583-1 01
NEW YORK STATE DEPARTMENT OF TRANSPORTATION Sections 200 - 599 STANDARD SPECIFICATIONS (USC) January 1, 202 4 Volume 2 SECTION 583 - SHOTCRETE
583-1 Description
583-1.01 Work. The work shall consist of removal and disposal of unsound structural concrete and
replacement with shotcrete where indicated in the contract documents and where ordered by the Engineer. The Contractor has the option of using either the Dry Mix Process or the Wet Mix Process.
583-1.02 Definitions
A Shotcrete. This is mortar conveyed through a hose and pneumatically projected at high velocity onto a surface.
B.Dry Mix Process. This is a process in which the dry cement -sand mixture is carried by compressed air to the nozzle where water is injected and the resulting mixture is jetted from the nozzle at high velocity onto the surface to be shotcreted.
C.Wet Mix Process. This is a process in which all the ingredients including water are thoroughly mixed and then jetted from the nozzle at high velocity onto the surface to be shotcreted.
D.Delivery System. This consists of the nozzle, water ring or air ring, and any necessary valves, connected to the delivery hose.
583-2 MATERIALS. Materials used in this work shall conform to the following requirements:
Portland Cement, Types 1 or 2 701-01 Quilted Covers (for curing) 711-02 Concrete Sand 703-07 Plastic Coated Fiber Blankets 711-03 Water 712-01 Membrane Curing Compound 711-05 Wire Fabric For Concrete Reinforcing1 709-02 Expansion Bolt Anchors GSA FF -S-325,Group III,Type 1 or Group VIII,Type 1 Hook Bolts Inserted in Expansion Bolt Anchors ASTM A307 Grade A NOTE. The wire fabric shall be galvanized in accordance with ASTM A641M regular coatings. The wire fabric shall be fabricated from No. 12 wire spaced 2 inches (nominal) in each direction or No. 10 wire spaced 3 inches (nominal) in each direction. Wire used shall have a minimum yield strength of 35 ksi .
583-2.01 Equipment
A.Batching and Mixing Equipment. The mixing equipment shall be capable of thoroughly mixing the materials in sufficient quantity to maintain placing continuity.
B.Air Supply. The compressor shall be of adequate capacity to maintain a sufficient, constant nozzle velocity for all parts of the work while simultaneously operating a blow pipe for cleaning away rebound. The air hose shall be equipped with a filter to prevent any o il or grease from contaminating the shotcrete.
C.Delivery Equipment
1.Dry Mix Process. The delivery equipment shall be capable of delivering a continuous, smooth, uniformly mixed material to the nozzle. The nozzle shall be equipped with a water ring and valve to permit adjustment of the water. The water added to the dry mix material at t he nozzle shall be
583-2 02
NEW YORK STATE DEPARTMENT OF TRANSPORTATION Sections 200 - 599 STANDARD SPECIFICATIONS (USC) January 1, 202 4 Volume 2 maintained at a pressure at least 16 psi greater than the air pressure. The nozzle shall be capable of delivering a conical discharge stream.
2.Wet Mix Process. Only pneumatic -feed type of delivery equipment will be allowed. Positive displacement type of equipment will be allowed pending a qualification test prior to the beginning of the work, which will also be the qualification test for the operator. The noz zle shall be equipped with an air ring for injecting compressed air into the material flow.
583-2.02 Qualification Test. If encasement of reinforcing bars is required, this test shall be performed to
qualify the shotcrete operator and the equipment, prior to beginning work. Each shotcrete operator shall be qualified by constructing a 2 x 2 foot test panel fabricated to duplicate the project shotcreting. Reinforcement shall be placed in the panel to provide a minimum 1 inch (front and rear) embedment and be of the same size and spacing encountered in the structure. Panels shall be shot in the v ertical, horizontal, and overhead positions as expected to be encountered. After setting, the test panel shall be broken open in a manner approved by and in the presence of the Engineer, to verify the reinforcement embedment. If voids are discovered, the work shall not proceed; additional panels shall be constructed until results acceptable to the Engineer are achieved. Small non -interconnected voids, as determined by the Engineer, shall not constitute failure. Additional qualification panels will be required whenever, in the opinion of the Engineer, the shotcrete operation significantly changes.
