B08 - Attachment B - Specifications - Section 03300 - Structural Concrete.pdf

Concrete Repairs at Crab Orchard Dam 03300-1 Structural Concrete October 2020

SECTION 03300

STRUCTURAL CONCRETE

PART 1 GENERAL

1.01 DESCRIPTION

A. The work includes designing mix, furnishing, placing, and curing structural concrete for the rehabilitation of the ogee crest of the Crab Orchard Dam Service Spillway.

1.02 RELATED SECTIONS

A. Section 01300: Submittals

B. Section 03100: Concrete Formwork

C. Section 03200: Concrete Reinforcement

D. Section 03370: Concrete Curing

E. Section 03811: Concrete Removal

1.03 REFERENCES

A. American Association of State Highway and Transportation Officials, AASHTO M 182 Burlap cloth made from Jute or Kenaf.

B. American Concrete Institute:

1. ACI 117; Specifications for Tolerances for Concrete Construction and

Materials and Commentary.

2. ACI 211.1; Standard Practice for Selecting Proportions for Normal, Heavyweight, and Mass Concrete.

3. ACI 221; Guide for Use of Normal Weight and Heavy Weight Aggregates in

Concrete.

4. ACI 301; Specifications for Structural Concrete.

5. ACI 304R; Guide for Measuring; Mixing, Transporting and Placing Concrete.

6. ACI 305R; Hot Weather Concreting.

7. ACI 306R; Cold Weather Concreting.

8. ACI 308R; Guide to Curing Concrete.

9. ACI 311.5; Guide for Concrete Plant Inspection and Testing of Ready-Mixed

Concrete

10. ACI 318; Building Code Requirements for Structural Concrete and

Commentary.

11. ACI 350; Code Requirements for Environmental Engineering Concrete

Structures and Commentary.

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C. American Society for Testing and Materials

1. ASTM C 31; Methods of Making and Curing Concrete Test Specimens in the

Field.

2. ASTM C 33; Specification for Concrete Aggregates.

3. ASTM C 39; Test Method for Compressive Strength of Cylindrical Concrete

Specimens.

4. ASTM C 42; Test Methods of Obtaining and Testing Drilled Cores and Sawed

Beams of Concrete.

5. ASTM C 78; Test Method for Flexural Strength of Concrete (Using Simple

Beam with Third-Point Loading).

6. ASTM C 94; Specification for Ready-Mixed Concrete.

7. ASTM C 114; Standard Test Methods for Chemical Analysis of Hydraulic

Cement.

8. ASTM C 143; Test Method for Slump of Portland Cement Concrete.

9. ASTM C 150; Specification for Portland Cement.

10. ASTM C 171; Specification for Sheet Materials for Curing Concrete.

11. ASTM C 172; Methods of Sampling Freshly Mixed Concrete.

12. ASTM C 173; Test Method for Air Content of Freshly Mixed Concrete by the

Volumetric Method.

13. ASTM C 192; Practice for Making and Curing Concrete Test Specimens in the Laboratory.

14. ASTM C 231; Test Method for Air Content of Freshly Mixed Concrete by the

Pressure Method.

15. ASTM C 260; Specification for Air-Entraining Admixtures for Concrete.

16. ASTM C 295, Guide for Petrographic Examination of Aggregates for

Concrete.

17. ASTM C 330; Specification for Lightweight Aggregate for Structural

Concrete.

18. ASTM C 494; Specification for Chemical Admixtures for Concrete.

19. ASTM C 618; Standard Specification for Coal Fly Ash and Raw or Calcined

Natural Pozzolan for Use in Concrete.

20. ASTM C 989; Standard Specification for Slag Cement for Use in Concrete and Mortars.

21. ASTM D 638; Standard Test Method for Tensile Properties of Plastics.

22. ASTM D 695; Test Method for Compressive Properties of Rigid Plastics.

23. ASTM C 1260; Standard Test Method for Potential Alkali Reactivity of

Aggregates (Mortar-Bar Method).

24. ASTM C 1567; Standard Test Method for Determining the Potential Alkali-

Silica Reactivity of Combinations of Cementitious Materials and Aggregate (Accelerated Mortar-Bar Method).

25. ASTM C1602; Standard Specification for Mixing Water Used in the Production of Hydraulic Cement Concrete.

26. ASTM D 1751; Specification for Preformed Expansion Joint Filler for Concrete Paving and Structural Construction (Nonextruding and Resilient Bituminous Types).

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27. ASTM D 1752; Specification for Preformed Sponge Rubber Cork and Recycled PVC Expansion Joint Fillers for Concrete Paving and Structural Construction.

28. ASTM E 329; Standard Specification for Agencies Engaged in Construction Inspection, Testing, or Special Inspection

D. U.S. Army Corps of Engineers Specifications:

1. U.S. Corps of Engineers CRD-C 572 Specification for Waterstop.

1.04 SUBMITTALS

A. Product Data: Submit manufacturer's descriptive product data and current specifications for the concrete accessories specified herein (admixtures, joint fillers, joint sealants, curing materials, waterstops, etc.). Include installation instructions.

B. Samples: Submit samples of materials being used when requested by the Contracting

Officer’s Representative, including names, sources and descriptions.

C. Certifications and test reports:

1. Cementitious materials manufacturer

2. Aggregate producer for:

a. ASTM C33 physical properties

b. ASR testing reports for each aggregate source, ASTM C 1260.

