DOT Standard Specifications

506.07 Reinforcing Steel Construction and Placement. (download pdf)
(a) General.
The reinforcing steel cage, consisting of longitudinal and transverse bars, ties, cage stiffeners, spacers, centralizers, and other necessary appurtenances, shall be completely assembled and placed as a unit immediately after the shaft excavation is inspected and accepted, and prior to concrete placement. The reinforcing steel in the shaft shall be securely tied and supported so that the reinforcing steel will remain within allowable tolerances given in Subarticle 506.11(c) of this Specification.
(b) Spacers.
1. Concrete spacers or other approved noncorrosive spacing devices shall be used at sufficient intervals near the bottom, and at intervals not exceeding 10 feet up the shaft, to insure concentric spacing for the entire cage length.
2. Spacers shall be constructed of approved material equal in quality and durability to the concrete specified for the shaft. The spacers shall be of adequate dimension to insure the proper annular space between the outside of the reinforcing cage and the side of the excavated hole and/or permanent casing as detailed on the plans or proposed in the installation plan. If not detailed on the plans, a minimum 4 inch {100 mm} annular space will be required.
(c) Cage Supports.
Cylindrical concrete feet (bottom supports) shall be provided to insure that the bottom of the cage is maintained at the proper distance above the base as specified by the project plans.

515-3.07 Reinforcing Steel Construction and Placement. (download pdf)
Use concrete wheels or other approved, non-corrosive spacing devices near the bottom and at intervals not exceeding 15 feet up the shaft to ensure concentric spacing for the entire length of the cage. Do not use block or wire type spacers. Use a minimum of one spacer for each 30 inches of cage circumference.

609-3.06 Reinforcing Steel Construction and Placement. (download pdf)
The reinforcing cage shall be adequately supported and anchored from the top to prevent movement from the required location during and for four hours after completion of concrete placement. If temporary casing is used, the reinforcing cage shall be supported prior to removing casing, and for four hours following removal of the casing. The rebar cage shall be kept plumb. The rebar cage shall not rest directly on the bottom of the excavation. Spacers shall be at sufficient intervals along the shaft to ensure concentric location of the reinforcing cage for the entire length of shaft. Spacers shall be placed at a maximum vertical spacing of 15 feet, with a minimum of four spacers around the circumference at each vertical elevation. For all drilled shafts of less than six feet in diameter, the spacers shall provide for a minimum of three inches of concrete cover between the reinforcing steel and the excavation wall. For all drilled shafts of six feet in diameter or greater, or for drilled shafts of any diameter constructed with the wet method, the spacers shall provide for a minimum of six inches of concrete cover between the reinforcing steel and the excavation wall. Only spacers approved by the Engineer shall be allowed, and in no case shall “dobies” or other rectangular “blocks” tied to the reinforcing steel be allowed in excavations with the wet method. When “dobies” are used, they shall be made from concrete of the same compressive strength as the concrete used in the drilled shafts.

804.06 Reinforcing Steel for Structures. Placing and Fastening. (download pdf)
Metal bar supports that are in contact with the exterior surface of the concrete shall have protection conforming with the CRSI Specifications, Class 1 for Plastic Protected Bar Supports or Class 2 for Stainless Steel Bar Supports, with the further provision that the plastic protection may be applied either by a dipping operation or by the addition of premolded plastic tips to the legs of the supports. All high chairs and bar bolsters shall be metal. When concrete is to rest on an excavated surface, layers of bars shall be supported above the surface by metal chairs or by precast mortar or concrete blocks.

49-3.02C(4) PILING. Reinforcement. (download pdf)
Place spacers at least 5 inches clear from any inspection tubes.
Place plastic spacers around the circumference of the cage and at intervals along the length of the cage under the manufacturer’s instructions.

602.02 Reinforcing Steel. (download pdf)
All accessories, including reinforcing steel supports, ties, and splicers used in conjunction with epoxy coated reinforcing steel, shall be plastic or epoxy coated.

