARY

A. Section includes the following applications of dry-laid and mortared stone masonry:

1. Reconstruction of stone gravity retaining walls to replace damaged existing stone walls.

2. Enlarging existing stone walls to increase overall wall height and accommodate additional lateral soil pressure.

3. Repairs of existing stone walls and laid-back stone revetment including local reconstruction and re-chinking voids.

4. Install new stones to replace missing stones.

5. Laying out the work.

6. Construction mock-ups.

7. Cutting stone to proper size and shape to incorporate into work.

8. Verifying the existing conditions are acceptable for work to be properly installed.

9. Mortar.

10. Cleanup.

B. Related Sections include the following:

1. Section 013591 - Historic Preservation Treatment Procedures

2. Section 031200 - Earth Moving

1.3 DEFINITIONS

A. Dry-Laid Stone Retaining Wall is a type of gravity wall. It is built without any mortar and relies on the mass of the stones and the friction between them to retain soil.

1. Terminology for Dry-Laid Stone Walls as used in these specifications:

a. Foundation Stones: Stones placed at the base of the wall on top of suitable bearing material as defined in General Notes on S0.0. Foundation Stones shall be at least 12” in height and have length and width at least 24 inches.

b. Face Stones: Stones seen in the face of the completed wall. Face Stones shall be at least 8 inches in height and extend at least 12 inches into the wall.

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c. Backing Stones: Stones used behind the face stones to add mass and structure to the wall. Backing Stones shall be at least 6 inches in height and at least 12 inches in length and width.

d. Tie-Stones: Long stones used to tie the face stones to the backing stones. Tie-stones are typically placed in level courses with a specified horizontal distance between them. Tie stones shall be at least 12 inches in height and long enough to extend through entire wall thickness.

e. Lift: A portion of wall vertically above or below a course with tie-stones. The First Lift Starts on top of the foundation stones and goes up to the first course of tie- stones. The second lift is the next in height and so on. The number of lifts is determined by the height of the wall.

f. Pinning Stones: Small stones precisely placed below larger wall stones to create full bearing contact for larger stone to courses below. Pinning stones shall be at least 2 inches thick.

g. Hearting: Stones used to tightly fill voids between face stones, backing stones, and pinning stones. Hearting Stones shall be at least 2 inches thick and at least 6 inches in length and width.

h. Coping Stones: Select stones that are full depth of wall at top of final lift. Select size and weight such that they are difficult to dislodge or move from placement with a minimum height of 10 inches. Select heaviest stones with random widths to use as Coping stones to apply gravity loads to dry-laid stone walls below.

i. Top of Wall Thickness: Is defined by the top of the Coping Stones

j. Batter: Angle that the face of wall leans back. Typically described in a ratio of

‘distance back’ to ‘height’ such as 1:6.

k. Covering or Breaking the Joints: Place wall stones to prevent vertical joints from aligning and creating weakness in the constructed wall. Break vertical joints where they occur in the front side, back side, and center of the wall.

l. Re-chinking (Re-chinking Stones): Re-chinking is the process of securing loose stones or setting new stones within an existing wall. Smaller stones (Re-chinking Stones) are driven by mallet or pneumatic hammer into joints around edges of larger stones so that all the stones are not removable by hand. Re-chinking Stones shall be at least 2 inches thick. Select and dress stones to provide suitable wedges around larger stones.

1) The re-chinking process should be limited to repairs of existing walls only, and should not be used while constructing dry-laid stone walls.

B. Mortared Stone Retaining Wall is a type of gravity wall. It is built with mortar and relies on the mass of the stones and the friction between them and the mortar to retain soil.

1. Terminology for Mortared Stone Walls as used in these specifications are similar to the Dry-Laid Stone Walls.

1.4 SUBMITTALS

A. Survey of Existing Conditions and Proposed Wall Treatment Shop Drawings.

1. Submit photographs and video tape of wall condition prior to and after vegetation removal. Provide photos with a vertical scale referenced to the Approximate Base Flow

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Water Elevation and a horizontal scale referenced to the Stone Wall Stations shown on the Civil Drawings. Conduct visual survey during periods of low water on the Potomac River.

