1006DRILLED CAISSONS

.1 DESCRIPTION—This work is construction of reinforced cement concrete drilled caisson foundations consisting of shaft sections with or without casings left in place, and with or without rock sockets or belled footings, formed within drilled excavations. The following definitions apply:

rilled Caisson. Cast-in-place foundation element consisting of shaft section with or without enlarged bearing area at its base, a minimum of 30 inches in diameter, and deriving load capacity through load transfer to the bearing strata in side resistance, tip resistance, or a combination of both.

will stand open.

earing Strata. Layer(s) of soil or rock providing principal support of applied loads.

than 250 pounds per square inch that cannot be drilled with conventional earth augers or underreaming tools, thus requiring the use of special rock augers, core barrels, air tools, blasting, or hand excavation.

haft Section in Soil. Length of caisson shaft from top of shaft to top of rock stratum.

haft Section in Rock. Length of caisson shaft from top of rock stratum to top of rock socket.

ock Socket. Length of caisson in rock stratum below the shaft, providing a fixed connection between the caisson and the rock stratum.

ermanent Casing. Steel pipe, typically of cylindrical shape, installed by drilling, driving, or vibrating that when filled with concrete, becomes a permanent part of the drilled caisson.

emporary Casing. Protective steel pipe, typically of cylindrical shape, installed by drilling, driving, or vibrating, that provides lateral earth support during shaft excavation, cleaning, and inspection; controls groundwater infiltration; and is removed as part of the concrete placement operation.

bstruction. A natural or manufactured object above designated rock socket tip elevation that cannot be drilled with conventional earth augers or underreaming tools, and that requires the use of special rock augers, core barrels, air tools, blasting, or hand excavation.

lass A Self Consolidating Concrete (SCC) for Drilled Caissons and Sockets. Class A SCC typically consists of a mixture of Portland cement, supplementary cementitious material, fine aggregate, coarse aggregate, water, viscosity-modifying admixtures, air -entraining admixture with high range water reducing admixture, and other ASTM C494, TypeS admixtures. (l) Thermal Image Profiling (TIP). Used to measure the temperature profile within a deep foundatio n el ement constructed using cast -in-place concrete. The thermal profile induced by the curing concrete is used to evaluate the homogeneity and integrity of the concrete mass for the entire height and diameter of the caisson within the deep foundation element. TIP will also show misalignment of the reinforcement cage within the caisson.

rosshole Sonic Logging (CSL). Used to measure the propagation time and relative energy of an ultrasonic pulse between parallel access ducts installed in the drilled shaft. The velocity reduction is correlated to a concrete quality and is used as an indicator of the homogeneity and integrity of the concrete mass between the access ducts.

ubmersible Inspection Device (SID). An inspection device consisting of a digital video camer a and v ideo control housing unit used for inspection of the bottom of the drilled caisson excavation capable

of being submersed in water.

housing unit used for inspection of the sides of the drilled shaft excavation, or rock socket capable of being submersed in water.

1006.2MATERIAL—

withstand handling and installation stresses and the pressure of concrete, water, and the surrounding earth; and to prevent water seepage. Casing diameters refer to inside diameters subject to applicable API tolerances for steel pipe. Weld any required casing splices according to ANSI/AWS D1.1 with no interior splice plates, producing true and straight casing.

spirals as specified in Section 709.1(a)1. Use mechanical splice systems as specified in Section 1002.2(c).

slump of 5 inches to 8 inches.

Submit mix designs to the DME/DMM for review and approval . Use of an approved workability retention admixture is required to ensure slump flow is maintained throughout the duration of the concrete placement. For concrete placed in caissons containing 3 inches or more of standing water , utilize a mix design using an anti-washout admixture and/or a viscosity modifying admixture to achieve a cement paste loss of no more than 8.0% according to PTM No. 641. Take immediate corrective action whenever the slump flow range limit or action points are exceeded. Perform plastic SCC slump, air, and temperature tests on the first three consecutive trucks at the beginning of placement operations or after significant st oppage such as plant or equipment breakdown to determine if material control has been established. Material control is established when all test results of SCC slump, air, and temperature for three consecutive trucks are determined to be within the established action points.