7.01.03 Drilled Shafts. Reinforcing Steel Cage Construction and Placement. (download pdf)
Concrete spacers or other approved noncorrosive spacing devices shall be used at sufficient intervals near the bottom and at intervals not exceeding 10 feet up the shaft, in order to ensure concentric spacing for the entire cage length. Spacers shall be constructed of approved material, equal in quality and durability to the concrete specified for the shaft.

606.03.9 Assembly and Placement of Reinforcing Steel. (download pdf)
Tie and support the reinforcing steel in the drilled shaft so that the location of the reinforcing steel will remain within allowable tolerance. Use concrete spacers or other approved non-corrosive spacing devices at sufficient intervals (near the bottom, the top and at intervals not exceeding 10 feet vertically) to ensure concentric spacing for the entire cage length.

455-16 DRILLED SHAFTS. Reinforcing Steel Construction and Placement. (download pdf)
Use wheels or other approved noncorrosive spacing devices within 3 feet of the bottom, within 6 feet of the top, and intervals not exceeding 10 feet along the shaft to ensure concentric spacing for the entire length of the cage. Do not use block or wire type spacers.

500 Concrete Structures. (download pdf)
3. Metal or Plastic Forms
Construct metal or plastic forms as follows:
a. Use metal or plastic to form concrete only if the Engineer approves the forms and if the forms produce satisfactory results.
b. Use metal forms that produce finished concrete equal to or superior to concrete made from comparable wooden forms.
c. Countersink bolts and rivets in the surfaces of metal forms that touch concrete.
d. Grind welds smooth in the surfaces of metal forms to provide a smooth plane surface.

511 Drilled Shafts. Reinforcing Steel Cage Construction and Placement. (download pdf)
Assemble and place reinforcing steel cage immediately after the Engineer inspects and accepts shaft excavation and before placing concrete. Reinforcing steel cage includes longitudinal bars, ties, cage stiffener bars, spacers, centralizers, and other appurtenances necessary to complete cage.
Tie and support shaft reinforcing steel such that reinforcing steel placement conforms to allowable tolerances as specified in Subsection 511.03(C)(10) – Construction Tolerances. Use concrete spacers at sufficient intervals (near bottom and at intervals not exceeding 10 feet along shaft length) to ensure concentric spacing for entire cage length. Use minimum of four spacers, equally spaced around circumference, at each vertical interval. Construct spacers of material accepted by the Engineer, equal in quality and durability to concrete specified for the shaft. Furnish spacers of adequate dimension to ensure a minimum 3-inch space between outer portion of reinforcing cage and side of excavated hole or casing. Provide cylindrical concrete bottom supports accepted by the Engineer to maintain proper distance between bottom of cage and base of shaft excavation.
Check top of steel cage elevation before and after placing concrete. When reinforcing steel placement does not meet specified tolerances, correct to required tolerances. Do not construct additional shafts until reinforcing steel cage support method has been modified and accepted.
When bottom of constructed shaft elevation is lower than shown in the contract documents, extend at least half of the longitudinal bars required in upper portion of shaft, to the shaft bottom. Continue tie bars for the extra depth, spaced 2 feet on center. Extend stiffener bars to final depth. Use lap splices or unspliced bars of proper length. Welding of reinforcing steel will not be allowed.

503.03 Metal Reinforcement (download pdf)
If concrete blocks are used, embed the appropriate tie wires or coated tie wires during their forming stage and tie each block to the reinforcing bar it supports to hold the block in place. Ensure concrete blocks have approximately the same strength quality as the concrete placed around them. The Department requires plastic coated tie wire and plastic coated metal bar supports whenever they will be in direct contact with epoxy coated reinforcing. Do not use pebbles, pieces of broken stone, broken concrete, metal pipe or wooden blocks.