2. Submit Stone Wall Treatment shop drawings. Shop drawings shall include Wall Treatment Schedule such as the one shown on structural drawing S1.0 and the following:

a. Top of existing wall elevation.

b. Bottom of existing wall elevation.

c. Condition of existing wall and type of damage present.

d. Extents of mortared and dry-laid masonry walls.

e. Confirm locations of trees with Civil Drawings.

f. Coping stone width (i.e. thickness of existing wall at top of wall) for all discrete reaches of Extended Wall Treatments

B. Existing Stone Masonry Dismantling Plan: Provide a written plan that includes a detailed description and example of a cataloging system to identify the types of each stone to be removed and reset. Describe the means and methods of removing the stone from the existing wall without damaging the stone and transporting the stone to and from temporary storage.

Describe the means used to clean the stones. Describe how the stones will be transported from their original position to temporary storage and the location of the storage.

C. Work Documentation: Submit detailed photographic documentation of the project from start to completion. This report is to verify correct building techniques and shall document the following milestones:

1. Prepared sub grade

2. Foundation Stone Placement

3. Completed First Lift

4. Tie-Stones Course Placement

5. Completed Second Lift

6. Second Tie-Stones Course Placement

7. Completed Third Lift

8. Third Tie-Stones Course Placement (if necessary)

9. Competed Fourth Lift (if necessary)

10. Coping Stones Placement

11. Completed Structure and Grading Above Wall

D. Special Inspection Reports

E. Product Data: Submit product data including annotated manufacturer’s literature for each product proposed for use in the work, showing compliance with the specified requirements.

Include test results and instructions for handling, storage and application of each material.

1. For stone varieties proposed for use on Project, include test data indicating compliance with physical properties specified.

2. Aggregates and Sand.

3. Cement.

4. Mortar.

F. Samples for Verification:

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1. Stone: Include at least four samples (minimum stone size of 12 in. x 12 in. x 12 in.) in each set for each type of stone, exhibiting extremes of the full range of color and other visual characteristics expected in completed Work.

2. Mortar Samples:

a. Provide three samples approximately 0.5" x 6" for approval of color. Samples shall have cured for 28 days. Each mortar sample shall use sand from a different source.

Color pigment shall not be used. Submit mix proportions and ingredients with each mix.

b. Three sets of three cubes shall be cast and tested for unconfined compressive strength at 7 and 28 days. (ASTM C270). Submit test reports.

G. List of Materials Used in Constructing Mockups: List generic product names together with sources of supply and other information as required to identify materials used.

1. Submittal is for information only. Neither receipt of list nor approval of mockups constitutes approval of any deviations from the Contract Documents and design intent unless such deviations are specifically brought to the attention of the Contracting Officer and approved in writing.

H. Construction Mockups: Construct in situ mockups described in Para. 1.5 at locations indicated on the Drawings and approved by the Contracting Officer. The approved mockups shall remain as part of the completed work if undisturbed at time of Substantial Completion. Notify the Contracting Officer at least 48 hrs before starting the work on each mockup. Reconstruct each mockup as many times as necessary to meet the approval of the Contracting Officer. Do not proceed with any part of the work before the mockup is approved by the Contracting Officer.

Mockups will be used to establish both technical and aesthetic standards for the remainder of the project.

I. Qualification Data: For qualified installer.

1.5 QUALITY ASSURANCE

A. Installer Qualifications: Provide resumes with references for all stone masons. List the project names and addresses, the Owner’s representatives, the General Contractors, the Engineers, and appropriate subcontractors with phone numbers and contact personnel.

1. Stone Mason Foreman: Designate a Stone Mason Foreman for the project who has completed at least five projects demonstrating at least five years’ successful experience with similar masonry construction and repair work on significant historic structures. The Stone Mason Foreman cannot be replaced during the work without prior approval by the Contracting Officer

2. Stone Masons: Select Stone Masons to complete the work who have completed at least 3 projects with similar masonry construction and repair work. Stone Masons shall be able to demonstrate adequate skill in this trade to the satisfaction of the Contracting Officer.