TABLE A SCC Requirements Cement Section 701, Type(s) I, II, IP, or IS - Water Section 720.1 - Admixtures Section 711.3 - Supplementary Cementitious Material Section 724 - Cement Factor, Diameters ≤ 6'-0" 564 lb/cy - 752 1b/cy Note 1 Cement Factor, Diameters > 6'-0" 400 lb/cy min. (including supplementary cementitious material) Note 1 250 lb/cy min. of Portland cement - Maximum Water Cement Ratio 0.45 lb/lb - Minimum Mix Design Compressive Strength 7 day 2,750 psi - 28 day 3,000 psi - 28 Day Structural Design Compressive Strength 3,000 psi - Minimum Allowable Compressive Strength 2,500 psi - Fine Aggregate Section 703.1 - Coarse Aggregate Section 703.2 Note 2 Coarse Aggregate Volume 9.10 cf/cy - 13.43 cf/cy -

Column Segregation (Mix Design Phase) ASTM C1610, 12% max. (9% where gravels are used having a crushed fragment percentage less than 55% - Slump Flow Target ASTM C1611, 20 inches - 30 inches Note 3 Visual Stability Index (VSI) ≤ 1 Note 4 J Ring ASTM C1621 Note 5 Plastic Air Content Target 6.5% within a ± 1.5% tolerance during the work Note 6 Hardened Entrained Air 2% min. Note 6 Cement Paste Lost (Wash-Out) PTM No. 641, 8.0% max - Notes:

Section 704.1(g). The minimum percentages listed are required to be met when one or more of the aggregates have a linear expansion listed in Bulletin 14 greater than 0.10%: • Slag Cement, Grade 100 or 120, 25% min. • Flyash (Type F or Type C**) 15% min. (for flyash minimum cement content equal to 580 pounds per cubic yard. **Type C may be used provided alkali–silica reaction (ASR) is mitigated using additional Supplementary Cementitious Materials. • Silica Fume 5% - 10% • The total substitution of Portland cement must not exceed 50%, including the amount in the blended cement.

segregation testing performed during mixture qualifications does not exceed 9%. The requirement for meeting established Section 703 gradations do not apply if an optimized aggregate gradation is submitted and approved during the mix design qualification phase and controlled/verified during production according to an approved QC plan.

the slump flow test is less than the lower limit, reject SCC unless approved for vibration and is vibrated.

unless approved for vibration and is vibrated.

Method B and as indicated. Provide a sufficient quantity of thermal wires as indicated. If not indicated, provide quantity of thermal wires to achieve a distribution of one embedded thermal sensor for every foot of caisson diameter, with a minimum of four embedded thermal sensors, extending the full length of each drilled caisson. Provide wire length sufficient to be attached to readout boxes upon completion of concrete placement. Provide connection supplies and necessary splices. Provide sufficient data loggers to maintain readings on each thermal wire for 96 hours from the completion concrete placement. Provide and maintain functional TIP equipment. At a minimum, maintenance includes protection during use and repair/replacement of any damaged equipment. Maintain redundant equipment based on manufacturer’s recommendations. Provide equipment according to the approved TIP supplier and the following:

• Thermal Wires (as indicated)

• Wire splices

• Data Logger (one per active wire)

• Connection and charging wires

• Software (most recent version available at time of shaft installation)

testing equipment only when indicated, as needed, or as directed to verify the integrity and homogeneity of drilled caissons.

pipe access tubes. Provide one tube for every foot of caisson diameter, with a minimum of three tubes per caisson. Prepare access tubes according to ASTM D6760. Fit each tube with a watertight shoe on the bottom and a removable cap on the top. Use threaded couplings according to ASTM A865. Provide a threaded joint at the top for use during testing. Hydrostatic test requirements are waived. CSL access tubes are required in all caissons. CSL access tubes may also be used for performing TIP according to ASTM D7949, Method A, as required or directed.

minimum, include the following CSL equipment:

• Microprocessor-based CSL system for display of individual CSL records, analog- digital conversion and recording of CSL data, analysis of receiver responses and printing of CSL logs .

• Ultrasonic source and receiver probes for use in 2-inch ID pipe.

• Ultrasonic voltage pulsar to excite the source with a synchronized triggering system to start the recording system.

• Depth measurement device to determine and record depths.

• Appropriate filter/amplification and cable systems for CSL testing.

video camera and probing tool in a submersible housing and employs pressurized nitrogen gas and water to enable viewing of the bottom of the hole in murky conditions. Provide electrical power, lighting, cable connections, color monitor, audio and video recording system and any other necessary electronic devices required to document the inspection operation. Provide a probe inside the SID with a visible gauge, graduated in 0.25 inch increments or smaller, to measure the amount of sediment on the bottom of the rock socket shaft.

camera conforming to the following requirements:

• Color camera with supplemental dive lighting.

• Capability of recording at low light and/or in turbid water.

• Capability of tilting vertically and horizontally using motorized panning and tilting.

• Fits into a 2 3/4-inch diameter hole.

• Waterproof to a depth of 120% of the indicated drilled shaft length.

• A high-resolution color video and audio recording system, with microphone, mounting bracket, and sunshade.

• 7-inch LCD color monitor or better.

• Operating cable capable of holding 200 pounds.

• Compass Attachment.

• Winch Manual Emergency Hand Crank.

• Carrying case to hold the monitor, compass attachment, LCD screen, and camera.

• Capability to operate on rechargeable battery power for eight hours - Batteries and charger to operate the camera for eight hours.

• Depth readout.

• Cable protection from top of hole or casing friction.