D. Design Mix: In accordance with applicable provisions of ACI 301. Include mix design provisions for pumping concrete, if applicable to Contractor's proposed means and methods for construction.

E. Test Reports: Submit concrete rest reports specified in Part 3 in this Specification.

F. Certificates: Furnish the Contracting Officer’s Representative and local authorities requiring same, certificates originated by the batch mixing plant certifying ready mixed concrete, as manufactured and delivered, to be in conformance with ASTM C 94.

G. Structural concrete placement schedule, including placement of all joints.

H. Independent Testing Laboratory: Prior to proceeding with testing, submit name and experience qualifications of the proposed Independent Testing Laboratory for approval. Include certificate documenting compliance with ASTM E 329 for laboratory, laboratory personnel, and field testing and inspection personnel.

I. Qualification of the Contractor’s Personnel: Submit experience qualifications of the person or persons designated to be responsible for Quality Control Sampling and Testing.

J. Waterstops: Submit product data for waterstops to be used by the Contractor.

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1.05 QUALITY ASSURANCE

A. Quality Control Testing Responsibilities:

1. The Contractor shall perform Quality Control Testing for each stage of work.

This includes testing as required in Article 3.08, Field Quality Control.

Contracting Officer’s Representative may, at any time, inspect any of the Contractor's Quality Control operations and perform such independent or supplemental tests as he believes necessary to corroborate or check results reported by the Contractor. Furnish equipment and personnel as necessary to secure samples for Quality Assurance Testing by Contracting Officer’s Representative. Quality Assurance Testing performed by Contracting Officer’s Representative does not relieve the Contractor of his responsibility for performing all of the quality control tests and inspections.

2. Independent Testing Laboratory: Quality control testing assigned as the responsibility of the Contractor shall be performed by a qualified approved independent testing laboratory. The independent testing laboratory shall be regularly engaged in performing work conforming to The American Society for Testing and Materials ASTM E 329, Recommended Practice for Inspection and Testing Agencies for Concrete and Steel in Construction. The Contractor shall submit detailed documentation adequately demonstrating that the laboratory meets these criteria. Contracting Officer’s Representative reserves the right to perform on-site inspections of the independent testing laboratory in advance of approval and at any time during the duration of this Contract to verify compliance with testing standards. Additionally, the independent laboratory testing must be performed under the general supervision of a Registered Professional Engineer.

B. Qualifications of Contractor's Personnel Responsible for Quality Control Sampling and Testing: The Contractor shall submit for approval the qualifications of the person or persons designated to be responsible for the Quality Control Sampling and Testing.

Submittals shall include resumes and other documentation adequately demonstrating their experience in performing similar work. Approval of personnel will be based on documentation adequately demonstrating that minimum qualification requirements are met. The Contracting Officer’s Representative reserves the right to reject any personnel not deemed to be fully qualified for the work. Minimum qualifications for personnel responsible for the sampling and testing are as follows:

1. Experience shall include testing and construction observation performed in connection with reinforced concrete construction. Field technicians responsible for testing shall have current certification as ACI Concrete Field Testing Technician – Grade I.

2. A minimum of one full-time quality control person shall be supplied by the Contractor for each concrete placement activity. This person shall have prior experience in the work task for which he is responsible and shall be approved by the Contracting Officer’s Representative. Work within that activity shall not be carried out without his presence on the site.

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C. Source Quality Control:

1. Laboratory Tests: Materials stated herein require advance examination or testing according to methods referenced, or as required by the Contracting Officer’s Representative.

2. Compression Test Cylinders: For laboratory trial batches, make in accordance with American Concrete Institute ACI 301. Test to consist of six compression test cylinders for each class of concrete with two broken at seven days, two broken at 28 days and two spares (if testing at 56 days is required); ASTM C 192 and ASTM C 39.

D. Waterstop Field Splices:

1. Both field and factory-formed splicing shall be done in accordance with the waterstop manufacturer’s specifications and recommendations.

2. Only straight butt joint splices will be allowed in the field. No other types of field splices are permitted.

3. Prior to installing any waterstops in the permanent work, the Contractor shall provide to the Government in writing the name(s) of employees designated to perform field splices. The designated Contractor’s employee(s) shall be trained at the jobsite by a qualified representative of the waterstop manufacturer in the proper method of performing field splices. Upon completion of the training, each designated Contractor employee(s) shall demonstrate in the presence of the Contracting Officer’s Representative and waterstop manufacturer the ability to complete at least two straight butt joint field splices of each size and type of finished waterstop in accordance with the manufacturer’s specifications and recommendations. Upon successful completion of the training, waterstop manufacturer shall certify that each designated Contractor employee(s) has been trained and that they have demonstrated sufficient competency to perform field splices in accordance with the manufacturer’s specifications and recommendations.

4. This training shall be provided at no additional cost to the Government as described in Article 1.06 B. in this Section.

5. Only Contractor employee(s) trained and certified by the waterstop manufacturer are permitted to perform field splicing in the permanent work.

6. Waterstop splicing defects that are unacceptable include, but are not limited to the following:

a. Tensile strength less than 80 percent of parent section.

b. Free lap joints.

c. Misalignment of center bulb, ribs, and end bulbs greater than 1/16 inch.

d. Misalignment that reduces waterstop cross section more than 15 percent.

e. Bond failure at joint deeper than 1/16 inch or 15 percent of material thickness.

f. Misalignment of waterstop splice resulting in misalignment of waterstop in excess of 1/2 inch in 10 feet.

g. Visible porosity in the weld area, including pin holes.

h. Charred or burnt material.

i. Bubbles or inadequate bonding.

j. Visible signs of splice separation when cooled splice is bent by hand at a sharp angle.