583-3 Construction Details
583-3.01 Preparation of Surfaces. All unsound concrete shall be removed until there are no offsets in
the cavity which would cause an abrupt change in thickness, except for a transition from above to below reinforcement. Minimum 1/2 inch square shoulders shall be left at the perimeter of the cavity. The final cut surface shall be sound and properly shaped. The sound surface shall be blast cleaned. Abrasive material used for blastcleaning shall contain no more than one percent free sili ca by weight. Air clean the surface with oil -free compressed air. After the surface preparation has been accepted, every effort should be made to thoroughly wet the concrete surface and all porous surfaces to be in contact with new concrete for 12 hours. This may be acc omplished by continuous wetting with soaker hoses or the use of burlap/burlene/etc. where moisture can be maintained. If in the opinion of the Engineer conditions or the situation prohibits this then the surfaces should be wetted for as long as possible. Surfaces must be wetted by a means acceptable to the Engineer using potable water. The Contractor shall remove any puddles of free standing water with oil -free compressed air, and protect the surfaces from drying, so the existing concrete remains in a cl ean, saturated surface dry condition until placement of the new concrete. TABLE 583 -1 SIZE AND SPACING OF HOOK -TYPE BOLTS (inches) Thickness of Placement Underside & Vertical Surfaces Nominal Size and Spacing1 Topside Nominal Size and Spacing1 2 1/4 dia. @ 18 ctrs. 1/4 dia. @ ctrs. 24 4 3/8 dia. @ 24 ctrs. 3/8 dia. @ ctrs. 36 5 3/8 dia. @ 21 ctrs. 3/8 dia. @ ctrs. 36 6 3/8 dia. @ 20 ctrs. 3/8 dia. @ ctrs. 36 7 3/8 dia. @ 18 ctrs. 3/8 dia. @ ctrs. 36 8 1/2 dia. @ 23 ctrs. 1/2 dia. @ ctrs. 36 9 1/2 dia. @ 22 ctrs. 1/2 dia. @ ctrs. 36 10 1/2 dia. @ 21 ctrs. 3/4 dia. @ ctrs. 24
583-3 02
NEW YORK STATE DEPARTMENT OF TRANSPORTATION Sections 200 - 599 STANDARD SPECIFICATIONS (USC) January 1, 202 4 Volume 2 11 1/2 dia. @ 20 ctrs. 3/4 dia. @ ctrs. 24 12 1/2 dia. @ 18 ctrs. 3/4 dia. @ ctrs. 24 NOTE: 1. Bolt diameters may be increased but not decreased. Spacing may be decreased but not increased. No material shall be placed if the ambient air, or concrete surface temperature is at, or below 45oF. Reinforcement may consist of either existing reinforcing bars or welded galvanized wire fabric, depending on the conditions and shall be clean and free from loose mill scale, loose rust, oil or other coatings that interfere with bonding. Chipping hammers shall meet the requirements of §580 -3.02. Sufficient clearance shall be provided around the reinforcement to permit complete encasement with sound shotcrete. The minimum clearance between the reinforcement and the form or other backup material shall be 1 inch . Where the chipped area is equal to or less than 2 inches in depth, the use of wire fabric or mechanical concrete anchors will not be required except for overhead surfaces. Where the chipped areas are overhead, and are 1 inch in depth or greater, galvanized wire fabric and mechanical concrete anchors shall be used. Mechanical concrete anchors shall be placed as required by Table 583 -1. Where the chipped area is over 2 inches in depth and existing bar reinforcement is available, galvanized wire fabric shall be attached to the bars with tie wires. If existing bar reinforcement is not available, wire fabric shall be installed by means of mechanical concrete anchors in accordanc e with the requirements of Table 583 -1. Wire fabric shall be cut in sheets of the proper size and shall be carefully bent in such a manner as to follow closely the contours of the areas to be repaired. The wire fabric shall be securely tied to the hook - type bolts or the reinforcing bars. Where sheets meet, they shall be lapped a minimum of 4 inches and shall be securely fastened together. Expansion bolt anchors shall be placed in holes drilled in the existing concrete surface to the diameter and depth recommended by the manufacturer of the expansion bolt anchors. Hook -type bolts of the proper length shall be inserted and securely attached to the expansion bolt anchors so as to provide a positive connection to sound concrete. Where the chipped area is 6 inches or greater in depth, the Contractor shall place galvanized wire fabric in layers 4 inches apart. Where it is necessary to place more than one layer of galvanized wire fabric in an area to be repaired, the innermost layer shall be covered by a shotcreting prior to the installation of the next outermost layer. Existing reinforcement which has lost significant section shall be repaired in a manner satisfactory to the Engineer as extra work.
583-3.02 Preparation of Materials
A.General. The sand shall be measured either by volume or weight, by means of batch boxes approved by the Engineer, or in a proportioning plant approved in accordance with section 501, Portland Cement Concrete - General. Wheelbarrows or shovels will not be permit ted for measuring. The same source of sand shall be used throughout each structure.