• Centralizer assembly.

• Corrosion resistance.

1006.3CONSTRUCTION—

drilled caissons. Do not construct drilled caissons before review and acceptance of submittals.

the construction of drilled caissons, and meeting the following qualifications:

• Submit a list containing at least five projects that, together, demonstrate a minimum of 3 years of experience in the construction of drilled caissons, including the proposed method of concrete placement. Required experience is drilling, reinforcement installation, concrete placement , and all aspects of caisson construction . Include a brief description of each project, and the name and telephone number of owner’s representative knowledgeable in each project listed.

• Provide the name of the Professional Engineer registered in the State, directing the work , with at least 3 years of experience in the design and construction of drilled caissons.

• Provide names of drill operators and on- site supervisors under the direction of the Professional Engineer. Each drill operator and on- site supervisor must have at least 1 year of experience in the construction of drilled caissons.

• Furnish names and experience of those performing bottom inspections using the SID, with at least five projects that demonstrate proficiency in the performance of bottom inspections.

• Provide the names of personnel, consultant companies, and manufacturers to meet the requirements of this Section. Do not provide only company names of consultants or manufacturers.

available soil or rock samples. Prospective bidders are to contact the District Geotechnical Engineer to schedule a viewing of the subsurface information.

TIP testing, and CSL testing (as necessary) . Include a list containing at least five projects that, together demonstrate a minimum of 3 years of experience with TIP and CSL testing for drilled caissons. Include names and experience of specific representatives and their roles. Include a brief description of each project, and the name and telephone number of owner's representative knowledgeable in each project listed. Include the name and experience of the independent testing agency Professional Engineer registered in the State who will oversee the testing and sign and seal reports.

information:

• List of proposed equipment to be used on the project, including cranes, templates, drill rigs, drills, augers, concrete and rock socket core barrels/downhole hammers, bailing buckets, final cleaning equipment (including airlift/suction equipment), core sampling equipment, welding equipment, tremie, concrete pumps, casing, lifting ring and cradle, etc.

• Details of the overall construction operation sequence and the sequence of drilled caisson construction, including a specific planned schedule for caisson installation.

• Details and methods for locating and maintaining non-drilled and drilled caisson and casing position and alignment during excavation, inspection, and concreting operations, including curing and the use of temporary tool casing. Floating templates attached to a barge will not be allowed. Provide stable templates fixed directly to the ground (or streambed).

• Details and methods for caisson excavation.

• Details and procedures for the installation and removal of casing including details f or cutting off permanent casing. Include details of methods proposed to backfill any remaining annular space between the caisson and adjacent ground surface.

• Details of methods to mechanically clean the drilled caisson excavation, including airlift or suction methods.

• Details, methods, equipment for bottom inspections using the SID and downhole camera. Include SID and downhole camera for sign structure, sound barrier, and highway lighting caisson foundations only when indicated.

• Details of reinforcing cage fabrication and handling, lifting and installation along with methods and devices that will be used to center the reinforcing cage and maintain concrete cover .

• Details of methods for concrete mixing, transport and placement including operational procedures. Placement procedures should demonstrate that a continuous supply of concrete is provided to the finished elevation. Include procedure used to ensure that unsuitable concrete is removed by overfilling or other methods. Describe concrete placement and curing procedures to be used during hot/cold weather to protect and provide acceptable concrete. Provide a procedure and detail for an emergency cold joint.

• Details of methods to monitor and maintain concrete temperatures below 75F during concrete placement. Also, for drilled caissons larger than 5 feet in diameter, include methods to monitor and maintain the concrete at a minimum temperature of 50F and a maximum temperature of 150F during curing. Develop the placement method, taking into account water condition, set time and hydraulic pressures.

• Sample of proposed drilled caisson report, including log of materials encountered; sample of proposed test boring log , and sample integrity testing TIP and CSL logs. Provide caisson integrity testing for sign structure, sound barrier, and highway lighting caisson foundations operated by qualified individuals only when indicated.

• Welding procedures and qualifications of welders and tackers according to ANSI/AWS D1.1 for casing steel.

• Mix designs for concrete and non-shrink grout.

• For SCC, submit slump flow, VSI and J-ring tests with a trial mix as follows:

design. Ensure that it is at least 3.5 cubic yards in volume and prepared in a mixing truck.

temperature and concrete temperatures anticipated during concrete placement. Obtain the Representative's approval of the test temperature.

Concrete properties must be within specification limits.

Accepted procedures are subject to trial in the field. If the procedures fail to perform, this failure will not result in additional cost to the Department or relieve the Contractor of the responsibility to satisfactorily complete the work. Do not begin construction on work affected by the Drilled Caisson Installation Plan until approved. Delays caused by resubmission of the Drilled Caisson Installation Plan will be at no additional cost to the Department and with no extension of contract time. After approval of the installation plan, make no changes in the procedures without review and approval.