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1.06 PROJECT CONDITONS

A. ACI Compliance: Cast-in-place concrete work shall conform to ACI 301 except as modified by these Specifications or the Drawings.

B. Waterstop Manufacturer Representative Site Visit. All Work associated with the manufacturer’s visits to the site to provide field splice training and certification or for any other reason will not be measured for payment. All costs associated with the manufacturer’s visit to the site shall be included in the various Bid Items that include placement of concrete with waterstop, and no separate payment will be made.

PART 2 PRODUCTS

2.01 CONCRETE MATERIALS

A. Cement: ASTM C 150, Portland Type II, or approved equivalent; gray color.

1. Meet equivalent alkalies requirements of ASTM C150 – Table 2.

2. Meet false-set requirements of ASTM C150 – Table 4.

B. Fine and Coarse Aggregates: ASTM C 33.

1. Coarse aggregate shall be ASTM C 33, Size No. 57, maximum 3/4-inch particle size.

2. Fine and coarse aggregate shall not be of a carbonate-based rock.

3. Testing for Alkali-Aggregate Reactivity: Aggregates from each source proposed for use in concrete shall be tested for susceptibility to alkali-aggregate reaction in accordance with the following procedures.

a. Perform a petrographic analysis in accordance with ASTM C 295. The analysis shall be performed by a petrographer experienced in identifying reactive constituents in aggregates. The analysis shall indicate rock type, mineralogical constituents, physical and chemical characteristics of the materials which have a bearing on the performance of the aggregate when it is used as concrete aggregate; particularly the identification of any potentially alkali-aggregate reactive constituents. Not more than one analysis is required for each aggregate source provided the parent rock type is the same, and the material is being mined from the same geologic formation and from the same approximate location within a single quarry.

b. Test the aggregate source(s) in accordance with ASTM C 1260. Aggregates tested in accordance with ASTM C 1260 shall be considered potentially reactive if expansion exceeds 0.10% at 16 days after casting.

c. Aggregates that are shown to be potentially reactive based on testing in accordance with ASTM C 1260 shall not be used without additional testing in accordance with procedures in ASTM C 1567 using the proposed cementitious material(s). If expansion exceeds 0.10% at 16 days after casting when the aggregate(s) are tested in accordance with ASTM C 1567 using the proposed blend of cementitious materials, the aggregates shall not be used.

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d. Aggregate sources that are shown to be susceptible to alkali-carbonate reactivity (ACR) based on testing performed for this project, based on prior field performance, or based on prior testing shall not be used in any concrete mixes.

C. Water:

1. Clean and free from injurious amounts of oils, acids, alkalis, salts, organic materials, or other substances that may be deleterious to concrete or reinforcement.

2. Meeting all requirements of ASTM C 94.

2.02 ADMIXTURES

A. Air Entrainment: ASTM C 260.

B. Chemical Admixture:

1. Do not use chemical admixtures which contain more than 0.1 percent chloride, by weight.

2. Admixtures shall be compatible with each other.

3. Allowable chemical admixtures:

a. ASTM C 494, Type A, D, F, G, or S.

b. ASTM C1017, Type I or II.

c. ASTM C494, Type C and E, provided they do not contain chloride.

C. Hydration Control: MasterSet, as manufactured by Master Builders Solutions, or approved equal.

D. Specialized chemical admixtures

1. If the Contractor has not previously used a specialized chemical admixture, admixture manufacturer shall provide on-site representative to assist with mix design and to trial batch plant personnel in dispensing and mixing operations.

2. Chemical and Drying Shrinkage Reducing Admixture

a. PREVent-C manufactured by Premier Magnesia, Construction Products

Group. www.premiercpg.com, or approved equal with the following essential characteristics:

i. Designed to facilitate expansion of concrete at essentially the same rate as shrinkage during curing period.

ii. Designed to reduce capillary surface tension of pore water.

iii. Provides at least 60% shrinkage reduction.

iv. Formulated for use in freezing weather.

v. Mortar and concrete under restrained shrinkage test, ASTM C1581:

No cracking for a minimum 90 days.

b. Coordinate with manufacturer regarding dosage.

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2.03 STRUCTURAL CONCRETE MIX

A. Mix concrete in accordance with ASTM C 94.

B. Provide structural concrete with the following characteristics:

1. Minimum compressive strength (28 days): 4,500 psi

2. Slump: 3 inches, ± 1 inch

3. Maximum water-cement ratio: 0.45

4. ¾-inch maximum aggregate size (ASTM C 33, #67)

5. Air Content: 5 to 8 percent.

C. Submit design mixes for concrete substantiated by either laboratory trial batch or field performance methods as specified in ACI 301. For the trial batch method, mix must be proportioned and stamped by a Professional Engineer. Concrete trial mixes:

1. Average compressive strength of trial batch cylinders at design stage: Design strength plus 1,200 psi for concrete between 3,000 and 5,000 psi.

2. Admixtures to be used in mix shall be incorporated into mix design submitted for approval.

3. Air content: within 1% of top of specified range.

4. Slump: Within 1 inch of top of specified range.

D. Use accelerating admixtures in cold weather only when approved by the Contracting Officer's Representative. Use of admixtures will not relax cold weather placement requirements.

