W912P5-16-B-0004_TSpecs-Am6pgs.pdf

Downstream Cofferdam Kentucky Lock W912P5-16-B-0004 Amendment No. 0006 Livingston County promote the training and employment of U.S. veterans while performing under a USACE contract. While no set-aside, evaluation preference, or incentive applies to the solicitation or performance under the resultant contract, USACE Contractors are encouraged to seek out highly qualified veterans to perform services under this contract. The following resources are available to assist USACE contractors in their outreach efforts:

Federal Veteran employment information at:

http://www.fedshirevets.gov/index.aspx

Department of Labor Veterans Employment Assistance:

http://www.dol.gov/vets/

Department of Veterans Affairs-VOW to Hire Heroes Act:

http://benefits.va.gov/vow/

Army Wounded Warrior Program:

http://wtc.army.mil/modules/employers/index.html

U.S. Chamber of Commerce Foundation-Hiring Our Heroes http://www.hiringourheroes.org/

Guide to Hiring Veterans - Reference Material:

http://www.whitehouse.gov/sites/default/files/docs/white_house_business_council_-_ guide_to_hiring_veterans_0.pdf

1.19 PROJECT SCHEDULE

The Contractor shall provide project schedule submittals in accordance with Contract Clause 52.236-15 SCHEDULES FOR CONSTRUCTION CONTRACTS and as specified in Section 01 32 01 PROJECT SCHEDULE.

1.20 SUMMARY OF WORK

1.20.1 Scopes of Base and Six Options

1.20.1.1 Base Scope

The scope of the Base contract has been developed to ensure that it can be awarded based upon available funds and that it contains the critical path activities required to meet the performance period of the contract.

Significant features of work included in the base contract are:

a. Underwater excavation for the entire cofferdam that includes both overburden and rock. An onsite disposal area in close proximity to the cofferdam is provided. This activity is expected to have the majority of time impacts to the operation of the existing lock.

b. Construction of a portion of the concrete segmental wall. The quantity specified under the Base contract will allow the Contractor to commence construction activities at the location or locations of his choosing.

Monoliths must be completed in their entirety and the length comleted must fall within 15% of the quantity specified under the Base Contract unless otherwise approved by the COR. It is not the intent of the Government to dictate the sequence of construction and as much latitude as possible has been incorporated into the resulting scope of work.

Bear in mind that the Government's design intent and the development of this contract's period of performance requires that Segment M-31C be constructed to full height prior to commencing the construction of Cell

SECTION 01 00 00 Page 15

1. If the Contractor chooses not to construct in this sequence, he must then demonstrate to the satisfaction of the Contracting Officer that it is feasible to do so and that Segment M-31C can be constructed after commencing or completing Cell 1.

c. Two circular sheet pile cells (Cells 1 and 2) and their connecting arc, 1A. Their interiors are to be excavated to the top of rock and then cleaned to allow a tremie concrete plug to be placed. They have a granular fill and then are capped with 18" of dense graded aggregate.

d. A helper boat is to be provided by the Contractor for 24 hours a day, seven days a week while work activities and contractor equipment is located in the lower approach to the existing lock.

e. The Contractor will be tasked to operate and maintain an existing dewatering system for the upstream cofferdam and its instrumentation system.

f. Several existing stockpiles of sheet piles will be removed and become the property of the contractor; however, all sheet piles used in this contract shall be new sheet piles.

g. Demolition and special construction techniques are included for the tie-in of the new segmental wall to the existing lock's lower approach wall.

h. Both overwater and land-based exploratory drilling. Required phased prosecution of these efforts are described in Contract Clause 52.211-10.

i. Two guard cells located immediately downstream of the cofferdam. One is concrete filled while the other is granular filled. Required phasing of their construction is also included in Contract Clause 52.211-10.

1.20.1.2 Option 1

The scope of this option is solely to continue construction of the segmental concrete wall. The linear footage quantity was developed to allow the completion of additional monolith segments in their entirety, though the quantity listed may not align with every potential monolith construction sequence combination. The Government's intent is to continue monolith construction in the contractor's chosen sequence with the total linear footage of monoliths constructed, in their entirety, falling within 15% of the quantity specified under Option 1.

1.20.1.3 Option 2

The scope of this option is solely to continue construction of the segmental concrete wall. The linear footage quantity was developed to allow the completion of additional monolith segments in their entirety, though the quantity listed may not align with every potential monolith construction sequence combination. The Government's intent is to continue monolith construction in the contractor's chosen sequence with the total linear footage of monoliths constructed, in their entirety, falling within 15% of the quantity specified under Option 2.