• Method for determining initial drilled caisson position and verticality, including the formed section, as well as method for monitoring and procedures for correction during excavation.

• Procedure for coring drilled caisson concrete.

• Methods and procedures for downhole inspection, including the use of downhole inspection camera, maintaining access for SID testing, TIP testing and for the use of CSL tests to verify the integrity of the caisson concrete.

• Include a plan and protocols to maintain continuous access for the Representative to observe TIP testing for the entire duration of the testing at each drilled caisson.

• Plan for compliance with applicable environmental regulations.

caisson construction after submittals are accepted and a minimum of 7 calendar days before beginning drilled caisson construction. D iscuss construction procedures, personnel, and equipment to be used. The following are required to attend: Project Superintendent, Drilled Caisson Superintendent, Testing Firm Representative, and other individuals designated by the Department. If key personnel change or if significant revisions to Drilled Caisson Installation Plan are proposed, an additional drilled caisson pre- construction meeting may be required at the discretion of the Representative.

drilling for rock sockets. The effective "top elevation" is based on observation of the boundary zone where broken or weathered rock becomes competent rock and is also influenced by the presence of any coal seams, which are not considered com petent rock. The top of the rock socket cannot be located within casing or within a coal seam. Competent rock is rock that cannot be drilled with conventional earth augers and/or under reaming tools and requires the use of special rock augers, core barrels, air tools, and/or other methods of hand excavation. Excavate to the dimensions and elevations indicated, or as directed. The estimated lengths indicated are considered to be approximate. Actual lengths and embedment will be verified by inspection. Additional shaft lengths may be required depending on actual subsurface conditions. Variations of indicated shaft lengths may only be constructed with the written approval of the Representative. Unless otherwise indicated, bore excavations for vertical caissons plumb to within a tolerance equal to 2% of the shaft length; and for battered caissons, as indicated, to within a tolerance equal to 5% of the shaft length but not more than 1 foot. If holes are more than 6 inches out of plumb, redesign the footing that is to be supported by the caissons. If caissons are out of tolerance, make needed corrections to the structure at no additional cost to the Department. Do not place the top of a caisson out of the indicated position by more than 1/24 of the shaft diameter or 3 inches, whichever is less. If belled footings are required, excavate to form a bearing area of the size and shape indicated. Do not disturb formations below or outside the limits

of the caisson under construction or any previously constructed caissons adjacent to the excavation. Blasting is not allowed. Provide excavation and drilling equipment with a capacity to excavate to a depth of 120% of the proposed drilled shaft length, but not less than 15 feet beyond the rock socket tip depths indicated. Submit the minimum output of the drill rig torque and crowd to the Representative. Do not excavate within three diameters of caissons with new concrete until 24 hours after concrete placement. If satisfactory foundation materials are encountered at other than the indicated elevations, adjust drilling depths as directed. Use permanent metal casing when indicated to prevent caving of the soil material, to exclude groundwater or surface water, and to form the non-drilled and drilled caisson, including the shaft section. Seal the casing a minimum of 2 feet into impervious materials and bedrock to create a tight seal. Use casing to control dimensions and alignment of excavations within tolerances and to execute other construction operations. If artesian water flow is encountered, extend the top of the casing to above the level required to achieve static water head conditions for proper placement of concrete. If a caving condition or excess groundwater is encountered, discontinue the drilling operation, and employ a construction method that prevents caving and groundwater infiltration, such as the installation of casings. Remove, as directed, caked material from the sidewalls and loose cuttings from the bottom of the excavation so that such material will not cause unanticipated settlement, reduce caisson capacity, or affect concrete strength. Do not expose the rock socket to water for more than 48 hours without approval. Ream rock socket exceeding 48 hours of water exposure, or that, as determined by the Representative, has deteriorated because of exposure to air or water, with an approved grooving tool to a depth of not less than 1/2 inch, or as directed. Reaming of the rock socket, if necessary, is incidental to drilling the rock socket. Unauthorized over -drilling, including the additional reinforcement and concrete resulting from over - drilling, will be at no additional cost to the Department. Promptly remove tools lost in the shaft during drilling and repair hole degradation caused by removal operations at no additional cost to the Department with no extension of contract time. Provide casing through soil and broken or unstable rock during hand cleaning and inspection of the excavation. If joining two or more sections of casing to obtain the required length, weld sections together as specified in Section 1105.03(m) to develop the full tensile strength of each section. Provide no interior splice plates. Maintain a log of excavation to complete the As-Built Record.

