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TOWNE HOUSE RESTORATIONS STANDARD SPECIFICATION FOR GLASS FIBER REINFORCED CONCRETE |
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This document provides a basis for specifying in-plant fabrication of glass fiber reinforced concrete (GFRC) panels.
Materials and processes used for manufacturing GFRC vary widely according to the aggregates locally available to the manufacturers and the processes and techniques used by the manufacturers to obtain the desired finish and physical properties. Of paramount importance in casting GFRC is the need to employ a properly proportioned mixture of white and/or grey cements, manufactured or natural sands, carefully selected crushed stone and mineral coloring pigments to achieve the desired appearance while maintaining durable physical properties.
Although a variety of casting methods are used, production conforming to this standard will produce post production non-load bearing qualities essential for normal installations as a suitable replacement for natural cut limestone, brownstone, sandstone, bluestone, granite, slate, keystone, travertine and other natural building stones.
It is hoped that this specification may be helpful to the specifiers in understanding the inherent qualities of GFRC and its use. For details and samples of finishes available, please contact Towne House Restorations.
GLASS FIBER REINFORCED CONCRETE (GFRC)
1.1 GENERAL PROVISIONS
A. Perform work of this Section in accordance with the General Conditions, Supplemental General Conditions, General Requirements, Drawings and all other requirements of the Contract Documents.
1.2 WORK INCLUDED
A. Furnish all labor, materials, tools and equipment required to perform the work of this Section as shown on the Drawings and as specified herein.
1.3 INSTALLERS QUALIFICATION
A. Work under this section shall be performed by a firm having a minimum of 10 years of recent experience in GFRC fabrication. Such experience shall include projects of comparable scope and extent to this project.
B. Obtain GFRC units where required from an established specialty plant with a minimum of 10 years experience and having the capacity and facilities for producing matching units of specified quality and finish and in sufficient quantity so as to not delay the work progress. Plant to be recognized as a manufacturer in the industry of this type of material and shall show successful completion of work of comparable quality and scope.
1.4 SHOP DRAWINGS, SAMPLES AND LITERATURE
A. Submit certifications and test results to demonstrate that the materials and units conform to specifications.
1. Preparation of the test specimens and test procedures shall be in accordance with PCI “Recommended Practice for Glass Fiber Reinforced Concrete Panels,” Chapter 8 - Quality Control and Appendix A.
2. Test Boards will be made for every 25 pieces or less.
3. For each test board, determine: a. Glass content by “wash-out test” b. Flexural yield strength c. Flexural ultimate strength
4. Keep quality control records available for two years after final acceptance.
B. Submit manufacturer’s shop drawings for review and approval by the Architect. Show production details, construction of each different GFRC unit, dimensions and relationship to adjacent material in sufficient detail to cover the manufacture, handling and erection. Show detail of sections and connections for fastening the block units, identify anchorage, flashing, counter flashing and accessory items. Photographs may supplement drawings. Indicate the color and texture of various portions of the work.
C. Engineering: The services of a licensed P.E. may be required as per conditions of the project contract in order to provide design calculations for the GFRC panel and steel frame details.
D. Submit samples of the finish material together with drawings and details as required to obtain approval of the Architect. Do not proceed with fabrication prior to completed review and approval of shop drawings and approval of material samples.
E. Samples 1. Prior to commencement of manufacture, submit samples to represent finished exposed face, showing typical range of color and texture for Architect’s approval. Sample may have to match the surface of an original stone selected by the Architect and submitted by the Contractor.
2. Sample size:Approximately 6” X 6” and of appropriate thickness, representative of the proposed finished product.
3. Acceptance of samples shall establish a standard of workmanship and finishing of surfaces, and are to be used throughout the remainder of the project. No work shall commence on the installation of the GFRC until all appropriate samples have been approved.
1.5 DELIVERY, STORAGE AND HANDLING
A. All materials shall be delivered to the site, safely packed and labeled.
B. Materials shall be stored in a dry location off the ground, and in such a manner to prevent damage or intrusion of foreign matter.
C. All GFRC units are to be delivered to the project site palletized and to remain in place until the unit is to be erected. Handle units so as to protect against damage during shipping.
D. Color and texture of GFRC shall be generally equal to the approved sample when viewed in direct daylight at a 10 foot distance.
E. The range of total acceptable color (lightness, color saturation and hue) variation shall not exceed CIELAB 3.0 provided that the difference in hue alone does not exceed CIELAB 1.0 as defined by the International Commission of Illumination, 1976 Standards.
PART 2 - PRODUCTS
2.1 MATERIALS
A. Obtain materials for GFRC replacements from a single source for each type of required replacement unit to ensure match of quality, color, pattern and texture.
1. Acceptable Manufacturers: Towne House Restorations Phone (718) 497-9200 341 Ten Eyck Street Fax (718) 497-3556 Brooklyn, NY 11206
B. Materials shall be of the following makes, brands and kinds, or approved equals as determined by the Architect: 1. Portland Cement a. ASTM C150, Type I or III b. For surfaces exposed to view in the finished structure, use same brand, type and source of supply throughout the GFRC production.