1.20.1.4 Option 3

The scope of this option is solely to continue construction of the

SECTION 01 00 00 Page 16 segmental concrete wall. The linear footage quantity was developed to allow the completion of additional monolith segments in their entirety, though the quantity listed may not align with every potential monolith construction sequence combination. The Government's intent is to continue monolith construction in the contractor's chosen sequence with the total linear footage of monoliths constructed, in their entirety, falling within 15% of the quantity specified under Option 3.

1.20.1.5 Option 4

The scope of this option is solely to construct an underwater stone dike off the downstream tip of the powerhouse island.

1.20.1.6 Option 5

The scope of this option is solely the construction of the pipe piles to be located in some of the sheet pile cells and connecting arcs.

1.20.1.7 Option 6

The scope of this option contains all the remaining features included in the contract. Significant features include:

a. Construction of two more sheetpile cells (3 and 4) and their connecting arcs, 2A and 3A. Unlike the other cells and arcs, Cell 4 and Arc 3A do not have concrete plugs and do not require excavation within them.

b. A flood gate and bridge between Cells 2 and 3.

c. A tied Z-pile wall connecting Cell 4 to high ground.

d. Installation of instrumentation including inclinometers and piezometers.

e. Installation of a lighting and electrical system.

1.20.2 Special Considerations

a. Although the scope of work of this contract is for a cofferdam, there are certain elements required for its functioning that will be included in a future contract; therefore, an unwatering behind this cofferdam is not included in this contract.

b. There are significant environmental controls that will affect work activities and the prosecution of work that are described in Section 01 57 19 of these Specifications. This contract's performance period has taken these controls into account in its development.

c. There are overhead powerlines crossing the Contractor's work area that are shown on the drawings. It is expected that some of these powerlines will affect the length of piles that can be placed.

1.21 MEASUREMENT AND PAYMENT

No separate payment will be made for the work covered under this section.

The costs thereof shall be included in the item to which the work pertains.

SECTION 01 00 00 Page 17

PART 2 PRODUCTS (NOT USED)

PART 3 EXECUTION

3.1 AVAILABILITY AND USE OF UTILITY SERVICES

3.1.1 Contractor Responsibilities

a. The Contractor shall be responsible for the availability of utilities for use on the project. Raw water is available with no charge at the site. The Contractor shall supply any other utilities needed at his cost. The Contractor shall carefully conserve any utilities furnished without charge.

b. The Contractor, at its expense and in a workmanlike manner satisfactory to the Contracting Officer, shall install and maintain all necessary temporary connections and distribution lines. Before final acceptance of the work by the Government, the Contractor shall remove all the temporary connections, distribution lines, and associated paraphernalia.

c. The Contractor is responsible for providing drinking water facilities for all personnel associated with this contract.

3.1.2 Interruptions of Utilities

a. No utility services shall be interrupted by the Contractor to make connections, to relocate, or for any purpose without approval of the Contracting Officer.

b. Request for Permission to shut down services shall be submitted in writing to the Contracting Officer not less than seventeen (17) days prior to date of proposed interruption. The request shall give the following information:

(1) Nature of Utility (Gas, L.P. or H.P., Water, etc.)

(2) Size of line and location of shutoff.

(3) Buildings and services affected.

(4) Hours and date of shutoff.

(5) Estimated length of time services will be interrupted.

c. Services shall not be shutoff until receipt of approval of the proposed hours and date from the Contracting Officer.

d. Shutoffs which will cause interruption of Government work operations as determined by the Contracting Officer shall be accomplished during regular non-work hours or on non-work days of the Using Agency.

e. Operation of valves on water mains will be by Government personnel.

Where shutoff of water lines interrupts service to fire hydrants or fire sprinkler systems, the Contractor shall arrange his operations and have sufficient material and personnel available to complete the work without undue delay or to restore service without delay in event of emergency.

-- End of Section --

SECTION 01 00 00 Page 18

PART 3 EXECUTION

3.1 CONCRETE PRODUCTION

The Government anticipates that the Contractor will use local concrete suppliers, as long as they meet the requirements of these specifications.

If the Contractor chooses to use an on-site batch plant for concrete production, it shall meet all the requirements of this paragraph and below listed subparagraphs. If the Contractor elects to use an off-site batch plant, that plant must be certified by the Kentucky Ready Mix Association and the Kentucky Transportation Cabinet or meet the requirements of this paragraph and below listed subparagraphs. All other requirements of these Specifications will still apply to both on-site and off-site batch plants, including paragraph 3.4 TESTING AND INSPECTIONS. The Contractor's quality control plan should address and ensure that both on-site and off-site batch plants meet the requirements of the Specifications.

3.1.1 General

If used, a temporary on-site batch plant shall be used for production of all concrete for the project incorporated into all parts of the lock, including all trial, test, technique, and demonstration components thereof.

