1 Scope
NOTE This specification covers the design coordination, materials, fabrication, finishing, handling, and erection of plant-fabricated precast and prestressed concrete elements for buildings. (1.1)
NOTE The work includes structural precast members — columns, beams, spandrels, double-tees, hollow-core plank, solid and insulated wall panels, and stair units — and architectural precast cladding panels with specified exposed concrete finishes. (1.2)
1.3All work shall conform to ACI CODE-318-25, Building Code Requirements for Structural Concrete.
1.4Work shall conform to the applicable PCI quality-control manual: PCI MNL-116 for structural precast and prestressed products, and PCI MNL-117 for architectural precast products.
1.5Design of the precast elements and their connections shall conform to the PCI Design Handbook, MNL-120.
NOTE Precast concrete is fundamentally different from cast-in-place concrete in that the element is manufactured under controlled plant conditions, cured, demolded, and then transported and erected as a finished structural unit; this shifts the locus of quality from the field to the plant and makes release strength, handling stresses, embedded connection hardware, dimensional tolerances, and erection sequence central to the work in a way that has no parallel in cast-in-place construction. (1.6)
NOTE An element stripped from the form before it has reached release strength, or lifted at the wrong pick points, can crack before it is ever installed, and a panel cast 1/2 in. out of square multiplies into an unbuildable joint condition across a facade; the requirements of this standard protect the element from the moment of casting through final connection. (1.7)
NOTE The most important conceptual distinction in this standard is between structural precast — which carries gravity and lateral load and is governed primarily by strength, prestress, and structural-tolerance requirements, with a utility surface finish — and architectural precast, a cladding element whose appearance is a specified deliverable governed by the tighter finish, color, and tolerance requirements of PCI MNL-117. (1.8)
1.9Elements that are simultaneously structural and architectural — an architectural spandrel, an insulated load-bearing wall panel — shall satisfy both sets of requirements.
NOTE In pretensioned (prestressed) production, high-strength seven-wire strand is tensioned against abutments before concrete is cast around it; after the concrete reaches its specified release strength the strand is detensioned and the prestressing force transfers into the member by bond, placing the member in compression, while conventionally reinforced (non-prestressed) precast is used for columns, short members, and some panels. (1.10)
1.11The boundary of work under this standard is the precast element itself, its embedded connection hardware, its bearing pads, the grout at its bearings and connections, and the field connections that join precast to precast and precast to the supporting structure.
1.12The supporting cast-in-place or steel structure is covered by Cast In Place Concrete and the structural steel standards, and reinforcement embedded in precast elements is detailed and supplied by the precast producer under this standard consistent with Concrete Reinforcement. 1.13Sealant in the joints between panels shall be coordinated with Joint Sealants. 2 Referenced Standards
2.1Materials, production, finishing, testing, and erection shall comply with the latest adopted edition of the following standards and codes.
| Standard |
Title |
| ACI CODE-318-25 |
Building Code Requirements for Structural Concrete and Commentary |
| ACI 117-10 (Reapproved 2015) |
Specification for Tolerances for Concrete Construction and Materials |
| PCI MNL-116 |
Manual for Quality Control for Plants and Production of Structural Precast Concrete Products |
| PCI MNL-117 |
Manual for Quality Control for Plants and Production of Architectural Precast Concrete Products |
| PCI MNL-120 |
PCI Design Handbook — Precast and Prestressed Concrete |
| PCI MNL-122 |
Architectural Precast Concrete (design and finish guidance) |
| PCI MNL-135 |
Tolerance Manual for Precast and Prestressed Concrete Construction |
| ASTM A416/A416M |
Standard Specification for Low-Relaxation, Seven-Wire Steel Strand for Prestressed Concrete |
| ASTM A615/A615M |
Standard Specification for Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement |
| ASTM A706/A706M |
Standard Specification for Deformed and Plain Low-Alloy Steel Bars for Concrete Reinforcement |
| ASTM A1064/A1064M |
Standard Specification for Carbon-Steel Wire and Welded Wire Reinforcement for Concrete |
| ASTM A36/A36M |
Standard Specification for Carbon Structural Steel (embedded plates and connection angles) |
| ASTM A572/A572M |
Standard Specification for High-Strength Low-Alloy Columbium-Vanadium Structural Steel |
| ASTM A123/A123M |
Standard Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel Products |
| ASTM A153/A153M |
Standard Specification for Zinc Coating (Hot-Dip) on Iron and Steel Hardware |
| ASTM A153 / ASTM F3125 |
Bolts and high-strength fasteners for field connections |
| AWS D1.1/D1.1M |
Structural Welding Code — Steel (connection hardware and field welding) |
| AWS D1.4/D1.4M |
Structural Welding Code — Reinforcing Steel |
| ASTM C39/C39M |
Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens |
| ASTM C150/C150M |
Standard Specification for Portland Cement |
| ASTM C595/C595M |
Standard Specification for Blended Hydraulic Cements |
| ASTM C33/C33M |
Standard Specification for Concrete Aggregates |
| ASTM C1107/C1107M |
Standard Specification for Packaged Dry, Hydraulic-Cement Grout (Nonshrink) |
| ASTM C1240 |
Standard Specification for Silica Fume Used in Cementitious Mixtures |
| ASTM C494/C494M |
Standard Specification for Chemical Admixtures for Concrete |
| ASTM D4014 |
Standard Specification for Plain and Steel-Laminated Elastomeric Bearings for Bridges (bearing pad reference) |
| IBC |
International Building Code (locally adopted edition) |
2.2Where the contract documents, the adopted building code, a referenced standard, or the precast producer's engineering conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
3 Submittals
3.1 Action Submittals
3.1.1The Contractor shall submit the following for the Engineer's review before fabrication begins.