E. Use set-retarding admixtures during hot weather only when approved by the

Contracting Officer's Representative.

F. Add air-entraining agent to concrete mix for all concrete work, in accordance with Table 4.2.2.4 of ACI 301, Manual of Concrete Practice. All exposures shall be considered “Severe”.

G. Concrete mix shall meet all specified requirements. Failure to meet any one specified requirement shall be sufficient cause for rejection.

2.04 RETROFIT WATERSTOPS

A. Retrofit waterstops shall be manufactured from virgin polyvinylchloride and shall meet or exceed all requirements set forth in the U.S. Army Corps of Engineers Specification CRD C 572.

B. All retrofit waterstops shall be of polyvinylchloride extruded from an elastomeric plastic compound of which the basis resin shall be polyvinylchloride. The compound shall contain any additional resins, plasticizers, stabilizers, or other materials needed to ensure qualities which will meet the requirements herein specified.

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C. The required minimum physical characteristics for this material are:

1. Tensile strength: 2,000 psi

2. Ultimate elongation: no less than 300%

D. No reclaimed materials shall be used for manufacture of the waterstops.

E. Products:

1. Model 667 by Greenstreak.

2. Or approved equal.

2.05 VINYL WATERSTOPS

A. Vinyl waterstops shall be manufactured from virgin polyvinyl chloride plastic compound conforming to the U.S. Army Corps of Engineers Specifications CRD C 572.

B. 9-inch Ribbed Waterstop: 9 x 3/8-inch with center bulb of 1-1/2-inch outside diameter and 7/8-inch inside diameter, such as Sika Greenstreak 696, or approved equal.

2.06 SURFACE APPLIED WATERSTOPS

A. A specially formulated joint sealant which swells upon contact with water. Provide waterstop packaged in continuous length coils. Material composition as follows:

1. Chloroprene rubber and chloroprene rubber modified to impart hydrophilic properties.

2. Waterstop shall have a coating formulated to inhibit initial expansion due to moisture presence in the fresh concrete.

3. Size: Dual extrusion design; 10 mm by 20 mm.

4. Waterstop shall be secured to hardened concrete with the waterstop manufacturer’s standard adhesive binder.

5. Acceptable Manufacturers:

a. Greenstreak: Hydrotite

b. ADEKA; Ultraseal

c. Or approved equal.

2.07 JOINT TREATMENT AT TOP OF OGEE

A. Contractor shall size insert diameter as appropriate for the approved waterstop bulb opening. Insert material may be a lubricated steel rod, flexible hose, or other methods as approved by the Engineer.

B. Sealant shall be a two component, self-leveling, polyurethane elastomeric sealant, SIKAFLEX-2C SL or approved equal.

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PART 3 EXECUTION

3.01 GENERAL

A. Place concrete in general conformance with ACI 301, ACI 304.2R, and ACI 314.2R.

3.02 INSPECTION

A. Verify that anchors, dowels, seats, plates, reinforcement, and other items to be cast into concrete are accurately placed, held securely, and will not cause hardship in placing concrete.

B. Verify lines, levels, and measurements before proceeding with formwork.

3.03 PREPARATION

A. All construction joints and existing concrete surfaces against or over which new concrete is to be placed shall be cleaned, roughened, and all laitance removed in preparation for placing adjoining concrete. Methods of roughening surfaces and removing laitance may include mechanical abrasion or cutting, sandblasting, or high-pressure water jetting of hardened (not green) concrete. Water jetting will normally be at pressures of at least 6,000 pounds per square inch. All methods are subject to the approval of the Contracting Officer's Representative. Construction joints shall be thoroughly cleaned of loose or defective concrete, coatings, sand, curing compound, and other foreign material on the surface.

B. After initial cleanup, and at the last opportunity prior to placing concrete, the surfaces shall be uniformly surface dried.

3.04 EMBEDDED ITEMS

A. Retrofit Waterstops

1. The location of the retrofit waterstops shall be indicated on the Drawings.

2. The existing concrete surface to which the waterstop will be attached shall be a smooth surface and cleaned to make sure epoxy can have the best adhesion and seal.

3. Apply a layer of epoxy to the existing concrete surface per manufacturer’s instructions.

4. Place the retrofit waterstop into the uncured epoxy, securing the waterstop with stainless steel batten bars and anchor bolts. Fasten one site at a time, making sure the waterstop profile is positioned to eliminate any air pockets or voids between the waterstop and existing concrete.

5. Butt splicing should be accomplished by thermally splicing the free ends of the waterstops together prior to attachment to the existing concrete per the manufacturer’s recommendations.

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B. Vinyl Waterstops

1. Install in all joints where watertightness is required, and at locations indicated in the Contract Documents, to form a continuous watertight diaphragm in each joint or series of interconnected joints.

2. Use continuous lengths without splices to the extent possible to minimize the number of field splices.

3. Connect all adjoining waterstops including vertical and horizontal runs to provide a continuous water barrier.

4. Adequately support waterstops in accordance with manufacturer’s recommendations to prevent displacement and deformity of the waterstops during concrete pours. Maintain two-inches minimum clearance between waterstop and reinforcing steel.

