USACE / NAVFAC / AFCESA / NASA UFGS-04 01 40 (April 2006)
--------------------------
Preparing Activity: USACE Replacing without change
UFGS-04900 (December 2003)
UNIFIED FACILITIES GUIDE SPECIFICATIONS
References are in agreement with UMRL dated January 2009
SECTION 04 01 40
RESTORATION AND CLEANING OF MASONRY IN HISTORIC STRUCTURES
04/06
NOTE: This guide specification covers the requirements for restoration and
cleaning of masonry in historic structures.
Edit this guide specification for project specific requirements by adding, deleting,
or revising text. For bracketed items, choose applicable items(s) or insert
appropriate information.
Remove information and requirements not required in respective project, whether
or not brackets are present.
Comments and suggestions on this guide specification are welcome and should
be directed to the technical proponent of the specification. A listing of technical
proponents, including their organization designation and telephone number, is
on the Internet.
Recommended changes to a UFGS should be submitted as a Criteria Change Request
(CCR).
PART 1 GENERAL
NOTE: Where the words "as indicated" are used, ensure that sizes, positions
and other designated information are indicated on the design drawings.
The following publications, from the United States Department of the Interior
- National Park Service, provide useful guidance in the restoration of historic
masonry and may be included as addenda to the specifications.
The Secretary of the Interior's Standards for the Treatment of Historic Properties
with Guidelines for Preserving, Rehabilitating, Restoring, and Reconstructing
Historic Buildings (1995).
Preservation Brief #1 - (1975) The Cleaning and Waterproof Coating of Masonry
Buildings
Preservation Brief #2 - (1976) Repointing Mortar Joints in Historic Brick Buildings
Preservation Brief #6 - (1979) Dangers of Abrasive Cleaning to Historic Buildings
Preservation Brief #7 - (1979) The Preservation of Historic Glazed Architectural
Terra-Cotta
1.1 REFERENCES
NOTE: This paragraph is used to list the publications cited in the text of
the guide specification. The publications are referred to in the text by basic
designation only and listed in this paragraph by organization, designation,
date, and title.
Use the Reference Wizard's Check Reference feature when you add a RID outside
of the Section's Reference Article to automatically place the reference in the
Reference Article. Also use the Reference Wizard's Check Reference feature
to update the issue dates.
References not used in the text will automatically be deleted from this section
of the project specification when you choose to reconcile references in the
publish print process.
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.
[ACI INTERNATIONAL (ACI)ACI C-20(1992) Repair and Rehabilitation II][AMERICAN CONFERENCE OF GOVERNMENTAL INDUSTRIAL HYGIENISTS (ACGIH)ACGIH 0100Doc(2005) Documentation of the Threshold Limit Values and Biological Exposure Indices][ASTM INTERNATIONAL (ASTM)ASTM A 36/A 36M(2008) Standard Specification for Carbon Structural SteelASTM C 109/C 109M(2008) Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or (50-mm) Cube Specimens)ASTM C 1324(2005) Standard Test Method for Examination and Analysis of Hardened Masonry MortarASTM C 150(2007) Standard Specification for Portland CementASTM C 1515(2001) Standard Guide for Cleaning of Exterior Dimension Stone, Vertical and Horizontal Surfaces, New or ExistingASTM C 207(2006) Standard Specification for Hydrated Lime for Masonry PurposesASTM C 881/C 881M(2002) Standard Specification for Epoxy-Resin-Base Bonding Systems for Concrete][BRICK INDUSTRY ASSOCIATION (BIA)BIA Tech Note 20(1990; R 2000) Cleaning Brick Masonry]1.2 SUBMITTALS
NOTE: Review submittal description (SD) definitions in Section 01 33 00 SUBMITTAL
PROCEDURES and edit the following list to reflect only the submittals required
for the project. Submittals should be kept to the minimum required for adequate
quality control.
A “G” following a submittal item indicates that the submittal requires Government
approval. Some submittals are already marked with a “G”. Only delete an existing
“G” if the submittal item is not complex and can be reviewed through the Contractor’s
Quality Control system. Only add a “G” if the submittal is sufficiently important
or complex in context of the project.
