03 45 33.pdf

Charleroi Locks and Dam - Upper and Lower Guard Walls

SECTION TABLE OF CONTENTS

DIVISION 03 - CONCRETE

SECTION 03 45 33

PRECAST PRESTRESSED STRUCTURAL CONCRETE

PART 1 GENERAL

1.1 REFERENCES

1.2 RESTRICTIONS TO ON SITE ACTIVITIES

1.3 SYSTEM DESCRIPTION

1.3.1 Design Requirements

1.3.1.1 Additional Analysis and Design

1.4 MODIFICATION TO REFERENCE

1.5 SUBMITTALS

1.6 QUALITY ASSURANCE

1.6.1 Qualifications

1.6.1.1 Manufacturer Qualifications

1.6.1.2 Designer Qualifications

1.6.1.3 Erector Qualifications

1.6.1.4 Welding Qualifications

1.6.2 Regulatory Requirements

1.6.3 Concrete Mix Design

1.6.4 Certificates: Record Requirement

1.7 DELIVERY, STORAGE, AND HANDLING

1.7.1 Transportation

1.7.1.1 Transporting Members

1.7.1.2 Lateral Deflection or Vibration

1.7.2 Storage

1.7.2.1 Storage Areas

1.7.2.2 Stacked members

1.7.3 Handling of Members

PART 2 PRODUCTS

2.1 CONTRACTOR-FURNISHED MIX DESIGN

2.2 MATERIALS

2.2.1 Cement

2.2.1.1 Pozzolan

2.2.1.2 Ground Granulated Blast-Furnace Slag

2.2.1.3 Silica Fume

2.2.2 Water

2.2.3 Aggregates

2.2.3.1 Aggregates Selection

2.2.4 Grout

2.2.4.1 Nonshrink Grout

2.2.5 Admixtures

2.2.5.1 Air-Entraining

2.2.5.2 Accelerating

2.2.5.3 Water Reducing

2.2.5.4 High-Range Water Reducing

2.2.6 Reinforcement

SECTION 03 45 33 Page 1 W911WN-09-B-0004 Revised by Amendment No. 0002

2.2.7 Metal Accessories

2.2.8 Grout

2.2.8.1 Cementitious Grout

2.2.8.2 Nonshrink Grout

2.3 PRODUCTION QUALITY CONTROL PROCEDURES

2.3.1 Forms

2.3.2 Reinforcement Placement

2.3.3 Concrete

2.3.3.1 Concrete Mixing

2.3.3.2 Concrete Placing

2.3.4 Prestressing

2.4 FINISHING

2.4.1 General

2.4.1.1 Precast Elements

2.4.2 Unformed Surfaces

2.4.2.1 Smooth Finish

2.4.2.2 Roughened Finish

2.4.3 Formed Surfaces

2.4.3.1 Smooth Finish

2.5 CURING AND PROTECTION

2.5.1 Curing with Steam at Atmospheric Pressure

2.5.1.1 Curing After Placing and Vibrating

2.5.1.2 Temperature Increase

2.5.1.3 Temperature Range

2.5.1.4 Temperature Decrease

2.5.1.5 Recording Thermometers

2.5.2 Curing with Radiant Heat and Moisture

2.5.2.1 Radiant Heat

2.5.2.2 Moisture Loss

2.5.2.3 Temperature Limits

2.5.2.4 Termination of Curing

2.6 SURFACE REPAIRS

2.6.1 General

2.6.2 Minor Defects

2.6.3 Major Defects

2.7 TESTS, INSPECTIONS, AND VERIFICATIONS

2.7.1 Factory Inspection

PART 3 EXECUTION

3.1 EXAMINATION

3.2 ERECTION

3.2.1 Storage Provisions

3.2.2 Seating of Precast Concrete Units

3.2.3 Welding

3.2.4 Erection Plans

3.3 BEARING SURFACES

3.4 ANCHORAGE

3.5 GROUTING

3.6 SEALANTS

3.7 CONCRETE INFILL

3.8 SPECIAL REQUIREMENTS FOR MEMBERS TO BE FURNISHED BUT NOT ERECTED

3.9 CONSTRUCTION RECORDS

-- End of Section Table of Contents --

SECTION 03 45 33 Page 2

SECTION 03 45 33

PRECAST PRESTRESSED STRUCTURAL CONCRETE

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 the basic designation only.

