Revised Specification Section_04 01 00 91.pdf

Section 04 01 00.91 Page 1

SECTION 04 01 00.91

RESTORATION AND CLEANING OF MASONRY IN HISTORIC STRUCTURES

PART 1 GENERAL

1.1 GENERAL REQUIREMENTS

It is the intent of this specification to protect historic structures to the greatest extent possible. Use the gentlest means to perform the work and take the greatest of care to ensure that the historic materials are not damaged in the process of the work. In addition to requirements in this section, comply with NPS Hist Prop.

1.2 REFERENCES

The publications listed below form a part of this specification to the extent referenced. The publications are referred to within the text by the basic designation only.

AMERICAN CONFERENCE OF GOVERNMENTAL INDUSTRIAL HYGIENISTS (ACGIH)

ACGIH 0100 (2001; Supplements 2002-2008) Documentation of the Threshold Limit Values and Biological Exposure Indices

ASTM INTERNATIONAL (ASTM)

ASTM A36/A36M (2014) Standard Specification for Carbon

Structural Steel

ASTM C136 (2014) Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates

ASTM C1364 (2017) Standard Specification for

Architectural Cast Stone

ASTM C144 (2017) Standard Specification for Aggregate for Masonry Mortar

ASTM C1489 (2015) Standard Specification for Lime Putty for Structural Purposes

ASTM C170/C170M (2017) Standard Test Method for Compressive Strength of Dimension Stone

ASTM C207 (2006; R 2011) Standard Specification for

Hydrated Lime for Masonry Purposes

ASTM C270 (2019) Standard Specification for Mortar for Unit Masonry

ASTM E11 (2017) Wire Cloth and Sieves for Testing Purposes

ASTM E2659 (2018) Standard Practice for Certificate

Programs

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ASTM E96/E96M (2016) Standard Test Methods for Water Vapor Transmission of Materials

NATIONAL PARK SERVICE (NPS)

NPS Hist Prop (1995) National Standards for the Treatment of Historic Properties with Guidelines for Preserving, Rehabilitating, Restoring, and Reconstructing Historic Buildings

NPS TPS Brief 1 (2000) Assessing Cleaning and Water-Repellent

Treatments for Historic Masonry Buildings

NPS TPS Brief 2 (1998) Repointing Mortar Joints in Historic Masonry Buildings

U.S. GENERAL SERVICES ADMINISTRATION (GSA)

GSA HTTP 07656-01 Installing Lead Stone Flashing to Protect

Masonry Joints

1.3 DEFINITIONS

Terms are defined below as applicable to this project.

1.3.1 Aggregates

The sand component of mortar.

1.3.2 Biocides

A chemical treatment meant to eliminate organic growth on the masonry units and mortar and prohibit re-growth.

1.3.3 Binder

The component of mortar that binds together the aggregate particles into a cohesive material.

1.3.4 Dispersed Lime Crack Injection / Dispersed Hydrated Lime (DHL)

A repair method in which dispersed lime material is injected into small hairline cracks by use of needle or syringe.

1.3.5 Insitu

A term referencing a repair procedure in which the masonry units and mortar remain in place and are repaired without removal from the wall system.

1.3.6 Joint Sealant

A flexible, chemical product that is used to create a weather-tight seal at the capstone skyward facing joints.

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1.3.7 Mockup

Specific area on the wall approved by Contracting Officer to demonstrate the contractor's ability to apply, match, and install specified materials.

1.3.8 Masonry Treatment Requirement (MTR)

Defined treatments that are required by the specification (contract) documents for project specific repairs to masonry.

1.3.9 New Elements

New, non-historic materials added to masonry structures to aid in their ability to resist loads (typically seismic) or to resist water infiltration.

1.3.10 Pier Capstones

The limestone or precast concrete units that sit on top of the stone piers.

1.3.11 Pitch-faced Stone

A stone that is dimensionally cut with a hammer and chisel. The technique leaves the stone with a rock-faced surface and straight at the edges due to the chisel technique applied. The Boundary Wall was constructed using this stone finishing technique.

1.3.12 Portland Cement Mortar

Mortar that was used to construct the Boundary Wall and repair the Old Post Wall as well as the Center Stone Wall. Generally smeared over the face of the existing stonework.

1.3.13 Random Coursed Ashlar

The bond pattern and stone design that was used in the construction of the Boundary Wall and steps on the Old Post Wall.

1.3.14 Random Rubble

A bond-coursing pattern that was used to construct the Center Stone Wall.

1.3.15 Remediate

The practice of restoring a historic masonry structure and its component materials with the intent to maintain the original fabric to the greatest extent possible.

1.3.16 Remove

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Specifically for historic masonry materials, the term means to detach an item from existing construction to the limits indicated.

1.3.17 Replace

To reinstall an item in its original position (or where indicated) after remedial treatment, or to duplicate and reinstall an entire item with new material; with the original item serving as the pattern for creating the duplicate.

1.3.18 Repoint

To remove existing mortar joints to the specified depth and replace with a mortar that matches in color, texture, and performance with maximum breathability, bond, and flexibility to accommodate movement.

1.3.19 Retool/Redress

A repair method in which a chisel is used to re-create the stone surface texture by removing delamination fragments and loose pieces of stone.

1.3.20 Saturated Surface Dry (SSD)

Defined as a condition of the wall surface after water has been applied and allowed to dry to a point with no standing water visible.

1.3.21 Skyward-facing Joints

Mortar joints that are located between the limestone and precast capstones and face the sky.