For submittals requiring Government approval on Army projects, a code of up
to three characters within the submittal tags may be used following the "G"
designation to indicate the approving authority. Codes for Army projects using
the Resident Management System (RMS) are: "AE" for Architect-Engineer; "DO"
for District Office (Engineering Division or other organization in the District
Office); "AO" for Area Office; "RO" for Resident Office; and "PO" for Project
Office. Codes following the "G" typically are not used for Navy, Air Force,
and NASA projects.
Choose the first bracketed item for Navy, Air Force and NASA projects, or choose
the second bracketed item for Army projects.
Government approval is required for submittals with a "G" designation; submittals not having a "G" designation
are for [Contractor Quality Control approval.][information only. When used, a designation following the "G"
designation identifies the office that will review the submittal for the Government.] The following shall be
submitted in accordance with Section 01 33 00 SUBMITTAL PROCEDURES:
SD-02 Shop Drawings
Masonry[; G][; G, [_____]]
Drawings showing location of masonry elements in the work, building elevations, interface
with adjacent materials, and special placing instructions, in sufficient detail to cover fabrication,
placement, and finishing.
SD-03 Product Data
Cleaning and Restoration Methods[; G][; G, [_____]]
Descriptive narrative in cleaning and repair methods to be employed in the work. Description
shall be organized in sequence from preparation through completion of the work. Schedule showing
estimated time, in calendar days, for completion of each phase of the work shall be included.
Qualifications
Documentation showing Contractor's experience of 5 consecutive years in masonry restoration,
plus a list of similar jobs to the one specified herein.
SD-04 Samples
Materials
Sample Masonry Panels[; G][; G, [_____]]
Samples of the materials listed below; indicating sizes, shapes, finishes, color, and pertinent
accessories: [_____]. Masonry Panels, as specified.
SD-07 Certificates
Materials
Certificates of compliance attesting that the materials, equipment, and cleaning agents (chemicals,
detergents, etc.) to be used in the work meet the specified requirements.
1.3 GENERAL REQUIREMENTS
Work shall be done in conformance with ACI C-20. Non-historic masonry work, including materials, procedures,
and requirements shall conform to Section 04 20 00 MASONRY, except as otherwise specified herein.
1.3.1 Cleaning and Restoration Methods
The cleaning and restoration methods, and materials selected for a specific structure, shall be submitted for
approval before work starts, and shall take into account the total construction system of the building to be
worked upon, including different masonry and mortar materials, as well as non-masonry elements which may be affected
by the work.
1.3.2 Ionic Cleaners
Ionic chemical cleaners shall be used as specified, in accordance with the manufacturer's instructions, and only
upon the direction of the Contracting Officer. Ionic cleaners shall be used only after gentler cleaning methods
have been determined to be ineffective through the use of test panels.
1.4 QUALIFICATIONS
The Contractor shall provide qualified workers, trained and experienced in restoration of masonry in historic
structures, and shall furnish documentation of 5 consecutive years of work of this type. A list of similar jobs
shall be provided identifying when, where, and for whom the work was done.
1.5 EQUIPMENT AND TECHNIQUES DEMONSTRATION
Equipment and techniques of operation shall be demonstrated in an approved location and shall be subject to approval.
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. The equipment
shall be maintained in good working condition throughout the project.
1.5.1 Cleaning Equipment
Cleaning equipment shall not cause staining, erosion, marring, or other damage or changes in the appearance of
the surfaces to be cleaned.
1.5.1.1 Sandblasting
Sandblasting equipment will not be allowed for cleaning masonry surfaces.
1.5.1.2 Water Blasting
Water blasting equipment shall include a trailer-mounted water tank, pumps, high-pressure hose, wand with safety
release cutoff control, nozzle, and auxiliary water re-supply equipment. The equipment shall not be operated
at a pressure which will cause etching or other damage to the masonry surface or mortar joints. The equipment
shall be operated at a discharge capacity of 0.38 to 3.5 Mpa 55 to 500 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. The Contractor shall provide protective covers and barriers as required
to prevent over-spray onto adjacent surfaces.
1.5.2 Drilling Equipment
Equipment used to drill holes in masonry, for patch anchors and other applications, shall be standard handheld
masonry drills, commonly used for drilling small holes in concrete and masonry. The drill shall be a small,
powered, handheld type, using rotary drilling mode only. Impact and rotary impact type drills will not be allowed.