ACI INTERNATIONAL (ACI)

ACI 304R (2000) Guide for Measuring, Mixing, Transporting, and Placing Concrete

ACI 305R (1999; Errata 2006) Hot Weather Concreting

ACI 306.1 (1990; R 2002) Standard Specification for Cold Weather Concreting

ACI 309R (2005) Guide for Consolidation of Concrete

ACI 318/318R (2008; Errata 2008) Building Code Requirements for Structural Concrete and Commentary

AMERICAN WELDING SOCIETY (AWS)

AWS D1.1/D1.1M (2008) Structural Welding Code - Steel

AWS D1.4/D1.4M (2005; Errata 2005) Structural Welding Code - Reinforcing Steel

ASTM INTERNATIONAL (ASTM)

ASTM C 1107/C 1107M (2008) Standard Specification for Packaged Dry, Hydraulic-Cement Grout (Nonshrink)

ASTM C 1240 (2005) Standard Specification for Silica Fume Used in Cementitious Mixtures

ASTM C 1260 (2007) Standard Test Method for Potential Alkali Reactivity of Aggregates (Mortar-Bar Method)

ASTM C 136 (2006) Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates

ASTM C 150 (2007) Standard Specification for Portland Cement

ASTM C 173/C 173M (2008) Standard Test Method for Air Content of Freshly Mixed Concrete by the Volumetric Method

SECTION 03 45 33 Page 3

ASTM C 231 (2008c) Standard Test Method for Air Content of Freshly Mixed Concrete by the Pressure Method

ASTM C 260 (2006) Standard Specification for Air-Entraining Admixtures for Concrete

ASTM C 33 (2007) Standard Specification for Concrete Aggregates

ASTM C 494/C 494M (2008a) Standard Specification for Chemical Admixtures for Concrete

ASTM C 618 (2008a) Standard Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use in Concrete

ASTM C 94/C 94M (2009) Standard Specification for Ready-Mixed Concrete

ASTM C 989 (2006) Standard Specification for Ground Granulated Blast-Furnace Slag for Use in Concrete and Mortars

PENNSYLVANIA DEPARTMENT OF TRANSPORTATION (PDT)

PDT 34 (2008) Bulletin 14, Aggregate Producers

PRECAST/PRESTRESSED CONCRETE INSTITUTE (PCI)

PCI MNL-116 (1999) Manual for Quality Control for Plants and Production of Structural Precast Concrete Products

PCI MNL-120 (2004) Design Handbook - Precast and Prestressed Concrete

U.S. ARMY CORPS OF ENGINEERS (USACE)

ER 1110-1-2002 (1998) Cement, Slag and Pozzolan Acceptance Testing

1.2 RESTRICTIONS TO ON SITE ACTIVITIES

No precasting operations will be allowed on any Government owned or controlled land, including the Left Bank Batch Plant Area, the Government-furnished disposal site, the left abutment area or the right bank area.

1.3 SYSTEM DESCRIPTION

The work includes the provision of precast, prestressed concrete herein referred to as prestressed members. Precast and Prestressed members shall be the product of a Pennsylvania Department of Transportation approved manufacturer specializing in the production of precast prestressed concrete members or a manufacturer certified by the PCI Plant Certification Program for Category C4 work. At the Contracting Officer's option, PCI Plant quality control program records shall be available for review.

SECTION 03 45 33 Page 4

1.3.1 Design Requirements

The design of precast concrete units are shown on the contract drawings.

1.3.1.1 Additional Analysis and Design

The manufacturer of these units shall perform additional analyses to evaluate the effects of any additional load conditions produced during fabrication, handling and erection. Analysis and additional design shall be in accordance with ACI 318/318R and PCI MNL-120. Loadings for precast concrete units shall include all dead load, live load, applicable construction loads such as handling, erection loads, and other applicable loads. Design calculations for precast units not shown in the contract drawings shall be made by a Registered Professional Engineer experienced in the design of precast-prestressed concrete and registered to practice in the in a State or possession of the United States, in Puerto Rico, or the District of Columbia.

1.4 MODIFICATION TO REFERENCE

In the ACI publications, the advisory provisions shall be considered to be mandatory, as though the word "shall" has been substituted for "should" wherever it appears; reference to the "Building Official," the "Structural Engineer" and the "Architect/Engineer" shall be interpreted to mean the Contracting Officer.

