524DRILLED SHAFTS

523.03 Equipment. Supply all required dynamic testing equipment necessary

to run the test set forth in ASTM D 4945. Supply personnel with an Advanced Master, or Expert Level Certification in High Strain Dynamic Pile Testing (HSDPT) from either Foundation QA or the Pile Driving Contractors Association (PDCA) to operate this equipment . Supply the Engineer a copy of the certificate showing that personnel operating dynamic testin g equipment are currently certified. Supply all personnel and equipment needed to strike the test piles with the pile hammer.

523.04 Test Report. Perform the dynamic test and signal matching analysis and

immediately provide the Engineer driving criteria fo r any piles to be driven within the next 48 hours. Within 48 hours after performing the dynamic pile test or restrike tests, supply the Engineer with a written report confirming driving requirements for piles represented by the test. Include in the report, the required blow count for:

523.05 Basis of Payment. The Department will pay for dynamic load testing

after being provided the written test at the contract price as follows: Item Unit Description 523 Each Dynamic Load Testing 523 Each Restrike ITEM 524 DRILLED SHAFTS

524.01 Description

524.02 Materials 524.01

453 524.03 Contractor’s Installation Plan

524.04 Hole Excavation

524.05 Friction Type Drilled Shafts

524.06 Casings

524.07 Slurry

524.08 Excavation Inspection

524.09 Reinforcing Steel for Drilled Shafts

524.10 Concrete for Drilled Shafts

524.11 Free Fall Concrete Placement

524.12 Tremie

524.13 Pumped Concrete

524.14 Construction Tolerances

524.15 Inspection Records

524.16 Method of Measurement

524.17 Basis of Payment

524.01 Description. This work consists of furnishing and installing drilled

shafts. The lengths of the drilled sha fts shown on the plans are estimated from available subsurface information. Furnish the proposed drilled shafts according to plan requirements, with the understanding that the actual length required is based on conditions encountered during construction an d may differ from the estimated length shown on the plans.

524.02 Materials. Furnish material conforming to:

Concrete, Class QC 5 or QC 4 for Mass Concrete ................................ ........... 499, 511 Epoxy coated reinforcing steel ................................ .... 509

524.03 Contractor’s Installation Plan. Submit, for t he Engineer’s acceptance,

a written installation plan of procedures to follow when excavating the hole, placing the concrete, and monitoring the concrete placement. Submit the installation plan at least 14 Calendar Days before constructing the drilled shaf ts. Include the following information:

524.04 Hole Excavation . Take precautions to prevent da maging existing

structures and utilities. Precautions include, but are not limited to, selecting construction methods and procedures that will prevent excessive caving of the shaft excavation, and monitoring and controlling the vibrations from the driving of casing or sheeting or drilling of the shaft. When encountered, remove objects such as large boulders. Do not blast unless shown on the plans or authorized in writing by the Engineer. Unless otherwise shown on the plans, where drilled shafts are to be in stalled in conjunction with embankment placement, construct shafts after the placement of the fill and completion of any specified settlement periods. Excavate for the shafts to the dimensions and elevations shown on the plans. Use methods and equipment su itable for the intended purpose and materials encountered. Use either the dry method, wet method, temporary casing method, or permanent casing method as necessary to produce sound, durable concrete foundation shafts free of defects. When a particular method of construction is required on the plans, that method shall be used. If no particular method is specified for use, select and use a method based on site conditions. If the excavation operation is stopped, protect the shaft cavity by installing a safety cover. The Contractor is responsible for the safety of the shaft excavation, surrounding soil, and the stability of the sidewalls. If necessary to ensure such safety and stability, use a temporary casing, slurry, or other methods accepted by the Engine er. Unless cased to the full depth, do not leave excavations unfilled overnight. Use appropriate means, such as a cleanout bucket or air lift, to clean the bottom of the excavation of all shafts. Promptly notify the Engineer when unexpected obstructions ar e encountered.