1.3.22 Snap-faced Stone Surface

Stone surface designed as a result of quarrying methods to facilitate the use of the stone in construction. The Center Stone Wall is comprised of quarry snap-faced units, which are smooth and flat at the surface.

1.3.23 Soil Grading / Compaction

Areas of the wall sections that require additional soil grading due to erosion shall be identified to reestablish the integrity of the wall structure.

1.3.24 Test Panel

Specific area on the wall approved by the Contracting Officer to demonstrate individual applicator competency in workmanship proficiency.

1.3.25 Wall Capstones

The limestone or precast concrete units that sit on the top of the wall system between the piers.

1.3.26 Wall System

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A term used to address the fact that masonry structures are comprised of different materials but function holistically, requiring that all restoration and cleaning processes take into account the implications of the treatment to the adjacent materials and the structure as a whole.

1.4 PRE-CONSTRUCTION CONFERENCE

Prior to beginning the work of this Section, convene a meeting with the Contracting Officer's Representative(s) to review the requirements of the Quality Control Plan, Project Training Program, installation procedures, location of required mockup areas, and all job conditions and processes.

All subcontracting firms involved with this work shall participate in this meeting.

1.5 SUBMITTALS

Government approval is required for submittals with a "G" designation;

submittals not having a "G" designation are for information only. When used, a designation following the "G" designation identifies the office that will review the submittal for the Government. Submit the following in accordance with Section 01 33 00 SUBMITTAL PROCEDURES:

SD-01 Preconstruction Submittals

Restoration Quality Control Plan G

Qualifications G Project Training Program G

SD-02 Shop Drawings G

Documentation G

SD-03 Product Data

Cleaning and Restoration Methods G Cleaning Materials G Water Infiltration G

SD-04 Samples

Mock-ups G

SD-07 Certificates G

Repair Materials G

1.6 QUALITY CONTROL

Submit resumes for all historic masonry workers, demonstrating the minimum experience required. Product manufacturers, vendors, distributors, or suppliers of materials will not be permitted to offer on-site project training certificates or historic masonry consultation services.

1.6.1 Quality Control Plan

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Prior to beginning restoration and cleaning work, submit a written Quality Control Plan. Include a separate section in the overall project Quality Control Plan specifically addressing this restoration and cleaning work. Do not proceed without written approval of the plan. At a minimum, include the items below in the Quality Control Plan.

a. Describe methods of dust containment during the work, specific to the restoration and cleaning work.

b. Describe the methods of protecting surrounding masonry as well as surrounding landscape. Provide drawings of protection when requested.

c. Describe the work procedures, materials, and tools the contractor proposes to use for each MTR specified.

d. Describe the sequence of each MTR.

e. Describe how the sequence of MTR and the construction schedule changes as it relates to climate changes and protection of completed work.

f. Describe the methods for surveying original layout and collecting datum points and plumb lines for rebuilding masonry.

g. Describe the methods for shoring and providing a safe working environment.

h. Describe the methods for select deconstruction of individual masonry units and tools for cleaning the masonry for reuse.

i. Describe the method and approach to mortar joint removal.

j. Describe the method and approach to cleaning mortar smears and old patching materials from the masonry surfaces.

k. Describe, in detail, the procedures relating to techniques and tools proposed for masonry matching.

l. Describe the complete masonry removal and matching procedures; include equipment, approach, length of time the masonry will be out of the wall, documentation on mapping the location, and where (on-site or in shop) the masonry units will be repaired.

m. Describe the procedure for matching of different colors at different locations.

n. Describe the procedure for mixing and matching of substitute repair materials.

o. Describe the methods and system by which the use of reclaimed masonry units can be utilized.

p. Describe the methods for setting masonry back into its original position and maintaining the original bond patterns and joint width.

q. Describe the methods of transition points where replacement/preservation work will meet the original historic work.

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r. Describe the on-site project-training program. Provide the opportunity for workers to be trained in each masonry treatment requirement (MTR) as work proceeds.

s. Describe the mortar joint cleaning process prior to repointing to remove biological growth and plant residue.

1.6.2 Qualifications

1.6.2.1 Masonry Firm

The firm performing the masonry work shall have a minimum of five years of experience on similar projects. The firm shall have completed work similar in material, design, and extent to that indicated for this Project and shall demonstrate a record of successful in-service performance. Proven implementation of NPS Hist Prop and related Preservation Briefs are required. Provide Point of Contact, phone number and final rating.

1.6.2.2 Field Supervision

Retain an experienced full-time supervisor on the project site at all times when masonry restoration is in progress. A single individual shall be responsible for supervising the historic masonry restoration work throughout the duration of the project.

1.6.2.3 Masonry Applicator

Employ craftspeople that are experienced with and specialize in restoration work of the types they will be performing. All masonry restoration treatments must be performed by a craftsperson that is familiar with historic masonry construction and has worked on historic masonry projects for at least five years. Only skilled journeyman masons who are familiar and experienced with the materials and methods specified may be used.

1.6.3 Project Training Definition and Use

It is desirable that workers be trained for each project specific task they will perform to ensure the highest quality results from the cleaning and restoration program.

The Project Training Program is the program by which the contractor provides instruction to workers prior to the beginning of a masonry task that requires specialized historic preservation methodology or considerations.

Such tasks are mentioned in this document by indicating that workers should have specialized training for each specific task that requires it. The contractor’s plan should address which tasks will have specialized training provided and by whom the training will be provided.

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1.6.4 Documentation

Submit digital photographic documentation of the all phases of masonry restoration, including prior to the start of restoration work. Provide thorough photo documentation of the project and project details and targeted areas.

