Cast Stone Specification
MasterSpec division 04720 CAST STONE
Feel free to cut and paste this short form specification.
The following specification has been developed to assure you of obtaining good quality Cast Stone that resembles natural cut building stone in color, texture, permanency and appearance.
PART 1 – GENERAL
- All labor, materials and equipment to provide the Cast Stone shown on architectural drawings and as described in this specification.
- Manufacturer shall furnish and deliver Cast Stone covered by this specification.
- Setting contractor shall unload, store, furnish all anchors, set and clean Cast Stone.
1.02 QUALITY ASSURANCE
- Manufacturer: Must have ten (10) years minimum continuous operating experience and have facilities for manufacturing Cast Stone as described herein.
- Manufacturer: Must be a member of the Cast Stone Institute
- Manufacturer: Must have a certified plant.
- Stone setter: Must have ten (10) years experience setting cast or natural building stone.
- Reference Standards: Comply with applicable provisions and recommendations of the following, except as otherwise shown or specified.
- Cast Stone Institute Technical Manual 04720-(current edition).
- ASTM C 150 – Specification for Portland Cement.
- ASTM C 33 – Specification for Concrete Aggregates.
- ASTM C 979 – Specification for Pigments for Integrally Colored Concrete.
- ASTM C 494 – Specification for Chemical Admixtures for Concrete.
- ASTM A 615 – Specification for Deformed and Plain Billet Steel Bars for Concrete Reinforcement.
- ASTM C 1194 – Test method for Compressive Strength of Architectural Cast Stone.
- ASTM C 1195 – Test method for Absorption of Architectural Cast Stone.
- ASTM C 1364 – Standard Specification for Architectural Cast Stone.
- ASTM D 2244 – Test Method for Calculation of Color Differences From Instrumentally Measured Color Coordinates.
- ASTM C 666 Test Method for Resistance of Concrete to Rapid Freezing and Thawing.
- Testing: Test three specimens per 500 cubic feet at random from jobsite or from plant production for compressive strength and absorption in accordance with referenced standards.
A. Submit for approval the following:
- Samples of the Cast Stone specified which will be representative of the general range of color and finish to be furnished. Submit test results of similar Cast Stone previously made by the manufacturer.
- Proof of plant certification.
- List of jobs furnished by the manufacturer, which were similar in scope and at least ten (10) years of age.
- Shop Drawings: Submit for approval the following:
- Copies of shop drawings showing details of the stone to be provided including: profiles, cross-sections, reinforcement, exposed faces, arrangement of joints (optional for semi-custom installation), anchoring methods, anchors, annotation of stone types and their location.
- Unless otherwise shown on contract drawings:
- Provide suitable wash on all exterior sills, coping, projecting courses and pieces with exposed top surfaces.
- Provide drips as needed.
1.04 MOCK-UP (Optional)
- Provide full size unit(s) for use in construction of sample wall. The mock-up becomes the standard of workmanship for the project.
PART 2 – PRODUCTS
A. 1. Physical properties: Provide the following:
a. Compressive Strength, ASTM C 1194: 6,500 psi min.
b. Absorption, ASTM C 1195: 6% max.
2. Raw materials:
a. Portland cement – Type I or III, white and/or grey, ASTM C 150
b. Coarse aggregates – Granite, quartz or limestone, ASTM C 33
c. Fine aggregates – Manufactured or natural sands, ASTM C 33
d. Colors – Inorganic iron oxide pigments, ASTM C 979
e. Admixtures – ASTM C 494
f. Water – potable.
g. Reinforcement – ASTM A 615
2.02 ACCEPTABLE MANUFACTURERS
- Continental Cast Stone Manufacturing
2.03 FABRICATION METHODS ALLOWED
A. Use Vibrant-Tamp method or machine manufacture using zero slump mixture to achieve desired appearance and physical properties.
2.04 COLOR AND FINISH
A. Match sample on file in architect’s office.
B. Exposed surfaces shall exhibit a fine grained texture similar to natural stone. No bugholes or air voids will be permitted.
C. <Optional> Color shall match (insert name of brick, natural stone or other material to be matched).
- Must match color and finish of approved sample when viewed in direct daylight at a 10 foot distance.
- Color variation allowed – 2%, hue; 6% lightness, chroma and hue combined.
A. New billet steel reinforcing bars – ASTM A 615
- Reinforce units when necessary for safe handling and structural stress.
- Reinforcement shall be galvanized or epoxy coated when covered with less than 1-1/2″ of material. Minimum cover shall be twice the diameter of the bars.
- Area of reinforcement in panels greater than 12″ wide shall be not less than 1/4 percent of the cross section area.
2.06 CURING AND FINISHING
- Cure cast stone components with a direct fired steam generator at a minimum temperature of 105 degrees F (41 degrees C) for a minimum of 6 hours, within 12 hours of fabrication.
- Cure cast stone components in presence of carbon monoxide and carbon dioxide to promote carbonation at surface, to minimize efflorescence.
- Yard cure for 350 degree-days (i.e. 7 days @ 50F or 5 days @ 70F) prior to shipment.
- Acid-etch exposed surfaces to remove cement film prior to packaging for shipment.
2.06 RELATED MATERIALS
A. Anchors – Non-corrosive; galvanized, brass or stainless steel type 304.
B. Mortar – Type N, ASTM C 270
PART 3 – EXECUTION
- Comply with Cast Stone Institute Technical Manual 04720-(current edition).
- Set stones 1/8″ within plane of adjacent unit.
C. Joints, +1/8″, -1/8″.
A. Joint size:
1. At stone/brick joints – 3/8″
2. At stone/stone joints in vertical position – 1/4″ (3/8″ optional)
3. Stone/stone joints exposed on topside – 3/8″
B. Joint material:
1. Use a full bed of mortar at all bed joints.
2. Flush vertical joints full with mortar.
3. Leave all joints with exposed tops open for sealant.
C. Location of joints:
1. As shown on approved shop drawings.
- Drench stones with clear, running water just prior to setting.
- Fill all dowel holes and anchor slots completely with mortar or non-shrink grout.
- Set all stones in a full bed of mortar. Leave head joints in coping and similar stones open for sealant.
- Rake mortar joints 3/4″ for pointing. Sponge the face of each stone to remove excess mortar.
- Tuck point stone joints to a slight concave.
- Sealant joints – Prime the ends of stones, insert properly sized foam backup rod and gun-in sealant. Use sealant on all cornices, copings and, in general, all stone areas either partially or totally horizontal.
- Protect stone while on ground (and after setting) from splashing, mortar and damage from other trades.
3.04 CLEANING AND REPAIR
- Clean stone by wetting with clear running water and applying a solution of “Sure Kleen #600” by ProSoCo Products, Inc. or equal.
- Repair obvious chips with touchup material furnished by the manufacturer.
- Inspect by Cast Stone Institute Standards.
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