The batch plant shall be a temporary structure and shall be removed from the project site at the conclusion of the work. The Contractor shall obtain all necessary federal, state and local permits for the construction and operation of the temporary batch plant at the site and submit them for approval by the Contracting Officer. The Contractor is responsible for developing the necessary layout and details for the batch plant structure and all necessary plant support features associated with the production of concrete. These features shall include but not limited to, aggregate stock piles, silos for materials, conveyor belts, screens, water, sedimentation and water quality controls. Concrete shall be batched and mixed using an automatic or semi-automatic central mixed concrete batch plant. The batching, mixing,conveying and placing system shall have a capacity of at least 150 cubic yards per hour. If the Contractor uses multiple crews, the capacity shall be increased accordingly. Truck mixers for transporting, agitators, and nonagitating transporting units shall comply with NRMCA TMMB 100 and ASTM C94/C94M. Site-mixed concrete shall conform to the following subparagraphs.

Concrete for ancillary components not related to the lock (such as for site development related components shall be from an approved source and suitable for the intent of the Contractor's purpose and design.

3.1.2 On-Site Batch Plant

The batch plant shall be located on site within the work limits of this contract at a location chosen by the contractor and approved by the Contracting Officer. The batch plant shall have a dual-drum configuration and shall conform to the requirements of NRMCA CPMB 100 and as specified;

however, rating plates attached to batch plant equipment are not required.

Batch Plant shall receive plant certification based on the requirements of

NRMCA CPMB 100.

3.1.2.1 Bins, Silos and Containers

Separate bins, compartments, and silos shall be provided for each size or classification of aggregate and for each of the cementitious materials. The

SECTION 03 30 03 Page 5 compartments shall be of ample size and so constructed that the various materials will be maintained separately under all working conditions. All compartments containing bulk cement, fly ash, silica fume, or ground granulated blast-furnace slag shall be separated from each other by a free-draining air space. All filling ports shall be clearly marked with a permanent sign stating the contents. The necessary storage bins and delivery lines shall be protected from the winter cold and summer heat.

The silica fume (dry) silo shall be at a minimum 3,000 foot3 capacity with rubber discharge hoses.

3.1.2.2 Batching Equipment

The batching controls shall be semiautomatic or automatic, as defined in NRMCA CPMB 100. A semiautomatic batching system shall be provided with interlocks such that the discharge device cannot be actuated until the indicated material is within the applicable tolerance. The batching system shall be equipped with accurate recorder or recorders that meet the requirements of NRMCA CPMB 100. The plant shall be arranged so as to facilitate the inspection of all operations at all times. Suitable facilities shall be provided for obtaining representative samples of aggregates from the feed into the batch plant after the aggregates are prescreened, and for sampling and calibrating the dispensing of cementitious material, water, and admixtures. The batching equipment must be designed to provide continuous placements at the required capacity.

a. Batchers - Aggregate shall be weighed in separate weigh batchers with individual scales. Aggregate shall not be weighed in the same batcher with cementitious material. Bulk cement and/or other cementitious materials shall each be weighed on a separate scale in a separate weigh batcher. Water may be measured by weight or volume. Water shall not be weighed or measured cumulatively with another ingredient. Ice shall be measured separately by weight. Admixtures shall be batched separately and shall be batched by weight or by volume in accordance with the manufacturer's recommendations. The weight or volume of all concrete constituents shall be recorded.

b. Water Batcher - A suitable water-measuring and batching device shall be provided that will be capable of measuring and batching the mixing water within the specified tolerances for each batch. The mechanism for delivering water to the mixers shall be free from leakage when the valves are closed. The filling and discharge valves for the water batcher shall be so interlocked that the discharge valve cannot be opened before the filling valve is fully closed. Piping for water shall be free from leaks and shall be properly valved to prevent backflow or siphoning. When a water meter is used, a suitable strainer shall be provided ahead of the metering device. The water and ice batcher shall be capable of ready adjustment to compensate for aggregate moisture content. An ice plant may be required for the summer months. If required, the ice machine's temperature must be less than 32 degrees F and must produce brittle-hard, dry, and finely broken ice. It shall be stored at a temperature to prevent lumps from forming due to refreezing. The ice machine and storage bin should be well insulated with a quick discharge into the mixer. The ice shall be weighed for correct proportioning. The refrigeration units shall be capable of both ice production and chilling water.

c. Admixture Dispensers - A separate batcher or dispenser shall be provided for each admixture. Each plant shall be equipped with the necessary calibration devices that will permit convenient checking of

SECTION 03 30 03 Page 6 the accuracy of the dispensed volume of the particular admixture. The batching or dispensing devices shall be capable of repetitively controlling the batching of the admixtures to the accuracy specified.

Piping for liquid admixtures shall be free from leaks and properly valved to prevent backflow or siphoning. The dispensing system shall include a device or devices that will detect and indicate the presence or absence of the admixture or provide a convenient means of visually observing the admixture in the process of being batched or discharged.

