Heads up: There are no amended sections in this chapter.
This chapter addresses (a) through (c):

(a) Design information that the licensed design professional shall specify in the construction documents, if applicable.

(b) Compliance requirements that the licensed design professional shall specify in the construction documents, if applicable.

(c) Inspection requirements that the licensed design professional shall specify in the construction documents, if applicable.

26.2.1

AMENDMENT
This section has been amended at the state or city level.
Design information:

(a) Samples for strength tests of each class of concrete placed each day shall be taken not less than once a day, or not less than once for each 50 cubic yards (345 m3) of concrete, or not less than once for each 2,000 square feet (186 m2) of surface area for slabs or walls. Additional samples for 7-day compressive strength tests shall be taken for each class of concrete at the beginning of the concrete work or whenever the mix or aggregate is changed.

(b) Loads used in design.

(c) Design work delegated to the contractor including applicable design criteria.

Design information:

(a) Member size, location, and related tolerances.

Compliance requirements:

(a) Cementitious materials shall conform to the specifications in Table 26.4.1.1.1(a).

Table 26.4.1.1.1(a)—Specifications for cementitious materials

Cementitious material Specification
Portland cement ASTM C150
Blended hydraulic cements ASTM C595, excluding Type IS (≥70) and Type IT (S ≥ 70)
Expansive hydraulic cement ASTM C845
Hydraulic cement ASTM C1157
Fly ash and natural pozzolan ASTM C618
Slag cement ASTM C989
Silica fume ASTM C1240

(b) All cementitious materials specified in Table 26.4.1.1.1(a) and the combinations of these materials shall be included in calculating the w/cm of the concrete mixture.

Compliance requirements:

(a) Aggregates shall conform to (1) or (2):

(1) Normalweight aggregate: ASTM C33.

(2) Lightweight aggregate: ASTM C330.

(b) Aggregates not conforming to ASTM C33 or ASTM C330 are permitted if they have been shown by test or actual service to produce concrete of adequate strength and durability and are approved by the building official.

Compliance requirements:

(a) Mixing water shall conform to ASTM C1602.

(b) Mixing water, including that portion of mixing water contributed in the form of free moisture on aggregates, shall not contain deleterious amounts of chloride ion when used for prestressed concrete, for concrete that will contain aluminum embedments, or for concrete cast against stay-in-place galvanized steel forms.

Compliance requirements:

(a) Admixtures shall conform to (1) through (4):

(1) Water reduction and setting time modification: ASTM C494.

(2) Producing flowing concrete: ASTM C1017.

(3) Air entrainment: ASTM C260.

(4) Inhibiting chloride-induced corrosion: ASTM C1582.

(b) Admixtures that do not conform to the specifications in 26.4.1.4.1(a) shall be subject to prior review by the licensed design professional.

(c) Calcium chloride or admixtures containing chloride from sources other than impurities in admixture ingredients shall not be used in prestressed concrete, in concrete containing embedded aluminum, or in concrete cast against stay-in-place galvanized steel forms.

(d) Admixtures used in concrete containing expansive cements conforming to ASTM C845 shall be compatible with the cement and produce no deleterious effects.

Compliance requirements:

(a) Steel fiber reinforcement used for shear resistance shall satisfy (1) and (2):

(1) Be deformed and conform to ASTM A820.

(2) Have a length-to-diameter ratio of at least 50 and not exceeding 100.

Design information:

(a) Requirements (1) through (11) for each concrete mixture, based on assigned exposure classes or design of members:

(1) Minimum specified compressive strength of concrete, fc'.

(2) Test age for demonstrating compliance with fc' if different from 28 days.

(3) Maximum w/cm applicable to most restrictive assigned durability exposure class from 19.3.2.1.

(4) Nominal maximum size of coarse aggregate not to exceed the least of (i), (ii), and (iii):

(i) one-fifth the narrowest dimension between sides of forms

(ii) one-third the depth of slabs

(iii) three-fourths the minimum specified clear spacing between individual reinforcing bars or wires, bundles of bars, prestressed reinforcement, individual tendons, bundled tendons, or ducts

These limitations shall not apply if, in the judgment of the licensed design professional, workability and methods of consolidation are such that concrete can be placed without honeycombs or voids.

(5) For members assigned to Exposure Category F, air content from 19.3.3.1.

(6) For members assigned to Exposure Class C, applicable chloride ion limits for assigned Exposure Class from 19.3.2.1.