5. Provide a smooth surface beneath the water stop.

C. Surface Applied Waterstops

1. Install at locations indicated on the Drawings.

2. Install in strict accordance with manufacturer’s installation instructions.

3. Use continuous lengths without splices to the extent possible to minimize the number of field splices.

D. Joint Treatment at Top of Ogee

1. Install 9” PVC waterstop and insert prior to concrete placement.

2. After concrete has cured, remove entire insert. Ream out insert by drilling methods if necessary.

3. Clean and prime the hole left by removal of the insert in accordance with the sealant manufacturer’s recommendations.

4. Insert backer rod plug into the top of the 9” pvc waterstop bulb, set plug 3-inches minimum below the top of the 9” pvc waterstop to create an overlap with the sealant.

5. Apply sealant within the hole in accordance with the manufacturer’s recommendations.

E. Anchoring Reinforcement Dowels into Existing Concrete:

1. Drill holes for each dowel to the size and depth indicated on the Drawings with carbide tip bit or star bit. Core drilling will not be permitted. Do not drill into or cut or otherwise damage existing reinforcement bars. If existing reinforcement bars are encountered during the drilling operation, relocate the hole to clear the existing reinforcement as directed by Contracting Officer’s Representative.

2. Blow clean each finished hole with an oil free air jet and then flush with a jet of clean water.

3. Immediately prior to the epoxy adhesive grouting operation, remove all water from the hole and from the walls of the hole.

4. Mix and place the epoxy adhesive completely around the dowel bar in strict accordance with the manufacturer's recommendations, with particular attention given to manufacturer's specified time limit within which the material must be placed after mixing. Do not retemper epoxy adhesive grout that has begun to stiffen; discard such material.

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3.05 CONCRETE DELIVERY TIME LIMIT

A. The Contractor shall have the capability to deliver the structural concrete to the site within 90 minutes from the time water is added into the concrete mix at the batching plant.

3.06 PLACING CONCRETE

A. Notify Contracting Officer’s Representative at least 24 hours before placing concrete.

B. Do no place concrete without approval of the Contracting Officer’s Representative.

C. Place concrete in presence of Contracting Officer’s Representative.

D. Placing concrete shall be performed under direct supervision of a Craftsman certified as ACI Concrete Flatwork Finisher.

E. Concrete shall not be placed when the ambient temperature drops below 40°F until provisions and procedures for cold weather concreting are implemented. During periods of cold weather, as defined by ACI 306.1, the Contractor will only be allowed to place concrete in accordance with the approved cold-weather placement plan.

Concrete may not be placed during heavy rain (more than 0.3 inch per hour or 0.03 inch in 6 minutes as defined by the Weather Bureau Glossary of Meteorology). If unusual adverse weather such as heavy rain, severe cold, heavy snow, etc. occurs, or is forecast to occur during placement, an interruption in placing operations may be approved or directed. All placed concrete materials shall be fully consolidated prior to stopping work. The Contractor should allow for any construction schedule risk and added expense that could occur as a result of adverse weather, and shall receive no additional compensation because of weather delays.

F. Concrete temperature at the time of placement shall be between 50°F and 70°F.

Concrete which does not meet this temperature requirement shall be rejected.

Rejected concrete shall not be paid for.

G. Preparation

1. Prepare formwork in advance and remove debris from within forms.

2. Pre-position reinforcement in advance of concrete pours.

3. Pre-position waterstops, expansion joint material, anchors, and embedded items in advance of concrete pours.

H. Conveying

1. Handle concrete from mixer to final deposit rapidly by methods which will prevent segregation or loss of ingredients to maintain required quality of concrete.

2. Do not convey concrete through aluminum or aluminum alloy.

3. Do not place concrete by pumps or other similar devices without prior written approval of Contracting Officer’s Representative.

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4. Placing concrete by pumping methods shall conform to the applicable requirements of ACI 304R, Chapter 9, and ACI 304.2R.

5. Concrete shall be placed within 1-1/2 hours of introduction of water to the cement and aggregates at the batching plant. Do not add water to the concrete mix at the site.

I. Depositing

1. Do not drop concrete freely where reinforcing will cause segregation, nor more than four (4) feet.

2. Deposit and consolidate concrete in approximately horizontal layers of 12 to 18 inches.

3. Do not allow concrete to flow laterally more than three feet.

4. Place concrete at such a rate that concrete which is being integrated with fresh concrete is still plastic.

5. Do not deposit concrete on concrete which has hardened sufficiently to cause the formation of seams or planes of weakness within sections.

6. Do not use concrete which has partially hardened or has been contaminated by foreign materials.

7. Do not subject concrete to procedures which will cause segregation.

8. Do not place concrete in forms containing standing water.

9. Make placement within sections continuously to produce monolithic unit.

10. Do not bend reinforcement out of position when placing concrete.

11. Ensure that reinforcement, inserts, embedded parts, and formed joints are not disturbed during concrete placement.

12. Maintain concrete cover around reinforcing as indicated on the Drawings and in accordance with ACI 318.

13. Excessive honeycomb or embedded debris in concrete is not acceptable. Notify the Contracting Officer's Representative immediately upon discovery of honeycombs or embedded debris in the concrete.

14. Allow at least 7 days between adjacent placements, or as approved by the Contracting Officer’s Representative or designated Government Representative.

J. Consolidation

1. Care should be taken to use proper vibration methods. Immersion-type vibrators should be used if there is suitable access. If not, this type of vibrator can sometimes be effectively used on the outside of the forms for smaller repairs.