Each system shall be capable of ready adjustment to permit varying the quantity of admixture to be batched. Each dispenser shall be interlocked with the batching and discharge operations so that each admixture is added separately to the batch in solution in a separate portion of the mixing water or in fine aggregate in a manner to ensure uniform distribution of the admixtures throughout the batch during the required mixing period. Admixtures shall be furnished as a liquid of suitable concentration for easy control of dispensing. Storage and handling of admixtures shall be in accordance with the manufacturer's recommendations. Admixture storage vats shall contain paddle-type agitators and the entire admixture system shall be adequately protected from extreme temperatures and conditions. During the summer months if batch water is added as ice, adjustments may need to be made to when and how the admixtures are added to the concrete mix.

d. Moisture Control - The plant shall be capable of ready adjustment to compensate for the varying moisture content of the aggregates and to change the weights of the materials being batched. A moisture meter complying with the provisions of COE CRD-C 143 shall be provided for measurement of moisture in the fine aggregate. The sensing element shall be arranged so that the measurement is made near the batcher charging gate of the fine aggregate bin or in the fine aggregate batcher. The accuracy of the meter shall be verified by comparing the moisture measurement taken by the meter with the moisture content of the aggregate as determined by ASTM C566 oven dried method. The accuracy shall be verified before the trial batch and uniformity testing of the batch plant for each mix. Additionally, moisture meter accuracy shall be tested at the beginning of each production run and at a period of not more than 8 hours.

e. Scales - Adequate facilities shall be provided for the accurate measurement and control of each of the materials entering each batch of concrete. The weighing equipment and controls shall conform to the applicable requirements of CPMB Concrete Plant Standard and of NIST HB 44, except that the accuracy shall be within 0.2 percent of the scale capacity. The Contractor shall provide standard test weights and any other auxiliary equipment required for checking the operating performance of each scale or other measuring devices. Tests shall be made at the frequency required in paragraph TESTING AND INSPECTIONS, in the presence of a Government inspector. Each weighing unit shall include a visible indicator that shall indicate the scale load at all stages of the weighing operation and shall show the scale in balance at zero load. The weighing equipment shall be arranged so that the concrete plant operator can conveniently observe the indicators.

f. Operation and Accuracy - The weighing operation of each material shall start automatically when actuated by one or more starter switches and shall end when the designated amount of each material has been reached.

These requirements can be met by providing a semiautomatic or automatic batching system as defined by NRMCA CPMB 100. There shall be equipment to permit the selection of five (5) preset mixes each by the movement

SECTION 03 30 03 Page 7 of not more than two switches or other control devices. Cumulative weighing will not be permitted. The weigh batchers shall be so constructed and arranged that the sequence and timing of batcher discharge gates can be controlled to produce a ribboning and mixing of the aggregates, water, admixtures, and cementitious materials as the materials pass through the charging hopper into the mixer. The plant shall include provisions to facilitate the inspection of all operations at all times.

g. Interlocks - Batchers and mixers shall be interlocked so that:

(1) The charging device of each batcher cannot be actuated until all scales have returned to zero balance within ± 0.2 percent of the scale capacity and each volumetric device has reset to start or has signaled empty.

(2) The charging device of each batcher cannot be actuated if the discharge device is open.

(3) The discharge device of each batcher cannot be actuated if the charging device is open.

(4) The discharge device of each batcher cannot be actuated until the indicated material is within the allowable tolerances.

(5) One admixture is batched automatically with the water.

(6) Each additional admixture is batched automatically with a separate portion of the water or with the fine aggregate.

(7) The mixers cannot be discharged until the required mixing time has elapsed.

h. Recorder - An accurate recorder or recorders shall be provided and shall conform to the following detailed requirements:

(1) The recorder shall produce a graphical or digital record on a single visible chart or tape of the weight or volume of each material in the batchers at the conclusion of the batching cycle.

The record shall be produced prior to delivery of the materials to the mixer. After the batchers have been discharged, the recorder shall show the return to empty condition.

(2) A graphical recording or digital printout unit shall be completely housed in a single cabinet that shall be capable of being locked.

(3) The chart, tape, or digital printout shall be so marked that each batch may be permanently identified and so that variations in batch weights of each type of batch can be readily observed. The chart or tape shall be easily interpreted in increments not exceeding 0.5 percent of each batch weight.

(4) The chart, tape, or digital printout shall show time of day at intervals of not more than 15 minutes.

(5) The recorder chart, tape, or digital printout shall become the property of the Government.

(6) The recorder shall be placed in a position convenient

SECTION 03 30 03 Page 8 forobservation by the concrete plant operator and the Government inspector.