1.5 SUBMITTALS

Government approval is required for submittals with a "G" designation;

submittals not having a "G" designation are for information only. When used, a designation following the "G" designation identifies the office that will review the submittal for the Government. The following shall be submitted in accordance with Section 01 33 00 SUBMITTAL PROCEDURES:

SD-01 Preconstruction Submittals

Delivery Work Plan; G, RE

A plan describing in detail the proposed methods of delivery and storage of the Upper and Lower Guard Wall components that are to be furnished, but not installed, shall be submitted. The plan shall address equipment, machinery and site limitations identified in the specifications and discussed at a pre-delivery meeting between the Contractor and the Contracting Officer. The plan shall be submitted at least 60 calendars prior to proposed delivery of the components. The plan shall include, but not be limited to the following:

a. Type and size of transportation equipment to be used for delivery

b. Blocking and protection plan for product handling and storage.

Erection Plan; G, ED

SD-02 Shop Drawings

SECTION 03 45 33 Page 5

Drawings of precast prestressed concrete members; G, ED

SD-03 Product Data

Anchorage and lifting inserts and devices

Bearing pads

SD-04 Samples

Sample Panels; G, RE

Sample panels demonstrate roughened finishes for unformed and unformed surfaces of precast units.

Surface finish

Submit two 12 by 12 by 2 inch thick sample panels representative of the color and finish for each type of precast member requiring a finish Grade A surface finish.

SD-05 Design Data

Precast Prestressed concrete members design calculations; G, ED

Concrete mix design; G, ED, RE

SD-06 Test Reports

Contractor-furnished mix design; G, ED, RE

Submit copies of laboratory test reports and certificates of compliance showing that the mix has been successfully tested to produce concrete with the properties specified and that mix will be suitable for the job conditions. The laboratory test reports shall include mill test and all other test for cement, ground granulated blast-furnace slag, pozzolan, silica fume, aggregates, and admixtures. Provide maximum nominal aggregate size, gradation analysis, percentage retained and passing sieve, and a graph of percentage retained versus sieve size. Test reports shall be submitted along with the concrete mix design. Obtain approval before concrete placement.

Cement

Pozzolan

Ground Granulated Blast-Furnace Slag

Silica Fume

Air-Entraining Admixture

Water-Reducing Admixture

High-Range Water Reducing Admixture

Accelerating Admixture

SECTION 03 45 33 Page 6

Aggregates

Submit test results for aggregates in accordance with ASTM C 1260 for potential alkali-silica reactions.

SD-07 Certificates

Quality control procedures

Submit quality control procedures established in accordance with PCI MNL-116 by the precast manufacturer.

Construction Records; G, ED

Complete construction records of the manufacturing, handling, and erection of the precast concrete units shall be submitted to the Contracting Officer, and shall include inspection and test reports of the precasting operations. The results of concrete strength testing by the Contractor shall be submitted not more than 5 days after the tests are completed.

Air Content; G, RE

Each precast unit delivered to the job site shall be accompanied by a certificate certifying that the air content in the concrete in that unit is in compliance with the specifications. The certification must be based on an air content test conducted in conformance with ASTM C 231 or ASTM C 173/C 173M on at least one of the batches of concrete from which the unit was cast.

SD-11 Closeout Submittals

Concrete batch ticket information

1.6 QUALITY ASSURANCE

1.6.1 Qualifications

1.6.1.1 Manufacturer Qualifications

PCI MNL-116. Plants shall be certified by the PCI Plant Certification Program for Category C4 work. At the Contracting Officer's option, PCI Plant quality control program records shall be available for review.

1.6.1.2 Designer Qualifications

The designer shall be a registered professional engineer in a State or possession of the United States, in Puerto Rico, or the District of Columbia, and experienced in the design of precast prestressed concrete.

1.6.1.3 Erector Qualifications

The erector shall be regularly engaged for at least three years in the erection of precast prestressed structural concrete similar to the requirements of this project.

1.6.1.4 Welding Qualifications

Provide AWS D1.1/D1.1M qualified welders who are currently certified at

SECTION 03 45 33 Page 7 contract award date and have maintained their certificates over the past year.

1.6.2 Regulatory Requirements

Provide precast prestressed members in conformance with ACI 318/318R and

AWS D1.4/D1.4M.

1.6.3 Concrete Mix Design

Thirty days minimum prior to concrete placement, submit a mix design for each strength and type of concrete. Submit a complete list of materials including type; brand; source and amount of cement, fly ash, pozzolans, silica fume, ground slag, and admixtures, and applicable reference specification. Provide mix proportion data using at least three different water-cement ratios for each class and type of concrete required. If source material changes, resubmit mix proportion data using revised source material. No material shall be provided unless proven by trial mix studies to meet the requirements of this specification, unless otherwise approved in writing by the Contracting Officer. The submittal shall clearly indicate where each mix design will be used when more than one mix design is submitted. Submit additional data regarding concrete aggregates if the source of aggregates changes.