B. Source Limitations for Stone: Obtain stone from one source, with resources to provide materials of consistent quality in appearance and physical properties.

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1. Reuse existing stone units where possible. Completely dry existing stone units previously submerged in water prior to reusing in wall construction.

C. Mockups: Construct one mockup for each type of wall treatment included in the Wall Treatment Schedule on structural drawing S1.0 (dry-laid wall reconstruction and wall extension, mortared wall extension, dry-laid and mortared wall repair, and scour repair), at locations approved by the Contracting Officer,. Show color, range, textures, pattern, and bond of masonry, any special shapes, and color and tooling of mortar joints (where required) including final cleaning. Approval of the sample is for color, texture, blending of stone, quality of workmanship, and overall consistency of matching pre-demolition appearance (or approved sample panel). Do no other masonry work until the sample section is approved by the contracting officer and becomes the standard of comparison for all masonry. The contractor is responsible for removing and correcting unacceptable work until the test area work is approved by the Contracting Officer.

1. Wall reconstruction mockup: Construct full height stone gravity retaining wall by 10-feet long per requirements indicated on drawings and specifications. Provide temporary shoring and excavation support as required to maintain stability of reconstructed wall and surrounding portions of existing wall and soil to remain.

2. Wall extension mockups: Complete two wall extensions (One Dry-Laid Extension and One Mortared Extension) 10-feet long by 3-feet tall xtend per requirements indicated on drawings and specifications. Provide temporary shoring and excavation support as required to maintain stability of extended walls and surrounding portions of existing wall and soil to remain.

3. Wall repair mockups: repair at least three voids in existing dry-laid walls and one void in existing mortared wall above the water line.

4. Scour repair mockup: Repair at least one void in existing wall below the water line per the requirements indicated on drawings and specifications.

a. Contracting Officer shall test various methods of stone removal to review engagement of scour repair stones with existing masonry and develop testing protocols to be used on future scour repairs.

5. Approval of mockups is for technical construction tolerances, color, texture, and blending of stone and aesthetic qualities of workmanship.

a. Approval of mockups is also for other material and construction qualities Contracting Officer specifically approves in writing.

b. Approval of mockups does not constitute approval of any deviations from the Contract Documents and design intent contained in mockups unless Contracting Officer specifically approves such deviations in writing.

6. Approved mockups may become part of the completed Work if undisturbed at time of Substantial Completion. Install backfill per drawings and specifications.

D. Pre-installation Conference: Conduct conference at Project site. Include the contractor’s representative, stonemason’s representative, and the Contracting Officer.

1. Conference will be scheduled before work begins, after mock-up has been completed and approved in writing by Contracting Officer.

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2. Construction schedule. Verify availability of materials, Restoration Specialist's personnel, equipment, and facilities needed to make progress and avoid delays.

3. Materials, material application, sequencing, and tolerances.

1.6 DELIVERY, STORAGE, AND HANDLING

A. Store aggregates and sand where grading and other required characteristics can be maintained and contamination avoided.

B. Store cementitious materials on elevated platforms, under cover, and in a dry location. Do not use cementitious materials that have become damp.

C. Store masonry accessories, including metal items, to prevent corrosion and accumulation of dirt and oil.

D. Stone masonry units:

1. Contractor is responsible for field dressing stone prior to use in field.

2. Handle stone to prevent breakage, chipping, staining, deterioration, and damage.

3. Stone shall be stored off the ground and under cover until installation to prevent soiling of bedding surfaces.

4. Existing stone units shall be stored and handled in same manner as new stone units with following additional requirements:

a. Clean debris and soiling from existing stone units prior to storage and reuse.

b. Completely dry existing stone units prior to reuse.

1.7 PROJECT CONDITIONS

A. Protection of Stone Masonry: During construction, cover tops of walls and projections with waterproof sheeting at end of each day's work. Cover partially completed stone masonry when construction is not in progress.