524.05 Friction Type Drilled Shafts. Friction type drilled shafts are defined as

drilled shafts that do not bear on bedrock and obtain their ability to support load 524.06 456 from a combination of end bearing on the soil and adhesion between soil and concrete along the length of the shaft. For friction type drilled shafts, dry construction method may be used for cohesive soils only. If using a casing for the construction of a friction type drilled shaft, remove the casing completely or partially as shown on the plans. If enough water is entering the hole through the sides and bottom of the hole such that the supporting soils are being eroded, maintain a positive head of fluid in the excavation hole to ensure that water is not continuously flowing into the hole. If the Engineer determines that the hole sidewall has softened due to excavation methods, swell ed due to delays in concreting, or degraded because of slurry cake buildup, over ream the sidewall to sound material. If the concrete is not placed the same day that the excavation is completed, protect the excavation with a temporary casing, and redrill t he hole at least 6 inches (150 mm) larger in diameter, clean the excavation, and perform slurry test before concreting.

524.06 Casings. Use smooth, watertight, steel casings of sufficient strength to

withstand handling and driving stresses and the concrete and surrounding earth pressures. Provide an outside diameter of the steel casing equal to or greater than the plan diameter of the shaft. If the plan diameter of the bedrock socket is same as the drilled shaft above the bedrock and a steel casing is used, provide a diameter of the bedrock socket as shown on the plans. Ensure that the diameter of the casing is large enough to allow the excavation of the bedrock socket. Where drilled shafts are located in open water areas, extend the casing a minimum of 12 inches (300 mm) above the water to protect the shaft concrete from water action during placement and curing of the concrete. Cut off the casing at the plan top of drilled shaft elevation after the concrete has cured. If practical, install the casing in a m anner that produces a positive seal at the bottom of the casing to prevent piping of water or entry of other material into the shaft excavation. If it becomes necessary to remove a casing and substitute a longer or larger diameter casing through caving soi ls, stabilize the excavation with slurry or backfill before installing the new casing. The Contractor may use other methods accepted by the Engineer to control the stability of the excavation and to protect the integrity of the foundation soils.

524.07 Slurry. Slurry used in the drilling process shall be a mineral or polymer

slurry. The mineral slurry shall have both a mineral grain size that remains in suspension and sufficient viscosity and gel characteristics to transport excavated material to a suitable screening system. Ensure that the percentage and specific gravity of the material used to make the suspension is sufficient to maintain the stability of the excavation and to allow proper concrete placement. Maintain the level of the slurry at a height su fficient to prevent caving of the hole. Thoroughly premix the mineral slurry with clean fresh water and allow adequate time for hydration before introduction into the shaft excavation. Agitate, circulate, and adjust the properties of the slurry to prevent the slurry from “setting up” in the shaft excavation. 524.08 457 Perform control tests using suitable apparatus on the mineral slurry to determine density, viscosity, and pH. Conform to the acceptable range of values for these physical properties as shown in Table 52 4.07-1. TABLE 524.07 -1 MINER AL SLURRY SPECIFICAT IONS RANGE OF VALUES AT 6 8 °F (20 °C) Property Test Method Time of Slurry Introduction Time of Concreting in Hole Density lb/ft³ (kg/m ³) Density Balance 64.3 to 69.1 (1030 to 1107) 64.3 to 75.0 (1030 to 1201) Viscosity s/qt (s/L) Marsh Cone 28 to 45 (30 to 48) 28 to 45 (30 to 48) pH pH Paper or meter 8 to 11 8 to 11 If de -sanding is required, do not allow the sand content to exceed 4 percent by volume at any point in the shaft excavation as determined by the American Petroleum Institute sand content test. Determine density, viscosity, and pH values before and during the shaft excavation to establish a consistent working pattern. Before placing shaft concrete, use an approved slurry -sampling tool to tak e slurry samples from the bottom and at mid -height of the shaft. Eliminate heavily contaminated slurry that has accumulated at the bottom of the shaft. Ensure that the mineral slurry conforms to the requirements specified immediately before shaft concrete placement. Only use polymer slurry after demonstrating to the Engineer that the stability of the hole perimeter can be maintained while advancing the excavation to its final depth by excavating a trial hole of the same diameter and depth as that of the production shafts. Use the same polymer slurry in the trial hole as proposed for the production shafts. If using different sizes of the shafts at the project, use the same size trial hole as that of the largest diameter shaft, except the depth of the trial ho le need not be more than 40 feet (12 meters). Only one trial hole per project is required. Do not use the trial hole excavation for a production shaft. After completing the trial hole excavation, fill the hole with sand. The acceptance of the polymer slurry does not relieve the Contractor of responsibility to maintain the stability of the excavation. Polymer slurry shall conform to the manufacturer’s requirements.