1.6.4 Certificates: Record Requirement

ASTM C 94/C 94M. Submit evidence that the proposed supplier's batch ticket meets ASTM C 94/C 94M.

1.7 DELIVERY, STORAGE, AND HANDLING

1.7.1 Transportation

1.7.1.1 Transporting Members

In transporting members by truck, railroad car, or barge, provision shall be made for supporting the members as described above, except battens can be continuous over more than one stack of units, with adequate bracing to ensure their maintaining the vertical position and damping of dangerous vibrations. Trucks with double bolsters are satisfactory provided the members are fully seated on the outer bolsters at not more than 3 feet or the depth of the member from the end and the inner bolster is not more than 8 feet from the end of the member or the designated pickup point. Adequate padding material shall be provided between tie chains or cables to preclude chipping of concrete.

1.7.1.2 Lateral Deflection or Vibration

Any noticeable indication of lateral deflection or vibration during transportation shall be corrected by rigid bracing between members or by means of lateral trussing.

1.7.2 Storage

1.7.2.1 Storage Areas

Storage areas for precast prestressed members shall be stabilized, and suitable foundations shall be provided, so differential settlement or twisting of members will not occur.

SECTION 03 45 33 Page 8

1.7.2.2 Stacked members

Stacked members shall be separated and supported by battens placed across the full width of each bearing point. Battens shall be arranged in vertical planes at a distance not greater than the depth of the member from designated pickup points. Battens shall not be continuous over more than one stack of precast units. Stacking of members shall be such that lifting devices will be accessible and undamaged. The upper members of a stacked tier shall not be used as storage areas for shorter members or equipment.

1.7.3 Handling of Members

The location of pickup points for handling of the members and details of the pickup devices shall be shown in shop drawings. Members shall be handled only by means of approved devices at designated locations. Members shall be maintained in an upright position at all times and picked up and supported as shown in approved shop drawings, except that the skirt and downstream panels may be transported, stored, and lifted in a horizontal position. Shop drawings and design calculations shall be provided to support horizontal positioning .

PART 2 PRODUCTS

2.1 CONTRACTOR-FURNISHED MIX DESIGN

ACI 318/318R. The minimum compressive strength of concrete at 28 days shall be 5000 psi, except the minimum compressive strength of concrete for the Lower Guard Wall Panels shall be7000 psi at 28 days, unless otherwise indicated. Add air-entraining admixtures at the mixer to produce between 4 and 6 percent air by volume. For marine exposure, ensure a dense concrete free of shrinkage cracks, with a minimum degree of permeability. The maximum water cement ratio shall be 0.40 .

2.2 MATERIALS

2.2.1 Cement

ASTM C 150, Type II, low alkali under Table 2, Optional Chemical Requirements and false set requirements in Table 4, Optional Physical Requirements of ASTM C 150 (Type II, FS). If no satisfactory test results are available (made within the past six months) to prove that the cement alkali content is less than 0.60 percent, then it shall be assumed that the cement contains greater than 0.40 percent alkali. Cement certificates shall include test results in accordance with ASTM C 150, including equivalent alkalies indicated in the optional chemical requirements. For exposed concrete, use one manufacturer for each type of cement, ground slag, fly ash, and pozzolan.

2.2.1.1 Pozzolan

ASTM C 618, Class F with the optional requirements for multiple factor, drying shrinkage, and uniformity from Table 3 of ASTM C 618. In addition, the calcium oxide (lime) content shall be restricted to a range of 3 to 8 percent. The Contractor should note that the calcium oxide restriction may preclude the use of flyash that is a by-product of the combustion of coal from western states. If pozzolan is used, it shall never be less than 15 percent nor more than 35 percent by weight of the total cementitious material, except where specified. Pozzolan shall be approved as a

SECTION 03 45 33 Page 9 qualified source in accordance with ER 1110-1-2002. The Contractor shall submit from the producer the information required under Section B-2C. The source shall maintain qualification for the duration of the pozzolan use.

2.2.1.2 Ground Granulated Blast-Furnace Slag

ASTM C 989, Grade 100 or 120.

2.2.1.3 Silica Fume

Silica fume shall conform to ASTM C 1240. The specific uniformity requirements shall conform with Table 3, Optional Physical Requirements of ASTM C 1240. Silica fume shall be furnished in densified form.