Form vibrators should also be considered. Form vibrators can be used to good advantage on forms for large inaccessible repairs, especially on a one-piece back form, or they can be attached to large metal fittings such as hinge base castings. If self-consolidating concrete is used, vibration is likely not needed or advised.

2. Vibrate concrete until concrete has been consolidated to maximum practical density, is free from pockets of coarse aggregate, and closes snugly against surfaces of forms and embedded materials.

3. Use vibration equipment of internal type and not the type attached to forms and reinforcement.

4. Use vibrators capable of transmitting vibration to concrete in frequencies sufficient to provide satisfactory consolidation.

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5. Do not leave vibrators in one spot long enough to cause segregation. Remove concrete segregated by vibrator operation.

6. Do not use vibrators to spread concrete.

7. Have sufficient reserve vibration equipment to guard against shutdown of work occasioned by failure of equipment in operation.

3.07 FINISHING

A. Notify the Contracting Officer’s Representative before finishing concrete.

B. Finish the concrete in the presence of the Contracting Officer’s Representative unless inspection is waived by the Contracting Officer’s Representative.

C. Ogee Crest: "Floated" Finish: After concrete has been placed, consolidated, struck off and leveled, do not work further until ready for floating. Begin floating when water sheen/bleed water has disappeared and when the surface has stiffened sufficiently to permit the operation. During or after first floating, check planeness of surface with a ten foot straightedge applied at not less than two different angles. Cut down high spots and fill low spots during this procedure to produce a surface with true planes within 1/4 inch in ten feet as determined by a ten foot straightedge placed anywhere on the slab in any direction. Following straightedge checking, refloat slab immediately to a uniform sandy texture.

D. Do not use dry Portland Cement or additional water during finishing.

3.08 FIELD QUALITY CONTROL

A. Testing and Inspection:

1. During the entire period when concrete is being placed, provide testing services by an independent testing laboratory at no cost to the Government.

2. The Contracting Officer’s Representative reserves the right to make any and all tests as he deems necessary during the progress of the Work.

3. Failure of the independent testing laboratory or the Contracting Officer’s

Representative to detect defective work will not prevent rejection when defect is later discovered, nor will it obligate the Contracting Officer’s Representative for final acceptance.

4. The Independent Testing Laboratory shall:

a. Obtain composite samples at random during the progress of the Work in conformity with ASTM C 172.

b. Mold and standard-cure six test specimens for each strength test in accordance with ASTM C 31 and as follows:

i. Concrete compression test: Use standard 6 inch x 12 inch cylinders.

ii. Concrete flexural strength: Use 6 inch x 6 inch x 12 inch beams.

iii. Identify each test by number, mix, amount of admixture, origin of sample in the structure, the date the test specimen was made, the date the test specimen was tested, the amount of slump determined, and the compressive and flexural strength test results.

iv. Test Methods:

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1) Compressive strength test: ASTM C 39.

2) Flexural strength test: ASTM C 78

3) Test two specimens at 7 days for information. Test two specimens at 28 days for acceptance. A strength test is the average of the strengths of the two cylinder specimens cast at the same time from a concrete sample taken from a single truck load tested at 28 days.

4) Hold two field control cylinder specimens of each set for testing (56-day) if low breaks are encountered.

5) At a minimum, perform one strength test for each 50 cu. yds. of concrete poured, but not less than one strength test for each structure. Not less than one set of cylinder specimens shall be taken on any one day.

c. At a minimum, perform one strength test for each 50 cu. yds. of concrete poured, but not less than one strength test for each structure. Not less than one set of cylinder specimens shall be taken on any one day.

d. Make slump tests for each truck load upon truck arrival at the job-site and whenever consistency of concrete appears to vary in accordance with

ASTM C 143.

i. If slump exceeds the maximum values specified in this Section and the batched water-cement ratio exceeds the approved mix design water-cement ratio, the concrete shall be rejected.

ii. If slump is less than the desired value at first discharge from the mixing drum, water may be added, but only up to the maximum water specified or approved water-cement ratio, to increase the slump to within the specified limits; water shall be incorporated into the mixture by further mixing equal to at least one-half the number of mix revolutions for normal mixing. Further addition of water is prohibited.

e. Make air content tests for each truck load upon truck arrival at the job-site in accordance with ASTM C 231 or ASTM C 173.

i. If the air content falls outside of the limits specified in this Section, the concrete shall be rejected.

f. Determine temperature of concrete sample for every truck-load.

g. Upon delivery to the independent testing laboratory, moist-cure cylinder specimens in accordance with ASTM C 31.

h. Prepare and submit all reports required in the various standards and specifications referenced herein.

i. Distribution of reports shall be:

1) Two copies to the Contracting Officer’s Representative.

2) One or more copies, as required, to the Contractor.

i. The Contractor shall require that the Independent Testing Laboratory immediately notify the Contractor and the Contracting Officer’s Representative of any test results which do not conform to the Specification requirements.

5. All cylinder specimen strength tests and any additional cylinder tests due to defective concrete shall be performed at the Contractor’s expense.

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B. Evaluation of Concrete Compressive Strength:

1. Test results for standard molded and standard cured test cylinder specimens shall be evaluated separately for each specified concrete mix design.

2. Concrete strength will be considered satisfactory if every arithmetic average of any three consecutive strength tests equals or exceeds the specified 28-day strength and no individual strength test falls below specified 28-day strength by more than 500 psi.