1.6.5 Cleaning and Restoration Mock-ups

1.6.5.1 Cleaning and Restoration Methods

Submit the cleaning and restoration methods, and materials selected for a specific wall for approval before work starts. Take into account the total construction system of the wall to be worked upon, including different masonry and mortar materials, as well as non-masonry elements, which may be affected by the work. Utilize mockups to identify the appropriate cleaning and restoration treatment and materials and set the standard for each project task.

It is desirable that workers be trained for each project specific task they will perform to ensure the highest quality results from the cleaning and restoration program.

1.6.5.2 Cleaning Products and Procedures

Establish cleaning products and procedures during the mockup process;

selecting the least aggressive method used to achieve the desired level of clean. Where chemical products are selected for cleaning, use them in accordance with the manufacturer's instructions.

1.6.6 Masonry Mock-ups

Present mock-ups submittals of each treatment proposed for use in the work.

No masonry or mortar shall be used in the work until the mock-ups and the represented material and workmanship have been approved. Materials shall be submitted and approved prior to the creation of mock-ups. The location for placement, size, and location of the mock-ups will be as directed by the Contracting Officer.

Mock-ups shall demonstrate the methods and quality of workmanship to be performed in each masonry treatment requirement (MTR). Provide a mockup for each MTR indicated and included in related specification Sections.

a. Prepare mock-ups on existing walls under the same weather conditions expected during the remainder of the work.

b. Throughout restoration, retain approved mock-up panels in undisturbed condition, suitably marked, as a standard for judging completed work.

c. Review manufacturer's product data sheets to determine suitability of each product for each surface.

d. Apply products using manufacturer-approved application methods, determining actual requirements for application.

e. Obtain approval as to the preservation treatment approach, design, and workmanship to include, but not limited to the verification of all

Section 04 01 00.91 Page 9 material applications and finishes as specified to the requirements of color, texture, profiles, and finishes before proceeding with work.

f. Mock-ups: May be performed on inconspicuous sections of actual construction

(1) Location and number as directed, but no more than six(6)sq. ft.

(2) Size: 600 mm by 900 mm (2 feet by 3 feet) or as appropriate for the repair specified

(3) Repair unacceptable work.

1.6.6.1 Repointing

Repoint mortar joints, minimum acceptable mock up dimensions: twelve feet in length - 2/3 horizontal joints and 1/3 vertical joints. Demonstrate method for cutting out mortar joints, preparing wall for repointing, mixing mortar, installing mortar, and curing the mortar. Prepare and place repointing mortar in accordance with NPS TPS Brief 2 and in compliance with NPS Hist Prop.

a. Repoint a mortar joint using an existing matching ribbon tool to match existing joint profiles. Repoint six (6) lineal feet.

b. Repoint a mortar joint using a concave rodding joint profile. Repoint six (6) lineal feet.

c. Repoint a mortar joint using a flush-cut method to match existing joint profiles. Repoint six (6) lineal feet.

1.6.6.2 Retooling/Redressing Stone Masonry Insitu

Demonstrate treatment technique and methods to retool three deteriorated stone faces insitu in all known historic profile textures identified.

Finishes include, but are not limited to, pitch-faced and snap-faced finishes.

1.6.6.3 Masonry Removal and Replacement

Fully remove masonry and replace to specified dimensions and texture. Select size of masonry units representing typical conditions. Return one masonry unit to same location, set to surrounding profile joint width and bond pattern. Set masonry unit using specified mortar. Confirm with Contracting Officer's Representative that the replacement masonry units meet specification requirements for matching and that sufficient quantity required for the work have been identified. Leave one stone dry-set into opening set on wood shims for evaluation and approval of preparation conditions.

1.6.6.4 Precast Concrete Repair Material

Precast Concrete Patching - Apply material on at least two precast concrete units for repair. Include one unit on which to demonstrate proficiency in removing previous patching material and repairing with new concrete repair material. Include the treatment of rusted rebar at two locations at pier capstone (where applicable).

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1.6.6.5 Crack Repair (DHL)

Repair one crack, 600 mm (2 feet) in length, using DHL mortar. Repair one crack, 300 mm (12 inches) in length; using dispersed hydrated lime injection technique with appropriate Spachtel repair material.

1.6.6.6 Joint Sealant Installation

Install joint sealant with backing at three (3) locations demonstrating the manufacturer’s recommendations for application. One installation on a limestone capstone skyward-facing mortar joint; one installation on a precast concrete skyward-facing mortar joint; and one installation on the concrete curb skyward-facing mortar joint.

1.7 DELIVERY, STORAGE, AND HANDLING

Furnish cement in suitable bags used for packaging cements. Labeling of packages shall clearly define contents, manufacturer, and batch identification. Detergents, masonry cleaners, paint removers, solvents, epoxies, and other chemicals used for masonry cleaning shall be in sealed containers that legibly show the designated name, formula or specification number, quantity, date of manufacture, manufacturer's formulation number, manufacturer's directions including any warnings and special precautions, and name of manufacturer. Store materials in weather tight structures, which will exclude moisture and contaminants. Accessories shall be stored avoiding contamination and deterioration. Admixtures which have been in storage onsite for six months or longer, or which have been subjected to freezing, shall not be used unless retested and proven to meet the specified requirements.