516.11 Drilled Shafts-Reinforcement (download pdf)
The cage centralizers or other approved non-corrosive spacing devices shall be used at sufficient intervals (near the bottom and at intervals not exceeding 10 ft (3 m) throughout the length of the shaft) to ensure proper cage alignment and clearance for the entire shaft.

SECTION 703 – REINFORCING BARS (download pdf)
703.06 Placing and Fastening
60 – Chairs and supports holding upper layers of reinforcing bars shall support the transverse bars.
70 – Reinforcing bars shall be separated from horizontal surfaces by being suspended or supported on approved chairs and spacers capable of supporting the designed loads. Supports and spacers shall be of such shape as to be easily encased in concrete. That portion which is in contact with the forms shall be non-corrosive and non-staining material. They shall be of an approved type.

Section 2404. Reinforcement (download pdf)
E. Reinforcing Supports and Spacers.
2. Use support devices and side-form spacers, either plastic or steel, meeting the requirements of Materials I.M. 451.01.
4. Do not use concrete block inserts, bricks, stones, wood blocks, wood stakes, and similar materials to support reinforcement if by their use they may become embedded in the concrete.

SECTION 703 | DRILLED SHAFTS (download pdf)
d. Placing Reinforcing Steel and Sonic Testing Pipes.
Use a minimum of 1 non-corrosive circular spacer per 30 inches of circumference of the reinforcing steel cage, within 2 to 4 feet of the bottom and top, and at intervals not to exceed 10 feet vertically. If the shaft is deepened and additional reinforcing steel cage is required, make the splice at the bottom of the steel cage.

SECTION 602 – STEEL REINFORCEMENT (download pdf)
602.03.04 Placing and Fastening.
Use precast blocks composed of mortar or Engineer approved metal chairs as supports for holding reinforcement from contact with the forms. Ensure that the tips of metal chair supports in contact with the surface of the concrete are plastic coated steel. When using plastic coated steel supports, provide a minimum of 1/8 inch thickness of the plastic material between the metal tips and the exposed surface of the concrete.

Section 803 – Drilled Shafts (download pdf)
Use concrete spacers or other acceptable non-corrosive spacing devices at sufficient intervals [near the bottom, the top, and at intervals not exceeding 10 feet vertically] to ensure concentric spacing for the entire cage length. The number of spacers required at each level will be one spacer for each foot of excavation diameter, with a minimum of four spacers at each level. The spacers shall be of adequate dimension to ensure an annular space between the outside of the reinforcing cage and the side of the excavation along the entire length of the drilled shaft as shown on the plans. The width of the spacer shall be a minimum of 1.75 inches. Acceptable feet (bottom supports) made of plastic or concrete shall be provided to ensure that the bottom of the cage is maintained at the proper distance above the base of the excavation unless the cage is suspended from a fixed base during concrete placement.

Section 504 – Reinforcing Steel (download pdf)
503.06 Placing and Fastening
Proper distances from the forms shall be maintained by means of chairs, stays, blocks, ties, hangers or other approved means. Chairs used for this purpose shall be plastic, plastic coated, epoxy coated or plastic tipped. Blocks shall not be used in cases where the blocks will be visible in the finished product. Layers of bars may be separated by precast portland cement mortar blocks or other approved devices. The use of pebbles, pieces of broken stone or brick, metal pipe or wooden blocks shall not be permitted. The placing of reinforcement as concrete placement progresses, without definite and secure means of holding the steel in its correct position, shall not be permitted except in the case of welded steel wire fabric or reinforcing bar grids.

421 REINFORCING STEEL (download pdf)
421.02.01 Supports. Use approved coated metal, plastic, plastic tipped, or galvanized material. Aluminum is unacceptable. All materials are subject to approval.
Support reinforcing bars and maintain their distances from faces of forms by using approved templates, blocks, ties, hangers, or other supports. Support bars in the bottom of footings on approved precast concrete blocks with embedded tie wires or suspend in place. Support bars in the tops of footings by using approved supports.
Do not use metal, metal with plastic tipped legs, or plastic chairs against formed surfaces that will be exposed in the finished structure.

