Lawrence History Center



SECTION 04500

HISTORIC MASONRY

GENERAL

1 General Provisions

The BIDDING REQUIREMENTS, CONTRACT FORMS, and Contract Conditions as listed in the Table of Contents, and applicable parts of Division 1 – GENERAL REQUIREMENTS, shall be included in and made a part of this Section.

Examine all Drawings and all other Sections of the Specifications for requirements therein affecting the work of this Section.

Refer to Section 01230 – Alternatives, for alternates which may affect the scope of Work of this Section.

2 Section Includes

Provide masonry restoration work where shown on the Drawings and as specified herein; work includes, but is not limited to the following:

Documentation of existing masonry layout for elements that need to be temporarily removed and reset or replaced.

Removal and re-setting of structural historic brickwork

Raking and repointing of mortared joints

Replacement of brick and stone only as may be needed

Installation of pins and ties

Reconstruction of missing or irreparable damaged masonry

Repair methods: The exact repair procedures shall be reviewed in the field, based on identifications in the Drawings, and the guidelines and materials specified herein. Review all procedures with the Engineer and obtain acceptance prior to commencing the work. Repair methods selected shall take into account the total construction system of the building to be repaired and the different original materials used for the main building and the various additions.

3 Related Sections

Section 02210 –Shoring, Bracing and Support

Section 05500 – Structural Steel Fabrications and Connections

4 Examination of Site and Documents

The bidders are expected to examine and to be thoroughly familiar with all contract documents and with the conditions under which work will be carried out. The Awarding Authority will not be responsible for errors, omissions and/or charges for extra work arising from General Contractor's or Subcontractor's failure to familiarize themselves with the contractor documents or existing conditions. By submitting a bid, the bidder agrees and warrants that he has had the opportunity to examine the site and the contract documents, that he is familiar with the conditions and requirements of both and where they require, in any part of the work a given result to be produced, that the contract documents are adequate and that he will produce the required results.

5 References

Comply with applicable requirements of the following standards. Where these standards conflict with other specified requirements, the most restrictive requirements shall govern.

ASTM C33 – Concrete Aggregates

ASTM C144 – Sand for Mortar and Grout

ASTM C150 – Portland Cement

ASTM C216 – Fire Clay Units

ASTM C270 – Mortar and Mortar Testing for Unit Masonry

ACI 301 – Concrete Mix Design and Placement

ACI 318 – Building Code Requirements for Reinforced Concrete for Buildings

US Department of Interior, National Park Service, technical preservation services: Preservation Briefs: 2, Repointing Mortar Joints in Historic Brick Buildings

United States Secretary of the Interior Standards for Rehabilitation Guidelines for Rehabilitating Historic Buildings

6 Submittals

Submit the following for review by the Engineer:

Literature

Masonry materials: Product data sheets, specifications, physical properties for each item furnished hereunder.

Manufacturer's descriptive data for materials including bricks, mortars, and mortar patching materials additives, fasteners, inserts, attachments, anchors and accessories. Descriptive data shall include test data demonstrating compliance with referenced standards. Descriptive data for premixed mortar, mortar additives shall include shelf life, curing time, mixing instructions, installation instructions and storage requirements.

Material certificates: Provide for the following, signed by manufacturer and Contractor certifying that each material complies with requirements.

Masonry materials: Each different cement product required for mortar, including name of manufacturer, brand, type, and weight slips at time of delivery.

Material test reports from a qualified independent laboratory employed and paid by Contractor indicating and interpreting test results relative to compliance of the following proposed masonry materials with requirements indicated:

Field prepared mortar complying with property requirements of ASTM C 270.

Samples: Prepared and cured mortar samples demonstrating color and shade. The Engineer reserves the right to reject samples, and request resubmissions, until a sample having the desired color and shade is considered an acceptable match to the existing mortar

Samples:

Mortar: (minimum three for each mortar mix) Prepared and cured mortar samples demonstrating color and shade. Set mortar in ½ by ½ by 6 inch channels (aluminum or plastic). The Engineer reserves the right to reject samples, and request resubmissions, until a sample for each mortar type has the desired color, shade, texture and composition matching the original pointing mortars.