1.8 FIELD CONDITIONS

1.8.1 General Ambient Conditions

Masonry, mortar, and epoxy adhesives shall not be placed when weather conditions detrimentally affect the quality of the finished product. No masonry or mortar shall be placed when the air temperature is below 5 degrees C (40 degrees F) in the shade. When air temperature or stone masonry material is likely to exceed 35 degrees C (90 degrees F) masonry and mortar shall have a temperature not exceeding 35 degrees C (90 degrees F) when deposited. Materials to be used in the work shall be neither produced nor placed during periods of rain or other precipitation. Stop material placements, and protect all in-place material from exposure during periods of rain or other precipitation. Masonry surfaces shall be cleaned only when air temperatures are above 5 degrees C (40 degrees F) and will remain so until masonry has dried out, but for not less than 7 days after completion of the work.

1.8.2 Masonry Installation Conditions

Do not perform any masonry repointing unless air temperatures are between 10 degrees C (40 degrees F) and 35 degrees C (90 degrees F) and will remain so for at least 48 hours after completion of work. Phase repointing during hot weather by completing process on the shady side of the wall or schedule installation of materials during cooler evening hours to prevent premature

Section 04 01 00.91 Page 11 evaporation of the water from the mortar. Do not use frozen materials or materials mixed or coated with ice or frost. Do not lower the freezing point of mortar by the use of admixtures or anti-freeze agents. Do not add chlorides to the mortar. Prevent repointing mortar from staining the face of the masonry or other exposed surfaces. Immediately remove all repointing mortar that comes in contact with such surfaces. Cover partially completed work when work is not in progress. Protect sills, ledges, and projections from mortar droppings. If the Contractor fails to protect against damage as a result of work of this Section, such damage shall be the Contractor's responsibility. The Contractor shall restore damaged areas to the complete satisfaction of the Owner at no expense to the Owner. Do not apply products under conditions outside manufacturer's requirements, which include:

a. Surfaces that are frozen; allow complete thawing prior to installation.

b. Surface and air temperatures below 5 degrees C (40 degrees F).

c. Surface and air temperatures above 35 degrees C (90 degrees F).

d. When surface or air temperature is not expected to remain above 5 degrees C (40 degrees F) for at least 48 hours after application.

e. Wind conditions that may blow materials onto surfaces not intended to be treated.

1.9 WARRANTIES

1.9.1 Cleaning Warranty

Warrant cleaning procedures for a period of two years against harm to substrate (masonry and mortar) or to adjacent materials including, but not limited to, discoloration of substrate from improper procedures or usage, chemical damage from inadequate rinse procedures, and abrasive damage from improper procedures.

1.9.2 Repair Warranty

Warrant repair procedures, including repointing, for a period of two years against: discoloration or mismatch of new mortar to adjacent original historic mortar, discoloration or damage to masonry from improper mortar clean-up, loss of bond between masonry and mortar, fracturing of masonry edges from improper mortar joint preparation procedures, or improper mortar formulation, and occurrence of efflorescence.

PART 2 PRODUCTS

2.1 CLEANING MATERIALS

Selection of appropriate cleaning products requires a clear understanding of the masonry materials to be cleaned, a rationale for the cleaning, and an understanding of the anticipated level of cleanliness expected from the cleaning program. Caution against over-cleaning of surfaces which may be detrimental, and which may remove desirable historic surface details or patinas. For example, if cleaning reveals unexpected joint deterioration of stone damage: suspend the cleaning action, protect the exposed area, and notify the Contracting Officer. Research has determined that overly aggressive cleaning methods and materials can cause subtle, long-term damage

Section 04 01 00.91 Page 12 to masonry units. Use products that have a minimum 5-year performance record on similar projects. Selection of the products shall be predicated on long-term negative effects to the masonry rather than current level of cleanliness of the comparable structure.

2.1.1 Chemical Cleaners

Chemical cleaners range from acidic to alkaline in their chemical makeup.

Along with the cleaner, provide the associated pre and post treatment material to neutralize the long-term effects of the chemicals. All products shall be commercially available and have a proven record of cleaning masonry without altering, damaging or discoloring the masonry units or mortar.

2.1.2 Biocides

Biocides are designed to remove organic growth from masonry. The manufacturer's literature for all biocides shall contain information on the product as well as the expected service life of the material and any detrimental effects it may have on the masonry or mortar.

Product: D/2 Biological Solution, or approved equal.

Product Distributor: Cemetery Preservation Supply, LLC, 10122 Cherry Tree Drive, Dallas, Texas 75243.

2.1.5 Cleaning Implements

Furnish brushes that contain natural or nylon fiber bristles only. Do not use wire brushes. Scrapers and application paddles shall be made of wood with rounded edges. Metallic tools are not permitted.

2.1.6 Water

Obtain potable water from a local source. Filter to remove minerals resulting in a neutral pH, prior to application.

2.2 REPAIR MATERIALS

Use materials, physical and chemical properties, and composition of masonry and mortar in renovation work that match the original existing masonry and mortar to be repaired, unless samples and testing determine that existing mixtures and materials are faulty or non-performing. Masonry materials used for repair and renovation shall match the original existing historic materials as closely as possible in composition, color, texture, strength, size, finishing, and porosity.

2.2.1 Mortar

The replacement mortar shall coexist with the old in a sympathetic, supportive and, if necessary, sacrificial capacity. The replacement mortar shall have greater vapor permeability and be softer (measured in compressive strength) than the masonry units. The replacement mortar shall be as vapor permeable, and as soft, or softer, (measured in compressive strength) than the existing historic mortar. Measure water vapor transmission in accordance with ASTM E96/E96M.