The Contractor shall provide at his expense the services of a manufacturer's technical representative, experienced in mixture proportioning, placement procedures, and curing of concrete containing silica fume. The manufacturer's representative shall be available for consultation by both the Contractor and the Government during mixture proportioning, planning, and production of silica-fume concrete and shall be on site immediately prior to and during at least the first placement of concrete containing silica fume and at other times, if directed.

2.2.2 Water

Water shall be fresh, clean, and potable; free from injurious amounts of oils, acids, alkalis, salts, organic materials, or other substances deleterious to concrete, ACI 318/318R.

2.2.3 Aggregates

2.2.3.1 Aggregates Selection

Fine and Coarse aggregates shall meet the requirements of ASTM C 33 except as modified herein and aggregate producers shall be listed in PDT 34. Fine aggreate shall be a natural sand and AASHTO No. 57 and No. 67 coarse aggregate shall be a crushed limestone. Aggregates shall not contain any substance which may be deleteriously reactive with the alkalies in the cement, nor in an amount sufficient to cause excessive expansion of concrete. Prior to fabrication, submit certificates of compliance and test reports for the following tests specified in ASTM C 33,in addition, twice during each shift when the concrete plant is operating, the gradation of the fine aggregate and each size of coarse aggregate shall be tested in accordance with ASTM C 136:

a. Grading

b. Amount of material finer than No. 200 sieve

c. Organic impurities

d. Soundness

e. Clay lumps and friable particles

f. Coal and lignite

g. Weight of slag

SECTION 03 45 33 Page 10

h. Abrasion of coarse aggregate

i. Fineness modulus

j. Reactive aggregates

k. Freezing and thawing

2.2.4 Grout

2.2.4.1 Nonshrink Grout

ASTM C 1107/C 1107M.

2.2.5 Admixtures

2.2.5.1 Air-Entraining

ASTM C 260.

2.2.5.2 Accelerating

ASTM C 494/C 494M, Type C or E.

2.2.5.3 Water Reducing

ASTM C 494/C 494M, Type A, E, or F.

2.2.5.4 High-Range Water Reducing

High-range water-reducing admixture (HRWRA) shall meet the requirements of ASTM C 494/C 494M, Type F, except the 6-month and 1-year strength requirements shall be waived. The admixture may be used only after mixture proportioning studies and when approved. The Contractor shall provide the services of a manufacturer's technical representative experienced in mixture proportioning and placement procedures of concrete containing HRWRA. The technical representative shall be available for consultation during mixture proportioning and shall be on-site for the first placement of concrete containing HRWRA.

2.2.6 Reinforcement

Reinforcement shall conform to the requirements of Sections 03 20 02 STEEL BARS AND WELDED WIRE FABRIC FOR CONCRETE REINFORCEMENT FOR CIVIL WORKS and

03 23 00 STEEL STRESSING TENDONS AND ACCESSORIES FOR PRESTRESSED CONCRETE.

2.2.7 Metal Accessories

Metal accessories shall conform to the requirements of Section 05 50 15

CIVIL WORKS FABRICATIONS.

2.2.8 Grout

2.2.8.1 Cementitious Grout

Shall be a mixture of portland cement, sand, and water. Proportion one part cement to approximately 2.5 parts sand, with the amount of water based on placement method. Provide air entrainment for grout exposed to the weather.

SECTION 03 45 33 Page 11

2.2.8.2 Nonshrink Grout

Nonshrink grout shall conform to ASTM C 1107/C 1107M and shall be a commercial formulation suitable for the application proposed.

2.3 PRODUCTION QUALITY CONTROL PROCEDURES

PCI MNL-116 unless specified otherwise.

2.3.1 Forms

Brace forms to prevent deformation. Forms shall produce a smooth, dense surface. Chamfer exposed edges of columns and beams 3/4 inch, unless otherwise indicated. Provide threaded or snap-off type form ties.

2.3.2 Reinforcement Placement

ACI 318/318R for placement and splicing. Reinforcement may be preassembled before placement in forms. Provide exposed connecting bars, or other approved connection methods, between precast prestressed and cast-in-place construction. Remove any excess mortar that adheres to the exposed connections.

2.3.3 Concrete

2.3.3.1 Concrete Mixing

ASTM C 94/C 94M. Mixing operations shall produce batch-to-batch uniformity of strength, consistency, and appearance.