B.Dry Mix Process. Dry mix shotcrete shall be composed of one part of cement to three to four and one-half parts of sand. Prior to mixing, the moisture content of the sand shall be between 3 and 6%. The sand shall be dampened or dried as required to bring the moisture within these limits. A wetting agent approved by the Engineer may be used at the Contractor's option in the dry mix process.
583-3 03
NEW YORK STATE DEPARTMENT OF TRANSPORTATION Sections 200 - 599 STANDARD SPECIFICATIONS (USC) January 1, 202 4 Volume 2 Sand -cement mixtures shall be applied within 75 minutes of the time the sand initially contacts the cement. Sand -cement mixtures which exceed the 75 minute limit shall not be incorporated in the work. They shall be disposed of in a manner acceptable to t he engineer.
C.Wet Mix Process. Wet mix shotcrete shall be composed of one part of cement to three parts of sand. The cement, sand and water shall be premixed to a desired consistency and in accordance with §501-3.03, Handling, Measuring and Batching Materials, and §501-3.04, Concrete Mixing, Transporting and Discharges - General Requirements.
583-3.03 Placement
A.Weather. Shotcrete shall not be applied during any precipitation which is of sufficient intensity to cause the placed shotcrete to run. Shotcrete shall not be placed during a wind that disrupts the nozzle spray. Shotcrete shall not be applied when the ambient air temperature is below 45 F unless it is placed in accordance with §555-3.08C.2., Provision of External Heat. Receiving surfaces shall be heated to, and maintained at, approximately 45 F by a method approved by the Engineer before shotcreting operations begin. Under no conditions shall shotcrete be applied against surfaces upon which any frost adheres.
B.Application. Before starting to shoot, precautions shall be taken to protect property in the area. Adjacent construction, openings, shrubbery, and all areas that might be discolored or damaged by rebound, cement, water or dust must be covered with tarpaulins or pla stic sheets to protect them from damage. When projecting the shotcrete, the stream of flowing materials shall be directed from the nozzle as nearly at a right angle as possible to the surface being treated, and shall be held uniformly at the same distance, less than 5 feet away from the surface at all times. Manufacturer's recommendations shall be followed. The size of the nozzle shall be consistent with the manufacturer's recommendation for the maximum size of the sand used. The use of rebound material shall not be perm itted. Shotcrete on vertical and overhead surfaces shall be built up in 3/4 inch maximum layers to prevent sloughing in heavy applications. Succeeding layers shall be applied just prior to the initial set to maintain a good bond. When encasing reinforcing steel, the stream from the nozzle shall be directed at an angle so as to fill the space behind the bars. An air jet shall be used to blow out any rebound ahead of the application of shotcrete. Should any such deposit of sand reb ound be covered with shotcrete, it shall be cut out and removed by the Contractor without compensation. Ground wires may be installed to establish the thickness and surface planes of the shotcrete build up. Both horizontal and vertical ground wires may be installed at corners and offsets not clearly established by exterior corners of walls, column or beam c orners, and other locations. They may also be used as screed guides. Eighteen or 20 gage hard steel piano wire is recommended for this purpose. Ground wires shall be tight and true to line, and placed in such a manner that they may be further tightened.
C.Quality Control
1.Test Panels. This test shall be used to determine the physical quality of the shotcrete and shall be performed immediately before shotcreting operations begin, after each additional 100 sf , and immediately after operations are ended. The test panels shall be 12 inches square, 3/4 inch thick plywood boards with galvanized mesh ( 1/2 inch square openings) strips projecting 4 inches attached around the perimeter of the board. The boards shall be erected horizontally, vertically, or overhead, depending on the
583-3 03
NEW YORK STATE DEPARTMENT OF TRANSPORTATION Sections 200 - 599 STANDARD SPECIFICATIONS (USC) January 1, 202 4 Volume 2 anticipated shooting positions. The shotcrete operator shall completely fill the test panel, after which it shall be screeded or cut with a trowel such that it contains a 4 inches uniform depth of shotcrete. The test panels shall then be covered with wet quilted covers or wet polyethylene - coated blankets; put in a shaded, protected place; kept wet and cured for a minimum of seven days. The test panels shall be sent to the Departm ent of Transportation's Materials Bureau for testing at fourteen days. Cor es will be drilled from the panels and compressive strengths at fourteen days will be reported to the Engineer. Additional information on the conditions of the shotcrete such as sand pockets, voids, and laminations will also be reported with the strength results.