1. Extend cover a minimum of 24 inches (600 mm) down both sides and hold cover securely in place.

B. Stain Prevention: Immediately remove soil to prevent them from staining the face of stone masonry.

C. Cold-Weather Requirements: Do not use frozen materials or materials mixed or coated with ice or frost. Do not build on frozen substrates. Remove and replace stone masonry damaged by frost or freezing conditions. Comply with cold-weather construction requirements contained in

ACI 530.1/ASCE 6/TMS 602.

1. Cold-Weather Cleaning: Use liquid cleaning methods only when air temperature is 40 deg F (4 deg C) and above and will remain so until masonry has dried, but not less than 7 days after completing cleaning.

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2. Cold Weather Mortar: Do not place mortar when temperature is below 40 degrees F unless the Contracting Officers has approved a written plan detailing means that will be provided to heat sand or water and ensure that mortar will harden without freezing.

D. Hot-Weather Requirements: Comply with hot-weather construction requirements contained in

ACI 530.1/ASCE 6/TMS 602.

1.8 COORDINATION

A. Advise installers of other work about specific requirements for placement of any miscellaneous items to be built into stone masonry.

PART 2 - PRODUCTS

2.1 STONE

A. Existing stone: Reuse existing stone wherever possible. Condition of existing stone shall meet new stone requirements in order to be reused.

B. Varieties and Sources for new stone: Subject to compliance with requirements, provide stone of varieties and from sources matching color, finish, and other stone characteristics relating to aesthetic effects of existing stone assemblies, as approved by Contracting Officer.

C. Reject stones with following defects unless they can be trimmed to remove the defect:

1. Cracked stones.

2. Soft or mud seams or other visibly defective conditions.

3. Depth less than 4-inches at all bedding surfaces.

4. Store rejected stone on-site in a common area for return to Owner.

D. Limestone: Comply with ASTM C 568.

1. Classification: Medium-Density, except change requirements per ASTM C 568 for absorption by weight, density, compressive strength, and modulus of rupture to, respectively, 5 percent maximum, 150 lb/cu. ft. minimum, 8000 psi, and 800 psi.

2. Match color, finish, and other stone characteristics relating to aesthetic effects.

3. Thickness: See stone sizes in Section 1.3.

E. Fabricate stone to comply with sizes, shapes, and tolerances recommended by applicable stone association or, if none, by stone source, for faces, edges, beds, and backs.

1. For limestone, comply with recommendations in ILI's "Indiana Limestone Handbook."

F. Select stone to produce pieces of thickness, size, and shape indicated, including details on Drawings. Dress joints (bed and vertical) straight and at right angle to face unless otherwise indicated.

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G. Carefully inspect stone at source or fabrication plant for compliance with requirements for appearance, material, and fabrication. Replace defective units before shipment.

1. Clean backs of stone to remove rust stains and iron particles.

H. Stone Dimensions: Shape stone to match masonry pattern of existing walls. Refer to Section 1.3 for minimum stone dimensions based on type of stone. Vary stone sizes and setting to overlap joints within walls and along walls.

I. Finish exposed faces and edges of stone to comply with requirements indicated for finish and to match approved samples and mockups.

1. Finish: Mixed split face, seam face, and rock face (pitched face).

2.2 MORTAR MATERIALS

A. Portland Cement: ASTM C 150 Type I or II, except Type III may be used for cold-weather construction. Provide natural color cement as required to produce mortar color directed by Contracting Officer. Do not use masonry cements, gypsum Portland cements, or blended cements.

1. Low-Alkali Cement: Not more than 0.60 percent total alkali when tested according to

ASTM C 114.

B. Lime: Hydrated lime meeting ASTM C207, Type S.

C. Aggregate for Mortar: Supply mortar sands meeting requirements of ASTM C 144 and as follows:

1. Color: Use natural color of sand necessary to produce mortar color directed by Contracting Officer.

2. Sand may contain no more than 50 parts per million of chloride ions as determined by testing mixed mortar in accordance with ASTM C 1152.

D. The mortar shall reach an unconfined compressive strength of 800 psi, but not more than 1500 psi, after 28 days curing.