524.08 Excavation Inspection. Provide equipment for checking the dimensions

and alignment of each shaft excavation. Determine the dimensions and alignment. Measure the final shaft depth after final inspection. Immediately before placing concrete, ensure that the bottom of the completed drilled shaft excavation is as clean as practical. Remove drilling spoils that adhere to the vertical sides of the bedrock socket.

524.09 Reinforcing Steel for Drilled Shafts. Place the reinforcing steel cage as

a unit immediately after inspection of the excavation and before placing concrete. If not placing the concrete immediately after installing the cage, the Contractor may have to remove the cage before placing the concrete to verify the integrity of the excavated area and to ensure loose material is removed from the bottom of the hole. 524.10 458 Tie and support the re inforcing steel so it remains within the required tolerances. Securely tie spacers at quarter points around the cage perimeter and space at intervals not to exceed 5 feet (1.5 m) along the length of the cage. If the size of the longitudinal reinforcing ste el equals or exceeds 1 inch (25 mm) in diameter, the Contractor may increase th e distance between the spacing devices to a maximum of 10 feet (3 m). Use spacers of adequate dimensions to ensure a minimum annular space between outside of cage and side of h ole or casing of 3 inches (75 mm) for shaft diameters up to 4 feet (1.2 m) and 6 inches (150 mm) for shaft diameters larger than 4 feet (1.2 m). The Contractor may use round plastic spacers. Maintain the top of the reinforcing steel cage no more than 6 inc hes (150 mm) above and no more than 3 inches (75 mm) below the required position. If the reinforcing steel cage is not maintained within tolerances, make acceptable corrections and do not construct additional shafts until the method of reinforcing steel ca ge support has been approved. When approved by the Engineer, the Contractor need not provide the reinforcing steel for the extended length of the drilled shaft if it is determined in the field that the Contractor must drill the shaft deeper than the estima ted length.

524.10 Concrete for Drilled Shafts. For all drilled shafts, use Class QC 5 or

QC 4 concrete for Mass Concrete,(drilled shaft diameter over 7 ft (2.1 m), a ccording to Item 511 except as modified and supplemented as follows. The required slump is 6  1 inch (150  25 mm). Achieve the additional slump over 4 inches (100 mm) by using chemical admixtures conforming to 705.12, Type F or G. The maximum water -cement ratio shall not exceed 0.44. If placing concrete under water, add 10 percent more cement to the concrete mix. If placing concrete using a tremie, further increase the slump to 8  1 inch (200  25 mm), by using chemical admixtures. For wet method construction, place concrete in one continuous operation from bottom to top of the shaft. After t he concrete has reached the top of the drilled shaft, continue pumping and remove all contaminated concrete until acceptable quality concrete is evident at the top of the shaft. Do not vibrate concrete with a vibrator. Carefully remove the casing so that t he reinforcing steel cage is not deformed by the force of the downward flowing concrete. Do not place concrete in any drilled shaft excavation without acceptance from the Engineer. Inspect the drilled shaft excavation immediately before placing the concret e. Provide a light powerful enough to thoroughly inspect the reinforcing steel cage, the sides, and the bottom of the drilled shaft. The inspection for the wet construction method consists of only probing and measuring. If the elevation of the top of the s haft is below ground at the time of concrete placement, use a casing to prevent caving of materials into fresh concrete.

524.11 Free Fall Concrete Placement. The Contractor may place the concrete

in a dry drilled shaft excavation using the free fall method provided the concrete falls to its final position through air without striking the sides of the hole, the reinforcing steel cage, or any other obstruction. Use a centering drop chute, at least 3 feet (1 m) long with the free fall method. Unless shown on t he plans, there is no limit to the height of free fall. If the concrete placement causes the shaft excavation 524.12 459 to cave or slough or if the concrete strikes the rebar cage or sidewall, reduce the height of free fall or the rate of concrete flow into the exca vation, or both. If the Engineer determines that dewatering is not practical or placement by free fall method cannot be accomplished, place the concrete using a tremie or a concrete pump.