901.62 Reinforcement (download pdf)
Blocks for holding reinforcement from contact with the forms shall be precast mortar blocks of approved shape and dimensions. Blocks for spacing reinforcing bars shall also be precast mortar blocks of approved designs and short enough to permit their ends to be adequately covered with concrete. The precast mortar blocks shall be made from the same materials and of the same proportions of sand and cement as that of the concrete in which they are to be used.

Section 718 Drilled Shafts (download pdf)
G. Placing Steel Reinforcement
Use non-corrosive spacers. The Contractor may use round plastic spacers. Do not use concrete blocks, wood blocks, or metal chairs on the sides of the shaft. The Contractor may use concrete blocks on the bottom of the shaft to maintain cover.

C.2 Special Requirements for Bridge Slabs (download pdf)
For bridge slabs, use slab bolsters as the primary support for the bottom transverse reinforcement bars meeting the requirements of “Bar Support Specifications and Standard Nomenclature” in the CRSI Manual of Standard Practice. Place the bolsters on the falsework sheathing in continuous lines, parallel to the beams, girders, or centerline of the roadway at locations that will permit placement of supports for the top transverse reinforcement bars directly over the bolsters on the bottom transverse bars.
Use continuous lines of upper continuous high chairs with wire runners as the support system for the top transverse reinforcement bars. Place the high chairs to transfer load to the bottom bolsters without causing deflection in the bottom transverse bars. Use individual type high chairs only as supplemental support or for sections where the use of continuous type high chairs is not practical and the Engineer approves, in writing, the use of the individual type high chairs.
Tie the top mat of epoxy-coated reinforcement bars at every transverse bar intersection along each continuous row of longitudinal bars. Tie the bottom mat of reinforcement bars and non-continuous rows of top mat bars at least at every second transverse bar intersection. Stagger the ties for the bottom mat along adjacent rows of longitudinal bars. Use plastic or nylon-coated tie wires.
Use plastic bar supports or epoxy-coated wire bar supports with coating resistant to abrasion. Provide epoxy coating for bar supports at least 0.005 inch thick and in accordance with 3301, “Reinforcement Bars.” Provide plastic coated tips or additional epoxy coating on the legs of the supports for wire bar supports that bear on falsework sheathing for exposed concrete surfaces. Ensure the additional material extends at least ½ inch above the sheathing, not including portions of the supports other than the legs. Use a grey-colored coating with a total coating thickness on the ½ inch portion, including the initial 0.005 inches of epoxy coating, of at least 3/32 inch. Use incompressible and abrasion resistant plastic or epoxy material.

Section 805 Reinforcement (download pdf)
805.03.3 Placing and Fastening. Reinforcement shall be accurately placed in the positions shown on the plans and firmly held during the placing and setting of concrete. Bars shall be tied at all intersections. Where spacing is less than one foot in each direction, alternate intersections shall be tied.
Distances from the forms shall be maintained by means of stays, blocks, ties, hangers, or other approved supports. Blocks for holding reinforcement from contact with the forms shall be precast mortar blocks of approved shape and dimensions or metal chairs, reference Subsection 711.02.7.

Section 706 REINFORCING STEEL FOR CONCRETE STRUCTURES (download pdf)
706.3.1 All reinforcing steel required for superstructure concrete, such as slabs, girders and beans and top slabs of culverts with more than a 4-foot span, shall be held securely in correct position with approved metal or plastic bar supports or ties.

Section 553 Prestressed Concrete Members (download pdf)
553.03.5 Placing Reinforcing Steel
Provide the distance between the reinforcing and side forms using approved stays, ties, or chairs. Do not use precast mortar blocks, pebbles, pieces of broken stone or brick, metal pipe, or wooden blocks.

