03450 Precast Conc.doc

Base Pavements IDIQ

JCGU 09-1700

DIVISION 03 - CONCRETE

SECTION 03450 - PRECAST CONCRETE FOR CURB

INLETS AND SURFACE INLETS

PART 1 – GENERAL:

1.1 REFERENCES: The publications listed below form a part of this specification to the extent referenced. The publications are referred to in the text by basic designation only. All publications shall be the latest version/edition/revision of the documents listed below, in effect on the date of this solicitation, except where a date is given.

AMERICAN CONCRETE INSTITUTE (ACI)

ACI 211.1

Selecting Proportions for Normal, Heavyweight and Mass Concrete

ACI 211.2

Selecting Proportions for Structural Lightweight Concrete

ACI 315

Details and Detailing of Concrete Reinforcement

ACI 318/318R

Building Code Requirements for Structural Concrete and Commentary

AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM)

ASTM A 416

Steel Strand, Uncoated seven-wire Stress-Relieved for Prestressed Concrete

ASTM C 494

Chemical Admixtures for concrete

ASTM C 1017

Chemical Admixtures for Use in Producing Flowing

AMERICAN WELDING SOCIETY (AWS)

AWS D1.1

Structured Welding Code-Steel

PRESTRESSED CONCRETE INSTITUTE (PCI)

PCI MNL-116

Manual for Quality Control for Plants and Production of Precast Prestressed Concrete Products

PCI MNL-117

Manual for Quality Control for Plants and Production of Architectural Precast Concrete Products

PCI MNL-121

Manual for Structural Design of Architectural Precast Concrete

1.2 GENERAL REQUIREMENTS:

Precast concrete units shall be designed and fabricated by an experienced and acceptable precast concrete manufacturer. The manufacturer shall have been regularly and continuously engaged in the manufacture of precast concrete work similar to that indicated on the drawings for at least 3 years. Precast work shall be coordinated with the work of other trades.

1.3 DESIGN:

1.3.1 Standards and Loads

Precast unit design shall conform to ACI-318 and PCI MNL-121. A differential temperature of 160 degrees F, between interior and exterior faces of the units, shall be considered in the design. Stresses due to retrained volume change caused by shrinkage and temperature differential, handling, transportation and erection shall be accounted for in the design

1.3.2 Connections

Connection of units to other members, or to other units shall be of the type and configuration indicated. The design and sizing of connections for all design loads shall be by the Contractor.

1.3.3 Concrete Strength

Precast concrete units shall have a 28-day compressive strength of 4000 psi.

1.3.4 Concrete Proportion

Selection of proportions for concrete shall be based on the methodology presented in ACI 211.1 for normal weight concrete and ACI 211.2 for light weight concrete. The concrete proportion shall be developed using the same type and brand of cement, the same type and gradation of aggregates, and the same type and brand of admixture that will be used in the manufacture of precast concrete units for the project. Calcium chloride shall not be used in precast concrete and admixtures containing chloride ions, nitrates, or other substances that are corrosive shall not be used in prestressed concrete.

1.3.5 Calculations:

Calculations for design of members and connections not shown shall be made by a Licensed Professional Engineer experienced in the design of precast architectural concrete. Calculation shall include the analysis of member for lifting stresses and the sizing of the lifting inserts.

1.4 SUBMITTALS:

The following shall be submitted in accordance with Specification SECTION 01010:

Design Analysis and Calculations:

Design calculations shall be submitted for approval and certified by a Licensed Professional Engineer prior to the manufacture of any precast concrete units for the project with the applicable inlet submittal.

Mix Design:

Prior to commencing operations, a statement giving the maximum nominal coarse aggregate size, the proportions of all ingredients and the type and amount of any admixtures that will be used in the manufacture of each strength and type of concrete shall be furnished. The statement shall be accompanied by test results from an approved testing laboratory, certifying that the proportions selected will produce concrete of the properties required. No substitutions shall be made without additional tests to verify that the concrete properties are satisfactory.

Detail Drawings:

Detail drawings shall show details in accordance with ACI 315 and ACI 318 including installation details. Detail drawings shall indicate separate identification marks for each different precast unit, location of units in the work, elevations, fabrication details, welding details, reinforcement, connections, dimensions, interface with adjacent members, blocking points for units stored at the precast concrete plant or at the job site, lifting points and special handling instructions in sufficient detail to cover manufacture, handling, and erection. All drawings shall be certified by a Licensed Professional Engineer.

Test Reports:

Tests for compressive strength of concrete shall be performed by an approved independent commercial testing laboratory, except that compressive strength tests for initial prestress may be performed in the manufacturer’s plant laboratory. Certified copies of test reports shall be furnished and shall include all test data and all test results.