E. Water: Potable.

F. Admixtures: No admixtures permitted without written approval by Contracting Officer.

G. Color pigment shall not be used.

2.3 MORTAR MIXES

A. General: Do not use admixtures, including pigments, air-entraining agents, accelerators, retarders, water-repellent agents, antifreeze compounds, or other admixtures, unless otherwise indicated.

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1. Do not use calcium chloride.

2. Limit cementitious materials to Portland cement.

B. Mortar for Stone Masonry: Comply with ASTM C 270, Proportion Specification and as required below.

1. Mortar for Setting and Pointing Stone: Type S with proportions of 1 part cement, 1/2 part lime, and 4-1/2 parts sand.

2. Setting mortar shall be mixed to and used at a masonry mortar consistency. "Dry pack" type setting mortar is not permitted. To ensure setting mortar is of workable consistency, the mortar penetration resistance shall be determined in accordance with ASTM C 780, Annex 3, a minimum of once per day by the Owner’s inspector. The acceptable range for the mortar penetration resistance is from 1.24 psi to 2.44 psi. Setting mortar with penetration resistance outside of this range shall not be used.

PART 3 - EXECUTION

3.1 GENERAL

A. Perform preparation, construction, and clean-up procedures in accordance with the materials and methods demonstrated by the accepted mockups. Do not begin general work until the Contracting Officer has approved the mockup panels.

B. Build work to dimensions and profiles indicated in the approved wall treatment shop drawings.

C. Coordinate with the Contracting Officer the installation of special stone units. Special stone units consist of over-sized units requiring a crane for setting, ground face units used for mounting fixtures, built-in monuments, and any other special type.

D. Unless otherwise specified, herein stone masonry shall comply with ACI 530.1 Standard Specification for Masonry Construction.

3.2 SURVEY OF EXISTING CONDITIONS AND WALL TREATMENT SHOP DRAWINGS

A. Perform survey of existing conditions to document extent of wall treatments based on requirements provided in Wall Treatment Schedule and structural details on the drawings.

Conduct survey during period of low water on Potomac River.

B. Submit photographs and video tape of wall condition prior to and after vegetation removal.

Provide photos with a vertical scale referenced to the Approximate Base Flow Water Elevation and a horizontal scale referenced to the Stone Wall Stations shown on the Civil Drawings.

C. Create Stone Wall Treatment shop drawings from survey results to indicate location and extent of each wall treatment type per requirements in structural drawings. Identify following locations in shop drawings:

1. Wall reconstruction

2. Wall extension

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3. Wall repairs

4. Dry-laid wall construction (new & existing)

5. Mortared wall construction (new & existing)

6. Revetment repairs

7. Culvert head walls

8. Coping stone width (i.e. thickness of existing wall at top of wall) for all discrete reaches of Extended Wall Treatments

D. Shop drawings shall include Wall Treatment Schedule such as the one shown on structural drawing S1.0. Submit shop drawings for review and approval by Contracting Officer prior to commencing work.

1. Shop drawings must include existing wall thickness at top of wall for all discrete reaches of wall extension treatments identified in wall treatment schedule on S1.0. This condition needs to be reviewed by Contracting Officer prior to commencing work.

2. Shop drawings do not need to include existing wall thicknesses for other wall treatments.

E. Confirm mock-up locations to include each type of wall treatment in Stone Wall Treatment shop drawings.

3.3 EXAMINATION

A. Examine surfaces indicated to receive stone masonry, with Installer present, for compliance with requirements for installation tolerances and other conditions affecting performance.

B. All conditions not meeting with requirements necessary to properly install the stone masonry shall be documented in writing and submitted to the Contracting Officer. Installation of stone masonry shall constitute acceptance of conditions by the stone masonry subcontractor.

C. Conditions shown in the Contract Drawings that conflict with the requirements of this specification section shall be brought to the attention of the Contracting Officer immediately.

D. Proceed with installation only after unsatisfactory conditions have been corrected.

3.4 PREPARATION

A. Existing Stone Masonry Dismantling: Following approved dismantling plan, remove and salvage existing loose stones using only hand tools to avoid marring or damaging stones.