(7) For members assigned to Exposure Category S, type of cementitious materials for assigned Exposure Class from 19.3.2.1.

(8) For members assigned to Exposure Class S2 or S3, admixtures containing calcium chloride are prohibited.

(9) Equilibrium density of lightweight concrete.

(10) Requirement for submittal of the volumetric fractions of aggregate in lightweight concrete mixtures for the verification of λ value if used in design.

(11) If used for shear resistance in accordance with 9.6.3.1, requirements for steel fiber-reinforced concrete.

(b) At the option of the licensed design professional, exposure classes based on the severity of the anticipated exposure of members.

(c) The required compressive strength at designated stages of construction for each part of the structure designed by the licensed design professional.

Compliance requirements:

(a) The required compressive strength at designated stages of construction for each part of the structure not designed by the licensed design professional shall be submitted for review.

(b) The maximum percentage of pozzolans, including fly ash and silica fume, and slag cement in concrete assigned to Exposure Class F3, shall be in accordance with Table 26.4.2.2(b) and (1) and (2).

(1) The maximum percentage limits in Table 26.4.2.2(b) shall include the fly ash or other pozzolans, slag cement, and silica fume used in the manufacture of ASTM C595 and C1157 blended cements.

(2) The individual limits in Table 26.4.2.2(b) shall apply regardless of the number of cementitious materials in a concrete mixture.

Table 26.4.2.2(b)—Limits on cementitious materials for concrete assigned to Exposure Class F3

Cementitious materials Maximum percent of total cementitious materials by mass
Fly ash or other pozzolans conforming to ASTM C618 25
Slag cement conforming to ASTM C989 50
Silica fume conforming to ASTM C1240 10
Total of fly ash or other pozzolans and silica fume 35
Total of fly ash or other pozzolans, slag cement, and silica fume 50

(c) For concrete exposed to sulfate, alternative combinations of cementitious materials to those specified in 26.4.2.1(a)(7) are permitted if tests for sulfate resistance satisfy the criteria in Table 26.4.2.2(c).

Table 26.4.2.2(c)—Requirements for establishing suitability of combinations of cementitious materials exposed to water-soluble sulfate

Exposure class Maximum expansion strain if tested using ASTM C1012
At 6 months At 12 months At 18 months
S1 0.10 percent No requirement No requirement
S2 0.05 percent 0.10 percent[1] No requirement
S3 No requirement No requirement 0.10 percent

[1]The 12-month expansion limit applies only if the measured expansion exceeds the 6-month maximum expansion limit.

(d) Steel fiber-reinforced concrete used for shear resistance shall satisfy (1) and (2):

(1) Conform to ASTM C1116.

(2) Contain at least 100 lb of deformed steel fibers per cubic yard of concrete.

Compliance requirements:

(a) Concrete mixture proportions shall be established so that the concrete satisfies (1) through (3):

(1) Can be placed readily without segregation into forms and around reinforcement under anticipated placement conditions.

(2) Meets requirements for assigned exposure class in accordance with either 26.4.2.1(a) or 26.4.2.1(b).

(3) Conforms to strength test requirements for standard-cured specimens.

(b) Concrete mixture proportions shall be established in accordance with Article 4.2.3 of ACI 301 or by an alternative method acceptable to the licensed design professional. Alternative methods shall have a probability of satisfying the strength requirements for acceptance tests of standard-cured specimens that meets or exceeds the probability associated with the method in Article 4.2.3 of ACI 301. If Article 4.2.3 of ACI 301 is used, the strength test records used for establishing and documenting concrete mixture proportions shall not be more than 24 months old.

(c) The concrete materials used to develop the concrete mixture proportions shall correspond to those to be used in the proposed Work.

(d) If different concrete mixtures are to be used for different portions of proposed Work, each mixture shall comply with the concrete mixture requirements stated in the construction documents.

Compliance requirements:

(a) Documentation of concrete mixture characteristics shall be submitted for review by the licensed design professional before the mixture is used and before making changes to mixtures already in use. Evidence of the ability of the proposed mixture to comply with the concrete mixture requirements in the construction documents shall be included in the documentation. The evidence shall be based on field test records or laboratory trial batches. Field test records shall represent conditions similar to those anticipated during the proposed Work.

(b) If field or laboratory test data are not available, and fc' ≤ 5000 psi, concrete proportions shall be based on other experience or information, if approved by the licensed design professional. If fc' > 5000 psi, test data documenting the characteristics of the proposed mixtures are required.