1.5.3 Finishing and Texturing Equipment
Equipment and hand tools used for placing, finishing and texturing masonry and mortar shall be commercially available
and commonly used in masonry construction and repair. Surface grinders, impact tools, and other equipment shall
conform to the specified requirements, except as specifically required by the type of finish and texture.
1.5.4 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.
The compressed air supply shall be tested during each shift for the presence of oil and moisture.
1.5.5 Material Handling and Associated Equipment
1.5.5.1 Mixing, Transporting, and Placing Job Materials
Equipment used for mixing, transporting, placing, and confining masonry and mortar placements shall be capable
of satisfactorily mixing material and supporting placement operations in an uninterrupted manner. Defects and
deficiencies in operation or capacity shall be resolved prior to use in the work. 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.
1.5.5.2 Associated Equipment
Associated equipment such as mixer timing equipment, valves, pressure gauges, pressure hoses, other hardware,
and tools shall be provided as required to ensure a continuous supply of material and operation control.
1.6 SAMPLE MASONRY PANELS
Sample panels of each procedure proposed for use in the work shall be submitted for approval. No masonry or
mortar shall be used in the work until the samples and the represented mixture have been approved.
1.7 MATERIAL REQUIREMENTS
1.7.1 Strength
Each class or mixture of mortar shall have a 28-day compressive strength matching the compressive strength of
the original existing mortar in the structure as determined by ASTM C 109/C 109M for mortar. Test specimens
of existing mortar shall be taken from a sound and intact representative portion of the structure, at locations
indicated.
1.7.2 Special Properties
Mortar may contain admixtures, such as pigments, to match the characteristics of the original mortar. Use of
all admixtures shall be subject to approval.
1.7.3 Cementitious Content of Mortar
Each class or mixture of mortar shall have a cement content matching the cement content of the original existing
mortar in order to provide uniform strength, weathering characteristics, and appearance of repaired surfaces
in relation to existing surfaces.
1.8 STORAGE OF MATERIALS
Materials shall be stored in weathertight structures which will exclude moisture and contaminants. Cement shall
be furnished 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. 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.
1.9 SAFETY AND HEALTH
Work shall comply with applicable federal, state, and local laws and regulations, and with the ACCIDENT PREVENTION
PLAN, including the Activity Hazard Analysis, specified in the CONTRACT CLAUSES. The Activity Hazard Analysis
shall include analyses of the potential impact of cleaning operations on personnel and on others involved in
and adjacent to the work zone.
1.9.1 Worker Exposures
Exposure of workers to chemical substances shall not exceed the limits established by ACGIH 0100Doc, or those
required by a more stringent applicable regulation.
1.9.2 Training
Workers having access to an affected work area shall be informed of the contents of the applicable material safety
data sheets, of potential health and safety hazard, and of protective controls associated with materials used
on the project. An affected work area is one which may receive dust, mists, and odors from the surface preparation
operations. Workers involved in masonry cleaning shall be trained in the safe handling and application, and
the exposure limit, of each material to be used in the project. Personnel having a need to use respirators and
masks shall be instructed in the use and maintenance of such equipment.
1.9.3 Coordination
Work shall be coordinated to minimize exposure of building occupants, other Contractor personnel, and visitors
to mists and odors from surface preparation, cleaning, and repair operations.
1.10 PROTECTION
Persons, motor vehicles, adjacent surfaces, surrounding buildings, equipment, and landscape materials shall be
protected from chemicals used and runoff from cleaning and paint removal operations. Temporary protection covers,
which shall remain in operation during the course of the work, shall be erected over pedestrian walkways and
at personnel and vehicular points of entrance and exit.
1.10.1 Interior Protection
The interior of buildings shall be protected from the weather, cleaning, and repair operations at all times.
1.10.2 Environmental Protection
The work shall comply with the requirements of Sections 01 57 20.00 10 ENVIRONMENTAL PROTECTION and
02 83 19.00 10 LEAD BASED PAINT HAZARD ABATEMENT, TARGET HOUSING & CHILD OCCUPIED FACILITIES.