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Acceptable manufacture: U.S. Heritage Group, Inc., 3516 N. Kostner Ave., Chicago, IL 60641, Phone 773-286-2100 or approved equal.

2.2.1.1 Matching

Take test samples of existing mortar from a sound and intact representative portion of the wall, at the Center Stone Wall, Old Post Wall (2-locations) and the Boundary Wall (2-locations). The replacement mortar shall match the original existing material in color, texture, and tooling. The sand shall match the sand in the original existing mortar by color, shape, and particle size distribution as defined using ASTM C144; ASTM E11 sieves. Use of admixtures is subject to approval. The mortar matching analysis and laboratory reports are attached as an appendix to this specification.

2.2.1.2 Replacement Mortar Formulation Mix Designs

Based upon the findings from the mortar analysis the following mortar formulations have been determined to match the requirements for this project:

a) Center Stone Wall: NPS TPS Brief 2, Type “L”, 1 parts hydrated lime and 3 parts aggregate.

b) Old Post Wall: ASTM C270 proportion specification, Type O, 1 part Portland cement, 2 parts hydrated lime, 9 parts aggregate.

c) Boundary Wall: ASTM C270 proportion specification, Type N, 1 part

Portland cement 1-1/4 parts hydrated lime and 6 parts aggregate. This mix design shall be used for below grade repointing and all mortar washes on all walls.

2.2.1.3 Binder Content of Historic Mortar

Historic mortars can represent four different binder types, or combination of them, depending on the time period of construction. A wall constructed in the early 1800s is likely built with a straight lime putty binder type because the discovery of natural cement binder types had not occurred until the early 1820s. A wall constructed in 1940 might be built with Portland cement (1871) and hydrated lime (1930s). The historic binder types include:

non-hydraulic lime (fat lime, lime putty or hydrated lime); hydraulic lime (feebly, NHL 2, moderately, NHL 3.5, and imminently, NHL 5.0); natural cement; and Portland cement. The binder types are all derived from limestone. Each successive type is fired at higher temperatures in a kiln to the point of vitrification or liquid phase (2200-2800F) when Portland cement is developed. Lime can be slaked into a hydrate powder or putty form by adding water due to the lower firing temperatures (1650-2000F), while cement products must be crushed mechanically into a powder form before use. Each binder type has its own unique performance properties in relation to historic masonry units and the wall design. A mortar formula made from lime putty (low compressive strength) will accommodate wall movement in load-bearing masonry much more effectively than a Portland cement formula of much higher compressive strength. Identify performance characteristics of the replacement mortar carefully based upon evaluation of the existing historic mortar. Each binder type or mixture of mortar (and stucco) shall have a cement, lime, or combination thereof consistent with the original existing mortar (and stucco) content in order to provide uniform durability, Section 04 01 00.91 Page 14 weathering characteristics, and the same, or better, life-cycle performance expectations.

2.2.1.4 Crack Injection

Comply with the dispersed hydrated lime manufacturer’s written instructions.

Inject cracks that are no greater than 3 mm (1/8 inch) in width and masonry is soundly bonded but cracked. Unless specifically instructed inject the full length of the cracks.

Product: Dispersed Hydrated Lime Injection Mortar DHL-IM; Product:

Spachtel Surface Treatment color matched to limestone or precast concrete surface, or approved equal. Distributed by U.S. Heritage Group, Inc., 3516 N. Kostner Ave., Chicago, Il 60641. Phone: 773-286-2100.

2.2.1.5 Precast Concrete Patching

Take test samples of existing precast concrete from a sound area representative of the capstone units. The test samples are to be delivered to a manufacturer for proper matching and formulation of a replacement patching repair material. A matching 3/8” aggregate will be required to be added to this mix design. Test replacement precast patching material in comparison to the existing historic precast concrete using ASTM C1364.

Note: A surface retarder will also need to be applied after the concrete has been poured in order to remove the cementitous paste and expose the 3/8” aggregate after the forms have been removed.

Product: Reconstec 300 AC, part A, or approved equal. Manufacturer:

Constec Inc., 914 Berlier, Laval (Qc) H7L 4K5, Canada. Phone: 450-967- 0792.

2.2.2 Replacement Masonry Materials

2.2.2.1 Replacement Stone

Replacement stone shall match in type, color, shape, size, texture, and finish-profile to the appearance of the existing historic stone units. Test replacement stone in comparison to the existing historic stone using ASTM C170/C170M.

Product: Silverdale Limestone, or approved equal, for pier caps and wall caps on the center stonewall. Smooth-saw finish with slightly chamfered edges to match original historic stone profiles. Distributor:

Earthworks, 4287 N. Hwy 51, Perryville, MO 63775.

Product: Lannon Sussex Dimensional to fabricate to specific sizes and lightly sandblast to match the texture of the stone on the boundary wall, or approved equal. Distributor, Earthworks, 4287 N. Hwy 51, Perryville, MO 63775.

2.2.2.2 Concrete Repair Material

Replacement concrete shall match in color, shape, size, texture and finish-profile to the appearance of the existing historic steps.

Product: SikaTop 111 Plus, or approved equal. Sika Corporation, 201 Polito Avenue, Lyndhurst, NJ 07071, Phone 800-933-SIKA.

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2.2.3 Masonry Elements

2.2.3.1 Metal attachments

Anchors for spall repairs shall be threaded stainless steel, size as indicated. Other plates, angles, anchors, and embedments shall conform to ASTM A36/A36M, and shall be prime painted with inorganic zinc primer.