2.Coring. The Contractor shall take a core, at a location determined by the Engineer, from each structural element, such as pier, abutment, arch, etc., to verify acceptability of reinforcement encasement. Cores which do not contain reinforcing bars will not be us ed to determine encasement acceptability. If interconnected voids are found, the structural element represented by that core shall be rejected. All rejected shotcrete shall by repaired or replaced at the Contractor's expense. Repair methods sh all be proposed by the Contractor for approval by the Engineer. The Contractor may take additional cores at locations approved by the Engineer to establish the limits of rejected work. The additional coring shall not jeopardize the design integrity of th e structural element. If additional cores are not taken, all work on that structural element shall remain rejected. Core holes shall be patched with an applicable concrete repair material from the Approved List.
D.Finishing. The natural gun finish will be sufficient unless the plans call for one of the following finishes:
1.Screed Finish. After the surface has taken its initial set, excess material outside the forms and ground wires shall be sliced off with a sharp -edged cutting screed. After screeding, the ground wires shall be removed.
2.Broom Finish. This type of finish may be applied after screeding.
3.Flash Coat Finish. This is a thin surface coating containing finer sand than normal, and the application nozzle is held well back from the work. This finish shall be applied to the surface as soon as possible after screeding. Any of the remaining three types of finish may be applied following flash coat:
a.Wood Float Finish. This gives a granular finish.
b.Rubber Float Finish. This gives a coarse finish.
c.Steel Trowel Finish. This gives a very smooth finish.
E.Curing. Curing shall be in accordance with §555-3.08, Curing, and the following modifications:
1.All curing covers shall be pre -wet and kept wet during the entire curing period in a manner satisfactory to the Engineer.
2.Curing compounds shall be applied twice. The second application shall be done when the first application has become tacky. The second application shall be done at a right angle to the first application. The rate of each application shall be that given in §555-3.08A.
583-5 01
NEW YORK STATE DEPARTMENT OF TRANSPORTATION Sections 200 - 599 STANDARD SPECIFICATIONS (USC) January 1, 202 4 Volume 2 583-4 METHOD OF MEASUREMENT. The quantity to be paid for under this item will be the number of square feet of finished shotcrete installed. Measurement will be taken as the plane projection of the finished surface. Measurement shall be made prior to the placement of shotcrete.
583-5 BASIS OF PAYMENT. The unit price bid per square foot shall include the cost of furnishing all
labor, materials and equipment necessary to complete the work.
583-5.01 Removal of Structural Concrete - Replacement with Shotcrete. No Reinforcement Bar
Encasement. The unit price bid per square foot shall include the cost of furnishing all labor, materials and equipment necessary to complete the work.
583-5.02 Removal of Structural Concrete - Replacement with Shotcrete, Reinforcement Bar
Encasement. The unit price bid per square foot shall include the cost of furnishing all labor, materials and equipment necessary to complete the work, except that replacement of deteriorated reinforcement shall be paid for separately. Payment shall not be made until cores verify acceptability. Payment will be made under: Item No. Item Pay Unit 583.02 Removal of Structural Concrete - Replacement with Shotcrete, No Reinforcement Bar Encasement Square Foot 583.03 Removal of Structural Concrete - Replacement with Shotcrete, with Reinforcement Bar Encasement Square Foot SECTION 584 - SPECIALIZED OVERLAYS FOR STRUCTURAL SLABS
584-1 DESCRIPTION. Prepare the surfaces that will be in contact with slab reconstruction concrete and
place slab reconstruction concrete. Prepare the structural slab surface and place a specialized concrete overlay.
584-1.01 Scope. Concrete removal work will be paid for under the appropriate item(s). Minimum
thickness of overlay concrete is 1 1/2 inches . Include the cost of any grade changes necessitated by this requirement in the unit bid price for overlay concrete. Use only one type of overlay concrete on any one structure.
584-1.02 Definitions
A.Class DP Concrete. A homogeneous mixture of portland cement, fly ash, microsilica admixture, fine and coarse aggregates, air entraining agent, set retarding water reducing admixture and water.
B.Microsilica Concrete. A homogeneous mixture of portland cement, microsilica admixture, fine and coarse aggregates, air entraining agent, high range water reducing admixture and water.
C.Overlay Concrete. Concrete placed over existing and slab reconstruction concrete. Overlay concrete will be Microsilica concrete for Method 1 and Method 2, and Class DP concrete for Method 3, as described in 584 -1.03 Placement Methods.
D.Slab Reconstruction Concrete. Concrete placed completely around the exposed top mat of bar reinforcement. Slab reconstruction concrete will be Class D or Class DP concrete for Method 1, Microsilica concrete for Method 2, and Class DP concrete for Method 3, as described in 584 -1.03 Placement Methods.
Source: New York Standard Specifications, 2024 Edition. Pages 439–443 of 1,264.