Section 707 Reinforcement (download pdf)
707.3 Construction Methods
(2) Reinforcing steel in concrete decks and slabs shall be positioned on plastic coated supports or chairs to accurately maintain the specified clearance to the surface of the concrete. Supports shall be spaced at distances not greater than 3 feet for #4 top bars or 4 feet for all other reinforcing.
(5) Bar support units shall be standard products from a reputable manufacturer of such items. Properly sized supports shall be furnished in sufficient numbers, manufactured to serve their intended purpose, and capable of carrying imposed loads without measurable deflection or displacement of the reinforcing steel. The type and adequacy of supporting units shall be at least equal to that recommended by the Concrete Reinforcing Steel Institute’s Manual of Standard Practice.
(6) Bar supports which are at exposed concrete surfaces shall be corrosion resistant as described in the Concrete Reinforcing Steel Institute’s Manual of Standard Practice.
e. Fiber reinforced concrete support spacers must have at least 4% Polyamide fiber. The flexural strength shall be at least 580 psi (4 MPa) and the compressive strength not less than 9,000 psi (62 MPa). The coefficient of expansion must be the same as for the cast-in-place concrete.

Section 505 Reinforcing Steel (download pdf)
505.02.04 Welded Hoop Reinforcing.
Fabricate metal chairs which are in contact with the exterior surface of the concrete of either galvanized steel, or with steel tips plastic coated to at least 19mm (3/4in.) into the concrete, or of stainless steel conforming to ASTM A493, Type 430. Do not use pebbles, pieces of broken stone, brick, metal pipe, or wooden blocks.
For epoxy coated reinforcing steel, use compatible types of bar supports to minimize damage to the coating on the bars during field placing. Make bar supports of dielectric material or coat with dielectric material. If precast concrete blocks with embedded tie wires or precast concrete doweled blocks are used, epoxy coat or plastic coat the wires or dowels. Epoxy coat reinforcing bars that are used as support bars. In walls reinforced with epoxy coated bars, epoxy coat spreader bars. Make proprietary combination bar clips and spreaders that are used in walls of corrosion resistant material or coat with dielectric material. Coat wire bar supports with dielectric material, such as epoxy or plastic, for a distance of at least 50 mm (2in.) from point of contact with the epoxy coated reinforcing bars.
Position reinforcing in concrete deck slabs on approved metal or plastic supports or chairs or on precast mortar blocks to maintain accurately the specified clearance to the surface of the concrete. Do not space metal support units greater than 1.2 m (4 ft) in either direction when supporting bar sizes No. 16 (#5) and larger. For No. 10 or 13 (#3 or #4) bars, do not space more than 0.9 m (3 ft) in either direction. Do not space plastic or mortar support units greater than 0.9 m (3 ft) in either direction for all bar sizes.

Section 544 Reinforcement for Concrete (download pdf)
3.4 Placing and fastening.
Blocking shall be by rust-resistant chairs unless otherwise permitted.
3.4.1 Bridge deck reinforcing steel shall be placed on epoxy or plastic-coated steel wire supports in accordance with 2.4 and the Concrete Reinforcing Steel Institute Manual of Standard Practice.
3.4.2 If plain reinforcing steel for the bridge deck is called for on the plans, then plastic protected or stainless steel protected supports may be used to support the bottom reinforcing mat and bright basic bar supports may be used between the top and bottom mats.
3.4.3 Concrete shall not be placed in any member until the placement of the reinforcing steel has been inspected and approved.

SECTION 503 – DRILLED SHAFT FOUNDATIONS (download pdf)
J. Constructing Reinforcement Steel Cages.
Use concrete spacers or other approved noncorrosive spacing devices at sufficient vertical intervals, near the bottom, and at intervals not exceeding 10 feet up the shaft, to ensure concentric location of the cage within the shaft. If the size of the spacers is not shown on the Plans, provide spacers that will create a minimum 3-inch annular space. Ensure that flat or crescent shaped centralizers (“sleds”) are not used in an uncased shaft.
Provide reinforcing cage bottom support to ensure that the bottom of the cage is maintained at the specified distance above the base. Use approved non corrosive devices such as cylindrical concrete feet, mortar or plastic chairs as the bottom supports.