2.2.3.2 Through-Wall Flashing

A lead-coated copper (12 oz.) flashing shall be set into position beneath the new capstones directly on the stone wall with over lapping joints of 3 inches sealed into place with the specified sealant. The flashing shall run lengthwise down the wall and project from beneath the capstones ¼ inch from the face of the bed joints on both sides.

2.2.3.3 Rust Inhibiting Coating

Chemically active, rust-inhibitive primer for exposed rebar conditions. Low VOC primer provides extended weathering for field priming of steel.

Product: Tnemec Primer Series V10, Red, or approved equal.

Manufacturer: Tnemec, 6800 Corporate Drive, Kansas City, MO 64120, Phone: 816-483-3400.

2.3 EQUIPMENT

2.3.1 Cleaning Equipment

Cleaning equipment shall not cause staining, erosion, marring, or other damage or changes in the appearance of the surfaces to be cleaned.

2.3.1.1 Sandblasting

Sandblasting equipment is not allowed for cleaning masonry surfaces.

2.3.1.2 Water Blasting

Provide water blasting equipment including a trailer-mounted water tank, pumps, high-pressure hose, wand with safety release cutoff control, nozzle, and auxiliary water re-supply equipment. Do not operate the equipment at a pressure, which will cause etching or other damage to the masonry surface or mortar joints. Operate the equipment at a discharge capacity of 0.38 to 3.0 MPa (55 to 400 psi) and 9.5 to 11.4 L/m (2.5 to 3 gpm) for general surface cleaning operations. The water tank and auxiliary re-supply equipment shall be of sufficient capacity to permit continuous operations. Provide

Section 04 01 00.91 Page 16 protective covers and barriers as required to prevent over-spray onto adjacent surfaces.

2.3.2 Spray Equipment

Spray equipment for chemical cleaners shall be low-pressure tanks or chemical pumps suitable for chemical cleaner indicated, and shall be equipped with stainless steel, cone-shaped spray-tip. Spray equipment for water shall disperse water through a fan-shaped spray tip at an angle of not less than 15 degrees. Spray equipment shall deliver water at a pressure not greater than 3.0 MPa (400 psi) and at a volume between 9.5 and 11.4 L/m (2.5 and 3 gpm). Spray equipment for heated water shall be capable of maintaining temperature, at flow rates indicated, between 60 and 82 degrees C (140 and 180 degrees F). Keep the spray-tip at a 508 mm (20-inch) minimum distance from the wall surface during operations.

2.3.3 Alternative Blasting Methods

Alternative blasting methods require equipment designed to discharge sponges, walnut shells, ice, soda, and other friable materials. These are specially designed systems that must be operated in accordance with manufacturer's recommendations and maintained in good working order. Do not operate the equipment at a pressure, which will cause etching or other damage to the masonry surface or mortar joints. Determine the discharge capacity on a case-by-case basis during the mockup test panel demonstration and approval process. Provide protective covers and barriers as required to prevent over-spray onto adjacent surfaces.

2.3.4 Drilling Equipment

Use standard handheld masonry drills, commonly used for drilling small holes in concrete and masonry to drill holes in masonry for patch anchors and other applications. The drill shall be a small, powered, handheld type, using rotary drilling mode only. Impact and rotary impact type drills will not be allowed.

2.3.5 Compressed Air Supplies

Compressed air equipment shall deliver clean, oil and moisture free compressed air at the surface to be cleaned. The compressed air line shall have at least two in-line air filters to remove oil and moisture from the air supply. Test the compressed air supply during each shift for the presence of oil and moisture.

PART 3 EXECUTION

3.1 EVALUATION AND ANALYSIS

Mortar evaluation and analysis report is available upon request from the

COR.

3.2 PREPARATION

3.2.1 Material Handling and Associated Equipment

3.2.1.1 Mixing, Transporting, and Placing Job Materials

Provide equipment used for mixing, transporting, placing, and confining

Section 04 01 00.91 Page 17 masonry and mortar placements capable of satisfactorily mixing material and supporting uninterrupted placement operations. Equipment used for mixing, conveying, and placing of materials shall be clean, free of old materials and contaminants, and shall conform to the material manufacturer's recommendations.

3.2.1.2 Associated Equipment

Provide associated equipment, such as mixer timing equipment, valves, pressure gauges, pressure hoses, other hardware, and tools, as required to ensure a continuous supply of material and operation control.

3.2.2 Protection

Protect persons, motor vehicles, adjacent surfaces, equipment, and landscape materials from chemicals used and runoff from cleaning operations. Erect temporary protection covers, which will remain in operation during the course of the work, over pedestrian walkways and at personnel and vehicular points of entrance and exit.

3.2.2.1 Tree and Landscape Protection

Protect the trees and root systems from cleaning and repair operations at all times. Use tarps to collect fallen debris in order to protect grass and landscape areas.

3.2.2.2 Worker Exposures

Exposure of workers to chemical substances shall not exceed the limits established by ACGIH 0100, or those required by a more stringent applicable regulation.

3.3 EQUIPMENT AND TECHNIQUES DEMONSTRATION

Demonstrate equipment and techniques of operation in an approved location.

Dependable and sufficient equipment, appropriate and adequate to accomplish the work specified, shall be assembled at the work site in sufficient lead time before the start of the work to permit inspection, calibration of weighing and measuring devices, adjustment of parts, and the making of any repairs that may be required. Maintain the equipment in good working condition throughout the project.

3.4 MASONRY CLEANING (MTR-1)

restoration program.