Contractor’s cold weather and hot weather masonry procedures: Show evidence of compliance with requirements of ACI 530.1/ASCE 6.

The Contractor shall submit, in written form, to the Engineer for review and recommendation, cold weather procedures for masonry restoration work. No masonry restoration work shall be performed in temperatures below 40 degrees Fahrenheit without the submittal to and review by the Engineer of cold weather procedures.

Certificates: Certificates of compliance stating that the materials meet the specified requirements for:

Mortar Coloring

Mortar Admixtures

Workmen Qualifications:

Statement of qualifications for each worker, as required under the Article entitled “Qualification” specified herein below, include certifications of workers who have completed a stone restoration certification program.

Certificates of qualifications for masonry restoration specialist, as required under the Article entitled “Qualification” specified herein below.

7 Quality Control

Comply with all referenced standards for the products employed.

Coordinate times of Special Inspections to comply with Article 18 of the Massachusetts State Building Code.

During periods of cold or questionable weather, keep a log of work including air temperature and weather conditions, work started and completed per day, and tests taken. No work shall be done when the ambient temperature of the structure or the air is less than 45 degrees F.

Produce mortar and grout samples in the form of 2" x 2” x 2” flat slabs, placed against wooden side forms and backing, for easy removal of cured sample. Provide 8 samples per mortar and grout type taken on different days and cured under conditions that match field conditions to testing laboratory for compression testing. Provide at least four 2" x 2" x 2" field cut samples of existing mortar to the testing laboratory for comparative compression testing. Contractor shall arrange for and pay for all testing and shall submit results at 7 days and at 28 days to the Engineer. Adjustments in mix and re-tests shall be made as required at no additional cost to the owner. Test existing mortar samples and trial mixes at least three weeks before commencing masonry work.

Masonry contractor shall be a qualified, well-referenced brick mason with at least 10 years of experience in historic brick reconstruction, repair, and restoration.

Retrofit Veneer Anchors and Adhesive-Set Rods and Anchors: See this Part 3 of this specification for Trial Load Testing. All trial load testing shall be performed as required at no additional cost to the owner. Adjustments shall be made in procedure and lead hole diameter and additional anchors shall be installed as required to successfully meet trial load test and installation requirements at no additional cost to the owner.

All joint preparation for repointing operations shall match the approved raking sample.

All pointing and repointing shall match the approved pointing / repointing sample. Any work that does not shall be redone.

All drilled facing tie installations shall match the approved test applications upon completion.

8 Mock-ups

General: Provide mockup panel of restored areas. Mock-ups shall be prepared in the presence of the Engineer, except as otherwise permitted. Prepare mock-ups in locations selected by the Engineer.

Approved mockups shall constitute a standard for acceptance of the remainder of the Work.

Protect approved mockups for the duration of the Work.

Scheduling of Mock-ups: Mock-ups shall be prepared only by certified workmen, after certification of workers as specified under the Article entitled “Qualifications” as specified herein above. Workmen preparing mock-ups shall be same as those performing the work.

Repeat as needed until accepted by the Engineer.

Accepted panel will become the standard for work of this Section.

Repointing mock-up: Repoint a 25 square foot area, to be located by Engineer, using materials and methods specified. Repeat using different mortar compositions up to three panels until mortar is acceptable by Engineer. All mock-up location are to be repointed to the standard of the accepted mock-up panel.

Accepted panel will become the standard for work of this Section.

Mock-ups shall include (1) cutting of brick masonry in preparation for repointing, (2) repointing of brick masonry, and (3) rebuilding of brick masonry.

9 Delivery, Storage, and Handling

General: Do not deliver cement, lime, and similar perishable materials to the site until suitable storage is available. Store such materials in weatherproof structures, and ensure that materials are in perfectly fresh condition when brought for use. Protect masonry units and manufactured products of all types from wetting by rain or snow, and keep covered when not in use.

Aggregates: Deliver, store and handle aggregate materials so as to prevent contamination with earth or other foreign materials.

Store cement, lime and similar products under cover and from direct contact with earth or floor slabs. Store metal accessories and the like under cover and from direct contact with ground, and in manner to prevent rust.