at each caisson location, to a minimum depth of 10 feet below the bottom of the excavation (caisson or rock socket), unless otherwise directed. Provide a PennDOT certified drilling inspector for this work. Advance a minimum of one test hole per substructure through overburden soil using continuous Standard Penetration Testing techniques. Begin test hole from the existing ground surface before site excavation. Advance additional test holes for other caissons at the same substructure locations using unsampled methods through overburden soils, unless otherwise directed. Begin coring at the top of bedrock (auger refusal) or the depth indicated or directed. Drill, log, store, and ship the samples according to the Department’s Standard Specification for Subsurface Boring, Sampling, and Testing, Publication 222. The Representative will use the samples to verify whether there is material of sufficient strength and thickness at the bearing elevations indicated to support the required load and for proper founding of caissons. Test holes will also be used to establish the presence of obstructions within the soil shaft of the caisson. Adjust depth or length of caisson shafts and/or rock sockets, as directed.

below the bottom of the excavation (caisson or rock socket), or as directed. The Representative will use the rate of drilling of the holes to determine whether there is satisfactory material or rock of sufficient thickness and type to support the required load, and to locate the presence of open joints, voids, soft rock, or other deleterious material that may be inadequate for support of the required load.

After completion of excavation and cleaning of the rock socket, perform required inspections and provide details of drilled caisson construction to the Representative for review. Inspect each drilled caisson excavation in the presence of the Representative. Check the dimensions and alignment of each drilled caisson for its full length, including the cased/ formed section and rock socket excavation us ing methods

indicated in this section or others approved by the Representative. Determine dimensions and alignment under the observation and/ or direction of the Representative. Measure the final drilled caisson depth (after final cleaning) using a weighted tape or other approved method. Record Caisson Bottom and Side Inspections. Provide a copy of recordings and field boring logs to the Representative within 7 calendar days of drilled shaft completion on flash drives or digital video disc (DVD) format compatible with Department approved software. Store and catalog flash drives or DVDs on-site in dust-free containers and label the project title, drilled shaft number, date, and other appropriate information. The Representative reserves the right to order an inspection dewatering and manual cleaning/inspection or by diving or other acceptable methods if the above- describe procedure does not obtain the appropriate information. Upon completion of each rock socket excavation and inspection, the Representative may accept the socket, or order deeper excavation. The adequacy of each rock socket will depend on the condition of its sides, bottom surface, and underlying layers. Concrete must be placed in the accepted drilled caisson within 18 hours of completion of excavation (including cleaning) and within 3 hours of final inspection.

inspection) using a SID according to the accepted Drilled Caisson Installation Plan and as directed. Use the SID water flushing jets to clean sediment from the rock as directed. Include SID for sign structure, noisewall and highway lighting caisson foundations only when indicated. Provide an approved, qualified individual to operate the SID and allow the Representative to visually evaluate the caisson bottom condition. Provide slack in line and ensure SID is fully seated on the bottom of the caisson before taking measurements of sediment. Using the SID, observe the bottom of the caisson at a minimum of five locations, including the center of the base and the 3, 6, 9, and 12 o'clock positions around the perimeter to verify cleanliness requirements are met. Locate perimeter positions approximately 1 foot from the wall of the socket. Based on the results of readings at these five locations, make additional observations at other locations as directed. Perform cleaning operations for the base of the rock socket so that, at the time of concrete placement, a minimum of 50% of the base of each socket will have less than 1/2 inch of sediment and the maximum depth of sediment or other debris at any place on the base of the socket cannot exceed 1- 1/2 inch.

using a downhole camera and/or other means considered appropriate by the Representative. Include downhole camera for sign structure, sound barrier, and highway lighting caisson foundations only when indicated. Using the downhole camera, observe the shaft and rock socket sides of the drilled caisson at a minimum of four locations, including the 3, 6, 9, and 12 o’clock positions around the perimeter to visually inspect the quality of the rock. Dewater or flush the drilled caisson with clean water to increase visibility as directed. Make additional observations as directed. Follow safety practices as specified in Section 107.08 and include, as a minimum, the following items specifically required for inspection of drilled caisson excavations:

• Cover open excavations immediately upon completion or, if work is discontinued for any period of time, with a cover capable of preventing persons from falling into or entering the excavation without proper authorization. Secure the cover by approved methods.

• Provide casing through soil cavities and broken or unstable rock for inspection of the excavation.

Provide a reinforcing cage that consists of longitudinal bars, spiral, hoop, or tie bars, cage stiffener bars, spacing devices, and any other appurtenances required to maintain alignment, shape, and clearances. Maintain an absolute minimum clearance of 5 times the maximum aggregate diameter between reinforcing steel, including spirals and hoops. Use concrete spacers or other approved non-corrosive spacing devices at sufficient intervals (within 5 feet of the top and bottom and at intervals not exceeding 10 feet along the length of the drilled caisson) to ensure concentric spacing for the entire cage length. Provide one centering device for each 36 inch of caisson perimeter but a minimum of four at each level. Install the indicated or required number of equally spaced steel tubes in the reinforcement cage for use in CSL testing. Install the indicated or required number of thermal wires to each drilled caisson reinforcement cage for use in TIP testing. Attach CSL access tubes and thermal wires according to the testing agency’s recommendations.