2.3.3.2 Concrete Placing

ACI 304R, ACI 305R for hot weather concreting , ACI 306.1 for cold weather concreting, and ACI 309R, unless otherwise specified.

2.3.4 Prestressing

Do not transfer prestressing forces during detensioning until the concrete has reached a minimum compressive strength of 3500 psi, unless a higher strength is required by the Contractor furnished design.

2.4 FINISHING

2.4.1 General

Surfaces of precast concrete elements shall be finished as listed below and specified hereunder.

Interior Surface Finish or Surface Adjacent Precast Concrete to Concrete Exterior or Exposed Element Surface Finish Surface Finish

1) Upper Guard Wall Box Beam Smooth (F) Smooth (F)

2) Upper Guard Wall

SECTION 03 45 33 Page 12

Interior Surface Finish or Surface Adjacent Precast Concrete to Concrete Exterior or Exposed Element Surface Finish Surface Finish

Pier Cap N/A Smooth (F)

3) Upper Guard Wall Flow Skirt Smooth (F) Smooth (F)

4) Lower Guard Wall Wall Panels Smooth (F) Smooth (F)

5) Lower Guard Wall Cap Beam Smooth (F) Smooth (F))

6) Lower Guard Wall Pier Enclosure Rough (F) Smooth (F)

U - Unformed Surface Finish F - Formed Surface Finish U/F - Unformed OR Formed Surface Finish

2.4.1.1 Precast Elements

A smooth finish shall be applied where exterior, formed, surfaces of the precast items are exposed. The interior surfaces of precast elements, or surfaces against which concrete will be placed shall have a roughened finish, in order to act compositely with the concrete.

2.4.2 Unformed Surfaces

Finishing of unformed surfaces shall conform to the requirements specified in Section 03 30 00.60 CONCRETE: PLACEMENT REQUIREMENTS, and as further explained hereunder.

2.4.2.1 Smooth Finish

Unformed surfaces shall receive a smooth finish in accordance with Section

03 30 00.60 CONCRETE: PLACEMENT REQUIREMENTS.

2.4.2.2 Roughened Finish

The Contractor shall provide a test panel with at least 4 roughed surfaces textures which shall be reviewed by the Contracting Officer. The Contracting officer shall select the roughened surface finish that will be used. The sample panel shall be preserved throughout the duration of panel fabrication, and shall be used for reference when finishing elements. The tools used to created the approved roughened surface shall be used for all elements. The methods used to create the roughened finish shall consider the characteristics of the concrete which will provide the roughened finish as well as the concrete which will be used as infill against the roughened finish, including but not limited to the maximum size of the aggregate.

The methods shall be designed to optimize the strength of the bond and composite action between the precast unit and the infill concrete.

SECTION 03 45 33 Page 13

2.4.3 Formed Surfaces

Formed surfaces shall conform to the requirements specified in Section 03 30 00.60 CONCRETE: PLACEMENT REQUIREMENTS, and as further explained hereunder. Architectural treatments shall match the texture and color of approved sample panels.

2.4.3.1 Smooth Finish

Forms for smooth surfaces for precast elements which are obtained by the forming shall be in accordance with paragraph Forms.

2.5 CURING AND PROTECTION

Curing of the precast concrete units shall be by methods further specified herein. Membrane-forming curing compounds shall not be used.

2.5.1 Curing with Steam at Atmospheric Pressure

Steam curing shall be under a suitable enclosure to retain the live steam to minimize moisture and heat losses. The enclosure shall allow free circulation of the steam around the sides and top of the beams. Steam jets shall be so positioned so they do not discharge directly on the concrete, forms, or test cylinders. The cycle of steam application shall conform to the following:

2.5.1.1 Curing After Placing and Vibrating

After placing and vibrating, the concrete shall be allowed to attain its initial set before the steam is applied. During the period between placement of the concrete and application of steam, provisions shall be made to prevent surface drying by means of moist covers, or equally effective methods. Membrane curing compounds shall not be permitted.

Application of the steam shall be delayed not less than 2 hours and not more than 10 hours after the time of concrete placement. If the ambient temperature is below 50 degrees F, enough heat shall be applied to maintain the concrete at its placing temperature.

2.5.1.2 Temperature Increase

The ambient temperature within the casting enclosure shall be increased at a rate not to exceed 40 degrees F per hour. Temperature increase shall be as uniform as possible.

2.5.1.3 Temperature Range

The temperature shall be increased until the ambient temperature in the casting enclosure is between 140 and 160 degrees F. Once this temperature range is reached, it shall be maintained until the concrete has reached the compressive strength necessary for handling and transporting the precast unit.