Damaged material: Remove any damaged or contaminated materials from job site immediately, including materials in broken packages, packages containing water marks, or which show other evidence of damage, unless Engineer specifically authorizes correction thereof and usage on project.

10 Scaffolds and staging

Scaffolds and staging: Filed Sub-contractors shall obtain required permits for, and provide scaffolds, staging, and other similar raised platforms, required to access their Work.

Scaffolding required for used by this Filed Sub-contractor shall be furnished, erected, maintained in a safe condition, and dismantled when no longer required.

Each Filed Sub-contractor is responsible to provide, maintain and remove at dismantling, all tarpaulins and similar protective measures necessary to cover scaffolding for inclement weather conditions and as additionally required for dust control.

Enclose all exterior scaffolding outside of the construction fence with 8 foot height plywood enclosure at end of each work day to prohibit access to the scaffolding by unauthorized individuals.

Portable ladders and mobile platforms of all required heights, shall be provided by individual users.

11 Hoisting Machinery and equipment

All hoisting equipment, rigging equipment, crane services and lift machinery required for the work by this Filed-Sub Contractor shall be furnished, installed, operated and maintained in safe conditions by this Filed-Sub Contractor.

12 Environmental conditions

In ambient temperatures below 40 degrees Fahrenheit make provisions to adequately protect the masonry materials and the finished work from frost by heating materials, enclosing the work or heating the enclosed spaces. No frozen work shall be worked upon nor shall anti-freeze admixtures be permitted in the mortar mix. Any completed work found to be affected by frost shall be removed and replaced at no additional expense to the Owner.

PRODUCTS

1 Materials and Products

Brick: Re-used or new as needed, or ASTM C216, Grade SW, Low Absorption. Minimum strength shall be 8,000 psi, maximum water absorption shall be 8%. Provide new brick only as required if existing units cannot be salvaged, to match size and shape of existing surrounding brick. Color shall be one shade darker than the existing brick in its present condition. Brick shall be as manufactured by Morin, Belden, or Glengery, available through Spaulding Brick of Somerville, MA, or equivalent.

Hollow Load Bearing Block Units (CMU): ASTM C90, Grade S, Type I - Moisture Controlled; normal weight.

Mortar:

Structural Mortar for Brick Masonry Reconstruction: ASTM C270, Type N with the following proportions: 1 part Cement, 1 part Hydrated Lime, 6 parts Bulked Moist Sand.

Mortar for Tuck Pointing of Exposed Masonry: ASTM C270, Type O of the following proportions: 1 part Cement, 2 parts Hydrated Lime, 7 parts Screened Sand. Vary proportions of white and gray portland cement and select an appropriate sand to match the color and texture of the existing mortar. Iron oxide may additionally be used as a pigment if the proper color cannot be obtained by the preceding. Color and texture shall be adjusted as necessary to match existing designated mortar per the approval of the architect.

Plug Mortar for Filling Drill Holes in Brick or Stone Units: ASTM C270, Type N of the following proportions: 1 part Cement, 1 part Hydrated Lime, 6 parts Screened Sand and Drill Powder. Vary proportions of white and gray Portland cement and obtain an appropriate sand and drill powder blend to match the color and texture of the parent brick or stone. Iron oxide pigment shall additionally be used to obtain the proper color but no less than 50% drill powder shall be used in the fine aggregate blend. Drill powder shall be obtained by collecting the powder “spoil” during the drilling operations in the parent brick or stone or by grinding matching pieces of the brick or stone material. Plug mortar shall have a compressive strength of between 750 psi and 1500 psi at 28 days. Color and texture shall be adjusted as necessary to meet the approval of the Engineer.

Cement Paste Slurry for Bonding New Work to Existing: Pasty mixture of 5 gallons of mixing water per bag of cement part cement applied by rubbing after initial wetting and surface drying of substrate with water, and immediately before placement of new material.

Coarse Aggregate For Grout: ASTM C-33, 3/8" dia. minimum gravel or stone.

Portland Cement: Type 1 white and/or gray cement as follows: Portland Cement: ASTM C150 complying with staining requirements of ASTM C91 for not more than 0.03% water soluble alkali. Mortar shall show no efflorescence when cast in a 2” x 7” x ½” slab consisting of 1 part of the cement to be used, 2 parts Ottawa sand and distilled water, and subjected to a 7 day “wick test” conforming to ASTM C67.