2. Aggregates: a. Sand shall be washed and dried silica or approved equal with a history of successful use in GFRC. All sand shall pass through a No. 20 (1.18mm) sieve.
3. Water:Free from deleterious matter that may interfere with the color, setting or strength of the concrete.
4. Admixtures: Conforming to ASTM C260, ASTM C494, ASTM C618 or acrylic thermoplastic copolymer dispersion conforming to PCI MNL-130, Appendix E.
5. Coloring Agent: Conforming to ASTM C979 a. Shall be harmless to concrete set and strength. b. Shall be stable at high temperature. c. Shall be sunlight fast and alkali-resistant.
6. Glass Fiber: Conforming to PCI MNL-130, Appendix D. a. Fibers specifically designed to be compatible with the aggressive alkaline environment of Portland cement based composites or fibers with a history of successful use in a Portland cement based composite that has been modified to be compatible with the fiber.
b. The fabricator shall submit on request evidence that the glass composition, Portland cement matrix, or both have been designed for glass fiber reinforced concrete applications.
7. Polymer Compound: Conform to requirements of PCI’s “Recommended Practice for Glass Fiber Reinforced Concrete Panels,” Appendix L.
C. Attachment Hardware and Sprayed-in Anchors: 1. Materials: a. Structural steel: ASTM A36. b. Cold drawn wire: ASTM A29 or ASTM A108, AISI grade 1018. c. Carbon steel plate: ASTM A283 d. Malleable iron castings: ASTM A47 e. Carbon steel castings: ASTM A27, grade 60-30. f. Anchor bolts: ASTM A307 or ASTM A325. g. Stainless steel: Type 304 h. Tube steel: ASTM A500 Grade A or B
D. Reglets: Polyvinyl chloride extrusions or other approved non-metallic types, or approved metallic types.
E. Stud Framing System: 1. Material a. Structural tubing shall be formed from steel conforming to ASTM A500, grade B or ASTM A513.
2. Finish a. Rust inhibitive paint shall conform to FS-TT-P-664.
2.2 MIXES A. GFRC Backing Mix:
1. GFRC shall consist of portland cement, water, AR glass fibers, sand and may contain admixtures. the component materials shall be in accordance with Section 2.1. Mix proportions must be left to producer’s discretion to achieve proper workability and property characteristics under the specific circumstances and with available materials. Physical properties for use as design parameters will very and must be determined from trial runs prior to establishing mix proportions and control limits. a. Depending on the application of the GFRC product, strength requirements and sizes of pieces, the GFRC manufacturer shall have the option to produce GFRC by the spray-up method or the premix method.
2. Nominal glass content shall be 5 percent for spray-up, long glass applications.
3. Nominal glass content shall be 3 - 3 1/2% for premix applications.
4. Average yield shall not be less than 900 psi and ultimate strength shall not be less than 2500 psi for long glass spray-up applications, or strength as determined by design calculations for the project.
5. Average yield shall not be less than 700 psi and ultimate strength shall not be less than 1450 psi for premix applications or strength as determined by design calculations for the project.
B. Face Mix: Thickness shall generally be the minimum possible to achieve the desired finish. Properties of face mix shall be determined by the manufacturer.
C. Coloring Agent: The amount of coloring agent shall not exceed 10 percent of cement weight.
2.3 FABRICATION A. Manufacturing procedures shall be in general compliance with PCI MNL-130.
B. Molds: 1. Molds for GFRC panels shall be rigid and constructed of materials that will result in finished products conforming to the profiles, dimensions and tolerances indicated by the contract documents and the approved shop drawings.
2. Release agents shall be applied and used according to manufacturer’s instructions.
C. Proportioning and Mixing: 1. All measurements of mix constituents shall be carried out in a careful manner to achieve the desired mix proportions.
2. The glass fiber and cement slurry shall be metered at rates to achieve the desired mix proportions and glass content. These shall be checked in accordance with standard procedures described in PCI MNL-130.
D. Hand Spray Application: 1. Spray operators shall be trained personnel.
2. A mist coat consisting of the cement-based matrix without fiber may if necessary be sprayed onto the mold. The thickness of this coating shall generally not exceed 1/8 in. in order to minimize the unreinforced surface.
3. Face mix shall be sprayed or placed in thickness shown on shop drawings.
4. Spray-up of the GFRC backing shall proceed before any mist coat or facing mix has set.
5. Application of GFRC backing shall be by spraying such that uniform thickness and distribution of glass fiber and cement matrix is achieved during the application process.
6. Consolidation shall be by rolling or such other techniques as necessary to achieve complete encapsulation of fibers and compaction.
7. Control of thicknesses shall be achieved by using a pin-gauge or other appropriate methods.
8. Manufacturing of premix GFRC products shall be done according to PCI “Recommended Practice for GFRC Panels,” Appendix J.