3.1.2No precast element shall be fabricated until the corresponding submittals have been reviewed and accepted.
3.1.3Submittals shall be complete and internally coordinated; piecemeal submissions shall be rejected.
3.1.4 Shop Drawings (Erection and Production Drawings)
3.1.4.1The precast producer shall prepare and submit erection drawings and production (shop) drawings.
3.1.4.2Erection drawings shall show the location, mark, and orientation of every precast element, the erection sequence, all field connections, joint widths, bearing conditions, and the interface with the supporting structure.
3.1.4.3Production drawings shall show, for each piece mark, the element geometry and dimensions, the reinforcing and prestressing layout, strand pattern and jacking force, debonding (strand sheathing) where used, concrete strengths at release and at 28 days, all embedded connection hardware with its location and orientation, lifting and handling insert locations, blockouts and openings, the finish on each face, and the chamfers and reveals.
3.1.4.4The relationship of fabrication and placement tolerances shall be reconciled on the production drawings so that the specified connections and joints are achievable, consistent with the cumulative-tolerance principle in Concrete Reinforcement. 3.1.5 Structural Design Calculations
3.1.5.1Where the precast producer is delegated the design of the precast elements or their connections, signed and sealed design calculations shall be submitted, prepared by a registered professional engineer licensed in the jurisdiction of the project.
3.1.5.2Calculations shall cover the in-service load condition, the prestress transfer (release) condition, and the handling conditions — stripping, storage, transportation, and erection.
NOTE The stresses during handling frequently govern the reinforcement and pick-point design of slender elements and control where lifting inserts are placed. (3.1.5.3)
3.1.6 Concrete Mix Designs
3.1.6.1Mix designs shall be submitted for each concrete class — structural backup concrete, and each architectural face mix — showing cementitious materials, aggregates (including the facing aggregate where an exposed-aggregate finish is specified), admixtures, water-to-cementitious-materials ratio, design release strength, and design 28-day strength.
3.1.7 Samples
3.1.7.1For architectural precast and for any structural element with an exposed finish, the producer shall submit samples that establish the accepted appearance.
3.1.7.2Samples shall progress from initial finish samples (representing color, texture, and aggregate) to a full-size sample panel or mockup where the contract documents require one.
3.1.7.3The accepted sample establishes the standard of appearance — color range, texture, aggregate exposure depth, and acceptable degree of color and texture variation — against which production units are judged.
3.1.8 Action Submittal Deliverables
3.1.8.1The Contractor shall submit the following action submittals for review:
- Erection drawings (piece marks, sequence, connections, joints)
- Production (shop) drawings for each piece mark
- Delegated-design structural calculations (sealed)
- Structural concrete mix design(s)
- Architectural face-mix design(s)
- Connection hardware and embedded-plate product data
- Prestressing strand and reinforcement certifications
- Bearing pad and grout product data
- Initial finish samples (color, texture, aggregate)
- Full-size sample panel / mockup
☐ Erection drawings (piece marks, sequence, connections, joints)
☐ Production (shop) drawings for each piece mark
☐ Delegated-design structural calculations (sealed)
☐ Structural concrete mix design(s)
☐ Architectural face-mix design(s)
☐ Connection hardware and embedded-plate product data
☐ Prestressing strand and reinforcement certifications
☐ Bearing pad and grout product data
☐ Initial finish samples (color, texture, aggregate)
☐ Full-size sample panel / mockup
3.2.1The Contractor shall submit the following informational submittals:
- The precast plant's current PCI Plant Certification status, in the product group(s) applicable to the work
- Certified mill test reports for prestressing strand (ASTM A416) and reinforcing steel (ASTM A615 or A706)
- Welder qualification records (AWS D1.1 for connection steel, AWS D1.4 for reinforcing) for personnel performing plant and field welds
- The producer's quality-control plan and the qualifications of the plant QC personnel
☐ PCI Plant Certification status (applicable product groups)
☐ Certified mill test reports for strand (ASTM A416) and reinforcement (ASTM A615/A706)
☐ Welder qualification records (AWS D1.1 and AWS D1.4)
☐ Producer's quality-control plan and QC personnel qualifications
3.3 Closeout Submittals
3.3.1The Contractor shall provide the following at project closeout:
- Concrete strength test reports, including release-strength and 28-day cylinder breaks, organized by mix and casting date
- Records of prestressing operations: strand jacking force, elongation measurements, and the gauge-pressure-versus-elongation reconciliation for each casting bed
- As-built erection records noting any field-authorized connection or joint modifications
- Repair records for any element repaired in the plant or in the field, with the method and materials used
- Warranty documentation for the installation and for any specified sealants and coatings
☐ Concrete strength test reports (release and 28-day), by mix and casting date
☐ Prestressing operation records (jacking force, elongation, reconciliation)
☐ As-built erection records of field-authorized modifications
☐ Repair records (method and materials)
☐ Warranty documentation for installation, sealants, and coatings
4 Quality Assurance
4.1 Plant Certification
4.1.1The required PCI Plant Certification group(s) shall be as follows:
☐ Structural products (PCI MNL-116) — beams, columns, double-tees, hollow-core, structural wall panels
☐ Architectural products (PCI MNL-117) — exposed-finish cladding panels and spandrels
☐ Bridge products (where bridge elements are within scope)
4.1.2The precast producer shall operate a plant that holds current PCI Plant Certification in the product group(s) covering the work to be furnished — structural products certified under PCI MNL-116 and architectural products certified under PCI MNL-117 — or shall hold an equivalent recognized plant certification accepted by the Engineer.