(c) If data become available during construction that consistently exceed the strength-test acceptance criteria for standard-cured specimens, it shall be permitted to modify a mixture to reduce the average strength. Submit evidence acceptable to the licensed design professional to demonstrate that the modified mixture will comply with the concrete mixture requirements in the construction documents.

Compliance requirements:

(a) Cementitious materials and aggregates shall be stored to prevent deterioration or contamination.

(b) Material that has deteriorated or has been contaminated shall not be used in concrete.

(c) Equipment for mixing and transporting concrete shall conform to ASTM C94 or ASTM C685.

(d) Ready-mixed and site-mixed concrete shall be batched, mixed, and delivered in accordance with ASTM C94 or ASTM C685.

Compliance requirements:

(a) Debris and ice shall be removed from spaces to be occupied by concrete before placement.

(b) Standing water shall be removed from place of deposit before concrete is placed unless a tremie is to be used or unless otherwise permitted by both the licensed design professional and the building official.

(c) Masonry filler units that will be in contact with concrete shall be prewetted prior to placing concrete.

(d) Equipment used to convey concrete from the mixer to the location of final placement shall have capabilities to achieve the placement requirements.

(e) Concrete shall not be pumped through pipe made of aluminum or aluminum alloys.

(f) Concrete shall be placed in accordance with (1) through (5):

(1) At a rate to provide an adequate supply of concrete at the location of placement.

(2) At a rate so concrete at all times has sufficient workability such that it can be consolidated by the intended methods.

(3) Without segregation or loss of materials.

(4) Without interruptions sufficient to permit loss of workability between successive placements that would result in cold joints.

(5) Deposited as near to its final location as practicable to avoid segregation due to rehandling or flowing.

(g) Concrete that has been contaminated or has lost its initial workability to the extent that it can no longer be consolidated by the intended methods shall not be used.

(h) Retempering concrete in accordance with the limits of ASTM C94 shall be permitted unless otherwise restricted by the licensed design professional.

(i) After starting, concreting shall be carried on as a continuous operation until the completion of a panel or section, as defined by its boundaries or predetermined joints.

(j) Concrete shall be consolidated by suitable means during placement and shall be worked around reinforcement and embedments and into corners of forms.

(k) Top surfaces of vertically formed lifts shall be generally level.

Design information:

(a) If supplementary tests of field-cured specimens are required to verify adequacy of curing and protection, the number and size of test specimens and the frequency of these supplementary tests.

Compliance requirements:

(a) Concrete, other than high-early-strength, shall be maintained at a temperature of at least 50°F and in a moist condition for at least the first 7 days after placement, except if accelerated curing is used.

(b) High-early-strength concrete shall be maintained at a temperature of at least 50°F and in a moist condition for at least the first 3 days after placement, except if accelerated curing is used.

(c) Accelerated curing to accelerate strength gain and reduce time of curing is permitted using high-pressure steam, steam at atmospheric pressure, heat and moisture, or other process acceptable to the licensed design professional. If accelerated curing is used, (1) and (2) shall apply:

(1) Compressive strength at the load stage considered shall be at least the strength required at that load stage.

(2) Accelerated curing shall not impair the durability of the concrete.

(d) If required by the building official or licensed design professional, results of tests of cylinders made and cured in accordance with (1) and (2) shall be provided in addition to results of standard-cured cylinder strength tests.

(1) At least two 6 × 12 in. or at least three 4 × 8 in. field-cured cylinders shall be molded at the same time and from the same samples as standard-cured cylinders;

(2) Field-cured cylinders shall be cured in accordance with the field curing procedure of ASTM C31 and tested in accordance with ASTM C39.

(e) Procedures for protecting and curing concrete shall be considered adequate if (1) or (2) are satisfied:

(1) Average strength of field-cured cylinders at test age designated for determination of fc' is equal to or at least 85 percent of that of companion standard-cured cylinders.

(2) Average strength of field-cured cylinders at test age exceeds fc' by more than 500 psi.

Design information:

(a) Temperature limits for concrete as delivered in cold weather.

Compliance requirements:

(a) Adequate equipment shall be provided for heating concrete materials and protecting concrete during freezing or near-freezing weather.

(b) Frozen materials or materials containing ice shall not be used.

(c) Forms, fillers, and ground with which concrete is to come in contact shall be free from frost and ice.

(d) Concrete materials and production methods shall be selected so that the concrete temperature at delivery complies with the specified temperature limits.

Design information:

(a) Temperature limits for concrete as delivered in hot weather.