Carefully remove excess mortar from stone pieces, if present. Do not remove any existing stones that are not easily removable by hand.

B. Clean dirty or stained stone surfaces by removing soil, stains, and foreign materials before setting. Clean stone by thoroughly scrubbing with fiber brushes and then drenching with clear water. Coordinate preparation methods with Contracting Officer.

C. Sorting New Stone Material: Group similarly sized stones together with attention to creating a safe and efficient work site. The following groups should be visible to the trained eye:

1. Foundation Stones (largest stones)

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2. Tie-Stones (must have appropriate length and shape)

3. Coping Stones (must have appropriate dimensions)

4. Wall Stone and Backing Stones (may be further sorted by size)

5. Pinning, Hearting and Re-chinking (small stones and stone chips)

D. Existing Stones: Separate salvaged existing stones from new stones and group in similar manner as noted above.

3.5 SETTING OF STONE MASONRY

A. General: Section applies to all wall work.

1. Reuse existing stones to the extent possible to preserve historic fabric.

2. Remove existing stones, where indicated in drawings and confirmed in Approved Stone

Wall Treatment shop drawings, down to sound material defined as:

a. Existing stones tightly packed and not easily removable by hand.

3. Refer to Specification 013591 - Historic Preservation Treatment Procedures for Remove and Reinstall procedure requirements of historic stone masonry.

4. Coordinate reconstruction, extension and repair details and requirements with Approved Stone Wall Treatment shop drawings.

5. Perform necessary field cutting and trimming as stone is set.

a. Use hammer and chisel to split stone that is fabricated with split surfaces. Make edges straight and true, matching similar surfaces that were quarry fabricated.

b. Pitch face at field-split edges as needed to match stones that are not field split.

6. Sort stone before it is placed in wall to remove stone that does not comply with requirements relating to aesthetic effects, physical properties, or fabrication, or that is otherwise unsuitable for intended use.

B. Dry-Laid Wall: Section applies to dry-laid wall construction requirements and provides provisions for wall reconstruction and extension details in drawings.

1. All stones shall be placed with their length into the wall structure (perpendicular to the face of the wall).

2. Stones should be placed so the joints near the face of the wall are tight. The wall stones should be in contact with the wall stones on either side.

3. Stones should be set level.

4. To the greatest extent possible, stones of the same height should be placed next to each other to form an even horizontal course.

5. The underside of the stone shall be free of voids and well packed with pinning stones.

6. Stones shall be set so that the top edge of the face (portion of stone visible in completed wall) is in line with the plane of the wall.

7. FOUNDATION STONES

a. Match existing foundation stones where present and set new foundation stones on suitable bearing material as described in General Notes on structural drawing S0.1.

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b. Backing stones of equivalent height and size to the foundation stones shall be placed behind the foundation stones. The length of each backing stone shall be placed perpendicular to the face of the wall.

c. Pinning and hearting shall be carefully placed by hand to fill all voids and gaps between all foundation stones and backing stones. Fewer larger pieces should be used rather than multiple small pieces.

8. FIRST LIFT: FACE STONES, BACKING STONES, PINNING & HEARTING:

a. Stones should be placed such that there is 3 to 4 points contact with the stone course below. At least two points of contact must be made near front face of the wall.

b. Backing stones of equivalent height and size to the wall stones shall be placed behind the face stones. The length of each back stone shall be placed perpendicular to the face of the wall.

c. Pinning and hearting shall be carefully placed by hand to fill all voids and gaps between all face stones and backing stones.

d. Lift height is determined to be whichever distance is greater: up to 30 inches or up to two courses.

9. TIE-STONES:

a. Tie-Stones are placed on the top of each Lift.

b. Shall be placed no farther apart horizontally than whichever is the greater of the following distances:

1) 3 ft. when measured center to center or

2) 2 Face stones between each Tie-Stone.

c. Shall be tightly pinned and hearted beneath so there are no voids.

d. Shall be placed on the wall so they extend all the way through the wall.

e. Should be set so that the length of the stone is approximately perpendicular to the face of the wall.

f. Should be set level.

g. Tie-Stones must span the vertical joints between stones in the course below. Each stone spanning a joint must have at least 1/3 of its width to either side of the joint, and must have contact with and bear weight on both wall stones below.

h. Tie-Stones of successive lifts should be placed such that they are centered between the Tie-Stones on the previous lift.