NOTE Plant certification is the principal quality assurance for precast because the controlling production steps (form setup, strand tensioning, casting, finishing, curing, and detensioning) occur out of sight of the project site and cannot be verified after the fact by inspecting the delivered element. (4.1.3)
4.1.4The Contractor shall furnish evidence of current certification before the first element is fabricated.
4.2 Producer's Engineer Qualifications
4.2.1Where design of the elements or connections is delegated to the precast producer, the responsible engineer shall be a registered professional engineer licensed in the jurisdiction of the project and experienced in precast and prestressed concrete design in accordance with PCI MNL-120.
NOTE The Engineer of Record's review of delegated submittals confirms conformance with the design intent and the imposed loads; it does not transfer responsibility for the precast element design from the producer's engineer. (4.2.2)
4.3 Welder Qualifications
4.3.1Personnel making welded connections shall be qualified under AWS D1.1 for connections of structural steel hardware and under AWS D1.4 for welds to reinforcing steel, for the processes and positions used.
4.3.2Qualification records shall be available at the plant and at the site.
4.4 Pre-Installation Conference
4.4.1A pre-erection conference shall be held before the first precast element is set, attended by the Contractor's superintendent, the erector, the precast producer's representative, and the Engineer.
4.4.2The agenda shall cover the erection sequence and crane plan, connection details and required welding or grouting, bearing and shimming, joint widths and tolerances, the survey control for setting, and the inspection hold points.
4.5 Mockup Acceptance
4.5.1Where a sample panel or mockup is required for architectural precast, no production casting of exposed units shall begin until the mockup is reviewed and accepted in writing.
4.5.2The accepted mockup shall be retained, protected from weathering, and available at the plant and the site for comparison throughout production and erection.
5 Environmental and Service Conditions
NOTE The durability of precast concrete is governed by the ACI CODE-318-25 Chapter 19 exposure framework. (5.1)
5.2The applicable freeze-thaw and corrosion exposure categories shall be as follows:
○ F0 — not exposed to freezing and thawing in a moist condition
○ F1 — exposed to freezing and thawing, moist, no deicing chemicals
○ F2 — exposed to freezing and thawing and to deicing chemicals (parking structures, exterior cladding)
○ C0 — dry or protected from moisture in service
○ C1 — exposed to moisture but not to external chlorides
○ C2 — exposed to moisture and an external source of chlorides (coastal, deicing salt)
5.3The producer's mix designs shall satisfy the maximum water-to-cementitious-materials ratio and minimum strength required for the applicable exposure categories.
5.4Architectural precast cladding is fully exposed to weather and to freeze-thaw cycling at its face, and the face mix shall be air-entrained and proportioned for that exposure even where the structural backup mix would not require it.
NOTE The C exposure category is particularly significant for prestressed precast because prestressing strand is highly sensitive to chloride-induced corrosion — a corroding strand loses cross-section and can fail by stress corrosion at far lower section loss than a passively stressed reinforcing bar. (5.5)
5.6In C2 exposure, the cover over strand and the crack-control provisions become critical, and connection hardware shall be hot-dip galvanized or otherwise protected as specified below.
6 Materials
6.1 Concrete
6.1.1 Cement and Cementitious Materials
6.1.1.1The architectural face-mix cement shall be as follows:
○ Not applicable — structural finish only, no exposed face mix
○ Gray portland cement, single source (standard architectural)
○ White portland cement, single source (light colors and high color uniformity)
○ Blended gray/white or pigmented to match accepted sample
6.1.1.2Portland cement shall conform to ASTM C150/C150M, or blended hydraulic cement to ASTM C595/C595M.
6.1.1.3Silica fume conforming to ASTM C1240 may be used to increase strength and reduce permeability.
6.1.1.4For architectural face mixes, white portland cement or a controlled gray cement shall be used where required to achieve the accepted sample color.