1.11 WEATHER LIMITATIONS
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 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. Material placements
shall be stopped, and all in-place material shall be protected from exposure, during periods of rain or other
precipitation.
1.12 WARRANTIES
1.12.1 Cleaning Warranty
Cleaning procedures shall be warranted 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.
1.12.2 Repair Warranty
Repair procedures, including repointing, shall be warranted 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 MATERIALS
Materials, physical and chemical properties, and composition of masonry and mortar used in renovation work shall
match that of original existing masonry and mortar to be repaired, unless samples and testing determine that
existing mixtures and materials are faulty or non-performing.
2.2 CLEANING MATERIALS
2.2.1 Paint Removers
Chemical paint removers shall be manufacturer's water soluble, low toxicity products, effective for removal of
paint on masonry without altering, damaging, or discoloring the masonry surface.
2.2.2 Detergent Cleaners
Detergent cleaners shall be in accordance with [_____].
2.2.3 Ionic Cleaners
2.2.3.1 Alkaline Prewash Cleaner
Alkaline prewash cleaners shall be as recommended by the manufacturer.
2.2.3.2 One-Part Masonry Cleaner
One-part masonry cleaners shall be the standard, acid formulation recommended by the manufacturer.
2.2.3.3 Two-Part Limestone Cleaner
Two-part limestone cleaners shall be manufacturer's standard, two-part masonry cleaning system consisting of
an alkaline prewash cleaner followed by acidic afterwash rinse.
2.2.3.4 Standard Strength Acidic Cleaner
Acidic cleaners shall be manufacturer's standard strength, acidic masonry restoration cleaner composed of hydrofluoric
acid blended with other acids and combined with special wetting systems and inhibitors.
2.2.3.5 Extra Strength Acidic Cleaner
Masonry restoration extra strength acidic cleaners shall be as recommended by the manufacturer.
2.2.4 Liquid Strippable Masking Agent
Liquid strippable masking agent shall be manufacturer's standard liquid, film-forming, strippable masking material
for protecting glass, metal, and polished stone surfaces from the damaging effect of acidic and alkaline masonry
cleaners.
2.2.5 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 3.5 Mpa 500 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.
2.2.6 Cleaning Implements
Brushes shall have natural or nylon fiber bristles only. Wire brushes shall not be used. Scrapers and application
paddles shall be made of wood with rounded edges. Metallic tools shall not be used.
2.2.7 Water
Potable water shall be obtained from a local source and shall be filtered to remove minerals resulting in a neutral
pH, prior to application. Backflow prevention devices shall be provided at the point of connection to the water
supply.
2.3 REPAIR MATERIALS
2.3.1 Masonry and Mortar
Masonry and mortar 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.
2.3.2 Cementitious Materials
Cementitious materials shall be of one type and from one source, when used in mortar which will have surfaces
exposed in the finished structure. Cement composition shall match that of cement used in existing mortar to
be repaired, as determined by samples and testing, and shall conform to the basic requirements of ASTM C 150,
Type [I] [II] [low alkali].
2.3.3 Epoxy Anchor Adhesives
An epoxy-resin grout shall be used to bond steel anchors to masonry, and shall be a 100 percent solids, moisture
insensitive, low creep, structural adhesive. The epoxy shall conform to ASTM C 881/C 881M, Type IV; Grade and
Class selected to conform to the manufacturer's recommendations for the application.
2.3.4 Metal attachments
Anchors for spall repairs shall be threaded stainless steel, size as indicated. Other plates, angles, anchors,
and embedments shall conform to ASTM A 36/A 36M, and shall be prime painted with inorganic zinc primer.
PART 3 EXECUTION
3.1 EVALUATION AND ANALYSIS
Evaluation and analysis shall conform to the requirements specified herein, and to Section 01 45 01 USACE QUALITY
CONTROL. Masonry renovation shall be undertaken only after complete evaluation and analysis of the areas to
be repaired are completed; this shall include sampling and testing of the existing mortar to determine its composition
and qualities. No repair work shall be undertaken until conditions that have caused masonry deterioration have
been identified; such conditions shall be corrected, if possible, prior to start of the work.