524.12 Tremie. The Contractor may use a gravity tremie to place concrete

placement instead of a concrete pump in either wet or dry holes. For uncased wet holes, maintain the drilled shaft excavation full of slurry or water to such a depth that water does not flow into the shaft excavation at any time. To place concrete, use tremies consisting of a tube of sufficient length, weight, and diameter to discharge concrete at the shaft base elevation. If the tremie contains aluminum parts, do not allow these parts to contact the concrete. Use tremies with an inside dia meter of at least 10 inches (250 mm). Ensure that the inside and outside surfaces of the tremie are clean and smooth to allow both flow of concrete and unimpeded withdrawal during concreting. Use tremies with a wall thickness adequate to prevent crimping or sharp bends that restrict concrete placement. For concrete placement, use water -tight tremies. Do not begin underwater placement until the tremie is placed to the shaft bottom elevation. Use valves, bottom plates, or plugs so concrete discharge can begin within one tremie diameter of the base. Either remove plugs from the excavation or use plugs of an Engineer approved material that does not cause a defect in the shaft if not removed. Construct the discharge end of the tremie to allow the free radial flow of concrete during placement operations. Immerse the tremie discharge end at least 10 feet (3 m) in concrete at all times after starting the flow of concrete. If the tremie line orifice is removed from the fluid concrete column during the concrete pour, a nd discharges concrete above the rising concrete level, consider the drilled shaft defective.

524.13 Pumped Concrete . Pump concrete into either wet or dry holes. For

uncased wet holes, maintain the drilled shaft excavation full of slurry or water to such a depth that water does not flow into the shaft excavation at any time. Use concrete pump pipe at least 4 inches (100 mm) in diameter and constructed with watertight joints. Arrange the concrete pump equipment so no vibrations result that might damage fresh concrete. Arrange pipes carrying concrete from the pump to the shaft with a minimum number of bends. Anchor the pipe used to convey the concrete to the bottom of the drilled shaft excavation to the steel casing or another suitable stationary object to pre vent the pipe from undulating during the initial placement of the concrete. Do not begin placing concrete until the pump line orifice is at the shaft base elevation. Do not use aluminum pipe as a conveyance for the concrete. Pump an adequate quantity of gr out, mortar, or concrete without coarse aggregate through the equipment ahead of the specification concrete to provide lubrication to the pumping system. Do not place the concrete used for lubrication in the shaft. The lubrication process will not be repea ted as long as the pumping operations are continuous. Operate the pump so a continuous stream of concrete without air pockets is produced. To prevent the contamination of the concrete placed initially at the bottom 524.14 460 of the shaft, seal the outlet end of the pumping pipe with a diaphragm or plug that is flushed out when the hydrostatic pressure from the column of concrete exceeds that of the water in the shaft. Control the initial rate of concrete placement so not to lift or displace the cage of reinforcing st eel. Use a watertight conveying system, and leave the outlet end well below the top of the freshly placed concrete. The preferred concrete placement procedure is to maintain the outlet end of the pumping system at approximately 10 feet (3 m) below the top of the fresh concrete. When the concrete reaches the top of the drilled shaft column, remove all laitance. If the concrete pump line orifice is removed from the fluid concrete column during the concrete pour, and discharges concrete above the rising concre te level, the drilled shaft shall be considered defective.

524.14 Construction Tolerances. For shafts supporting single columns,

position the drilled shaft within 3 inches (75 mm) of the plan location in the horizontal plane at the plan elevation for the t op of the shaft. For shafts supporting footings, position the center within 6 inches (150 mm) of the plan location. Do not allow the vertical alignment of the shaft to vary from the required alignment by more than 1/4 inch per foot (21 mm/m) of depth. Cons truct the supported elements at the plan location. Perform all corrections required to construct the supported elements.

524.15 Inspection Records. Provide all necessary equipment and labor needed

to obtain measurements for completing the Inspection Record s. Obtain measurements before placing concrete.

524.16 Method of Measurement. The Department will measure Drilled Shafts

by the number of feet (meters), measured along the axis of the drilled shaft from the required bottom elevation of the shaft to the pro posed top plan elevation. The Department will not measure the length of reinforcing steel projecting from the drilled shaft into the pier column or the footing supported on Drilled Shafts as shown on the plans. If the drilled shaft extends into the bedrock , The Department will divide the total length of each drilled shaft into two segments. The length of the lower segment is the length of the bedrock socket, and the length of the upper segment is the length of the drilled shaft above the bedrock socket. If a steel casing extending down to bedrock is used, the Department will measure the bedrock socket from the bottom of the casing to the bottom of the drilled bedrock excavation. If the Engineer is assured that a portion of the metal casing is embedded in sol id bedrock, and upon the Engineer’s concurrence, the Department may include the embedded distance as a part of the bedrock socket.