E. Insert and Embedments: 1. Inserts shall be properly embedded in built-up homogeneous GFRC bosses or bonding pads to develop their strength. Waste material such as overspray is not acceptable to encapsulate inserts or for bonding pads.
2. Rigid embedded items bonded to the GFRC shall not create undesirable restraint to volume changes.
F. Stud Frame System: 1. Stud frame shall be a prefabricated welded frame produced in accordance with the approved shop drawings.
2. All accessible welds shall be touched-up after welding.
G. Allowable Tolerances: Manufacture units so that each panel complies with the dimensional tolerances listed in PCI MNL 117, “Manual for Quality Control for Plants and Production of Architectural Precast Concrete Products,” or PCI, “Recommended Practice for GFRC Panels.”
H. Finishes: Exposed face of panels to match approved sample. Exposed face of panels shall be manufactured free from joint marks, “grain” or other obvious defects.
I. Cover: Provide embedded anchors, inserts, and other sprayed-in items with sufficient anchorage and embedment for design requirements.
J. Curing: 1. Immediately after the completion of spraying of the panels, an initial curing method shall be used to ensure sufficient strength for removing the units from the mold.
2. An acrylic thermoplastic copolymer dispersion shall be used as a curing admixture. Only copolymers shown to eliminate the need for moist curing through independent laboratory test data shall be used.
K. Panel identification: 1. Mark each GFRC panel to correspond to identification mark on erection drawings for panel location.
2. Mark each GFRC panel with date cast.
L. Acceptance: GFRC units which do not meet the color and texture range or the dimensional tolerances may be rejected at the option of the Architect if they cannot be satisfactorily corrected.
PART 3 - EXECUTION
3.1 PRODUCT DELIVERY, STORAGE AND HANDLING
A. Delivery and Handling: 1. Handle and transport units in a position consistent with their shape and design in order to avoid excessive stresses or damage.
2. Lift or support units only at the points shown on the shop drawings.
3. Place non-staining resilient spacers of even thickness between units.
4. Support units during shipment on non-staining shock-absorbing material.
5. Protect units from dirt and damage during handling and transport.
B. Storage at Jobsite: 1. Store units to protect them from contact with soil, staining, and from physical damage.
2. Store units, unless otherwise specified, with non-staining, resilient supports located in same positions as when transported.
3. Store units on firm, level and smooth surface.
4. Place stored units so that identification marks are easily readable, and so that product can be inspected.
3.2 PRE-INSTALLATION RESPONSIBILITY
A. General Contractor’s Responsibility: 1. The General Contractor shall provide building lines, center and grades in sufficient detail to allow installation of the GFRC units.
2. The General Contractor shall provide true, level, clean support surfaces.
3. The General Contractor shall provide for the accurate placement and alignment of connection hardware on the structure.
B. Erector’s Responsibility: Prior to installation of the units, the erector shall check the jobsite dimensions affecting the work under the contract. Any discrepancies between design dimensions and field dimensions which could adversely affect installation in accordance with the contract document shall be brought to the attention of the General Contractor and Architect. If discrepancies do exist, installation shall not proceed until they are corrected or until installation requirements are modified and reviewed by the Architect and Engineer.
3.3 ERECTION
A. Unloading Areas and Access: Clear, well-drained unloading areas and road access around and in the building (where appropriate) shall be provided and maintained by the General Contractor to a degree that the hauling and erection equipment for the GFRC units are able to operate under their own power.
B. Safety Aspects: The General Contractor shall provide adequate traffic control, barricades, warning lights or signs to safeguard traffic in the immediate area of hoisting and handling operations.
C. Setting: 1. GFRC units shall be lifted with suitable lifting devices at points provided by the manufacturer.
2. GFRC units shall be set level, plumb, square and true within the allowable tolerances.
D. Supports and Bracing: The erector shall provide temporary supports and bracing as required to maintain position, stability and alignment until units are permanently connected.
E. Fastening: 1. Fasten GFRC units in place by bolting or welding or both as shown on approved erection drawings.
2. Field welding shall be done by qualified welders using equipment and materials compatible to the base material.
3.4 PATCHING
A. Mix and place patching mixture to match color and texture of surrounding GFRC.
3.5 CLEANING
A. Cleaning methods shall be approved by fabricator.
B. After Installation: Contractor shall clean soiled GFRC surfaces.
C. Use extreme care to prevent damage to GFRC surfaces and to adjacent materials.
D. Surface must be thoroughly rinsed with clean water immediately after using cleaner.
E. At completion of project, General Contractor shall provide building wash down as required.
3.6 PROTECTION
A. The erector shall be responsible for any chipping, spalling, cracking or other damage to the units after delivery to the jobsite unless damage is caused by others during site storage.
B. After installation is completed, any further damage shall be the responsibility of the General Contractor.
3.7 INSPECTION AND ACCEPTANCE
A. Immediately after the erection, final inspection and acceptance of erected GFRC panels shall be made by the Architect to verify conformance with plans and specifications. |
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