Section 502 Drilled Shafts (download pdf)
502.3.4.3 Reinforcing Steel Unit Placement
Use concrete spacers or other approved non-corrosive spacing devices at sufficient intervals, near the bottom and at maximum intervals of ten (10) ft up the shaft, to ensure concentric spacing for the entire reinforcement unit length. Use spacers equal in quality and durability to the concrete specified for the shaft. Inspect the bottom of the shaft immediately before placing of the cage to ensure that there is no sloughing.

SECTION 556 – REINFORCING STEEL FOR CONCRETE STRUCTURES (download pdf)
556-2.01 Devices for Supporting and Tying Reinforcement.
Chairs, tie wires, and other devices used to support, position, or fasten the reinforcement shall be made of or coated with, a dielectric (electrically insulating) material. Stainless steel chairs without polyethylene tips and meeting the requirements of ASTM A493, AISI Type 430, may also be used. The specific hardware that the Contractor proposes to use shall be approved by the Engineer.

SECTION 411 DRILLED PIERS (download pdf)
411-2 MATERIALS – Reinforcing Steel
(C) Rollers and Chairs
Use rollers and chairs that are non-metallic and resistant to corrosion and degradation. Provide rollers with the necessary dimensions to maintain the minimum required concrete cover shown in the plans and center rebar cages within excavations. Use chairs of sufficient strength to support rebar cages in excavations and of the size necessary to raise cages off bottom of holes to maintain the minimum required distance shown in the plans.

Section 612 REINFORCING STEEL (download pdf)
612.03 MATERIALS – Reinforcing Steel, Dowel Bars, and Tie Bars
Placing and Tieing.
Ties shall be two wraps of 14 gauge non-corrosive ties.
Use bar supports that are made of plastic or metal. Use corrosion-proof legs if metal bar supports rest on the forms. Place bolsters and bar supports for deck slabs and approach slab at a maximum of 4-foot spacing.

Section 509 Reinforcing Steel (download pdf)
Method of Placing (509.04) – Clearances
Bolsters or chairs should be used, or the cage should be assembled and wired so that the proper clearances are obtained before encasement. The bolsters or chairs used to support reinforcing steel in slabs, beams, or girders must be spaced no more than 4 feet (1.2 m) apart both transversely and longitudinally. This spacing is a maximum. The Contractor needs to install enough supports to keep the reinforcing steel from experiencing substantial deflections induced from construction loads.
Supports (509.08)
Reinforcement may be spaced by metal supports, plastic supports, or precast mortar blocks. Supports should be checked as soon as possible to determine that they will provide the proper clearance. The bolsters or chairs used to support reinforcing steel in slabs, beams, or girders must be spaced no more than 4 feet (1.2 m) apart both transversely and longitudinally.

Section 511 REINFORCING STEEL FOR STRUCTURES (download pdf)
511.04 Construction Methods
B. Placing and Fastening
(2) Support System
Support reinforcing steel with mortar blocks, wire bar supports, supplementary bars, or other approved devices. Use enough supports to maintain the bar position within tolerances. Space slab bar supports no more than 4 ft [1.2 m] apart, transversely or longitudinally.

Section 00921 – Major Sign Support Drilled Shafts (download pdf)
00921.45 Reinforcing Steel
(d) Concrete Cover – Maintain the required concrete cover shown by placing concentric spacer bars or other approved devices around the reinforcing cage.
Do not use wood spacers or concrete dobies.