Historic materials shall not be damaged or marred in the process of cleaning. Cleaning shall conform to NPS TPS Brief

1. It is not the intention of this specification to clean all masonry surfaces. Only those specific areas that require repointing work shall be cleaned to ensure proper bond strength of the new replacement mortar. Thus it is understood that some open mortar joints will be cleaned allowing some water into the wall cavity. The walls should be allowed to dry-out after cleaning for a period of seven days prior to repointing. Protect non-masonry materials and severely deteriorated masonry by approved methods prior to initiation of cleaning operations. Masonry cleaning shall remove all

Section 04 01 00.91 Page 18 organic and inorganic contaminants from the surface and pores of the substrate, without causing any short or long-term negative consequences.

Surfaces shall be evenly cleaned with no evidence of streaking or bleaching.

The cleaning process shall not affect the density, porosity, or color of the masonry or mortar. Cleaned masonry shall have a neutral pH. Use the gentlest methods possible for cleaning historic masonry to achieve the desired results. Make test patches to determine a satisfactory cleaning result. The cleaning materials, equipment, and methods shall not result in staining, erosion, marring, or other damage to the surfaces of the structure.

Following an initial inspection and evaluation of the wall and mortar joint surfaces, give the wall a surface cleaning which shall be completed prior to start of repointing work. The following sequence of methods shall be used to determine the least aggressive, effective cleaning method:

1. Water with brushes

2. Water with mild soap

3. Water with stronger soap

4. Water with stronger soap plus ammonia

5. Water with stronger soap plus vinegar (but not on calcareous, chalky, masonry)

6. Stronger chemical cleaners, only when above methods are determined to be ineffective by the Contracting Officer

7. Allow the wall to dry a minimum of seven days prior to repointing

3.4.1 Chemical Cleaners

Do not use acidic chemical cleaners on limestone, concrete, and other calcareous (calcium containing) masonry materials. If chemical cleaners are used on such materials, they shall be alkaline based and utilized with neutralizing afterwashes.

3.4.2 Test Patches

Demonstrate the materials, equipment, and methods to be used in cleaning on a test section approximately 1 m by 1 m (3 feet by 3 feet). The location of the test section, and the completed test section is subject to approval.

Adjust the cleaning process as required and the test section rerun until an acceptable process is obtained. Locate test patches in inconspicuous areas of the walls. The areas tested shall exhibit soiling characteristics representative of those larger areas to be cleaned. Allow tested areas to dry before a determination is made on the effectiveness of a particular treatment.

3.4.4 Water Cleaning

3.4.4.1 Pressure Spraying

Spray water to masonry surfaces to comply with requirements indicated by test patches for location, purpose, water temperature, pressure, volume, and equipment. Unless otherwise indicated, the surface washing shall be done with clean, low pressure water (pressure of less than 0.38 MPa (400 psi) and

9.5 to 11.4 L/m (2.5 to 3 gpm) discharge) and the spray nozzle shall not be held less than 508 mm (20 inches) from surface of masonry. Water shall be applied side to side in overlapping bands to produce uniform coverage.

3.4.4.2 Hand Scrubbing

Pre-wet surfaces and use hand-held natural bristle or nylon brushes. Scrub surfaces to be cleaned to remove surface contaminants. Do not use wire

Section 04 01 00.91 Page 19 brushes.

3.4.4.3 Rinsing

Rinse scrubbed surfaces clean of all contaminants and cleaning solutions with water in a low-to-moderate pressure spray, working upwards from bottom to top of each treated area. The rinsing cycle shall remove all traces of contaminants and cleaning solutions.

3.4.5 Chemical Cleaning

Chemical cleaning of historic masonry shall use the gentlest means possible to achieve the desired result as determined by test patches. Chemical cleaning is the use of any product in addition to water, including detergents, ammonia, vinegar, and bleach. Proceed in an orderly manner, working from bottom to top and from one end of each elevation to the other.

Cleaning shall result in uniform coverage of all surfaces, including corners, moldings, interstices, and produce an even effect without streaking or damage to masonry. Do not apply chemical cleaners to the same masonry surfaces more than twice.

3.4.5.1 Surface Prewetting

Wet with water any masonry surfaces to be cleaned with chemical cleaners using a low-pressure spray before application of any cleaner.

3.5 MASONRY REPAIR

Match repaired surfaces with adjacent existing surfaces in all respects.

Proceed with masonry repair only after the cause of deterioration has been identified and corrected. Demonstrate the materials, methods, and equipment proposed for use in the repair work in test panels. The location, number, size, and completed test panels are subject to approval. Use products in accordance with the manufacturer's instructions.

3.5.1 Repointing Masonry (MTR-2)

Repoint masonry in accordance with NPS TPS Brief 2.

3.5.2.1 Wall Preparation (MTR-3)

Remove old caulking, grout, or non-original mortar from previously repaired joints to a minimum depth of 2.5 times the width of the joint. Cut all joints (unless otherwise noted) back to sound, solid, back up material.