Provide testing agency(ies) representative(s) onsite during CSL access tube and thermal wire installation, reinforced steel installation, and concrete placement for the initial caisson construction. Use splicing methods for the reinforcement as indicated or approved. Tie intersections of drilled caisson reinforcing steel with cross or figure 8 ties. Tie and support reinforcing steel in the drilled caisson so that the reinforcing steel remains within allowable tolerances for position. Before placing the reinforcing cage, demonstrate to the satisfaction of the Representative that the fabrication and handling methods to be used will result in a reinforcing cage placed in the proper position, with the proper clearances, and without bending or racking of the reinforcing cage. Before installation of reinforcing steel cage, check and clean the cage of any materials that would prevent bonding. Immediately upon approval of the condition of the cage, acceptance of the rock socket, and just before placement of concrete, install the fully assembled cage into the hole. Use of a lifting ring and a rigid cradle is required to achieve full support of the cage. Place each cage as one unit by lowering into the hole in a manner that will prevent distortion. Remove cages distorted by placement and replace with a new approved cage. Remove internal stiffeners as the cage is placed in the caisson so there is no interference with the placement of concrete. Epoxy-coat reinforcing bars and steel centering devices. Support the cage from the top by use of a frame or other positive means. Place the bottom of reinforcing steel cage a minimum of 3 inches and a maximum of 6 inches from the bottom of the drilled caisson excavation. The Representative may approve additional clearance. Do not set the cage on the rock socket bottom without support. If the caisson has been excavated below the anticipated tip elevation, extend the reinforcing cage at the tip

Unless otherwise indicated or specified, place No. 6 deformed bars vertically around the circumference at a 6-inch spacing, and No. 4 bars as tie bars on 12-inch centers. Furnish bars with hooks meeting seismic requirements.

caisson excavation is considered dry if less than 3 inches of groundwater is present in the bottom of the excavation at the start of concrete placement and the groundwater infiltration rate is less than 1/4 inch rise per minute. Remove water that has accumulated in the excavation after final inspection and before concrete placement using approved methods.

barrier, and highway lighting caisson foundations. Use SCC for all other drilled caisson foundations. Before production placement of SCC, produce and transport a mock batch of not less than 3 cubic yards of SCC to the project for testing to verify plastic concrete test requirements will be met. The mock batch for previously approved SCC mixes may be eliminated b y the Representative. If the time between batches of concrete could exceed 30 minutes, submit a procedure to the DME/DMM before placement describing how the placed concrete will be evaluated to ensure the minimum slump value is maintained and the concrete does not reach initial set. Ensure uninterrupted delivery of concrete to avoid cold joints. Do not start production concrete placement without written acceptance. Place concrete within 18 hours of the completion of excavation, within 3 hours of final inspection approval and after the reinforcing steel cage has been installed in the shaft section and rock socket and is approved. Keep the excavation free from accumulated seepage water and loose material until concrete is placed. If the Representative determines that water seepage will be detrimental to the quality of the caisson or hinder proper placement of concrete by the free fall method , fill the excavation to the surrounding groundwater level with clean, fresh water and place concrete to the cutoff elevation by the tremie method, as specified in Section 1006.3(h)2, in one continuous operation. Mix, place, vibrate, and cure concrete as specified in Section 1001.3. Place concrete for each caisson in one continuous operation. Thoroughly work and vibrate the upper 5 feet of concrete. Vibration of the concrete is required unless the clear distance between bars is more than three times the bar diameter or three times the maximum aggregate size. Do not allow concrete to come in contact with aluminum during placement. Do not exceed 75F concrete placement temperature unless otherwise noted. For drilled caissons larger than 5 feet in diameter, maintain the concrete at a minimum temperature of 50F and a maximum temperature of 150F during curing.

unobstructed excavations that are at least 30 inches in diameter. Provide a hopper and a section of rigid pipe not less than 5 feet long and 10 inches in diameter to direct concrete fall and avoid impact with reinforcement on the sides of the excavation. Unless otherwise directed, limit depth of free fall to 25 feet. Do not place SCC by free fall method.