SECTION 1002—REINFORCEMENT BARS (download pdf)
1002.2 MATERIAL
2.c Plastic Supports. Use chairs and bolsters that do not deflect more than 1/4 inch under the minimum point load requirement of 350 pounds-force as described in PTM No. 430. Use supports molded in a configuration that does not restrict concrete flow.

Section 810 Reinforcing Steel (download pdf)
810.03.5 Placing and Fastening.
3. Support Systems. All bars shall be maintained the correct distance from the forms by means of blocks, hangers, chairs or other approved devices. The use of pieces of stone, brick, wood or metal pipe is not permitted. If required, precast concrete blocks placed with the small face down may be used. All metallic support systems shall have a protective coating for corrosion protection. For metallic support hardware resting against formwork, plastic tips shall be provided.
4. Fastening. All metallic wire ties and miscellaneous metallic hardware used for placement of reinforcing shall be plastic coated. For metallic hardware resting against formwork, plastic tips shall be provided.

Section 703 Reinforcing Steel (download pdf)
703.2.6.3 Plastic Bar Supports
1. Ensure that plastic bar supports meet the following requirements:
A. Chairs and bolsters are of adequate strength to resist a 300 pound concentrated load without permanent deformation or breakage.
B. The plastic bar support material is manufactured from either resin or first generation recycled thermoplastic resin, is colored white, gray, or black, and is chemically inert in concrete.
C. Plastic reinforcing bar supports are in a configuration that does not restrict concrete flow and consolidation around and under the rein-forcing bar support.

DRILLED SHAFT CONSTRUCTION (download pdf)
465.3 Construction Requirements
G. Reinforcing Steel Cage Construction and Placement
Concrete centralizers or other approved noncorrosive centering devices shall be used within 1 foot of the bottom. Centralizers shall also be used at intervals not exceeding 5 feet along the length of the shaft. Each level of centralizers shall be rotated 45 degrees in the horizontal plane relative to the level below. Concrete centralizers shall be constructed of concrete equal in quality and durability to the concrete specified for the shaft. The concrete centralizers shall have the ends beveled to minimize the potential for catching on obstructions during reinforcing steel placement and they shall have a minimum of two tie wires cast in the concrete. Wrapping wires around the concrete centralizers to hold them in place is not an acceptable method of attachment. Any type of steel used as centralizers shall be epoxy coated. The reinforcing steel cage shall not be in contact with the bottom of the shaft.

604.08 Reinforcement (download pdf)
F. Placing and Fastening
Securely space all reinforcing steel from the forms and between adjacent reinforcement with approved metal spacers, concrete blocks, or other approved devices or methods, except only use metal spacers in slabs of bridges and top slabs of box type structures.

Item 416 Drilled Shaft Foundations (download pdf)
3.5 Reinforcing Steel.
Center the reinforcing steel cage in the excavation using approved “roller” type centering devices unless otherwise approved. Use concrete or plastic chairs to keep the reinforcing cage off of the bottom of the hole. Use centering devices starting at 1.5 ft. off from the bottom of the cage and spaced vertically at intervals not exceeding 10 ft. Use a minimum of 3 centering devices per level at a spacing not to exceed 30 in. Flat or crescent-shaped centralizers (“sleds”) are not allowed.

Section 03211 REINFORCING STEEL AND WELDED WIRE (download pdf)
E. Maintain the required distance from the forms and between layers of reinforcement with prefabricated chairs, ties, hangers, or other devices.
F. Use precast concrete block bar supports only when the concrete is placed in contact with the soil and then only as the support for the bottom mat of bars

Section 507 REINFORCING STEEL (download pdf)
507.05 PLACING AND FASTENING REINFORCING STEEL
Support material within 1-1/2 inches of a finished concrete surface shall be stainless steel, epoxy, plastic coated galvanized steel, or plastic.
Tie wires and supports used for installation of reinforcement shall be composed of the same material as any steel being contacted or shall be plastic. When forms are to be removed in their entirety, uncoated steel chairs equipped with snug-fitting, high-density, polyethylene tips which provide a 1/4-inch clearance between the metal and any exposed surface may be used.