Leave a clean, square face at the back of the joint to provide for maximum contact of repointing mortar. Capture any debris and remove from project site. It is desirable that workers be trained for each project specific task they will perform to ensure the highest quality results from the cleaning and restoration program.

a. Shallow or feather edging is not permitted. Remove loose particles from joints. Clean joints, followed by blowing with filtered, dry, compressed air or vacuum.

b. Existing horizontal mortar joints (bed joints) that are filled with a

Section 04 01 00.91 Page 20 hard Portland mortar may be cut out using a diamond blade that is narrower than the joint width. The middle one-third of the mortar joint may be cut using a rotary power saw. The remaining mortar shall be removed from the masonry joints by hand using masonry chisels or pneumatic carving tools.

c. Vertical joints (head joints) shall not be cut out using rotary power saws. All vertical head joints must be removed by hand using a pneumatic carving tool, or hammer and chisel.

d. Remove existing historic lime-based mortar using only small-headed chisels that are no wider than half the width of the existing masonry joints. Pneumatic air carving chisels are permitted as are specially designed mortar removal reciprocating tools (i.e. Arbortech Saw).

e. Do not widen the existing masonry joints. The surrounding masonry edges shall not be spalled or chipped in the process of mortar removal.

Damage to surrounding masonry units resulting from rotary blade over running is not permitted. Replace all masonry units damaged during mortar removal with replacement units that match the original.

f. Permit workers to be trained at the project site in this masonry treatment requirement.

3.5.2.2 Mixing and Installation

Repointing mortar shall be pre-blended in single containers in a factory-controlled environment.

Repointing mortar may be site mixed, Type N, Type O, and Type “L”. Ensure appropriate material proportions as regards to the affect of moisture content on the individual components (cement, sand, and lime). Batch materials using volumetric measurement devices (not shovels) and consistently consolidate the material in these devices to ensure the uniformity of the mortar.

a. Batching

(1) Utilize a calibrated measuring device for batching Portland cement.

(2) Utilize a calibrated measuring device for batching hydrated lime or lime putty.

(3) Utilize a calibrated measuring device for batching the sand.

b. Cement and Lime Proportions: Fill the measuring device with Portland cement and hydrated lime.

(1) Briskly strike the bottom of the measuring device against the ground a minimum of ten times and then strike the top flush.

(2) For dry hydrate lime, fill the measuring device using a minimum of 3 lifts, strike the bottom of the measuring device against the ground a minimum of ten times and then strike the top flush. Dry hydrate lime experiences a significant volumetric loss when converted to a wet paste during mixing; therefore, add additional 25 percent dry hydrate lime to the formulation.

Section 04 01 00.91 Page 21

c. Sand Proportions

(1) Proportion sand when the sand is in saturated surface dry (SSD), loose damp condition.

(2) Proportion the sand by filling a measuring device using a minimum of 3 lifts, striking the ground a minimum of ten times, and then striking the top flush.

3.5.2.3 Mortar Formulations (combined by volume)

(1) Type N: 1 part Portland cement, 1-1/4 parts hydrated lime, 6 parts sand

(2) Type O: 1 part Portland cement, 2 parts hydrated lime, 9 parts sand

(3) Type “L”: 1 parts hydrated lime, 3 parts sand

3.5.3 Presoaking Masonry / Mortar Consistency / Lifts

Use the same mortar as the repointing mortar for setting the replacement masonry. Soak exposed surfaces of historic masonry adjacent to joint with water prior to repointing. Allow time for excess water to run off and evaporate prior to repointing. Joint surfaces shall be damp but free from standing water. Maintain a water sprayer on site at all times during the repointing process. The mortar material shall resemble the consistency of brown sugar during installation. This drier consistency enables the material to be tightly packed into the joint, allows for cleaner work, and prevents shrinkage cracks as the mortar cures. Repoint joints in layers or "lifts" where the joints are deeper than 32 mm (1-1/4 inch). Apply in layers not less than 1/2 the depth but not more than 32 mm (1-1/4 inch) or until a uniform depth is formed.

3.5.4 Compression / Joint Finish / Curing

a. Compress each layer thoroughly and allow it to become thumbprint hard before applying the next layer.

b. When mortar is thumbprint hard at the surface of the wall, finish the joints to match the original historic joint profile. Allow water evaporation from the freshly repointed walls in order to initiate the carbonation process in high lime content mortars. The carbonation of lime mortar initially requires wet-and-dry cycles, which can be created by water misting the joints after the mortar application when dry weather conditions prevail. Finish the joint profile before these cycles are started. Depending on the environmental conditions (temperature and humidity), carry out water misting until a full nine alternating wet-and-dry cycles are completed. Mist the wall with water 3 times per day for the first three days after installation when temperatures exceed 90°F. Do not repoint mortar into stone that exceeds 90°F.

c. Adjust curing methods to ensure that the repointing mortar is damp without eroding the surface of the mortar.

3.5.5 Protection

Keep the mortar from drying out too quickly or from becoming too wet.

Protect it from direct sun and high winds for the first 72 hours after installation or from driving rain for the first 24 hours, using Burlene sheeting (burlap/canvas material) if necessary. Be careful not to create a

Section 04 01 00.91 Page 22 greenhouse effect by sealing off air movement in an attempt to protect the wall. Allow for air circulation to facilitate the carbonation process.

3.5.6 Retooling/Redressing Stone Masonry Insitu (MTR-4)

Scale off all loose pieces of original stone from masonry intended to remain in place, including surface material in powder or granular form and detachments of planer elements, spalls and chips. Capture any debris and remove from project site. Sound all stone on wall by using the "ring test method" in order to distinguish fully intact stone from those in which delamination may be hidden or pieces of unstable material may not be immediately visible. Any stone that is designated for retooling/redressing insitu can became a candidate for removal if, after chiseling is completed, the solid stone substrate is no longer in plane or plumb with the surrounding stone masonry surfaces.

It is desirable that workers be trained for each project specific task they

3.5.7 Stone Masonry Unit Removal and Replacement (MTR-5)

Before removing any deteriorated masonry units, establish bonding patterns, levels, and coursings.