6.1.1.5Cement for the face mix shall be supplied from a single source and a consistent production run for the duration of the project to control color uniformity.
NOTE Cement is the single largest contributor to base concrete color and a change in cement source is the most common cause of a visible color shift across a facade. (6.1.1.6)
6.1.2 Aggregates
6.1.2.1Aggregates shall conform to ASTM C33/C33M.
6.1.2.2For exposed-aggregate architectural finishes, the facing aggregate color, size, and gradation shall match the accepted sample, and it shall be supplied from a single source for the duration of the project.
6.1.2.3The nominal maximum aggregate size of the structural backup mix shall be compatible with the element thickness, the reinforcement congestion, and the cover over strand.
6.1.3 Concrete Compressive Strength
NOTE The specified 28-day compressive strength of precast concrete is typically higher than that of comparable cast-in-place concrete, both because the structural design exploits the higher strength and because high early strength is needed to permit a daily casting cycle. (6.1.3.1)
6.1.3.2The specified 28-day compressive strength shall be as follows:
5000 psi
6000 psi — common for prestressed members
7000 psi
8000 psi
10000 psi — high-strength members
6.1.3.3The release strength — the strength at which prestress is transferred and the element is stripped — governs the production schedule and shall be specified separately from the 28-day strength.
6.1.3.4 Concrete Release (Transfer) Strength
6.1.3.4.1The specified concrete strength at prestress transfer shall be as follows:
30005000
30003500400045005000
Default: 3500 psi
6.1.3.4.2The concrete shall attain the specified release strength, verified by test, before prestress is transferred (strand is detensioned) or before a non-prestressed element is stripped and lifted.
NOTE Detensioning before the concrete reaches release strength overstresses the concrete at transfer and causes cracking, excessive camber, or end-zone splitting that may not be visible until later. (6.1.3.4.3)
6.1.3.4.4Release strength shall not be less than that required by the producer's design for the transfer condition.
6.2 Reinforcement
6.2.1 Conventional Reinforcement
6.2.1.1The conventional reinforcing bar grade shall be as follows:
Grade 60 (ASTM A615)
Grade 60, weldable (ASTM A706) — where welded to hardware
Grade 80 (ASTM A615) — where designed
6.2.1.2Deformed reinforcing bars shall conform to ASTM A615/A615M (Grade 60 standard) or, where welding of reinforcement or enhanced ductility is required, to ASTM A706/A706M.
6.2.1.3Welded wire reinforcement shall conform to ASTM A1064/A1064M.
6.2.1.4The precast producer shall detail and supply the embedded reinforcement under this standard following the reinforcement detailing principles of Concrete Reinforcement. 6.2.2 Prestressing Strand
6.2.2.1The prestressing strand grade and diameter shall be as follows:
○ Grade 270, low-relaxation, 7-wire (ASTM A416) — standard
○ Grade 250, low-relaxation, 7-wire (ASTM A416) — where designed
3/8 in.
7/16 in.
1/2 in. — most common in building products
0.6 in. — high-capacity members
6.2.2.2Pretensioning strand shall be uncoated, low-relaxation, seven-wire steel strand conforming to ASTM A416/A416M.
6.2.2.3Low-relaxation strand shall be used in lieu of stress-relieved (normal-relaxation) strand.
NOTE Its much lower long-term relaxation (not more than 2.5% at 1000 hours from an initial stress of 70% of guaranteed ultimate tensile strength) preserves more of the effective prestress over the life of the member and is the current production standard. (6.2.2.4)
6.2.2.5Strand shall be Grade 270 (270,000 psi guaranteed ultimate tensile strength) unless the producer's design requires a different grade.
6.2.2.6 Strand Cleanliness
6.2.2.6.1Strand shall be free of loose rust, oil, grease, dirt, paint, and any other bond-reducing contaminant at the time of casting, because the prestress force transfers into the concrete entirely through bond between the strand surface and the concrete.
NOTE Tightly adhered surface rust that does not produce visible pitting is acceptable and can improve bond; loose flaky rust, lubricants, and form-release overspray are not. (6.2.2.6.2)
6.2.2.6.3Contaminated strand shall be cleaned or rejected.
6.3 Connection Hardware and Embedded Plates
6.3.1 Embedded Steel
6.3.1.1Embedded connection plates, angles, weld plates, and inserts shall be fabricated from carbon structural steel conforming to ASTM A36/A36M or, where higher strength is required, high-strength low-alloy steel conforming to ASTM A572/A572M.
6.3.1.2Anchorage of embedded plates into the concrete shall be by welded headed studs or deformed bar anchors developed for the design force.
6.3.1.3Embedded hardware shall be positioned and held during casting so that its as-cast location and orientation are within the connection tolerance.