(7) The recorded weights or volumes when compared to the weights or volumes actually batched shall be accurate within ± 2 percent.

i. Batch Counters - The plant shall include devices for automatically counting the total number of batches of all concrete batched and the number of batches of each preset mixture.

j. Washing Plant - All coarse aggregates shall be washed immediately prior to entering the rescreening plant. The rewashing plant shall contain adequate water nozzles and vibrating screens to remove foreign materials and coatings from aggregate particles. Water used for washing shall meet the requirements of Section 03 30 01 CONCRETE: MATERIALS, paragraph WATER. If aggregate is mashed and not used, it shall be mixed back into the stockpile. The sediment ponds for the wash racks shall be of adequate size to contain the amount of water and sediment produced and must be easily accessible for clean-out.

k. Rescreening Plant - All coarse aggregates shall be rescreened prior to entering the batching plant. The coarse aggregate shall be rescreened on horizontal vibrating screens without intermediate storage. The rescreening shall limit the undersize to 4 percent of the larger coarse aggregates, 3 percent of the intermediate size, and 2 percent of the fine coarse aggregates. The reclaiming, washing, and rescreening facilities shall have the capacity to maintain all of the bins over the batchers at least half full when the plant is producing concrete at its maximum rate.

l. Trial Operation - In coordination with the first trial batching operation required under Section 03 30 02 CONCRETE: MIXTURE PROPORTIONING, a test of the batching and mixing plant shall be made in the presence of the Contracting Officer to check operational adequacy.

Exact admixture dosages, concrete workability, and set time for the particular mix(s) shall be determined through the trial operation. The trial run of the plant shall not exceed 50 cubic yards of product. All concrete produced in these tests shall be wasted or used for purposes other than inclusion in structures covered by this specification. All deficiencies found in plant operation shall be corrected prior to the start of concrete placing operations. No separate payment will be made to the Contractor for labor or materials required by provisions of this paragraph. The Contractor shall notify the Contracting Officer of the trial operation not less than 7 days prior to the start of the trial operation.

m. Protection - The weighing, indicating, recording, and control equipment shall be protected against exposure to dust, moisture, and vibration so that there is no interference with proper operation of the equipment.

3.1.2.3 Batching Tolerances

(A) Tolerances with Weighing Equipment

PERCENT OF REQUIRED

MATERIAL WEIGHT

Cementitious Materials 0 to plus 2 Aggregate plus or minus 2

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PERCENT OF REQUIRED

MATERIAL WEIGHT

Water plus or minus 1 Chemical admixture 0 to plus 3

(B) Tolerance with Volumetric Equipment

For volumetric batching equipment used for water and admixtures, the following tolerances shall apply to the required volume of material being batched:

PERCENT OF REQUIRED

MATERIAL MATERIAL

Water plus or minus 1 percent Chemical admixtures 0 to plus 3 percent

3.1.2.4 Laboratory Areas

A room shall be provided in the plant to house the moisture and grading testing equipment for aggregate and to provide working space. Another room shall be provided for testing fresh concrete and for fabricating and initial curing of concrete test specimens in accordance with ASTM C31/C31M.

The size, arrangement, and location of these rooms will be subject to Contracting Officer approval. The Contractor shall provide electricity, air conditioning, heat, and water as required for use in these laboratory areas.

3.1.2.5 Batch Plant Layout Drawings

Drawings showing the layout of the plant the Contractor proposes to use on the work shall be submitted by the Contractor for review and approval by the Contracting Officer. The drawings shall show the locations of the principal components of the construction plant; offices; shop and storage building; and storage areas and yards which the Contractor proposes to construct at the site of the work and elsewhere. The Contractor shall also furnish for review drawings showing the general features of his aggregate processing plant; aggregate transporting; storage and reclaiming facilities; aggregate washing plant; coarse aggregate rescreening plant;

concrete batching and mixing plant; concrete conveying and placing plant;

and when precooling of concrete is required, the cooling plant. The drawing shall appropriately show the capacity of each major feature of the plant including the rated capacity of the aggregate production plant in tons (2000 lb) per hour of fine and coarse aggregates; rated capacity of the aggregate transporting, storage and reclaiming facilities; volume of aggregate storage; capacity of cement and fly ash, GGBF slag and silica fume storage; rated capacity of the concrete batching and mixing plant in cubic yards per hour; rated capacity of the concrete transporting and placing plant in cubic yards per hour; and when used rated capacity of plant for precooling of concrete. The drawing shall also show the location, storage container design and capacity, and enclosure for the admixtures.

All batch plant layout drawings shall be approved by the Contracting Officer before any equipment is delivered to the site. Drawings showing any changes in plant made during design and erection or after the plant is in operation shall be submitted for review and approval of the Contracting Officer.

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3.1.3 Mixers

Mixers shall be stationary mixers. Mixers shall be capable of combining the materials into a uniform mixture and of discharging this mixture without segregation. The mixers shall not be charged in excess of the capacity recommended by the manufacturer. Excessive over-mixing requiring introduction of additional water will not be permitted. The mixers shall be operated at the drum or mixing blade speed designated by the manufacturer.