Section 406 REINFORCING STEEL (download pdf)
406.03 Procedures
d) Placing and Fastening: The use of precast concrete block supports will be permitted provided blocks are furnished in correct thicknesses and are shaped or tied to pre-vent slippage from beneath reinforcing bars. The clear distance between bars shall be at least 1 1/2 times the specified maximum size of coarse aggregate but not less than 1 1/2 inches. Before concrete is placed, the Engineer will inspect reinforcing steel and determine approval for proper position and the adequacy of the method for maintaining position.

6-02 Concrete Structures (download pdf)
6-02.3(24)C Placing and Fastening
In lieu of mortar blocks, the Contractor may use metal or plastic chair supports to hold uncoated bars. Any surface of a metal chair support that will not be covered by at least ½ inch of concrete shall be one of the following:
1. Hot-dip galvanized after fabrication in keeping with AASHTO M232 Class D;
2. Coated with plastic firmly bonded to the metal. This plastic shall be at least 3⁄32 inch thick where it touches the form and shall not react chemically with the concrete when tested in the State Materials Laboratory. The plastic shall not shatter or crack at or above -5°F and shall not deform enough to expose the metal at or below 200°F; or
3. Stainless steel that meet the requirements of ASTM A493, Type 302. Stainless steel chair supports are not required to be galvanized or plastic coated.
Plastic chair supports shall have rounded seatings, shall not deform under load during normal temperatures, and shall not shatter or crack under impact loading in cold weather. Plastic chair supports shall be placed at spacings greater than 1 foot along the bar and shall have at least 25 percent of their gross place area perforated to compensate for the difference in the coefficient of thermal expansion between plastic and concrete. The shape and configuration of plastic supports shall permit complete concrete consolidation in and around the support.

Section 602 REINFORCING STEEL (download pdf)
602.6-PLACING AND FASTENING:
602.6.1-General: All reinforcing steel shall be accurately placed and, during the placing of concrete, firmly held by supports in the position shown on the Plans. Reinforcing bars shall be securely fastened together. Bars shall be tied at all intersections except where spacing is less than 1 feet (300 mm) in each direction, in which case alternate intersections shall be tied. Distance from the forms shall be maintained by means of stays, blocks, ties, hangers, chairs, or other approved supports. Blocks for holding reinforcement from contact with forms shall be precast mortar blocks of approved shape and dimension; the use of pebbles, broken stone, metal pipe or wooden blocks will not be permitted. Reinforcement in any member will be inspected and approved before any concrete is placed.

Section 505 Steel Reinforcement (download pdf)
505.3.4 Placing and Fastening
(1) Place steel reinforcement precisely in the position the plans show and hold firmly during the concrete placing and setting by using spacer strips, stays, recycled plastic chairs, metal chairs, or other engineer-approved devices or supports. The contractor may use recycled plastic supports for a bottom layer of steel reinforcement which in turn supports upper layers on continuous bar chairs; but do not use individual plastic chairs to directly support upper layers. Unless the contract provides otherwise, use coated high-strength bar steel reinforcement in the top layer of reinforcement in the concrete deck.

Section 506 Drilled Shaft Foundations (download pdf)
506.4.3 Reinforcing Steel
2) Anchor the reinforcing cage adequately to prevent movement after installation. Use spacers to ensure proper clearance between the reinforcing steel cage and shaft face.

Section 514 Reinforcing Steel
514.4.5 Placing and Fastening
7) Hold reinforcing bars in position with precast mortar blocks, ferrous metal chairs, spacers, metal hangers, plastic supports, and supporting wires capable of supporting applied loads. Do not use wooden or aluminum supports. Do not place bars on fresh concrete, adjust bars during concrete placement, or insert bars after placing concrete.