NOTE A weld plate cast 1 in. off position or rotated out of plane can make a field connection unweldable without remedial work. (6.3.1.4)
6.3.2 Corrosion Protection of Hardware
6.3.2.1The connection hardware corrosion protection and field connection method shall be as follows:
○ Bare steel — interior, dry, non-corrosive service (fully embedded hardware)
○ Hot-dip galvanized after fabrication (ASTM A123 / A153) — exterior or exposed (standard for cladding)
○ Stainless steel — severe chloride or aggressive chemical exposure
☐ Welded — embedded plate to embedded plate, or plate to structural steel (AWS D1.1)
☐ Bolted — through embedded inserts or clip angles
☐ Grouted — keyways, sleeves, and bearing connections
☐ Doweled and grouted — column-to-foundation and column splices
6.3.2.2Embedded steel hardware and exposed connection steel shall be protected against corrosion as required by the service exposure.
6.3.2.3For interior, dry, non-corrosive service (C0/C1), bare steel with the concrete cover providing protection is acceptable for fully embedded hardware.
6.3.2.4For exterior, moist, or chloride exposure (C2), and for all exposed connection hardware, the steel shall be hot-dip galvanized after fabrication in accordance with ASTM A123/A123M (structural shapes and plates) and ASTM A153/A153M (hardware and fasteners), or shall be stainless steel where galvanizing is insufficient.
6.3.2.5Galvanized hardware shall not be welded in the field without removing the zinc coating in the weld zone and re-protecting the weld and heat-affected zone, because welding through zinc produces porous welds and toxic fume.
6.4 Bearing Pads
6.4.1The bearing pad type shall be as follows:
Plain elastomeric (chloroprene/neoprene) — light to moderate bearing (common for plank and tees)
Steel-laminated elastomeric — high load with rotation
Random-oriented-fiber reinforced elastomeric — higher bearing stress, less rotation
Cotton-duck reinforced (high-load, low-movement)
Thermoplastic / high-density polyethylene — high bearing, low friction
6.4.2Precast members that bear on supports shall bear on pads that distribute the reaction, accommodate end rotation and volume-change movement, and prevent hard concrete-to-concrete or concrete-to-steel contact that would spall the bearing edges.
6.4.3Bearing pad material shall be selected for the bearing stress and the movement demand: elastomeric (chloroprene/neoprene or natural rubber, plain or steel-laminated, referencing ASTM D4014), random-oriented-fiber reinforced elastomeric, cotton-duck reinforced, or thermoplastic (high-density polyethylene) pads.
6.4.4The pad type and dimensions shall be as required by the producer's design and PCI MNL-120.
6.5 Grout
6.5.1The connection and bearing grout shall be as follows:
○ Nonshrink, ASTM C1107 — structural connections, column bases, load-transfer bearings (standard)
○ Sand-cement keyway grout — hollow-core plank keyways (diaphragm shear)
○ Both — nonshrink at connections, keyway grout at plank joints
6.5.2Grout at bearings, leveling beds, column bases, keyways between hollow-core plank, and grouted connection sleeves shall be selected for its function.
6.5.3Nonshrink grout for structural connections and column base plates shall conform to ASTM C1107/C1107M.
NOTE Nonshrink grout is specified at load-transferring connections because ordinary grout shrinks as it cures and loses contact with the bearing surfaces, leaving a gap that concentrates load and defeats the connection. (6.5.4)
6.5.5Sand-cement grout or flowable grout may be used to fill plank keyways where the function is diaphragm shear transfer and load-bearing precision is not required.
7 Fabrication
7.1.1Forms shall be mortar-tight, dimensionally accurate, and rigid enough to hold shape under the casting and (for self-stressing beds) the prestressing loads.
7.1.2Form-release agent shall be compatible with the specified finish, and for architectural face mixes and form-liner finishes shall not stain, discolor, or interfere with the subsequent finishing operation or any applied sealer.
7.1.3Concrete shall be placed and consolidated so that the element is fully dense and free of honeycombing, with particular care at congested end zones, around blockouts, and at the face of architectural panels where surface voids (bug holes) are an appearance defect.
7.2 Pretensioning (Prestress Transfer)
7.2.1The prestress force verification method shall be as follows:
○ Jack gauge force and measured elongation reconciled within PCI MNL-116 tolerance (standard)
○ Per producer's quality-control plan and PCI MNL-116
7.2.2In pretensioned production, strand shall be tensioned against the abutments of a self-stressing bed (or against external abutments) to the jacking force shown on the production drawings before concrete is cast.
7.2.3The applied force shall be verified by two independent means — the jack gauge pressure and the measured strand elongation — and the two shall agree within the tolerance of PCI MNL-116 (commonly ±5%).
NOTE Reconciling gauge force against elongation is the fundamental check that the design prestress is actually being delivered: a gauge-only reading can be wrong because of jack friction or a faulty gauge, and an elongation-only reading can be wrong because of strand seating and anchor slip. (7.2.4)
7.2.5After the concrete attains the specified release strength, the strand shall be detensioned in a controlled, symmetrical sequence so that the member is not subjected to eccentric or sudden transfer that could crack it.
7.2.6 Strand Debonding and Draping
7.2.6.1Where the design requires the prestress profile to vary along the member or to be reduced at the ends, strand shall be debonded (sheathed) at the ends or draped (harped) as shown on the production drawings.
7.2.6.2Debonding and draping shall be executed exactly as designed because relocating or omitting a debonded length changes the transfer-condition stresses the design relied on.
