This specification encompasses basic requirements for Cast Stone, a building stone manufactured from a mixture of Portland Cement and coarse and fine aggregates, to simulate natural stone. Cast Stone is generally used as a masonry product, as an architectural feature, trim, ornament or facing for buildings or other structures.

 

            Materials and processes used for manufacturing Cast Stone 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 molding Cast Stone is the need to employ a properly proportioned mixture of white and/or grey cements, manufactured or natural sands, carefully selected crushed stone or well graded natural gravel 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 exceed minimum requirements for compressive strength and weathering qualities essential for normal installations as a suitable replacement for architectural terra cotta, 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 Cast Stone and its use. For details and samples of finishes available, please contact Towne House Restorations.

 

 

CSI FILE 04435 - CAST STONE

 

PART 1 - GENERAL

 

1.1        SCOPE

 

            A.         This specification covers all labor, material and services incidental to and including the furnishing and                           setting of all Cast Stone as indicated on the drawings and specified herein.

 

            B.         The Manufacturer shall be responsible for all labor, materials, equipment and services necessary for and                           incidental to providing all Cast Stone covered by this specification.

 

            C.         The Setting Contractor shall unload, receipt for, store and set all Cast Stone covered by this specification                           and shall provide and install all anchors for same.

 

1.2        QUALIFICATION OF MANUFACTURER

 

            A.         The Manufacturer shall be a producer member of the Cast Stone Institute and have a minimum of 10 years                          continuous operation, having experience, adequate facilities and capacity to furnish the quality, size and                          quantity of Cast Stone required without delaying the progress of the work, and whose products have been                          previously used and exposed to the weather with satisfactory results.

 

1.3        DRAWINGS

 

            A.         Scale and/or full size detail drawings will be furnished where necessary by the Architect, and they shall be                          accurately followed in the execution of this work.

 

            B.         The Cast Stone Manufacturer shall prepare and submit for approval complete, properly marked                          fabrication and setting drawings, showing details and sizes of stones, arrangement of joints, bonding,                          inserts, joints, connections to adjoining walls or materials, reinforcing and method of installation and                                 anchoring.

 

            C.         Unless otherwise specified, shop drawings shall provide for the following:

 

                        1. Provide suitable wash on all exterior sills, copings, projecting courses and pieces with exposed top                             surfaces.

 

                        2. Window sills shall have raised fillets at the back.

 

                        3. All projecting pieces and soffit stones shall have drips under the outer edge.

 

                        4. The shop drawings shall show the setting mark of each stone and its location on the structure. The                             stone when delivered shall bear the same corresponding setting mark on an unexposed surface.

 

            D.         The Manufacturer shall submit the shop drawings to the General Contractor. The General Contractor                           shall verify all dimensions and coordinate the drawings with field conditions. The General Contractor                           shall submit the shop drawings to the Architect for approval.

           

            E.         The shop and setting drawings shall be approved by the Architect and the General Contractor before the                          Manufacturer shall be required to proceed with the work.

 

PART 2 - PRODUCTS

 

2.1        MANUFACTURER

 

            A.         Obtain materials for Cast Stone from a single source to insure the match of quality, color, pattern and                          texture.

 

2.2        APPROVED MANUFACTURERS

            A.                    Towne House Restorations          Phone    (718) 497-9200

                                    341 Ten Eyck Street                    Fax       (718) 497-3556

                                    Brooklyn, NY 11206

 

2.3        MODELS AND MOLDS

 

            A.         Should models of ornaments be required, all models shall be prepared by skilled craftsmen in a correct                          and artistic manner in strict accordance with the spirit and intent of the approved drawings. Models shall                          be approved by the Architect before any work is executed therefrom.

 

2.4        MATERIALS

 

            A.         Cement - Portland Type I or Type III White and gray meeting ASTM C 150

          

            B.         Fine aggregate - carefully graded and washed natural sands, or manufactured granite, quartz or limestone                          sands meeting ASTM C33 expect that gradation may vary to achieve desired finish and texture.

 

            C.         Coarse aggregate - carefully graded and washed natural gravels, or crushed, graded stone such as granite,                          quartz, limestone or other durable stone meeting ASTM C33 except that gradation may vary to achieve                          desired finish and texture.

 

            D.         Color - All colors added shall be inorganic (natural or synthetic) iron oxide pigments meeting ASTM                          C979 excluding the use of a cement grade of carbon black pigment, and shall be guaranteed by the

                        pigment manufacturer to be lime-proof. The amount of pigment shall not exceed 10% by weight of the                          cement used.

 

            E.         Admixtures - ASTM C494

 

            F.         Water - shall be potable tap-water free from impurities.

 

2.5        PROPERTIES OF MIX DESIGN

 

            A.         The manufacturer shall be responsible to design a mix which achieves both the strength and the surface                          finish desired.

 

            B.             Compressive strength shall be not less than 6500 psi at 28 days when tested in accordance with

                         ASTM C-39.

 

            C.         The average water absorption of Cast Stone shall not exceed 6% by dry weight when tested in accordance                          with ASTM C-1195.