as specified in Section 1001.3(k)3.c. Place concrete using a tremie tube of sufficient length, height, and diameter to discharge concrete at the drilled shaft base elevation. Provide a tremie pipe with a minimum inside diameter of 10 inches to a maximum inside diameter of 18 inches and marked clearly on the outside at 1-foot intervals. Use a tremie pipe which is clean and watertight with smooth inside and outside surfaces to allow both flow of concrete and unimpeded withdrawal during concreting. Provide a tremie pipe that does not crimp or restrict the flow of concrete. Test the tremie tube joints for water tightness in the presence of the Representative before using it for concrete placement using a method acceptable to the Representative. Do not begin concrete placement until the tremie tube is placed at the bottom of the caisson. Valves, bottom plates, or plugs may be used only if concrete discharge starts within approximately 2 inches above the excavation bottom. Provide plugs that either can be removed from the excavation or of an approved material that will not cause defects in the drilled shaft if not removed. Once the tremie flow begins, set the tremie tube on the bottom of the caisson and allow the tremie tube to completely fi ll with concrete. Once full then raise the tube and begin placing the concrete. Place concrete for each caisson in one continuous operation. Pumping of concrete into the drilled caisson will not be allowed, but concrete may be pumped to the tremie. Thoroughly work the concrete. Provide documentation to satisfactorily demonstrate experience in the use of the tremie method. Construct the discharge end of the tremie pipe to allow the free radial flow of concrete during placement operations. Maintain the tremie pipe discharge end at or near the bottom of excavation as long as practicable during concrete placement. Maintain the tremie discharge end immersed as deep as practicable in the concrete, consistent with the approved construction methods, and at least 5 feet but not more than 20 feet in concrete after starting the flow of concrete. Maintain a continuous flow of concrete. Maintain the concrete in the tremie at a positive pressure differential to prevent water intrusion into the concrete. The entire drilled caisson will be considered defective if at any time during concrete placement, the tremie pipe orifice is removed from the fluid concrete column and discharges concrete above the rising concrete level or it is found that the tremie pipe is not watertight. In such case, remove the reinforcing cage and concrete, complete necessary rock socket sidewall removal as directed, and reconstruct the drilled caisson at no additional cost to the Department. Overflow the concrete until only fresh, uncontaminated concrete is visible at or above the indicated top of caisson elevation, as determined by the Representative. Completely remove overflow concrete. Use tremie method to place SCC under all conditions.

means. Place concrete by pumping, as specified in Section 1001.3(k)4, through a flexible; ferrous metal, rubber, or plastic pipe with a minimum diameter of 6 inches. Do not allow the concrete to segregate during pumping. If directed, pump 1 cubic foot of concrete into a container so that the Inspector may verify that the concrete is not segregating during the pumping operation. Begin pumping with the pipe discharge positioned not more than 6 inches off of the bottom of the excavation. Maintain a concrete head of not less than 5 feet above the discharge. Keep the pump hopper continuously filled with concrete to prevent entrapment of air in the discharge.

in dewatered excavations supported by casing. Pump Class A cement concrete within casing only if placement cannot be done by other means. Use the tremie method to place Class A cement concrete under water in casing supported excavations. Use tremie method to place SCC under all conditions. If the top of shaft elevation is below ground level at the time of concrete placement, provide an oversized casing from ground elevation to a point below the top of shaft to prevent extraneous material from falling into fresh concrete during and after placement. Keep the oversized casing in place until concrete has cured at least 24 hours. For permanently cased drilled caissons that carry lateral loads, grout the area between casing and excavation to provide adequate bearing.

5.a Before placement of SCC, obtain acceptance of a Field Operation QC Plan as specified in Section 704.1(d)1.a.

5.b Provide a Concrete Field Testing Technician as specified in Section 704.1(d)2 during placement of concrete to perform the required acceptance testing.

5.c Conduct concrete tests as specified in Table A.

admixtures may be added in the field following the manufacturer’s recommendations. Submit a QC plan for acceptance. Clearly identify the process for incorporating the admixtures in the field in the QC Plan and include a personnel matrix listing names and titles of individuals involved in the field addition process. A representative of the admixture supplier is required to be onsite during the mock batch and initial production placement.

a minimum of four concrete test cylinders for each lot placed. Mold additional test cylinders for Department acceptance testing if directed. Test cylinders according to PTM No. 604. Match-mark test cylinders with the lot represented. Record test results and give records to the Representative.

and projections. Do not add water or curing agents to the concrete surface to assist in finishing. Ensure the top elevation of the caisson is within plus 1 inch or minus 3 inches of the indicated top elevation.

partial stages, as concrete is deposited, at a rate that keeps the bottom of the casing below the top of the fresh concrete. During removal, ensure that there is no reduction in shaft cross -section and that displacement of steel reinforcement is less than 2 inches upward and less than 2 inches downward per 20 feet of shaft length. Maintain the specified 3 inch reinforcement bar clearance at bearing level and on the sides during casing removal. If observations indicate otherwise, reduce the rate of casing removal and establish a head of concrete within the casing sufficient to offset the forces tending to cause concrete arching or displacement of the reinforcing cage. As concrete is deposited, withdraw the final section of casing to a point 2 feet below existing ground elevatio n and allow it to remain for approximately 2 hours, depending on the temperature. Then, completely withdraw the section or cut it off flush with existing ground. If cavities or unstable materials are encountered and the danger exists of losing concrete or of the concrete becoming mixed with extraneous material, cut off the casing at the top of shaft elevation and leave in place. When temporary casing is used to form caisson above the ground surface or in open water, remove the casing at the prescribed elevation after the drilled caisson has been completed and the concrete has attained sufficient strength so as not to be damaged as specified in Section 1001. If split casings, forms or other special casing systems are proposed for use in open water, design the casing or forms to be watertight and to prevent damage to the finished concrete during their removal.