10. SECOND LIFT AND ADDITIONAL LIFTS:

a. Shall follow all specifications in First Lift

11. PINNING AND HEARTING

a. Shall be placed by hand to the fill voids between other stones.

b. Shall not be placed (pushed in) from the front face of the wall.

c. Pinning stones shall be placed from the interior of the wall.

d. Each void should be placed with the fewer larger stones, rather than multiple small ones.

e. Shall be placed to securely wedge all other stones in the wall tightly together.

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f. Shall not be placed so that downward force will push wall stones out of the wall.

12. COPING STONES

a. Shall be placed so they cover the full width of the top of the wall

b. Coping Stones should be placed so the vertical joints between the stones are not over vertical joints in the course below.

c. Coping Stones shall be placed so they do not tip or shift when weight is applied to the top.

d. Coping stones should be set so the top of the stones are even, creating a smooth top of the wall.

e. Coping stones should be set level (from the front to the back of the wall).

f. Voids below Coping Stones shall be tightly filled with pinning and hearting stones.

g. Coping Stones should not sit up on pinning stones at the face of the wall. The

Coping Stones should make contact with the wall stones.

C. Dry-Laid Wall Repairs: Section applies to resetting loose stones and installing large stones within existing voids and re-chinking around these stones.

1. Reset loose existing stones at top of walls where indicated in Approved Stone Wall Treatment shop drawings. Follow procedures noted in Dry-Laid Wall section above based on type of stone resetting.

2. Reset loose stones on pinning stones within face of existing walls as follows:

a. Stones should be placed such that there is 3 to 4 points contact with the stone course below. At least two points of contact must be made near front face of the wall.

b. Pinning and hearting shall be carefully placed by hand to fill all voids and gaps between all face stones and backing stones.

c. Drive re-chinking stones into joints at top and sides of reset face stone to wedge in place.

3. Install large stones into voids within existing walls as follows:

a. Size to fill majority of void such that only re-chinking stones fit above and beside it.

b. Stones should be placed such that there is 3 to 4 points contact with the stone course below. At least two points of contact must be made near front face of the wall. Drive stone into place to secure hearting stones behind it.

c. Pinning and hearting shall be carefully placed by hand to fill all voids and gaps between all face stones and backing stones.

d. Drive re-chinking stones into joints at top and sides of reset face stone to wedge in place.

D. Mortared Wall: Section applies to mortared wall extension and repairs.

1. Arrange stones in coursed rubble pattern with joint widths to match existing conditions.

Lay and course the stone masonry such that stone-to-stone contact is provided between all adjacent stones. Insert small stones into spaces between larger stones to produce joints as uniform in width as practical.

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2. Arrange stones with color and size variations uniformly dispersed for an evenly blended appearance.

3. Set stone to comply with existing conditions and requirements indicated on Drawings.

Install supports, fasteners, and other attachments as necessary to secure stone masonry in place. Set stone accurately in locations indicated with edges and faces aligned according to established relationships and indicated tolerances.

4. Maintain joint widths for variations to match existing conditions due to different stone sizes and where minor variations are required to maintain alignment.

5. Do not use mortar when masonry surface temperature is below 40°F or above 90°F.

Protect the mortar from direct sunlight and exposure to wind at temperatures over 80°F to prevent rapid evaporation of water in the mortar.

6. Measure cementitious and aggregate material for use in mortar in a dry condition by volume only. Measure materials with an approved device, not by shovel. Mix materials following recommendations in ACI 531 in a clean mechanical batch mixer. Thoroughly mix cementitious and aggregate materials together before adding any water. Add enough water to produce a damp, unworkable mix that will retain its form when pressed into a ball. Maintain mortar in this dampened condition for 1 to 1-1/2 hrs. Add remaining water in small portions until mortar of desired consistency is reached. Use within 30 minutes of final mixing. Do not re-temper mortar or use partially hardened material.