 

2.6        REINFORCEMENT

 

            A.         Cast Stone shall be reinforced with new billet Steel reinforcing bars meeting ASTM A615, grade 40 or                          grade 60, when necessary for safe handling, setting and structural stress, and the size of the reinforcing                          shall be specified. If the surfaces are to be exposed to the weather, the reinforcement shall be galvanized                              or epoxy coated when covered with less than 2 inches of material for bars larger than 5/8 inch and 1 1/2                          inches for bars 5/8 inch or smaller. The material covering in all cases shall be at least twice the diameter                            of the bars.

 

            B.         Cast Stone panels shall be reinforced as may be required for handling, and to allow for temperature                          changes and structural stress. There shall be a minimum steel reinforcement amounting to 1/4 percent of                          the sectional area of the panel and should the panel be greater than 12 inches in any sectional dimension,                            the temperature steel shall be placed in both directions.

           

            C.         Where applicable, cold-drawn steel wire reinforcement meeting ASTM A 82, Welded Wire Fabric                          Reinforcement meeting ASTM A 185 or ASTM A 497 or steel bar or rod mat reinforcement meeting                          ASTM A 184 may be used.

 

2.7        COLOR AND FINISH

 

            A.         The Manufacturer shall submit to the Architect, for selection and approval, samples of the Cast Stone                          specified which will be typical of the general range of color and finish to be furnished.

           

            B.         Exposed surface, unless otherwise specified, shall exhibit either a smooth concrete surface or a fine                          grained texture similar to natural stone with no bugholes permitted.

           

            C.         The samples shall be approved by the Architect before the Manufacturer shall be required to proceed with                          the work.

           

            D.         Color and Texture of Cast Stone shall be generally equal to the approved sample when viewed in direct                          daylight at a 10 foot distance.

 

            E.         ASTM color variation allowed: -2% hue, 6% lightness, chroma and hue combined.

 

 

2.8            CURING AND FINISHING

 

            A.             Yard cure units for 350 degree days prior to shipment.

 

            B.             Acid-etch and/or grout all exposed surfaces to match approved sample.

 

           

2.9        TOLERANCES

 

            A.         Stone Dimensions - the numerically greater of plus or minus 1/8" or length/360.

           

            B.         Setting Tolerances - plus or minus 1/8" allowable out of plane from adjacent unit.

 

2.10      TESTING

 

            A.             Testing shall be performed in accordance with ASTM C-39 and ASTM C-1195.

           

               B.         Test 3 specimens per 500 cubic feet at random from plant production in accordance with referenced

            standards.

           

            C.         The results of compression tests shall be divided by a factor of 0.8 when saw-cut or core-drilled specimens                          are used.

 

2.11      DELIVERY AND STORAGE

 

            A.         All Cast Stone shall be carefully loaded and packed for transportation exercising customary and                          reasonable precaution against damage while in transit.

           

            B.         All Cast Stone shall be received and unloaded at the project site by competent workmen with the                          necessary care and handling to avoid damage and soiling.

           

            C.         The Cast Stone material shall be stored clear of the ground on non-staining planking or pallets in such a                          manner as to be protected from damage while in storage. Should Cast Stone be stored for an extended                          period, cover with polyethylene or other non-staining water-proof material.

 

2.12         RELATED MATERIALS

 

            A.             Anchors – non corrosive; galvanized, brass or stainless steel type 304.

 

            B.         Mortar – Type N, ASTM C-270.

 

PART 3 - EXECUTION

           

3.1        JOINTING

 

            A.             Joint Size:

1. At stone/brick joints – 3/8”.

2. At stone/stone joints in vertical position – ¼” (3/8” optional).

3. Stone/stone joints exposed on top side – 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 or under relieving angles open for sealant.

 

            C.             Location of Joints:

1. As shown on approved shop drawings.

2. Unless otherwise shown: at control and expansion joints per plans.

 

3.2            SETTING

 

            A.             Drench stones with clear, running water just prior to setting.

            B.             Fill all dowel holes and anchor slots completely with mortar or non-shrink grout.

            C.             Set all stones in a full bed or mortar. Leave head joints in coping and similar stones open for sealant.

            D.             Rake mortar joints ¾” for pointing. Sponge the face of each stone to remove excess mortar.

            E.             Tuck point stone joints to a slight concave.

            F.             Sealant joints – Prime the ends of stones, insert properly sized foam backup rod and gun-in sealant.

            G.            Protect stone while on ground (and after setting) from splashing, mortar and damage from other trades.

 

3.3        CLEANING AND REPAIR

 

            A.             Clean stone by wetting with clear running water and applying a solution of “Sure Kleen #600” by ProSoCo                          Products, Inc. or equal. Follow manufacturer’s instructions.

           

            B.         Repair obvious chips with touchup material furnished by the manufacturer.

 

 

3.4        INSPECTION AND ACCEPTANCE

 

            A.             Applicable standards for inspection and quality control shall be PCI MNL-117 Manual for Quality Control                          for Plants and Products of Architectural Precast Concrete Products.

 

            B.         Cast Stone shall show no obvious repairs or imperfections other than minimal color variations when                          viewed with the unaided eye at a 10 ft. distance in good typical daylight illumination.