Hydrated Lime: ASTM C207, Type S.

Fine Aggregate / Sand:

Sand For mortar and grout: ASTM C144, washed.

For surface fill: Clean, fine sand free of salts.

Adhesive Anchoring System for Anchoring Miscellaneous Embedded Items: Equal or equivalent to Hilti Hit “HY20” Adhesive Injection System with appropriate screen tubes.

Epoxy Injection Resin for Solid Masonry Unit Repairs (as needed): Equal or equivalent to “Sikadur Injection Gel” as manufactured by the Sika Corporation of Lyndhurst, NJ.

Steel Braces, Pinning Rods and Connectors: See SECTION 05400 – Structural Metals

Chemical Cleaning Agent: Equal or equivalent to “Sureclean 600” as manufactured by Prosoco Corp.

EXECUTION

1 EXCAVATION AND/OR REMOVAL OF DAMAGED OR DESIGNATED MASONRY

Within selected sequentially located limited areas, (following removal of veneer or facing units) remove the following back-up materials:

All loose, weakened and/or shifted units.

Internal back-up materials that are designated to be removed as part of overall reconstruction and stabilization.

Cracked brick units that follow structural cracks that need to be replaced in order to stitch cracks together.

Clean the exposed interior surfaces of the remaining material, and remove shards of material which have become loose during work or have shifted from their proper positions. Notify Engineer immediately of the number of brick wythes that need to be removed before preceding with work.

Provide and install all temporary shoring, bracing and support to surrounding construction before beginning removal. Removal and replacement shall be done sequentially to avoid weakening too much of the structure at one time. Contractor shall be responsible for maintaining integrity and safety of surrounding work as well as the tower, in general, during work per the requirements of Section 02210 - Temporary Construction Shoring, Bracing and Support.

Notify the Engineer of any adjacent stones or brickwork beyond immediate work area that become loosened during work. Stop work immediately, provide additional bracing and review with Engineer before resuming.

2 INSTALLATION OF TIES AND ANCHORS INTO EXISTING MASONRY

The following work shall be performed by an experienced mason who had at least 10 years of practical experience with work on older brick and stone structures and who has been successfully trained in the installation of the adhesive anchorage systems. The following requirements apply to anchoring new brick work and stone facing work to existing construction.

Anchor Installation (using epoxy adhesive and stainless steel threaded rod):

Hole size shall be 1/8" greater in diameter than rod.

Fill holes in back-up masonry with injection gel before inserting 3/16" diameter rods.

Simultaneously pre-butter pinning rod surfaces with injection gel so that there is a uniform coating all around the rod of between 1/16” and 1/8” in thickness and insert rod immediately thereafter.

Install one retrofit veneer tie per retrofit masonry anchor location in the same brick or stone unit. Follow all related subsections of this specification.

Wipe off excess resin and bend rod to suit masonry attachment requirements. Monitor progress and quality of work, adjusting techniques as may be necessary with approval of the Engineer. Check that annular space is filled around the end of each pinning rod following insertion. If properly installed, resin (gel) should be oozing out beyond end of rod all around annular space, showing that the annular space and the hole are completely filled. If this does not happen consistently after the third installation, notify the Engineer before continuing. Supplementary injection may be necessary due to the presence of voids.

Work shall only be done when the ambient air, material, and substrate temperatures are above 40° F. by 9:00 AM and rising.

3 INSTALLATION OF ANGLE LINTELS AND POCKETED BEAMS

Shore affected areas of masonry over locations being worked on.

Install angle lintel(s) and/or beam end with sufficient bearing as indicated. Set steel bearing surfaces on grout or mortar.

Fill around pocketed beam ends with grout or brick, fill all around lintels with brick.

All construction shall match that of surrounding masonry, and shall be subject to the approval of the Engineer.

4 RE-SETTING OF BRICK MASONRY

Install retrofit internal ties in accordance with applicable requirements of this specification and contract drawings to anchor new brick wythes or facing stones to existing construction. Ties shall fall within coursing or jointing of new (re-set) work and shall be provided on a 16”x12” pattern from the face of each bonded wythe of masonry. As a preferred alternate, standard header bricks may be installed where possible between brick wythes on a 16”x24” pattern.