The mixers shall be maintained in satisfactory operating condition, and the mixer drums shall be kept free of hardened concrete. Mixer blades or paddles shall be replaced when worn down more than 10 percent of their depth when compared with the manufacturer's dimension for new blades.

Should any mixer at any time produce unsatisfactory results, its use shall be promptly discontinued until it is repaired or replaced.

3.1.3.1 Stationary Mixers

Concrete plant mixers shall be drum-type mixers of tilting, horizontal-shaft, or vertical-shaft type, and shall be provided with an acceptable device to lock the discharge mechanism until the required mixing time has elapsed.

a. Stationary Mixer Uniformity Requirements.

The size of the batch, the mixing time, the charging sequence, and other factors identified by the Contractor shall be adjusted to provide concrete that meets the uniformity limits specified herein. All testing shall be performed in accordance with COE CRD-C 55. When regular testing is performed, the concrete shall meet the limits of any five of the six uniformity requirements. When abbreviated testing is performed, the concrete shall meet only those requirements listed for abbreviated testing.

The initial mixer evaluation test shall be a regular test and shall be performed prior to the start of concrete placement. Mixer evaluation testing shall be conducted for each type of concrete mixture used on the project. Regular testing shall consist of performing all six tests on three batches of concrete. The range for regular testing shall be the average of the ranges of the three batches. Abbreviated testing shall consist of performing the three required tests on a single batch of concrete. The range for abbreviated testing shall be the range for one batch. If more than one mixer is used and all are identical in terms of make, type, capacity, condition, speed of rotation, etc., the results of tests on one of the mixers shall apply to the others, subject to approval. Mixer evaluations shall be performed by the Contractor in accordance with paragraph "Mixer Uniformity". Tests shall be performed in the presence of the Government. The Contractor shall provide labor and equipment as directed to assist the Government in performing any evaluation made by the Government.

ABBREVIATED

REGULAR TESTS TESTS

ALLOWABLE ALLOWABLE

MAXIMUM RANGE FOR MAXIMUM RANGE

PARAMETER AVERAGE OF 3 BATCHES FOR 1 BATCH

Unit weight of air-free mortar, lb/cu ft 2.0 2.0

Air content, percent 1.0 ---

SECTION 03 30 03 Page 11

ABBREVIATED

REGULAR TESTS TESTS

ALLOWABLE ALLOWABLE

MAXIMUM RANGE FOR MAXIMUM RANGE

PARAMETER AVERAGE OF 3 BATCHES FOR 1 BATCH

Slump, inches 1.0 ---

Coarse aggregate, percent 6.0 6.0 Compressive strength at 7 days, percent 10.0 10.0

Water content, percent 1.5 ---

3.1.4 Sampling Facilities

3.1.4.1 Concrete

The Contractor shall provide suitable facilities and labor for obtaining representative samples of concrete in accordance with ASTM C172 for Contractor Quality Control (QC) and Government Quality Assurance (QA) testing.

3.1.4.2 Coarse Aggregate

Suitable facilities shall be provided for readily obtaining representative samples of coarse aggregate for test purposes immediately prior to the material entering the mixer. The facilities shall include automatic equipment capable of obtaining, sieving, and weighing samples of the coarse aggregate containing a minimum of 100 pounds for coarse aggregate with a maximum aggregate size of 1-1/2 inches or a minimum of 500 pounds for coarse aggregate with maximum aggregate equal to or larger than 2 inches.

The equipment shall be capable of running a complete sieving, of any required sample, without the necessity of intermittent loading. To accomplish this, adequate areas of individual sieves and controlled feeding of samples shall be provided. The assembly shall be designed to permit selection, screening, and weighing of any individual sample in 10 minutes or less. The equipment shall be designed by a company engaged in the design and manufacture of aggregate sieving devices. The Contractor shall have complete responsibility for providing equipment that will accomplish the desired purpose. Sieves shall meet the applicable requirements of ASTM E11, except for the frame size requirements. The equipment shall be arranged so that all controls will be enclosed and operable from a single position commanding a view of the screen device and the scale or scales.

Communication shall be provided from the batch plant operation to this control area. The Contractor shall be responsible for charging of the assembly as directed, disposal of waste material, and proper service and maintenance of the assembly. Each sieve shall be provided with individual controls for frequency and angle. The Contractor shall run correlation tests with equipment as used for ASTM C136 before concrete placement begins and at least every 60 days while concrete is being placed. The correlation test will determine the optimum angle, volume of feed, and the frequency for each sieve.

3.1.4.3 Fine Aggregate

Suitable facilities shall be provided for readily obtaining representative samples of fine aggregate for test purposes immediately prior to the

SECTION 03 30 03 Page 12 material entering the mixer. Access shall be provided so that a cross-section of fine aggregate may be removed from the feed belt supplying the bin from which fine aggregate is batched.