7.3 Curing
NOTE Accelerated curing — typically by controlled radiant or low-pressure steam heat under a cover — is commonly used to reach release strength overnight for a daily casting cycle. (7.3.1)
7.3.2The curing method and maximum curing temperature shall be as follows:
○ Accelerated curing (radiant or low-pressure steam) under controlled time-temperature, per PCI MNL-116 (standard for daily cycle)
○ Ambient / moist curing (where production schedule permits)
140170
140150160170
Default: 160 °F
7.3.3Precast elements shall be cured to develop the specified release strength on the production schedule and to develop the specified 28-day strength and durability.
7.3.4Accelerated curing shall follow a controlled time-temperature regime per PCI MNL-116: a presetting (delay) period before heat is applied, a limited rate of temperature rise, a maximum holding temperature, and a controlled cooldown.
NOTE Exceeding the maximum curing temperature or heating before initial set can cause delayed ettringite formation and reduced ultimate strength, and an uncontrolled cooldown causes thermal cracking. (7.3.5)
7.4 Architectural Finishes
NOTE The finish of an architectural precast element is a specified deliverable matched to the accepted sample, produced by the selected combination of face mix, form surface or form liner, and post-strip surface treatment. (7.4.1)
7.4.2The producer shall maintain a consistent face-mix proportion, consistent depth of treatment, and consistent timing so that the appearance does not drift across the production run.
NOTE A smooth as-cast finish takes the texture of the form face directly and shows surface imperfections (bug holes, form-joint marks) readily, making it the least forgiving architectural finish. (7.4.3.1)
7.4.3.2A smooth as-cast finish shall be used only where the form quality and the producer's bug-hole control can achieve the accepted sample.
7.4.4 Form-Liner (Textured) Finish
NOTE A form-liner finish reproduces a relief texture or pattern — board-form, fluted, brick, stone — cast into the panel face by a liner placed in the form. (7.4.4.1)
7.4.5 Exposed-Aggregate Finish
NOTE An exposed-aggregate finish removes the surface cement paste to reveal the facing aggregate. (7.4.5.1)
NOTE It is produced by chemical surface retarder applied to the form face (which delays set of the surface paste so it can be washed off after stripping), by aggregate-transfer methods, or by abrasive blasting. (7.4.5.2)
7.4.5.3The depth of exposure (light, medium, or deep reveal of the aggregate) is a specified appearance parameter and shall match the accepted sample.
7.4.6 Acid-Etched Finish
NOTE An acid-etched finish uses a controlled acid wash to dissolve a thin layer of surface paste, producing a fine, uniform, matte texture that reveals the fine aggregate and sand without exposing the coarse aggregate. (7.4.6.1)
7.4.6.2Acid etching shall be neutralized and thoroughly rinsed; residual acid will continue to attack the surface and can cause efflorescence and staining.
7.4.7 Sandblasted (Abrasive-Blast) Finish
NOTE A sandblasted finish removes surface paste by abrasive blasting to a light, medium, or heavy texture. (7.4.7.1)
7.4.7.2Blast depth and uniformity shall match the accepted sample, and the blast shall be carried consistently to panel edges and around reveals so that texture does not fade or intensify at the margins.
7.4.8 Architectural Finish Selection
7.4.8.1The architectural face finish and acceptable appearance standard shall be as follows:
Not architectural — structural / utility finish only
Smooth as-cast (form finish)
Form-liner / textured pattern
Exposed aggregate — light reveal
Exposed aggregate — medium reveal
Exposed aggregate — deep reveal
Acid-etched (fine matte texture)
Sandblasted — light
Sandblasted — medium
Sandblasted — heavy
○ Match accepted full-size mockup, viewed at the specified distance and lighting
○ Match accepted initial finish sample (no full-size mockup required)
8 Tolerances
8.1 Product Tolerances
8.1.1The product tolerance basis shall be as follows:
○ PCI MNL-135 product tolerances — structural precast (standard)
○ PCI MNL-117 architectural tolerances — exposed cladding panels (tighter)
○ Project-specific tolerances tighter than PCI — per contract documents
8.1.2Dimensional tolerances for fabricated precast elements shall conform to PCI MNL-135 (Tolerance Manual for Precast and Prestressed Concrete Construction) for product tolerances, except where the contract documents or the architectural finish require tighter tolerances.
NOTE Product tolerances govern the dimensions of the manufactured element — length, width, thickness, squareness, position of embedded hardware and blockouts, bowing, and warping. (8.1.3)
NOTE Architectural panels carry tighter tolerances than structural elements under PCI MNL-117 because their dimensional deviations are visible in the finished facade and accumulate into joint-width variation. (8.1.4)
8.1.5 Position of Embedded Hardware
8.1.5.1The as-cast position of connection hardware, weld plates, and inserts shall be held within the tolerance of PCI MNL-135 so that field connections fit without forcing or remedial work.
8.1.5.2Where the connection design requires a tighter hardware position than the standard product tolerance, the production drawings shall flag the location and the tighter tolerance.