3.2 MASONRY CLEANING
Historic materials shall not be damaged or marred in the process of cleaning. Cleaning shall conform to [ASTM C 1515
] [BIA Tech Note 20]. Open joints shall be temporarily caulked or otherwise protected to prevent water and cleaner
intrusion into the interior of the structure from pressure spraying. Non-masonry materials and severely deteriorated
masonry shall be protected by approved methods prior to initiation of cleaning operations. Masonry cleaning
shall remove all organic and inorganic contaminants from the surface and pores of the substrate, returning the
masonry to its natural color. 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. Methods used for cleaning historic masonry shall be the gentlest possible to achieve
the desired results. Test patches shall be made to determine a satisfactory cleaning result. Cleaning shall
proceed in an orderly manner, working from top to bottom of each scaffold width and from one end of each elevation
to the other. Cleaning shall be performed in a manner which results in uniform coverage of all surfaces, including
corners, moldings, interstices and which produces an even effect without streaking or damage to masonry. 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 structure and surfaces,
the structure shall be given a surface cleaning. The surface cleaning shall be completed prior to start of repair
work, and sampling and testing of mortars. The cleaning shall provide for the complete cleaning of all exterior
masonry surfaces of the structures, removing all traces of moss, dirt, and other contaminants. The cleaning
shall provide a clean masonry surface to allow determination of the masonry's color and shades, finish and texture,
and other properties. Following completion of the surface cleaning of the structure (or side of structure) the
masonry shall be dried prior to the start of any repair 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 masonry)
6. Stronger chemical cleaners, only when above methods are determined to be ineffective by the Contracting
Officer
3.2.1 Project Conditions
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.
3.2.2 Chemical Cleaners
Acidic chemical cleaners shall not be used on limestone, marble, 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.
3.2.3 Test Patches
The materials, equipment, and methods to be used in cleaning shall be demonstrated in a test section approximately
1 by 1 m 3 by 3 ft square. The location of the test section, and the completed test section shall be subject
to approval. The cleaning process shall be adjusted as required and the test section rerun until an acceptable
process is obtained. Test patches shall be located in inconspicuous areas of the building. The areas tested
shall exhibit soiling characteristics representative of those larger areas to be cleaned. Tests shall also be
conducted on areas to be stripped of paint. Tested areas shall be allowed to dry before a determination is made
on the effectiveness of a particular treatment.
3.2.4 Paint Removal
Paint and other coatings shall be removed from masonry surfaces in areas indicated prior to general cleaning.
Masonry shall not be damaged or marred in the process of paint removal. Areas where paint is to be removed shall
first be cleaned with water and detergent solution to remove surface dirt, rinsed, and allowed to dry. Chemical
paint removers shall be applied in accordance with manufacturer's instructions. Surrounding painted surfaces
to remain intact shall be protected from exposure to chemical paint removers to avoid damage. Paint containing
lead that is to be removed shall be removed in accordance with Section 02 83 19.00 10 LEAD BASED PAINT HAZARD
ABATEMENT, TARGET HOUSING & CHILD OCCUPIED FACILITIES.
3.2.5 Water Cleaning
3.2.5.1 Pressure Spraying
Water shall be spray applied 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 55 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 300 mm 12 inches from surface of masonry.
Water shall be applied side to side in overlapping bands to produce uniform coverage.
3.2.5.2 Handscrubbing
Pre-wetted surfaces shall be scrubbed using hand-held natural bristle or nylon brushes. Wire brushes shall not
be used. Surfaces to be cleaned shall be scrubbed to remove surface contaminants.
3.2.5.3 Rinsing
Scrubbed surfaces shall be rinsed 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.
3.2.6 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 shall be the use of any product in addition to water, including
detergents, ammonia, vinegar, and bleach. Cleaning shall proceed in an orderly manner, working from top to bottom
of each scaffold width and from one end of each elevation to the other. Cleaning shall result in uniform coverage
of all surfaces, including corners, moldings, interstices and shall produce an even effect without streaking
or damage to masonry. Chemical cleaners shall not be applied to the same masonry surfaces more than twice.
3.2.6.1 Surface Prewetting
Masonry surfaces to be cleaned with chemical cleaners shall be wetted with water using a low pressure spray before
application of any cleaner.