3. If the concrete fails to meet the specified strength requirements submit a remediation plan to the Contracting Officer’s Representative for approval which shall include, at a minimum, one or more of the following:

a. Submit a revised mix design to increase the strength of the remaining project concrete to be placed.

b. Perform tests on the in-place concrete. Such testing shall be performed by the

Contractor at no increase in Contract price.

i. Testing shall be performed in accordance with ACI 301.

ii. Testing by impact hammer, sonoscope, or other nondestructive device may be permitted by Contracting Officer’s Representative to determine relative strengths at various locations in the structure as an aid in reevaluating concrete strength in place or for selecting areas to be cored.

Such tests shall not be used as a basis for acceptance or rejections.

iii. Core Tests

1) Where required, cores shall be obtained and tested in accordance with ASTM C 42. If the concrete in the structure will be dry under service conditions, the cores shall be air dried (temperature 60 to 80 degrees F, relative humidity less than 60 percent) for 7 days before test and shall be tested dry. If the concrete in the structure will be more than superficially wet under service conditions, the cores shall be tested after moisture conditioning in accordance with

ASTM C 42.

2) At least three representative cores shall be taken from each member or area of concrete in place that is considered potentially deficient. The location of cores shall be subject to approval by the Contracting Officer’s Representative. If, before testing, one or more of the cores shows evidence of having been damaged subsequent to or during removal from the structure, it shall be replaced.

3) Concrete in the area represented by a core test will be considered adequate if the average strength of the cores is equal to at least 85 percent of, and if no single core is less than 75 percent of, the specified strength f’c.

4) Core holes shall be filled in accordance with the approved remediation plan.

iv. The Contracting Officer’s Representative may require removal and replacement of any and all concrete not meeting the compressive strength acceptance criteria. Any removal and replacement due to low compressive strength test results shall be performed by the Contractor at no increase in Contract price.

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3.09 ACCEPTANCE OF STRUCTURE

A. General

1. Completed concrete work which meets all applicable requirements will be accepted without qualification.

2. Completed concrete work which fails to meet one or more requirements but which has been repaired to bring it into compliance will be accepted without qualification.

3. Completed concrete work which fails to meet one or more requirements, and which cannot be brought into compliance, may be accepted or rejected as provided in this Specification.

B. Concrete Compressive Strength: The 28 day compressive strength test results will be used as basis of acceptance of concrete with respect to strength requirements and as a minimum criteria for measuring concrete for payment. If the concrete fails to meet the compressive strength requirements, additional curing as specified by Contracting Officer’s Representative may be required and modifications, including removal and replacement of low-strength concrete and change in the concrete mix design, may be required for the remaining concrete work, all at the expense of the Contractor.

C. Dimensional Tolerances:

1. Dimensional tolerances shall be in accordance with the requirements in

ACI 117-10. Dimensional tolerance requirements shall be applied to the work of this contract in accordance with Table A.

2. Formed surfaces resulting in concrete outlines smaller than required by an amount exceeding the requirements stated above shall be considered deficient in strength and subject to the provisions of Article 3.10 in this Section.

3. Formed surfaces resulting in concrete outlined larger than required, by an amount exceeding the requirements stated above may be rejected and the excess material shall be subject to removal. If removal of the excess material is permitted, it shall be accomplished in such a manner as to maintain the strength of the section and to meet all other applicable requirements of function and appearance.

4. Concrete members cast in the wrong location may be rejected if the strength, appearance or function of the structure is adversely affected or the misplaced items interfere with other construction.

5. Inaccurately formed concrete surfaces exceeding the requirements stated above and which are exposed to view may be rejected and shall be repaired or removed and replaced if required.

6. Finished flatwork exceeding the allowable tolerances may be repaired provided that strength or appearance is not adversely affected. High spots may be removed with a terrazzo grinder, low spots filled in with an approved patching compound, or other remedial measure performed as permitted.

TABLE A: APPLICATION OF STRUCTURAL TOLERANCES

Feature ACI 117-10 Reference Section

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Spillway Slabs 4.2.1, 4.4.1, 4.4.3, 4.4.5, 4.5.3, 4.5.4, 4.6.1, 10.1.1, 10.1.2, 10.2.1, 10.2.2, 10.2.3, 10.3.1, 10.4.1.1, 10.4.1.2

Hydraulic Control Weirs 4.2.1, 4.7.1, 4.8.1, 8.3.2, 10.1.1, 10.1.2, 10.2.1, 10.2.2, 10.2.3, 10.3.1, 10.4.1.1, 10.4.1.2 - End Sill

- Spillway Crest

D. Appearances:

1. Concrete exposed to view with defects which adversely affect the appearance of the specified finish may be repaired, if possible. If, in the opinion of the Government, the defect cannot be repaired, the concrete may be accepted or rejected as provided in these specifications.

E. Strength of Structure – Potential Deficiency:

1. The strength of the structure in place will be considered potentially deficient if it fails to comply with any requirements which control the strength of the structure, including but not necessarily limited to the following conditions:

a. Low concrete strength.

b. Reinforcing steel size, quantity, strength, position, or arrangement at variance with the requirements of the contract documents.

c. Concrete which differs from the required dimensions or location in such a manner as to reduce the strength.

d. Curing less than that specified.

e. Inadequate protection of concrete from extremes of temperature during early stages of hardening and strength development.

f. Mechanical injury, construction fires, accidents or premature removal of formwork likely to result in deficient strength.

g. Poor workmanship likely to result in deficient strength. Structural analysis and/or additional testing may be required when the strength of the structure is considered potentially deficient.