Compliance requirements:

(a) Concrete materials and production methods shall be selected so that the concrete temperature at delivery complies with the specified temperature limits.

(b) Handling, placing, protection, and curing procedures shall limit concrete temperatures or water evaporation that could reduce strength, serviceability, and durability of the member or structure.

Design information:

(a) If required by the design, locations and details of construction, isolation, and contraction joints.

(b) Details required for transfer of shear and other forces through construction joints.

(c) Surface preparation, including intentional roughening of hardened concrete surfaces where concrete is to be placed against previously hardened concrete.

(d) Locations where shear is transferred between as-rolled steel and concrete using headed studs or welded reinforcing bars requiring steel to be clean and free of paint.

(e) Surface preparation including intentional roughening if composite topping slabs are to be cast in place on a precast floor or roof intended to act structurally with the precast members.

Compliance requirements:

(a) Joint locations or joint details not shown or that differ from those indicated in construction documents shall be submitted for review by the licensed design professional.

(b) Except for prestressed concrete, construction joints in floor and roof systems shall be located within the middle third of spans of slabs, beams, and girders unless otherwise approved by the licensed design professional.

(c) Construction joints in girders shall be offset a distance of at least two times the width of intersecting beams, measured from the face of the intersecting beam, unless otherwise approved by the licensed design professional.

(d) Construction joints shall be cleaned and laitance removed before new concrete is placed.

(e) Surface of concrete construction joints shall be intentionally roughened if specified.

(f) Immediately before new concrete is placed, construction joints shall be prewetted and standing water removed.

Design information:

(a) Details required to accommodate dimensional changes resulting from prestressing, creep, shrinkage, and temperature.

(b) Identify if a slab-on-ground is designed as a structural diaphragm or part of the seismic-force-resisting system.

(c) Details for construction of sloped or stepped footings designed to act as a unit.

(d) Locations where slab and column concrete placements are required to be integrated during placement in accordance with 15.3.

(e) Locations where steel fiber-reinforced concrete is required for shear resistance in accordance with 9.6.3.1.

Compliance requirements:

(a) Beams, girders, or slabs supported by columns or walls shall not be cast until concrete in the vertical support members is no longer plastic.

(b) Beams, girders, haunches, drop panels, shear caps, and capitals shall be placed monolithically as part of a slab system, unless otherwise shown in construction documents.

(c) At locations where slab and column concrete placements are required to be integrated during placement, column concrete shall extend full slab depth at least 2 ft into floor slab from face of column and be integrated with floor concrete.

(d) Saw cutting in slabs-on-ground identified in the construction documents as structural diaphragms or part of the seismic-force-resisting system shall not be permitted unless specifically indicated or approved by the licensed design professional.

Design information:

(a) ASTM designation and grade of reinforcement.

(b) Type, size, location requirements, detailing, and embedment length of reinforcement.

(c) Concrete cover to reinforcement.

(d) Location and length of lap splices.

(e) Type and location of mechanical splices.

(f) Type and location of end-bearing splices.

(g) Type and location of welded splices and other required welding of reinforcing bars.

(h) ASTM designation for protective coatings of nonprestressed reinforcement.

(i) Corrosion protection for exposed reinforcement intended to be bonded with extensions on future Work.

Compliance requirements:

(a) Mill test reports for reinforcement shall be submitted.

(b) Nonprestressed reinforcement with rust, mill scale, or a combination of both shall be considered satisfactory, provided a hand-wire-brushed representative test specimen of the reinforcement complies with the applicable ASTM specification for the minimum dimensions (including height of deformations) and weight per unit length.

(c) Prestressing reinforcement shall be free of mill scale, pitting, and excessive rust. A light coating of rust shall be permitted.

(d) At the time concrete is placed, reinforcement to be bonded shall be clean of ice, mud, oil, or other deleterious coatings that decrease bond.

Design information:

(a) Tolerances on location of reinforcement taking into consideration tolerances on d and specified concrete cover in accordance with Table 26.6.2.1(a).

Table 26.6.2.1(a)—Tolerances on d and specified cover

d, in. Tolerance on d, in. Tolerance on specified concrete cover, in.[1]
≤ 8 ±3/8 Smaller of: —3/8
— (1/3) • specified cover
> 8 ±1/2 Smaller of: —1/2
— (1/3) • specified cover

[1]Tolerance for cover to formed soffits is —1/4 in.