2.5.1.4 Temperature Decrease

In discontinuing the steam curing, the ambient air temperature shall decrease at a rate not to exceed 40 degrees F per hour. Temperature decrease shall be as uniform as possible.

SECTION 03 45 33 Page 14

2.5.1.5 Recording Thermometers

Recording thermometers showing the time-temperature relationship shall be provided through the curing period from placing concrete until a minimum of 8-hours after the enclosure is removed. At least one recording thermometer per casting enclosure shall be used. The desired curing time-temperature relationship shall be placed on the recording chart of the recording thermometer to aid the personnel controlling the temperature during curing. Recording charts shall be made available upon request and shall be clearly visible during the curing process.

2.5.2 Curing with Radiant Heat and Moisture

2.5.2.1 Radiant Heat

Radiant heat may be applied to beds by means of pipe circulating steam, hot oil, or hot water or by electric blankets or heating elements on forms.

Pipes, blankets, or elements shall not be in contact with concrete, form surface, or test cylinders/beams.

2.5.2.2 Moisture Loss

During the cycle of radiant heat curing, effective means shall be provided to prevent rapid loss of moisture in any part of the unit. Moisture may be applied by a covering of moist burlap or cotton matting. Moisture may be retained by covering the unit with a plastic sheet in combination with an insulating cover. Membrane curing compounds shall not be permitted.

2.5.2.3 Temperature Limits

Temperature limits and use of recording thermometer shall be as specified for curing with steam at atmospheric pressure.

2.5.2.4 Termination of Curing

Termination of curing shall be as specified in Section 03 30 00.60 CONCRETE: PLACEMENT REQUIREMENTS unless the concrete has been cured by one of the two methods stated above. Termination of curing for concrete cured by either the steam at atmospheric pressure method or the radiant heat with moisture shall be determined based on the compressive strength of the concrete necessary for handling and transporting the precast units.

2.6 SURFACE REPAIRS

2.6.1 General

All honeycombed areas, chipped corners, air pockets over 1/4 inch in diameter, and other minor defects shall be repaired. Form offsets of fins over 1/8 inch shall be ground smooth. All unsound concrete shall be removed from defective areas prior to repairing. All surfaces permanently exposed to view shall be repaired by a blend of portland cement and white cement properly proportioned so that the final color when cured will be the same as adjacent concrete. Repair methods shall be in accordance with Section 03 30 00.60 CONCRETE: PLACEMENT REQUIREMENTS.

2.6.2 Minor Defects

Minor defects are those which involve less than 36 square inches of concrete and do not expose reinforcing steel. These defects will be

SECTION 03 45 33 Page 15 repaired as specified hereinafter. Cracks which are visible but are 0.01 inch wide or less will be accepted.

2.6.3 Major Defects

Major defects are those which involve more than 36 square inches of concrete or expose reinforcing steel. If one or more major defects appear in a unit, it shall be rejected. Cracks of a width of more than 0.01 inch shall be cause for rejection of the unit.

2.7 TESTS, INSPECTIONS, AND VERIFICATIONS

2.7.1 Factory Inspection

At the option of the Contracting Officer, precast and prestressed units may be inspected by the Contracting Officer precast and prestressed units shall be inspected by the QC Representative prior to being transported to the job site. The Contractor shall give notice 14 days prior to the time the units will be available for plant inspection. Neither the exercise nor waiver of inspection at the plant will affect the Government's right to enforce contractual provisions after units are transported or erected.

PART 3 EXECUTION

3.1 EXAMINATION

Prior to erection, and again after installation, precast and prestressed members shall be checked for damage, such as cracking, spalling, and honeycombing. As directed by the Contracting Officer, precast and prestressed members that do not meet the surface finish requirements specified in Part 2 in paragraph entitled "Surface Finish" shall be repaired, or removed and replaced with new precast or prestressed members.

3.2 ERECTION

Erection of precast elements shall be in accordance with the drawings.

Precast and prestresed members shall be erected after the concrete has attained the specified compressive strength, unless otherwise approved by the precast and prestressing manufacturer. In addition, prestressed members shall not be rigidly fixed in position until the prestressed member has "aged" 90 days after detensioning. Erect in accordance with the approved shop drawings. PCI MNL-116 and PCI MNL-120 (Chapter 8), for tolerances. Provide a 1:500 tolerance, if no tolerance is specified. Brace precast and prestressed members, unless design calculations submitted with the shop drawings indicate bracing is not required. Follow the manufacturer's recommendations for maximum construction loads. Place precast and prestressed members level, plumb, square, and true within tolerances. Align member ends.