Repeatedly pre-soak surfaces to which new work will be bonded to a period of not less than 24 hours. Allow to surface dry to a dull but saturated finish an hand rub a cement paste slurry within 30 minutes before applying new work.

Lay a bed of mortar against intact masonry surfaces to surround the unit(s) to be reset. Hand rub a mortar paste slurry over contact surfaces of stones to be set and existing surfaces to which new work will be bonded, and pre-butter depressions that are deeper than 1/4" to provide a non-concave surface. The bedded mortar should match the finished joints in thickness plus an allowance for sloughing.

Brick units shall be re-set to within ¼” of their previous positions and surface alignment, with individual joints’ widths along all sides within 1/8” of their cumulative average width per stone. Reconstruct masonry using conventional and accepted techniques. Add header bricks between new wythes at a 24”x16” pattern and anchor new wythes to existing construction using bent Retrofit Masonry Anchors. All horizontal and vertical joints (including collar joints) shall be completely filled with mortar that shall match the existing construction.

Strike outer joints to a depth of ½” recess from brick faces and surrounding masonry at exterior wall surfaces to allow for final tuck pointing, and tool joints at interior surfaces to meet the outer surfaces of the bricks with a profile that matches the surrounding existing work.

Following a curing period of not less than one nor more than 7 days, final tuck-point exterior surfaces of walls to match the adjacent original construction and the approved test sample. Provide feathered transitions from new to adjacent, existing mortar, angled at approx. 45 degrees from the brick ashlar line.

Moist Cure all completed work for periods of not less than 72 hours.

Work under this subsection shall only be done when the ambient air, material, and substrate temperatures are above 40 degrees F. by 9:00 AM and rising.

5 RE-POINTING OF EXISTING MASONRY TO REMAIN

The following pertains to excavation and repointing of existing historic masonry.

Rake existing joints where designated to a depth of 2 to 2 ½ times the joint width, 1” minimum, or as deeply as necessary to reach sound mortar, but not to exceed one half of the thickness of the stone nor three quarters of the outer wythe of brick without supplementary means of support. Employ tools that are sharp and will completely cut out joints at intersections without splitting or damaging stones or bricks. Raking work shall match the approved test sample.

Employ tools that are sharp and will completely cut out joints at intersections without splitting or damaging bricks. Limit use of mechanical removal to horizontal joints with a single pass down the center of the joint.

Gently drive wedges or hardwood shims into wide, deep cracks in masonry where there is a possibility that the vertical and in-plane lateral support of masonry work will be compromised during deep raking of the joints. This should at least be done where more than half of the length of a specific joint is removed to a depth of more than one third of the thickness of the stone or brick or beyond the limitations noted in paragraph

Remove stones and bricks that become loose during this operation per subsection 3.02 of this specification and monitor condition and stability of existing construction during all phases of the work. Provide additional support if required and to conform to Section 02210 - Temporary Shoring, Bracing, and Support.

Wire brush clean and then pre-wet the joints and allow for the existing mortar to dry or saturate to a dull, non-glossy finish immediately before applying new mortar.

Push new mortar into the joints, evacuating air bubbles with the sharp end of a trowel, and strike surface of joints to match existing surrounding joints.

Strike outer joints to a depth of ½” recess from brick faces and surrounding masonry at exterior wall surfaces to allow for final tuck pointing, and tool joints at interior surfaces to meet the outer surfaces of the bricks with a profile that matches the surrounding existing work.

Following a curing period of not less than one nor more than 7 days, final tuck-point exterior surfaces of walls to match the adjacent original construction and the approved test sample. Provide feathered transitions from new to adjacent, existing mortar, angled at approx. 45 degrees from the brick ashlar line.

Work under this subsection shall only be done when the ambient air, material, and substrate temperatures are above 40 degrees F. by 9:00 AM and rising.

6 FINAL CLEANING

Remove all spatter, dirt and laitance from all masonry surfaces using a combination of light hand tools, brushes, water and pre-approved cleaner. Masonry cleaner is to be ProSoCo Safety Klean used in strict accordance with manufacturer’s specification.

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