524.17 Basis of Payment. Payment is full compensation for performing

required excavation; furnishing and placing steel casings; furnishing and placing reinforcing steel and concrete by free fall, pumping, or tremie method; removing casings; casings left in place; supplying equipment and performing slurry testing; supplying and disposing of slurry; and disposing excess exca vated material. The Department will not pay for the cost of performing slurry tests before concreting. The Department will not make separate payment for the trial holes. 526.01 461 The Department will not pay for corrections required to construct the supported elemen ts. The Department will pay for accepted quantities at the contract prices as follows: Item Unit Description 524 Foot (Meter) Drilled Shafts, ___" (___ mm) Diameter, above Bedrock 524 Foot (Meter) Drilled Shafts, ___" (___ mm) Diameter, into Bedroc k 524 Foot (Meter) Drilled Shafts, ___" (___ mm) Diameter ITEM 526 APPROACH SL ABS

526.01 Description

526.02 Materials

526.03 Forming and Placing Reinforcing Steel

526.04 Placing and Sampling Concrete

526.05 Finishing and Curing

526.06 Side Curbs

526.07 Method of Measurement

526.08 Basis of Payment

526.01 Description. This work consists of constructing reinforced portland

cement concrete approach slabs for bridges on the completed and accepted subgrade or subbase.

526.02 Materials. Furnish mat erials conforming to:

Concrete, Class QC 2* ................................ ................. 499 Epoxy coated reinforcing steel ................... 509.02 , 709.00 Preformed joint filler ................................ .............. 705.03 Joint sealer ................................ .............. 705.04 or 705.11 * Use the same class of concrete used in the bridges superstructure that the approach slab is attached to unless otherwise shown in the plans. If the super -structure concrete class for the bridge is not identified in the plans use Class QC 2.

526.03 Forming, Furnishing and Placing Reinforcing Steel. Furnish true and

straight steel or wooden side forms. Securely brace and hold forms to the line and grade shown on the plans. Do not allow form s to vary more than 1/8 inch (3 mm) from a 10 foot (3 m) straightedge. Do not remove forms for a minimum of 36 hours. Clean and oil forms after each use. Furnish reinforcing steel and place it in the position shown on the standard construction drawing and firmly secure the steel during placing and setting of the concrete. Tie reinforcing bars at all intersections, except tie reinforcing bars at alternate intersections where bar spacing is less than 1 foot (0.3 m) in any direction. 526.04 462 526.04 Placing and Sampli ng Concrete. Immediately before placing concrete according to Item 511. 07, thoroughly moisten the subgrade or subbase with water in the a mount and manner directed by the Engineer. When the bridge superstructure and the approach slab require QC/QA, make at least one set of test cylinders for each 50 cubic yards (35 cubic meters) of concrete. Include the results of the cylinders into the L ot for the 511 superstructure item.

526.05 Finishing and Curing. Mechanically screed, at a vibration frequency of

1500 to 5000 pulses per minute, the concrete surface to the proper elevation in one complete pass with a minimum of hand finishing. Cure approach slabs according to

511.14 A. Seal joints and cracks according to 511.19. If the approach slab is to serve

as a base for an asphalt concrete wearing course, texture the approach slab according to Item 305. If the approach slab is to serve as a wearing surface, test the surface according to 451.13 , and diamond groove the surface according to 511.17. Open approach slabs to traffic according to Table 511.14 -1A or Table 511. 14- 1B.

526.06 Side Curbs. If concrete curb extends across the approach slab, construct

side curbs of the dimensions required, and place the c oncrete curb at the same time as the approach slab. Finish the curb according to Item 609 .

526.07 Method of Measurement. The Department will measure Reinforced

Concrete Approach Slabs by the number of square yards (square meters) complete in place.

526.08 Basis of Payment . The Department will calculate the final adjusted

payment per 511 and Supplement 1127. The Department will pay for accepted quantiti es at the contract price as follows which includes all concrete, curbs, reinforcing steel, dowels, joints and other materials: Item Unit Description 526 Square Yard Reinforced Concrete Approach Slabs (Square Meter) 526 Square Yard Reinforced Concrete Approach Slabs with (Square Meter) QC/QA