1.5 STORAGE AND INSPECTION AT MANUFACTURER’S PLANT:

Precast units temporarily stored at the manufacturer’s plant shall be protected from damage in accordance with PCI MNL-116 and PCI MNL-117 and PCI MNL-121. Immediately prior to shipment to the job site, all precast concrete units shall be inspected for quality to insure all precast units conform to the requirements specified. Inspection for quality will include but not necessarily be limited to the following elements; color, texture, dimensional tolerances, chipping, cracking, staining, warping and honeycombing. All defective precast concrete units shall be replaced or repaired as approved.

1.6 HANDLING AND STORAGE:

Precast units shall be delivered to the site with delivery scheduled to avoid excessive build-up of units in storage at the site. Upon delivery to the job site all precast units shall be inspected for quality as specified in paragraph “STORAGE AND INSPECTION AT MANUFACTURER’S PLANT.” If the precast units cannot be unloaded and placed directly into the work, they shall be stored on site, off the ground and protected from weather, marring, or overload. Precast units shall be handled in accordance with manufacturer’s instructions.

PART 2 – PRODUCTS:

2.1 MATERIALS:

Except as otherwise specified, material shall conform to Specification SECTION 03300 - CAST-IN-PLACE CONCRETE and SECTION 03200 - CONCRETE REINFORCEMENT.

2.1.1 Prestressing Strands

Prestressing strands shall conform to ASTM A 416

2.1.2 Tie Wire

Tie wire shall be soft monel or 18-8 stainless steel

2.1.3 Inserts

Inserts shall be manufacturer’s standard, suited for the application.

2.1.4 Plates, Angles, Anchors and Embedments

Material shall be as specified in PCI MNL-117. Steel items, other than stainless, shall be coated with a rust-inhibiting paint or shall be hot-dip galvanized. Steel Items, including items embedded in concrete, shall be either stainless steel or hot dip galvanized steel.

2.1.5 Form Release Agent

Release agent shall be manufacturer’s standard nonstaining type.

2.1.6 Admixtures

Admixtures shall conform to ASTM C 494. Plasticizing admixture, if used, shall conform to ASTM C 1017.

2.2 PRECAST CONCRETE UNITS:

Precast concrete units shall be manufactured and cured in accordance with the applicable provisions of PCI MNL-115 and PCI MNL-117. Units shall be manufactured within the allowable tolerances given in PCI MNL-116, PCI MNL-117 and PCI-MNL-121.

2.2.1 Formwork

Forms shall be steel of adequate thickness, braced, stiffened, anchored and aligned to produce precast architectural concrete units within required dimensional tolerances. forms shall be sufficiently rigid to provide dimensional stability during handling and concrete placement and consolidation. Fiberglass-reinforced plastic, plastic coated wood, elastomeric or other non-absorptive material shall be used for making tight joints and rustication pieces.

2.2.2 Reinforcement

Fabrication and placement of reinforcement shall conform to the details shown on the approved detail drawings and PCI MNL-116 and PCI MNL-117.

2.2.3 Embedded Accessories

Anchors, inserts, lifting devices, and other accessories which are to be embedded in the precast units shall be furnished and installed in accordance with the approved detail drawings. Embedded items shall be accurately positioned in their designed location, and shall have sufficient anchorage and embedment to satisfy design requirements.

2.2.4 Stripping

Precast concrete units shall not be removed from forms until units develop sufficient strength to safely strip the formwork and to remove the precast concrete units from the forms to prevent damage to the units from over stress or chipping.

2.2.5 Identification

Each precast concrete unit shall be marked to correspond to the identification marks for each different precast unit shown on the detail drawings.

2.2.6 Finishes

Manholes and concrete pull boxes shall have a smooth as cast-produced finish using smooth, nonporous forms.

2.2.7 Knockouts

All precast curb inlets and surface inlets shall come with the appropriate knockouts to allow for easy connection to storm sewer pipe.

PART 3 – EXECUTION:

3.1 ERECTION:

Precast units shall be erected in accordance with the detail drawings and without damage to other units or to adjacent members. Units shall be set true to alignment and level, with joints properly spaced and aligned both vertically and horizontally. Erection tolerances shall be in accordance with the requirements of PCI MNL-117 and PCI MNL-121. As units are being erected, shims and wedges shall be placed as required to maintain correct alignment. After final attachment, precast units shall be grouted as shown. After erection, welds and abraded surfaces of steel shall be cleaned and touched-up with a zinc-rich paint. Welds shall be made by a certified welder in accordance with the manufacturer’s erection drawings. Pickup points, boxouts, inserts, and the like shall be finished to match adjacent areas after erection. Erection of precast units shall be supervised and performed by workmen skilled in this type of work. Welding and the qualifications of welders shall be in accordance with AWS D1.1.

END OF SECTION

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