3.2.6.2 Acidic Chemical Cleaning
Acidic chemical cleaners shall be applied according to manufacturer's instructions. Acidic chemical cleaners
shall not be applied to masonry with high calcium content (e.g. marble, limestone). Acidic cleaners shall be
applied to masonry surfaces by low pressure spray 0.35 MPa 50 psi max., roller, or brush. Cleaner shall remain
on masonry surface for the time period recommended by manufacturer. Manual scrubbing by brushes shall be employed
as indicated by test patches for the specific location. Cleaned surfaces shall be rinsed with a low-to-moderate
pressure spray of water to remove all traces of chemical cleaner.
3.2.6.3 Alkaline Chemical Cleaning - Prewash Phase
Alkaline chemical cleaners shall be applied according to manufacturer's instructions. Alkaline cleaners shall
be applied to masonry surfaces by low pressure spray 0.35 Mpa 50 psi max., roller, or brush. Cleaner shall remain
on masonry surface for the time period recommended by the manufacturer. Manual scrubbing by brushes shall be
employed as indicated by test patches for the specific location. Cleaned surfaces shall be rinsed with a low-to-moderate
pressure spray of water.
3.2.6.4 Alkaline Chemical Cleaning - Afterwash Phase
Immediately after rinsing of alkaline cleaned surfaces, a neutralizing afterwash shall be applied to the cleaned
masonry areas. Neutralizing afterwash shall be applied according to manufacturer's instructions. Neutralizing
afterwash shall be applied to masonry surfaces by low pressure spray 0.35 MPa 50 psi max., roller, or brush.
Afterwash shall remain on masonry surface for the time period recommended by manufacturer. Cleaned surfaces
shall be rinsed with a low-to-moderate pressure spray of water to remove all traces of chemical cleaners.
3.2.6.5 pH Testing
Masonry surfaces which have been chemically cleaned shall be pH tested using pH monitoring pencils or papers.
Chemically cleaned masonry shall be rinsed of all chemical residues until a neutral pH (7) reading is obtained
from the masonry surface.
3.3 MASONRY REPAIR
NOTE: Provide missing information; if a reference is added, revise paragraph
REFERENCES accordingly.
Repaired surfaces shall match adjacent existing surfaces in all respects. Masonry repair shall proceed only
after the cause of deterioration has been identified and corrected. Masonry repair shall conform to ACI C-20
. Repair of terra cotta masonry shall [be as directed] [conform to [_____]]. Masonry repair shall proceed only
after the area to be repaired has been cleaned. The materials, methods and equipment proposed for use in the
repair work shall be demonstrated in test panels. The location, number, size and completed test panels shall
be subject to approval. Products shall be used in accordance with the manufacturer's instructions.
3.3.1 Repointing
NOTE: Provide missing information; if a reference is added, revise paragraph
REFERENCES accordingly.
Repointing work shall be [as directed] [in accordance with [_____]]. Old caulking, grout, or mortar shall be
removed from previously repaired cracks where it is failing. Loose particles shall be removed from cracks.
Cracks shall be cleaned, rinsed with water followed by blowing with filtered, dry, compressed air.
3.3.1.1 Mortar Analysis
Existing original historic mortar shall be analyzed before repointing in order to provide a match with the new
repointing mortar. Historic mortars are usually softer than newer mortars, often using lime as a binder rather
than cement. Lime for repointing mortar shall conform to ASTM C 207, Type S, unless otherwise specified. Full
laboratory analysis of the existing mortar shall conform to ASTM C 1324. Field analysis of the existing mortar
shall be as specified below.
3.3.1.2 Taking and Preparation of Samples
Samples of unweathered original historic mortar shall be taken and analyzed in order to match the new mortar
to be used for repointing. Samples of each different type of mortar in the structure shall be taken and analyzed.
Three or four samples of each type of mortar to be matched shall be removed with a hand chisel from several locations
on the building. The largest sample shall be set aside for comparison with the repointing mortar. The remaining
samples shall be broken apart with a wooden mallet, powdering them into their constituent parts.
3.3.1.3 Binder Analysis
A part of the sample shall be stirred into diluted hydrochloric acid. If a vigorous chemical reaction (bubbling)
occurs and most of the binder disappears, leaving clean aggregate, the binder was lime. A portland cement binder
will result in a murky liquid and will dissolve very slowly over several days.