(b) Tolerance for longitudinal location of bends and ends of reinforcement in accordance with Table 26.6.2.1(b). The tolerance for specified concrete cover in Table 26.6.2.1(a) shall also apply at discontinuous ends of members.

Table 26.6.2.1(b)—Tolerances for longitudinal location of bends and ends of reinforcement

Location of bends or reinforcement ends Tolerances, in.
Discontinuous ends of brackets and corbels ±1/2
Discontinuous ends of other members ±1
Other locations ±2
Compliance requirements:

(a) Reinforcement, including bundled bars, shall be placed within required tolerances and supported to prevent displacement beyond required tolerances during concrete placement.

(b) Spiral units shall be continuous bar or wire placed with even spacing and without distortion beyond the tolerances for the specified dimensions.

(c) Splices of reinforcement shall be made only as permitted in the construction documents, or as authorized by the licensed design professional.

(d) For longitudinal column bars forming an end-bearing splice, the bearing of square cut ends shall be held in concentric contact.

(e) Bar ends shall terminate in flat surfaces within 1.5 degrees of a right angle to the axis of the bars and shall be fitted within 3 degrees of full bearing after assembly.

Compliance requirements:

(a) Reinforcement shall be bent cold prior to placement, unless otherwise permitted by the licensed design professional.

(b) Field bending of reinforcement partially embedded in concrete shall not be permitted, except as shown in the construction documents or permitted by the licensed design professional.

(c) Offset bars shall be bent before placement in the forms.

Compliance requirements:

(a) Welding of all nonprestressed bars shall conform to the requirements of AWS D1.4. ASTM specifications for bar reinforcement, except for ASTM A706, shall be supplemented to require a mill test report of material properties that demonstrate conformance to the requirements in AWS D1.4.

(b) Welding of crossing bars shall not be used for assembly of reinforcement unless permitted by the licensed design professional.

Design information:

(a) Requirements for assessment and qualification of anchors for the applicable conditions of use in accordance with 17.1.3.

(b) Type, size, location requirements, effective embedment depth, and installation requirements for anchors.

(c) Minimum edge distance of anchors in accordance with 17.7.

(d) Inspection requirements in accordance with 26.13.

(e) For post-installed anchors, parameters associated with the strength used for design, including anchor category, concrete strength, and aggregate type.

(f) For adhesive anchors, parameters associated with the characteristic bond stress used for design in accordance with 17.4.5, including minimum age of concrete, concrete temperature range, moisture condition of concrete at time of installation, type of lightweight concrete if applicable, and requirements for hole drilling and preparation.

(g) Qualification requirements for installers of anchors in accordance with 17.8.1.

(h) Adhesive anchors installed in a horizontal or upwardly inclined orientation, if they support sustained tension loads.

(i) Required certifications for installers of adhesive anchors that are installed in a horizontal or upwardly inclined orientation to support sustained tension loads in accordance with 17.8.2.2 and 17.8.2.3.

(j) For adhesive anchors, proof loading where required in accordance with 17.8.2.1.

(k) Corrosion protection for exposed anchors intended for attachment with future Work.

Compliance requirements:

(a) Post-installed anchors shall be installed in accordance with the manufacturer's instructions. Post-installed adhesive anchors shall be installed in accordance with the Manufacturer's Printed Installation Instructions (MPII)

Design information:

(a) Type, size, details, and location of embedments designed by the licensed design professional.

(b) Reinforcement required to be placed perpendicular to pipe embedments.

(c) Specified concrete cover for pipe embedments with their fittings.

(d) Corrosion protection for exposed embedments intended to be connected with future Work.

Compliance requirements:

(a) Type, size, details, and location of embedments not shown in the construction documents shall be submitted for review by the licensed design professional.

(b) Aluminum embedments shall be coated or covered to prevent aluminum-concrete reaction and electrolytic action between aluminum and steel.

(c) Pipes and fittings not shown in the construction documents shall be designed to resist effects of the material, pressure, and temperature to which they will be subjected.

(d) No liquid, gas, or vapor, except water not exceeding 90°F or 50 psi pressure, shall be placed in the pipes until the concrete has attained its specified strength.

(e) In solid slabs, piping, except for radiant heating or snow melting, shall be placed between top and bottom reinforcement.

(f) Conduit and piping shall be fabricated and installed so that cutting, bending, or displacement of reinforcement from its specified location is not required.

Design information:

(a) Dimensional tolerances for precast members and interfacing members.

(b) Details of lifting devices, embedments, and related reinforcement required to resist temporary loads from handling, storage, transportation, and erection, if designed by the licensed design professional.