3.6 CONSTRUCTION TOLERANCES

A. Measure variation from level, plumb, and position as variation of the average plane of the face of each stone from level, plumb, or dimensioned plane to match existing conditions.

B. Variation in Plane between Adjacent Stones: Do not exceed one-half of tolerance for thickness of stone.

3.7 QUALITY CONTROL INSPECTION

A. The Contractor shall employ a testing and inspection agency to perform inspections and to submit reports every day stone walls work occurs.

B. The testing and inspection agency shall review the following checklist and verify conformance with the specifications and drawings for each day’s work:

1. The size and batter of the wall meets the minimum dimensions indicated or existing wall batter.

2. The foundation stones do not wobble when walked on.

3. Stones have been placed in contact with all their neighboring stones.

4. Stones are laid so that vertical joints between stones of adjacent courses do not line up.

5. Hearting and pinning stones are placed with each course.

6. The hearting stones or mortar is placed with no gaps or spaces that allow movement.

7. The spacing and lap of tie stones has been verified.

8. Tie stones are set level and are well pinned and hearted to stones below so weight is shared among stones below tie stones.

9. The coping stones are placed level and do not move easily by hand.

10. Mortar is mixed in the specified proportions.

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11. Mortar that is more than 30 minutes old is discarded.

12. Wall repair stones are engaged to existing stone masonry with re-chinking stones such that repair stones are not easily removable by hand.

13. All Scour Repairs must be inspected and documented following testing protocols established during mockups.

C. The testing and inspection agency shall provide Work Documentation Submittals per schedule included in Section 1.3.

D. Prepare one set of mortar cubes for compression testing in accordance with ASTM C270 for each day’s work. Complete compression tests and provide reports with test results to Contracting Officer.

E. Work that is determined to be non-compliant shall be removed and replaced at no additional cost to the Government.

F. Submit a report to the Contracting Officer for each day’s work.

3.8 CORRECT DEFECTS AND CLEANING

A. Remove and replace stone masonry of the following description:

1. Broken, chipped, stained, or otherwise damaged stone. Stone may be repaired if methods and results are approved by the Contracting Officer.

2. Defective joints.

3. Stone masonry not matching approved samples and mockups.

4. Stone masonry not complying with other requirements indicated.

B. Replace in a manner that result in stone masonry matching approved samples and mockups, complying with other requirements, and showing no evidence of replacement.

C. In-Progress Cleaning: Clean stone masonry as work progresses.

D. Final Cleaning: Clean stone masonry as follows:

1. Test cleaning methods on mockup panels (9 sq ft minimum area for each panel); leave one-half of panel uncleaned for comparison purposes. Complete up to three mockups for each type of cleaning material and method, at locations selected by the Contracting Officer. Obtain the Contracting Officer 's approval of sample cleaning before cleaning stone masonry.

2. Use the cleaning materials and procedures approved during the mockup process to clean all walls from dirt, soot, pollutants, paint, and other foreign contaminants to a level equal to the level of cleanliness of the approved mockup.

3. After all work is complete, perform a final wash-down of all walls using water.

3.9 EXCESS MATERIALS AND WASTE

A. Excess Stone: Stack excess stone where directed by Contracting Officer for Owner's use.

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B. Disposal as Fill Material: Dispose of clean masonry waste, by crushing and mixing with backfill material as backfill is placed.

1. Crush masonry waste to less than 4 inches (100 mm) in greatest dimension.

2. Mix masonry waste with at least two parts of specified backfill material for each part of masonry waste. Backfill material is specified in Division 31 Section 312000 "Earth Moving."

3. Do not dispose of masonry waste as backfill within 18 inches (450 mm) of finished grade.

C. Excess Masonry Waste: Remove excess clean masonry waste that cannot be used as backfill, as described above, and other waste, and legally dispose of off Owner's property.

END OF SECTION 044300

6. Approved mockups may become part of the completed Work if undisturbed at time of Substantial Completion. Install backfill per drawings and specifications.