3.3.1.4 Aggregate Analysis
Aggregate of the mortar sample shall be separated from the binder. This shall be accomplished by taking the
crushed mortar sample and either gently blowing away the fine binder material, placing the crushed sample in
a centrifuge, or chemically separating the aggregate from the binder. The separated aggregate shall be rinsed
clean with water and dried. The aggregate shall be examined with a magnifying glass, and the component materials
shall be recorded as to range of materials, sizes, colors, as well as the presence of other materials.
3.3.2 Mechanical Repair
Original historic masonry materials shall be repaired or replaced only if surfaces are extensively deteriorated
(surface missing to a depth of 100 mm 4 inches or more) or are threatening the safety of the structure or individuals.
Deteriorated surfaces shall be removed and repaired or replaced only upon approval. Repairs and replacements
shall match the materials, colors, and finish of the existing historic masonry as closely as possible.
3.3.2.1 Areas To Be Removed
Unsound, weak, or damaged masonry and mortar shall be removed in areas as indicated. Loose particles, laitance,
spalling, cracked, or debonded masonry and mortar and foreign materials shall be removed with hand tools unless
otherwise noted. Surfaces prepared for repair shall be cleaned free of dust, dirt, masonry chips, oil or other
contaminants, rinsed with water, and dried before repair work is begun. Surfaces of the structure, and surfaces
adjacent to the work area shall be protected from damage which may result from removal, cleaning, and repair
operations.
3.3.2.2 Application of Masonry and Mortar
Masonry and mortar shall be placed to rebuild spalled or damaged areas to match the original surface finish,
level, texture, and color. The finished appearance of the patch shall match the adjacent existing surface.
3.3.2.3 Patch Anchors
Patch anchors shall be provided to ensure that the patch is tied to the existing masonry structure. Patch anchors
shall be provided at a frequency of at least one patch anchor per 93 square mm square foot of patch plan surface
area; specific locations for patch anchors shall be as indicated. Small handheld, low-speed rotary masonry drills
shall be used to produce holes in the existing masonry, within the limits for the patch anchor installation.
3.3.2.4 Holes
Holes shall be drilled into the existing substrate material of the masonry using rotary (non-hammer) drills.
Holes shall have a diameter of 3 mm 1/8 inch larger than the anchor diameter. The holes shall be drilled to
a depth of 100 mm 4 inches, except as otherwise indicated or directed. Drill holes shall not penetrate completely
through the masonry, and shall provide at least 25 mm 1 inch of cover around the drill hole. Holes shall be
cleaned by water blasting to remove drill dust and other debris and then blown dry with filtered, dry, compressed
air. Drill holes shall be conditioned in accordance with the epoxy adhesive manufacturer's recommendations.
3.3.2.5 Anchor Installation
Anchors shall be cleaned to remove all contaminants which may hinder epoxy bond. Epoxy adhesive shall be pressure
injected into the back of the drilled holes. The epoxy shall fill the holes without spilling excess epoxy when
the anchors are inserted. Anchors shall be inserted immediately into the holes. The anchors shall be set back
from the exterior face at least 25 mm 1 inch. Anchors shall be installed without breaking or chipping the exposed
masonry surface.
3.3.2.6 Cleanup
Excess epoxy and spills shall be removed from the surface of the masonry. The surface of the masonry shall be
left in a clean and uncontaminated condition. Spills on adjacent surfaces shall also be removed and surfaces
repaired as required.
3.3.2.7 Dutchman Repairs
The piecing-in of small patches of masonry to repair or replace damaged areas (Dutchman repair) shall be used
in areas indicated. Repair pieces shall be held in place with epoxy with the joint between the new and old materials
kept as narrow as possible to maintain the appearance of a continuous surface. Repairs shall be made to blend
in with the surrounding original materials as closely as possible.
3.4 EPOXY-RESIN GROUT
The epoxy adhesive shall be conditioned, proportioned, mixed, applied, protected, and cured in accordance with
the manufacturer's recommendations, except as otherwise specified herein or indicated on the drawings. The adjacent
surfaces and ambient conditions shall be maintained within the manufacturer's recommendations. The patch anchors
and epoxy adhesive shall be protected from displacement and disturbances.