8.1.6 Bowing and Warping
8.1.6.1Wall panels and spandrels shall be controlled for bowing (out-of-plane curvature) and warping (twist), which arise from differential prestress, differential drying, and a thermal gradient through an insulated panel.
8.1.6.2Bowing and warping shall be within the PCI MNL-135 limits for the panel type so that adjacent panels align at their joints.
8.2 Erection Tolerances
8.2.1The erection tolerance basis and nominal joint width shall be as follows:
○ PCI MNL-135 erection tolerances (standard)
○ Project-specific erection tolerances per contract documents
0.51.5
0.50.7511.251.5
Default: 0.75 in
8.2.2Erection (installation) tolerances are distinct from product tolerances and shall conform to PCI MNL-135 for the erected position — the location, plumb, level, and joint width of the element as set in the structure.
NOTE A piece that is within product tolerance can still be erected out of tolerance, and the joint between two pieces must absorb the sum of both pieces' product tolerances and the erection tolerance. (8.2.3)
8.2.4Joint widths shall be designed and erected so that the specified sealant joint can accommodate the cumulative tolerance and the in-service movement, coordinated with Joint Sealants. 9 Connections and Embedments
9.1 Reinforcement Cover
9.1.1The concrete cover over strand and reinforcement exposed to weather shall be as follows:
1-1/2 in. — typical exposed precast
2 in. — chloride (C2) exposure or owner requirement
Per producer's design and ACI 318 for the exposure category
9.1.2Concrete cover over reinforcement and prestressing strand in precast elements shall conform to ACI CODE-318-25, which permits reduced cover for plant-precast elements manufactured under controlled conditions relative to cast-in-place values, but never less than the cover required for the strand or bar size and the service exposure.
9.1.3For prestressed members in corrosive or chloride exposure, the cover over strand is a primary corrosion-protection control and shall not be reduced below the value the producer's design requires for the C exposure category.
9.2 Welded Connections
9.2.1Welded connections joining embedded plates to one another or to the supporting structural steel shall be made under a welding procedure qualified to AWS D1.1, by welders qualified for the process and position.
9.2.2Welds to embedded reinforcing bar anchors shall comply with AWS D1.4.
9.2.3The heat of field welding shall not be concentrated against the concrete in a way that spalls the surface at the embed, and the embed anchorage shall be designed to carry the connection force into the concrete without overstressing the cover.
9.3 Bolted and Doweled Connections
9.3.1Bolted connections shall use fasteners of the specified grade, protected against corrosion to match the exposure.
9.3.2Doweled connections — column-to-foundation, column splice, and panel-to-foundation — shall set the dowel into a preformed sleeve or cored hole and shall be filled with nonshrink grout (ASTM C1107) so that the dowel is fully encased and the connection develops the design force.
9.4 Bearing and Shimming
9.4.1Each member shall bear on its support through the specified bearing pad, set on a leveling surface established by shims or a leveling grout bed.
9.4.2The erector shall not reduce the bearing length below the design minimum by setting a member short on its support.
9.4.3Shims used to set elevation shall be of a durable, non-staining material and shall be left in place or removed and drypacked as the connection detail requires.
9.4.4Steel shims left in an exposed exterior joint shall be corrosion-protected to avoid rust staining.
10 Testing
10.1 Concrete Strength Testing
10.1.1The release-strength cylinder curing method shall be as follows:
○ Match-cured or companion-cured with the product (standard — reflects in-form strength)
○ Standard-cured per ASTM C39 (28-day acceptance only)
10.1.2Concrete compressive strength shall be verified by testing cylinders in accordance with ASTM C39/C39M, cured alongside the elements they represent for the release-strength determination and standard-cured for the 28-day acceptance strength.
10.1.3Release-strength cylinders shall be cured under the same conditions as the product (match-cured or companion-cured) so that the release-strength break reflects the actual in-form concrete, not a standard-cured specimen that may be stronger or weaker than the heated element.
10.1.4Prestress shall not be transferred and elements shall not be stripped until the release-strength cylinders confirm the specified f'ci.
10.2 Finished-Product Inspection
10.2.1Each element shall be inspected at the plant before shipment for dimensional conformance to product tolerances, for surface defects, for the specified finish (against the accepted sample for architectural units), and for correct location of embedded hardware and lifting inserts.
10.2.2Elements with cracks, honeycombing, exposed strand, or finish defects beyond the accepted criteria shall be repaired to an accepted standard or rejected.
10.3 Field Connection Inspection
10.3.1Field welds shall be visually inspected and, where the contract documents or the building code require, subjected to nondestructive examination.
10.3.2Grouted connections shall be inspected for complete fill and for the specified grout strength.
10.3.3Bolted connections shall be inspected for the specified installation.
11 Erection and Installation
11.1 Survey and Control
11.1.1Before erection begins, the erector shall verify the supporting structure against the erection drawings — bearing elevations, embed and anchor-bolt locations, and the dimensional control of the cast-in-place or steel frame — and shall reconcile any out-of-tolerance support condition with the Engineer before setting precast on it.