3.2.1 Storage Provisions

All provisions for storage and handling as specified shall be observed at the casting yard and at the erection site.

3.2.2 Seating of Precast Concrete Units

The precast concrete units shall be set into place in a manner which assures full bearing. If the bearing called for in the contract drawing is

SECTION 03 45 33 Page 16 not obtained, then the units shall be removed and the situation corrected.

3.2.3 Welding

Welding during erection shall be done in accordance with Section 05 50 14 STRUCTURAL METAL FABRICATIONS. Welding and burning shall not be allowed within 2-feet of concrete where heat may damage the concrete, except where specifically designated on the drawings. When welding or burning with a welding electrode, the ground shall be attached directly to the base metal. Under no circumstances shall the precast concrete unit be used as a conductor for the ground.

3.2.4 Erection Plans

An erection plan shall be submitted. A separate erection plan shall be submitted for all precast items, including separate coverage for erection of precast items for the Upper Guard Wall box beam, flow skirt and cap beams; and the Lower Guard Wall panels, pier enclosures, and cap beams.

These erection plans shall be in sufficient detail so that adequacy of equipment, techniques, and accessories can be determined and comments offered. Acceptance of the Contractor's erection plans shall not relieve the Contractor of his responsibility for erecting precast concrete units into position as required by the plans and specifications.

3.3 BEARING SURFACES

Shall be flat, free of irregularities, and properly sized. Size bearing surfaces to provide for the indicated clearances between the precast and prestressed member and adjacent precast or prestressed members or adjoining field placed surfaces. Correct bearing surface irregularities with nonshrink grout. Provide bearing pads where indicated or required. Place precast and prestressed members at right angles to the bearing surface, unless indicated otherwise, and draw-up tight without forcing or distortion, with sides plumb.

3.4 ANCHORAGE

Provide anchorage for fastening work in place. Conceal fasteners where practicable. Make threaded connections up tight and nick threads to prevent loosening.

3.5 GROUTING

Clean and fill indicated areas, solidly with nonshrink grout or cementitious grout. Provide reinforcing where indicated. Remove excess grout before hardening.

3.6 SEALANTS

Provide as indicated and as specified in Section 07 92 00, "Joint Sealants."

3.7 CONCRETE INFILL

Provide as indicated and as specified in Section 03 37 26.10 CONCRETE:

FLOWABLE.

3.8 SPECIAL REQUIREMENTS FOR MEMBERS TO BE FURNISHED BUT NOT ERECTED

As specified in Sections 35 49 23.23 25 UPPER GUARD WALL and 35 49 23.23 26

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LOWER GUARD WALL, some components of the Upper and Lower Guard Walls are to be furnished and delivered to the designated storage, but are not to be erected. The following special requirements apply only to these members.

a. Reinforcing steel for Lower Guard Wall cap beam CB1 shall be epoxy coated.

b. All exposed metal on the precast items that is to be embedded in cast-in-place concrete after erection shall be painted with a corrosion-resisting alkyd primer and two topcoats of exterior alkyd enamel.

c. Members shall be placed in storage at the designated area at the Upper Guide Wall. The Contractor shall also provide all blocking and protection required to prevent distortion or deterioration of delivered products during anticipated storage period at the delivery site. The Contractor shall meet with the Government representative at the delivery location at least 30 days prior to delivery of products to the site. The Contractor shall submit a delivery work plan addressing the limitations established by the Government and the field visit and briefing. The delivery plan will be reviewed by the Government and the Government reserves the right to revise and/or alter the Contractor's delivery and positioning plan.

3.9 CONSTRUCTION RECORDS

Complete construction records shall be kept of the manufacturing, handling, and erection of the precast-prestressed concrete members. Records shall be kept for, but not limited to, the following items:

a. Specifications of material used in the manufacture of the members.

b. Time-temperature history of the concrete members from casting to the transfer of the prestress force.

c. Records of the tendon stressing operation including initial prestress force, measured elongation, how it was measured, and how the tendons were stressed and destressed.

d. Records of inspection of the members before and after the prestress force is transferred to the members.

e. Records of the inspection of the members each time they are moved.

f. Records of any defects in the member and any corrective measures taken.

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SECTION 03 45 33 Page 18

1.7.3 Handling of Members

2.3.4 Prestressing