Compliance requirements:

(a) Members shall be marked to indicate location and orientation in the structure and date of manufacture.

(b) Identification marks on members shall correspond to erection drawings.

(c) Design and details of lifting devices, embedments, and related reinforcement required to resist temporary loads from handling, storage, transportation, and erection shall be provided if not designed by the licensed design professional.

(d) During erection, precast members and structures shall be supported and braced to ensure proper alignment, strength, and stability until permanent connections are completed.

(e) If approved by the licensed design professional, items embedded while the concrete is in a plastic state shall satisfy (1) through (4):

(1) Embedded items shall protrude from the precast concrete members or remain exposed for inspection.

(2) Embedded items are not required to be hooked or tied to reinforcement within the concrete.

(3) Embedded items shall be maintained in the correct position while the concrete remains plastic.

(4) The concrete shall be consolidated around embedded items.

Design information:

(a) Magnitude and location of prestressing forces.

(b) Stressing sequence of tendons.

(c) Type, size, details, and location of post-tensioning anchorages for systems selected by the licensed design professional.

(d) Tolerances for placement of tendons and post-tensioning ducts in accordance with Table 26.6.2.1(a).

(e) Materials and details of corrosion protection for tendons, couplers, end fittings, post-tensioning anchorages, and anchorage regions.

(f) Requirements for ducts for bonded tendons.

(g) Requirements for grouting of bonded tendons, including maximum water-soluble chloride ion (Cl) content requirements in 19.4.1.

Compliance requirements:

(a) Type, size, details, and location of post-tensioning anchorage systems not shown in the construction documents shall be submitted to the licensed design professional for review.

(b) Tendons and post-tensioning ducts shall be placed within required tolerances and supported to prevent displacement beyond required tolerances during concrete placement.

(c) Couplers shall be placed in areas approved by the licensed design professional and enclosed in housings long enough to permit necessary movements.

(d) Burning or welding operations in the vicinity of prestressing reinforcement shall be performed in such a manner that prestressing reinforcement is not subject to welding sparks, ground currents, or temperatures that degrade the properties of the reinforcement.

(e) Prestressing force and friction losses shall be verified by (1) and (2).

(1) Measured elongation of prestressed reinforcement compared with elongation calculated using the modulus of elasticity determined from tests or as reported by the manufacturer.

(2) Jacking force measured using calibrated equipment such as a hydraulic pressure gauge, load cell, or dynamometer.

(f) The cause of any difference in force determination between (1) and (2) of 26.10.2(e) that exceeds 5 percent for pretensioned construction or 7 percent for post-tensioned construction shall be ascertained and corrected, unless otherwise approved by the licensed design professional.

(g) Loss of prestress force due to unreplaced broken prestressed reinforcement shall not exceed 2 percent of the total prestress force in prestressed concrete members.

(h) If the transfer of force from the anchorages of the pretensioning bed to the concrete is accomplished by flame cutting prestressed reinforcement, the cutting locations and cutting sequence shall be selected to avoid undesired temporary stresses in pretensioned members.

(i) Long lengths of exposed pretensioned strand shall be cut near the member to minimize shock to the concrete.

(j) Prestressing reinforcement in post-tensioned construction shall not be stressed until the concrete compressive strength is at least 2500 psi for single-strand or bar tendons, 4000 psi for multistrand tendons, or a higher strength, if required. An exception to these strength requirements is provided in 26.10.2(k).

(k) Lower concrete compressive strength than required by 26.10.2(j) shall be permitted if (1) or (2) is satisfied:

(1) Oversized anchorage devices are used to compensate for a lower concrete compressive strength.

(2) Prestressing reinforcement is stressed to no more than 50 percent of the final prestressing force.

Design information:

(a) Requirement for the contractor to design, fabricate, install, and remove formwork.

(b) Location of composite members requiring shoring.

(c) Requirements for removal of shoring of composite members.

Compliance requirements:

(a) Design of formwork shall consider (1) through (5):

(1) Method of concrete placement.

(2) Rate of concrete placement.

(3) Construction loads, including vertical, horizontal, and impact.

(4) Avoidance of damage to previously constructed members.

(5) For post-tensioned members, allowance for movement of the member during application of the prestressing force without damage to the member.

(b) Formwork fabrication and installation shall result in a final structure that conforms to shapes, lines, and dimensions of the members as required by the construction documents.

(c) Formwork shall be sufficiently tight to inhibit leakage of paste or mortar.