3.4.1 Mixing Epoxy-Resin Grout Components
Epoxy-resin grout components shall be mixed in the proportions recommended by the manufacturer. The components
shall be conditioned within 20 to 30 degrees C 70 to 85 degrees F for 48 hours prior to mixing. The two epoxy
components shall be mixed with a power-driven, explosion-proof stirring device in a metal or polyethylene container
having a hemispherical bottom. The polysulfide curing agent component shall be added gradually to the epoxy-resin
component with constant stirring until a uniform mixture is obtained. The rate of stirring shall be such that
the entrained air is at a minimum.
3.4.2 Tools and Equipment
Tools and equipment to be used again in the work shall be cleaned before the epoxy-resin grout sets.
3.4.3 Health and Safety Precautions
Full-face shields shall be provided for mixing, blending, and placing operations as required. Protective coveralls
and neoprene-coated gloves shall be provided for workers engaged in the operations. Protective creams of a suitable
nature for the operation shall be supplied. Adequate fire protection shall be maintained at mixing and placing
operations. Smoking or the use of spark- or flame-producing devices shall be prohibited within 15 m 50 feet
of mixing and placing operations. The mixing, placing, or storage of epoxy-resin grout or solvent shall be prohibited
within 15 m 50 feet of any vehicle, equipment, aircraft, or machinery that could be damaged from fire or could
ignite vapors from the material.
3.5 MASONRY REPLACEMENT
Masonry shall be replaced with material that matches the original in terms of composition, color, texture, strength,
finishing, and porosity as closely as possible. If a few isolated masonry units are to be replaced, each shall
be removed without disturbing the surrounding masonry. Deteriorated masonry units and mortar requiring replacement
shall be removed by hand chiselling. Adjoining masonry units shall not be damaged during the removal of deteriorated
units and mortar. The new element shall be tested for fitting into its space without mortar. If wedges are
used to support and align the new unit, they shall be covered with at least 38 mm 1-1/2 inches of mortar when
pointing is complete. The four sides and back of the space shall be covered with sufficient mortar to ensure
that there will be no air spaces when the new unit is set. The new unit shall be lined up and set by tapping
it into place with a wooden or rubber mallet. Face of new unit shall align with that of existing masonry. Joints
shall be repointed to match the rest of the wall after new units have been properly installed and adjusted.
Replacement areas shall be cleaned with a non-metallic brush and water to remove excess mortar
3.6 MASONRY AND MORTAR FINISHES AND COLOR
The exposed surfaces of masonry and mortar repair shall match the finish, color, texture, and surface detail
of the original surface. Mechanical finishing and texturing may be required to produce the required finish and
appearance. The finishing and texturing shall conceal bond lines between the repaired area and adjacent surfaces.
The texturing shall provide replication of all surface details, including tooling and machine marks. The equipment
used in finishing and texturing shall be a low-impact energy type which will not weaken the patch or damage the
patch bond and the adjacent concrete.
3.7 JOINT SEALING
Joint sealing shall be as specified in Section 07 92 00 JOINT SEALANTS.
3.8 FINAL CLEANING
No sooner than 72 hours after completion of the repair work and after joints are sealed, faces and other exposed
surfaces of masonry shall be washed down with water applied with a soft bristle brush, then rinsed with clean
water. Discolorations which cannot be removed by these procedures, shall be considered defective work. Cleaning
work shall be done when temperature and humidity conditions allow the surfaces to dry rapidly. Adjacent surfaces
shall be protected from damage during cleaning operations.
3.9 PROTECTION OF WORK
Work shall be protected against damage from subsequent operations.
3.10 DEFECTIVE WORK
Defective work shall be repaired or replaced, as directed, using approved procedures.
3.11 FINAL INSPECTION
Following completion of the work, the structure shall be inspected for damage, staining, and other distresses.
The patches shall be inspected for cracking, crazing, delamination, unsoundness, staining and other defects.
The finish, texture, color and shade, and surface tolerances of the patches shall be inspected to verify that
all requirements have been met. Surfaces exhibiting defects shall be repaired as directed.