2. Core tests may be required when the strength of the concrete in place is considered potentially deficient.

F. Failure to Meet Requirements:

1. The Government and Contracting Officer’s Representative reserve the right to reject any or all items which do not meet the requirements of the Contract Documents. The Contractor will replace these items covering all expenses in connection with such replacements.

2. If strength tests of concrete fail to meet the minimum requirements as specified herein, the concrete represented by such tests shall be considered questionable and shall be subject to further testing at the expense of the Contractor.

3. Additional tests of the hardened concrete may be required by the Government and/or Contracting Officer’s Representative if in their opinion there is cause for concern over the adequacy of the structure regardless of the results of Contractor Quality Control Testing. If the Contractor’s quality control testing meets all other requirements of this specification, the Contractor shall not be required to bear the

Concrete Repairs at Crab Orchard Dam 03300-19 Structural Concrete costs of such additional tests unless results confirm the concrete in place is deficient.

4. If core tests fail to demonstrate strengths adequate for the intended purpose of the member or members in question, as determined by the Government and/or Contracting Officer’s Representative, or are inconclusive or impractical to obtain or if structural analysis does not confirm the safety of the structure, load tests may be required and their results evaluated in accordance with Chapter 20 of “Building Code Requirements for Structural Concrete” (ACI 318).

5. If the structural members are accepted on the basis of tests other than the original cylinder tests, the Contractor shall compensate the Government for the Contractor’s failure to meet specified strength requirements by deducting from the Contract price an amount equal to one hundred ($100) dollars per cubic yard for each one hundred pounds per square inch (100 psi) below the specified strength.

The original laboratory cured 28-day test cylinder results shall be used to determine the difference between specified and furnished strengths.

6. Concrete work judged inadequate by Contracting Officer’s Representative and/or the Government based on structural analysis or by results of a load test shall be reinforced with additional construction if so directed by Contracting Officer’s Representative and the Government or shall be replaced, at the Contractor’s expense.

7. Unless indicated otherwise in this Article, the Contractor shall pay all costs incurred in providing the additional testing and/or analysis required by this Section.

3.10 REPAIR OF DEFECTIVE CONCRETE

A. Notify Contracting Officer's Representative immediately upon removal of forms.

B. Defective Concrete:

i. Porous areas, open or porous construction joints and honeycombed concrete will be considered to indicate that the requirements for mixing, placing and handling have not been complied with and will be sufficient cause for rejection of the members of the structure thus affected.

ii. Defective work exposed upon removal of forms shall be entirely removed or repaired within forty-eight hours after forms have been removed.

iii. Repaired areas will not be accepted if:

a. The structural requirements have been impaired by reducing the net section of compression members.

b. The bond between the steel and concrete has been reduced.

c. The area is not finished to conform in every respect to the texture, contour, and color of the surrounding concrete.

iv. If the above requirements are not satisfied or if there are excessive honeycombs or other defects, the Contracting Officer’s Representative may require that the members of unit involved be entirely removed and satisfactorily replaced at no additional expense to the Government.

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v. The Contracting Officer’s Representative will determine the extent and manner of action to be taken for the correction of defective concrete as may be revealed by surface defects or otherwise.

a. Prior to repair of structural defects or defects which impair watertightness, including but not limited to shrinkage cracks, use of improper form ties, etc., submit proposed material and repair methods to the Contracting Officer’s Representative for approval.

vi. As soon as the forms have been stripped and the concrete surfaces exposed, remove fins and other projections, fill recesses left by the removal of form ties, and repair surface defects which do not impair structural strength. Clean all exposed concrete surfaces and adjoining work stained by leakage of concrete to the satisfaction of the Contracting Officer’s Representative.

vii. Hammer pack tie holes and other small cavities with a stiff mortar of the same material, but somewhat leaner than that in the concrete. Clean the cavity and the area wetted before mortar is placed.

viii. Repair and patch defective areas with cement mortar of mix proportions and materials identical to those used in the surrounding concrete. Produce a finish on the patch that is indistinguishable from the surrounding concrete.

ix. Where the honeycomb or voids are not excessive and repairs are authorized by the Contracting Officer’s Representative, chip out the defective areas in a square shape to sound solid concrete with a depth not less than 2 inches. Make edges of cuts perpendicular to concrete surface or slightly undercut to provide a key at the edge of the patch. Before placing cement mortar, thoroughly clean, dampen and brush coat area to be patched with neat cement grout. Other patching materials may be used if accepted by Contracting Officer’s Representative in writing prior to start of repair work. The patch should be kept damp for seven days at a temperature above 50F.

3.11 PROTECTION

A. Protect finished concrete work in accordance with applicable provisions of ACI 301.

B. Immediately after placement, protect concrete from premature drying, excessively hot or cold temperatures, and mechanical damage.

C. Maintain concrete with minimal moisture loss at relatively constant temperature for period necessary for hydration of cement and hardening of concrete.

PART 4 MEASUREMENT AND PAYMENT

4.01 MEASUREMENT

A. Service spillway crest repairs will not be measured for payment. For bidding purposes, the Contractor shall assume concrete removal and repair to the dimensions as shown on the Drawings.

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B. Should additional concrete removal or repair be required based on the conditions observed during concrete removal, additional concrete removal and repair shall be measured for payment in cubic yards.

4.0…