(d) Formwork shall be braced or tied together to maintain position and shape.

Compliance requirements:

(a) Before starting construction, the contractor shall develop a procedure and schedule for removal of formwork and installation of reshores, and shall calculate the loads transferred to the structure during this process.

(b) Structural analysis and concrete strength requirements used in planning and implementing the formwork removal and reshore installation shall be furnished by the contractor to the licensed design professional and to the building official, when requested.

(c) No construction loads shall be placed on, nor any formwork removed from, any part of the structure under construction except when that portion of the structure in combination with remaining formwork has sufficient strength to support safely its weight and loads placed thereon and without impairing serviceability.

(d) Sufficient strength shall be demonstrated by structural analysis considering anticipated loads, strength of formwork, and an estimate of in-place concrete strength.

(e) The estimate of in-place concrete strength shall be based on tests of field-cured cylinders or on other procedures to evaluate concrete strength approved by the licensed design professional and, when requested, approved by the building official.

(f) Formwork shall be removed in such a manner not to impair safety and serviceability of the structure.

(g) Concrete exposed by formwork removal shall have sufficient strength not to be damaged by the removal.

(h) Formwork supports for post-tensioned members shall not be removed until sufficient post-tensioning has been applied to enable post-tensioned members to support their dead load and anticipated construction loads.

(i) No construction loads exceeding the combination of superimposed dead load plus live load including reduction shall be placed on any unshored portion of the structure under construction, unless analysis indicates adequate strength to support such additional loads and without impairing serviceability.

Compliance requirements:

(a) A strength test shall be the average of the strengths of at least two 6 × 12 in. cylinders or at least three 4 × 8 in. cylinders made from the same sample of concrete and tested at 28 days or at test age designated for fc'.

(b) The testing agency performing acceptance testing shall comply with ASTM C1077.

(c) Qualified field testing technicians shall perform tests on fresh concrete at the job site, prepare specimens for standard curing, prepare specimens for field curing, if required, and record the temperature of the fresh concrete when preparing specimens for strength tests.

(d) Qualified laboratory technicians shall perform required laboratory tests.

(e) All reports of acceptance tests shall be provided to the licensed design professional, contractor, concrete producer, and, if requested, to the owner and the building official.

26.12.2.1

AMENDMENT
This section has been amended at the state or city level.
Compliance requirements:

(a) Samples for strength tests of each class of concrete placed each day shall be taken not less than once a day, or not less than once for each 50 cubic yards (38.2 m3) of concrete, or not less than once for each 2,000 square feet (186 m2) of surface area for slabs or walls. Additional samples for seven-day compressive strength tests shall be taken for each class of concrete at the beginning of the concrete work or whenever the mix or aggregate is changed.

(b) On a given project, if total volume of concrete is such that frequency of testing would provide fewer than five strength tests for a given concrete mixture, strength test specimens shall be made from at least five randomly selected batches or from each batch if fewer than five batches are used.

(c) If the total quantity of a given concrete mixture is less than 50 yd3, strength tests are not required if evidence of satisfactory strength is submitted to and approved by the building official.

Compliance requirements:

(a) Specimens for acceptance tests shall be in accordance with (1) and (2):

(1) Sampling of concrete for strength test specimens shall be in accordance with ASTM C172.

(2) Cylinders for strength tests shall be made and standard-cured in accordance with ASTM C31 and tested in accordance with ASTM C39.

(b) Strength level of a concrete mixture shall be acceptable if (1) and (2) are satisfied:

(1) Every arithmetic average of any three consecutive strength tests equals or exceeds fc'.

(2) No strength test falls below fc' by more than 500 psi if fc' is 5000 psi or less; or by more than 0.10fc' if fc' exceeds 5000 psi.

(c) If either of the requirements of 26.12.3.1(b) are not satisfied, steps shall be taken to increase the average of subsequent strength results

(d) Requirements for investigating low strength-test results shall apply if the requirements of 26.12.3.1(b)(2) are not met

Compliance requirements:

(a) If any strength test of standard-cured cylinders falls below fc' by more than the limit allowed for acceptance, or if tests of field-cured cylinders indicate deficiencies in protection and curing, steps shall be taken to ensure that structural adequacy of the structure is not jeopardized.

(b) If the likelihood of low-strength concrete is confirmed and calculations indicate that structural adequacy is significantly reduced, tests of cores drilled from the area in question in accordance with ASTM C42 shall be permitted. In such cases, three cores shall be taken for each strength test that falls below fc' by more than the limit allowed for acceptance.