3.1.5 Transporting Equipment

Transporting equipment shall be designed, operated, and maintained so that it does not cause or permit segregation or loss of material. Aluminum pipe or equipment shall not be used for conveying or placing concrete. The capacity of the transporting equipment shall exceed the batch plant capacity to ensure a continuous supply of concrete during placement.

3.1.5.1 Buckets

The interior hopper slope shall be not less than 58 degrees from the horizontal, the minimum dimension of the clear gate opening shall be at least 5 times the nominal maximum-size aggregate, and the area of the gate opening shall not be less than 2 square feet. The maximum dimension of the gate opening shall not be greater than twice the minimum dimension. The bucket gates shall be essentially grout tight when closed and may be manually, pneumatically, or hydraulically operated except that buckets larger than 2 cubic yards shall not be manually operated. The design of the bucket shall provide means for positive regulation of the amount and rate of deposit of concrete in each dumping position.

3.1.5.2 Transfer Hoppers

Transfer hoppers shall be capable of receiving concrete directly from delivery vehicles and shall have conical-shaped discharge features. The transfer hopper shall be equipped with a hydraulically operated gate and with a means of external vibration to effect complete discharge.

3.1.5.3 Trucks

Truck agitators used for transporting central-mixed concrete shall conform to the applicable truck certification requirements of NRMCA TMMB 100.

Truck mixers shall not be used to transport concrete with larger than 1-1/2 inch nominal maximum aggregate or 2 inch or lower slump. Non-agitating trucks shall be used only for transporting central-mixed concrete over a smooth road where the hauling time is less than 15 minutes and the slump is less than 3 inches. Bodies of non-agitating trucks shall be smooth water tight, metal containers specifically designed to transport concrete, shaped with rounded corners to minimize segregation, and equipped with gates that will permit positive control of the discharge of the concrete.

3.1.5.4 Chutes

When concrete can be placed directly from a truck mixer, agitator, or nonagitating truck, the chutes supplied by the truck manufacturer as standard equipment may be used. A discharge deflector shall be used when required by the Contracting Officer. Separate chutes and other similar equipment shall not be permitted for conveying concrete except when specifically approved and in no case shall slump be increased to accommodate their use.

3.1.5.5 Belt Conveyors

Belt conveying equipment shall be designed and operated to ensure a uniform flow of aggregate or concrete from point of origin to final place of

SECTION 03 30 03 Page 13 deposit without segregation of ingredients or loss of fines or mortar and shall be provided with positive means, such as discharge baffle fines or hopper, for preventing segregation of the aggregate or concrete or loss of mortar at the transfer point(s) and the point of placing. The idler spacing shall not exceed 36 inches. Belt speed shall be a minimum of 300 feet per minute and a maximum of 750 feet per minute. Belt width shall be a minimum of 16 inches if the NMSA is 3 inches or less. The NMSA required in mixture proportions furnished by the Government will not be changed to accommodate the belt width. The conveyor must be able to stop, hold, and restart a fully loaded belt. All parts of the conveyor system must be watertight and waterproof. Down time must be allowed for repair of the system and replacement of worn parts. All concrete spills must be cleaned immediately from any part of the system. All parts of the conveyor must be accessible via walkways for removal of aggregate or concrete in case of system breakdown.

3.2 TRANSPORTING CONCRETE AT PROJECT SITE

Concrete shall be transported to the placing site in truck mixers, agitators or nonagitating transporting equipment conforming to NRMCA TMMB 100, or by approved pumping equipment or conveyors.

3.3 CONVEYING CONCRETE ON SITE

Concrete shall be conveyed from mixer and transporting unit to the point of placement as rapidly as possible and within the time interval specified by methods that will prevent segregation or loss of ingredients. Conveying equipment shall be cleaned before each placement. Methods and equipment for conveying and depositing the concrete into the form shall be subject to approval by the Contracting Officer. The capacity of the transporting system shall be sufficient to supply concrete at a rate to prevent cold joints forming during placement. The concrete shall not be dropped vertically more than 5 feet except where suitable equipment is provided to prevent segregation and where specifically authorized. A properly designed and sized elephant trunk and rigid drop chute bottom section which will prevent free-fall within the elephant trunk and rigid drop chute shall be used. If concrete is to be placed through installed horizontal or sloping reinforcing bars, the concrete shall discharge into a pipe or elephant trunk that is long enough to extend through the reinforcing bars to within 5 feet of the placing surface. In no case shall concrete be discharged to free fall through the reinforcing bars.