NOTE Precast erection tolerances assume the support is within its own tolerance; setting precast to a support that is itself out of tolerance compounds the error into the joints. (11.1.2)
11.2 Handling and Rigging
11.2.1The lifting and handling method shall be as follows:
○ Designed lifting inserts and rigging per producer's production drawings (standard)
○ Erector-engineered lifting plan reviewed by producer's engineer
11.2.2Elements shall be lifted only at the designed lifting inserts and pick points shown on the production drawings, using rigging (spreader beams, lifting frames) that controls the lifting stresses.
NOTE Slender elements — long double-tees, tall thin wall panels — develop their highest tensile stresses during stripping and lifting, not in service, and lifting at the wrong points or without the designed spreader can crack an otherwise sound element. (11.2.3)
11.2.4The erector shall follow the producer's handling instructions for orientation and support during lifting and turning.
11.3 Setting and Connection
11.3.1Elements shall be set in the sequence shown on the erection drawings, supported and braced as required until their permanent connections are complete.
11.3.2Members shall not be released from the crane until they are stable on their bearings or temporarily braced.
11.3.3Tall wall panels and columns shall be braced against wind and construction loads until the permanent lateral connections and any diaphragm or grouted bases are complete.
11.3.4Permanent connections — welds, grouted dowels, grouted keyways — shall be completed within the time the erection sequence and the bracing plan require.
11.4 Bracing
11.4.1The temporary bracing of vertical elements shall be as follows:
○ Required until permanent lateral connections complete; designed for wind and construction loads (standard)
○ Not applicable — elements stable on bearings without bracing
11.4.2Temporary bracing shall be designed for the wind and construction loads on the unconnected element and shall remain in place until the permanent connections that replace its function are complete.
11.4.3Removing bracing before the permanent connection is made — a frequent cause of erection-stage collapse — is prohibited.
11.5 Grouting of Joints and Bearings
11.5.1Keyways between hollow-core plank shall be cleaned, wetted, and filled with keyway grout to develop diaphragm shear.
11.5.2Column bases and grouted dowel sleeves shall be filled with nonshrink grout (ASTM C1107).
11.5.3Grout shall not be placed against frozen surfaces or below the manufacturer's minimum temperature, and shall be cured to develop its strength before the connection is loaded.
11.6 Joint Sealing
11.6.1After erection and after the panels have undergone initial volume-change movement, the joints between architectural panels shall be sealed in accordance with Joint Sealants. 11.6.2The joint design — width, sealant type, backer rod, and bond-breaker — shall accommodate the cumulative product and erection tolerance and the thermal and moisture movement of the panels.
NOTE Sealing the joints is coordinated with, but not part of, the precast erection scope. (11.6.3)
12 Delivery, Storage, and Handling
12.1The storage support method shall be as follows:
○ Dunnage at designed support / pick points, elements separated and protected (standard)
○ Per producer's storage instructions for the specific element
12.2Elements shall be marked with their piece mark and orientation and shall be transported and stored in the orientation and on the support points the producer specifies.
12.3Storage dunnage shall be placed at or near the designed support points so that the element is not subjected to handling stresses (or sustained creep deflection) it was not designed for.
NOTE A long member stored on dunnage placed at its ends instead of its design pick points can take a permanent sag or crack. (12.4)
12.5Architectural units shall be stored and protected so that their finished faces are not stained by runoff from other materials, by dunnage, or by rust from adjacent steel, and so that differential weathering does not mark the face before erection.
13 Repair and Patching
13.1The architectural face repair acceptance standard shall be as follows:
○ Color- and texture-matched to accepted sample, viewed at specified distance and lighting (standard for cladding)
○ Structural soundness only — utility finish, appearance not governed
13.2Minor defects — chips, spalls, surface voids (bug holes) in architectural faces, and damage from handling — may be repaired to an accepted standard rather than rejecting the element, where the defect does not compromise the structural function.
13.3Repairs to architectural faces shall match the accepted sample in color and texture when viewed at the specified distance and lighting.
NOTE A repair that is structurally sound but visibly mismatched is a finish defect on a cladding panel. (13.4)
13.5Repair materials shall be compatible with the parent concrete and, for exposed faces, color-matched using the same face-mix constituents.
13.6Cracks, exposed or corroded strand, and defects that affect structural capacity shall be evaluated by the producer's engineer and the Engineer of Record, and the element shall be repaired by an engineered method or rejected.
14 Warranty
14.1The installation warranty period shall be as follows:
1 year from substantial completion
2 years from substantial completion
14.2The Contractor shall warrant the precast concrete work against defects in materials and workmanship — including cracking attributable to handling or erection, connection failure, grout failure, finish defects beyond the accepted criteria, and corrosion staining from inadequately protected hardware — for a period of not less than one year from substantial completion, or for the period stated in the contract documents if longer.
14.3The warranty shall not limit the Engineer's right to require corrective work for nonconforming conditions discovered during the warranty period.
14.4Material warranties provided by the producer, the sealant manufacturer, and any applied-coating manufacturer shall be passed through to the Owner and included in the closeout submittals.