(c) Cores shall be obtained, moisture-conditioned by storage in watertight bags or containers, transported to the testing agency, and tested in accordance with ASTM C42. Cores shall be tested between 48 hours and 7 days after coring unless otherwise approved by the licensed design professional. The specifier of tests referenced in ASTM C42 shall be the licensed design professional or the building official.

(d) Concrete in an area represented by core tests shall be considered structurally adequate if (1) and (2) are satisfied:

(1) The average of three cores is equal to at least 85 percent of fc'.

(2) No single core is less than 75 percent of fc'.

(e) Additional testing of cores extracted from locations represented by erratic core strength results shall be permitted.

(f) If criteria for evaluating structural adequacy based on core strength results are not met, and if the structural adequacy remains in doubt, the responsible authority shall be permitted to order a strength evaluation in accordance with Chapter 27 for the questionable portion of the structure or take other appropriate action.

Compliance requirements:

(a) Steel fiber-reinforced concrete used for shear resistance shall satisfy (1) through (3):

(1) The compressive strength acceptance criteria for standard-cured specimens

(2) The residual strength obtained from flexural testing in accordance with ASTM C1609 at a midspan deflection of 1/300 of the span length is at least the greater of (i) and (ii):

(i) 90 percent of the measured first-peak strength obtained from a flexural test and

(ii) 90 percent of the strength corresponding to .

(3) The residual strength obtained from flexural testing in accordance with ASTM C1609 at a midspan deflection of 1/150 of the span length is at least the greater of (i) and (ii):

(i) 75 percent of the measured first-peak strength obtained from a flexural test and

(ii) 75 percent of the strength corresponding to

Concrete construction shall be inspected as required by the general building code.
In the absence of general building code inspection requirements, concrete construction shall be inspected throughout the various Work stages by or under the supervision of a licensed design professional or by a qualified inspector in accordance with the provisions of this section.
The licensed design professional, a person under the supervision of a licensed design professional, or a qualified inspector shall verify compliance with construction documents.
For continuous construction inspection of special moment frames, qualified inspectors under the supervision of the licensed design professional responsible for the structural design or under the supervision of a licensed design professional with demonstrated capability to supervise inspection of these elements shall inspect placement of reinforcement and concrete.
Inspection reports shall document inspected items and be developed throughout each construction Work stage by the licensed design professional, person under the supervision of a licensed design professional, or qualified inspector. Records of the inspection shall be preserved by the party performing the inspection for at least 2 years after completion of the project.
Inspection reports shall document (a) through (d):

(a) General progress of the Work.

(b) Any significant construction loadings on completed floors, members, or walls.

(c) The date and time of mixing, quantity, proportions of materials used, approximate placement location in the structure, and results of tests for fresh and hardened concrete properties for all concrete mixtures used in the Work.

(d) Concrete temperatures and protection given to concrete during placement and curing when the ambient temperature falls below 40°F or rises above 95°F.

Test reports shall be reviewed to verify compliance with 20.2.2.5 if ASTM A615 deformed reinforcement is used to resist earthquake-induced flexure, axial forces, or both in special moment frames, special structural walls, and components of special structural walls including coupling beams and wall piers.
Unless otherwise specified in the general building code, items requiring verification and inspection shall be continuously or periodically inspected in accordance with 26.13.3.2 and 26.13.3.3.
Items requiring continuous inspection shall include (a) through (d):

(a) Placement of concrete.

(b) Tensioning of prestressing steel and grouting of bonded tendons.

(c) Installation of adhesive anchors in horizontal or upwardly inclined orientations to resist sustained tension loads in accordance with 17.8.2.4 and where required as a condition of the anchor assessment in accordance with ACI 355.4.

(d) Reinforcement for special moment frames.

Items requiring periodic inspection shall include (a) through (g):

(a) Placement of reinforcement, embedments, and post-tensioning tendons.

(b) Curing method and duration of curing for each member.

(c) Construction and removal of forms and reshoring.

(d) Sequence of erection and connection of precast members.

(e) Verification of in-place concrete strength before stressing post-tensioned reinforcement and before removal of shores and formwork from beams and structural slabs.

(f) Installation of cast-in anchors, expansion anchors, and undercut anchors in accordance with 17.8.2.

(g) Installation of adhesive anchors where continuous inspection is not required in accordance with 17.8.2.4 or as a condition of the assessment in accordance with ACI 355.4.

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