3.3.1 Transporting by Bucket

The Contractor shall provide indicating and signaling devices for the control of identification of types or classes of concrete as they are mixed and discharged into buckets for transfer to the forms. Each type or class of concrete shall be visually identified by placing a colored tag or marker on a bucket as it leaves the mixing plant so that the concrete may be positively identified in the forms and placed in the structure in the desired position.

3.3.2 Transfer Hoppers

Concrete may be charged into nonagitating hoppers for transfer to other conveying devices. Concrete shall not be held in nonagitating transfer hoppers more than 30 minutes.

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3.3.3 Transporting by Belt Conveyor

Methods and equipment for transporting the concrete by belt conveyor into the form shall be subject to approval. If enclosures over the conveyor are not provided, concrete shall not be conveyed when precipitation may affect the concrete quality.

3.4 TESTING AND INSPECTIONS

The Contractor shall perform the inspection and tests described below and, based upon the results of these inspections and tests, shall take the action required and shall submit specified reports. When, in the opinion of the Contracting Officer, the concreting operation is out of control, concrete placement shall cease and the operation shall be corrected. The laboratory performing the tests shall be onsite and shall conform with ASTM C1077. Materials may be subjected to check testing by the Government from samples obtained at the manufacturer, at transfer points, or at the project site. The Government will inspect the laboratory, equipment, and test procedures prior to start of concreting operations and at least once per six (6) months thereafter for conformance with ASTM C1077.

3.4.1 Scales, Batching and Recording

a. Weighing Accuracy - The accuracy of the scales shall be checked by test weights at least once a month for conformance with the applicable requirements of paragraph "Batching Equipment". Such tests shall also be made as directed whenever there are variations in properties of the fresh concrete that could result from batching errors.

b. Batching and Recording Accuracy - Once a week the accuracy of each batching and recording device shall be checked during a weighing operation by noting and recording the required weight, recorded weight, and the actual weight batched. At the same time, the Contractor shall test and ensure that the devices for dispensing admixtures are operating properly and accurately.

c. Scales Corrective Action - When either the weighing accuracy or batching accuracy does not comply with specification requirements, the plant shall not be operated until necessary adjustments or repairs have been made. Discrepancies in recording accuracies shall be corrected immediately.

d. Moisture Meter Accuracy - The accuracy of the fine aggregate moisture meter shall be checked at least once a month for conformance with the applicable requirements of paragraph "Batching Equipment". Such tests shall also be made as directed whenever there are variations in properties of the fresh concrete that could result from batching errors.

3.4.2 Batch-Plant Control

The measurement of concrete materials including cementitious materials, each size of aggregate, water, and admixtures shall be continuously controlled. The aggregate weights and amount of added water shall be adjusted as necessary to compensate for free moisture in the aggregates.

The amount of air-entraining agent shall be adjusted to control air content within specified limits. Water reducing admixtures shall be adjusted to control the slump and slump flow within specified limits. All information shall be recorded on concrete batch tickets prepared in accordance with ASTM C94/C94M for each batch produced.

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3.4.3 Mixer Uniformity

The mixer uniformity test shall be conducted for each type of concrete mixture.

a. Stationary Mixers. Mixer uniformity testing shall be conducted prior to the start of concrete placing and once every 3 months when concrete is being placed. Uniformity of concrete mixing shall be determined in accordance with COE CRD-C 55.

The initial and every fourth set of tests shall be regular tests performed on three batches of concrete. Intermediate uniformity tests shall be abbreviated tests performed on a single batch of concrete.

b. Mixer Uniformity Corrective Action. When a mixer fails to meet mixer uniformity requirements, either the mixing time shall be increased, batching sequence changed, batch size reduced, or adjustments shall be made to the mixer until compliance is achieved. If inspection of the mixer blades shows excessive wear, broken or missing components, concrete operations shall cease until such necessary repairs are made.

If the mixer fails the abbreviated test, a regular test shall be immediately performed. Whenever adjustments in a mixer or increased mixing time are required because of failure of a uniformity test, the mixer shall be reevaluated by a regular test after the adjustments have been completed. If the Contractor proposes to reduce a mixing time, a regular test shall be performed to evaluate the proposed time.

Additional testing shall be performed when directed when there is visible evidence of possible improper mixer performance. Results of all uniformity tests shall be reported in writing. In addition, drum mixer blades shall be inspected every 30 days, and shall be examined for worn, broken or missing components.

3.4.4 Reports

All results of tests or inspections conducted shall be reported informally as they are completed and in writing daily. Concrete batch tickets shall be issued for each batch produced. A weekly report shall be prepared for the updating of control charts covering the entire period from the start of the construction season through the current week. During periods of cold-weather protection, reports of pertinent temperatures shall be made daily. These requirements do not relieve the Contractor of the obligation to report certain failures immediately as required in preceding paragraphs.

Such reports of failures and the action taken shall be confirmed in writing in the routine reports. The Contracting Officer has the right to examine all Contractor quality control records.

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