and homogeneity of each drilled caisson. If an equipment malfunction occurs, there is a loss of data, or other conditions that results in a failure to produce acceptable TIP data, perform CSL Testing at no additional cost to the Department. Retain a qualified independent testing agency(ies) to perform TIP testing according to ASTM D7949, and CSL testing according to ASTM D6760. Prepare and label thermal wires and CSL tubes according to the respective ASTM standards as if both tests were required. Provide caisson integrity testing for sign structure, sound barrier, and highway lighting caisson foundations operated by qualified individuals only when indicated. Log TIP data for a minimum of 96 hours immediately following concrete placement at each drilled caisson. Provide safe and secure access for the Representative and TIP testing agency representative during TIP data logging at each drilled caisson.

Submit TIP reports and evaluations to the Representative within 5 calendar days of completion of TIP testing at each caisson. The TIP results will determine conformance with diameter and quality requirements or if additional testing is necessary. If the Representative does not accept the drilled caisson based on the TIP test results , or if the TIP method fails to produce acceptable data, perform CSL testing to evaluate the quality of the drilled caissons. Do not perform CSL testing until a minimum of 96 hours after concrete placement, but before 10 calendar days after placement. Do not perform CSL testing until the concrete has gained sufficient strength for a satisfactory test. Perform CSL testing in the presence of the Representative. Submit CSL reports and evaluations to the Representative within 5 calendar days of completion of CSL testing at each caisson tested. The CSL results will then be used to determine the integrity and acceptability of each drilled caisson tested. CSL is backup testing and is incidental to TIP testing.

minimum, include the following in the report:

• Date of test.

• Description of the testing apparatus unit and probes.

• Identification of testing agency and person responsible for the validity of the test report.

• Identification and location of shaft.

• As-built geometry of shaft including nominal and/or actual diameter and length.

• Arrangement and identification of access tubes and wires, relative separation of tubes and wires, and identifying designation documentation.

• Documentation of water removal and replacement in access tubes, if applicable.

• Thermal profiles including the access location for each profile with temperature and depth axes and scales allowing clear data interpretation (TIP).

• Report any failure of the probes to penetrate the full depth of the access tubes (CSL, if applicable).

• Initial pulse arrival time or compression wave velocity versus depth (CSL, if applicable).

• Pulse energy/amplitude versus depth (CSL, if applicable).

• A log that presents results for each tube/wire pair tested with any anomaly/defect zones indicated on the log and discussed in the report as appropriate.

• Analysis, evaluation, and summary of any defect zones indicated on the logs with recommendations regarding acceptability and soundness.

reports and other information on the drilled caisson construction, the Representative will decide if each drilled caisson is accepted. The Representative may allow the construction of additional drilled caissons to continue before acceptance of the completed drilled caisson, if observations of the drilled caisson construction, integrity testing, and other information are satisfactory. Acceptance criteria of the drilled caisson based on the test results will be determined by the Representative according to guidance set forth in FHWA Publication No. FHWA-NHI-18-024 dated September 2018.

anomalous. Anomalies identified by the TIP results will require further investigation. Perform CSL testing or core drilling as further investigation methods.

• A Good test cannot exhibit reductions in relative velocities of greater than 10% and cannot exhibit any reductions in relative signal strength energies of greater than 6 dB. These caissons are accepted provided that no other indicators of potential defects have been identified by other means or test methods.

• A Questionable test exhibits a reduction in relative velocities of greater than 10% but less than 20%, or a reduction in relative signal strengths of greater than 6 dB but less than 9 dB. In no case can the reduction in relative velocity exceed 20%, nor can the reduction in relative signal strength exceed 9 dB. Submit for acceptance, sufficient justification with supporting evaluation, analysis, or testing . The Representative reserves the right to reject the caisson based on CSL or other non- destructive testing and subsequent justification, and to require additional analysis and/or testing, or verification by core drilling.

• A Poor test exhibits a reduction in relative velocities greater than 20%, or a reduction in relative signal strengths of greater than 9 dB. These caissons will be rejected and require verification by core drilling.

If the review of the caisson integrity test results determine that a drilled caisson is acceptable, dewater the tubes at the accepted caisson location and fill with non-shrink grout having a strength equal to or greater than the 28-day compressive strength of the concrete used in the caisson.

test results and/or other non-destructive testing, verify the drilled caisson conditions using concrete coring. Core drilled caissons using HQ double-tube core barrels, with a split inner barrel, to core drilled caissons that have been rejected. Provide a PennDOT certified drilling inspector for this work. Drill one or more core holes at the location(s) determined by the Representative. Adjust coring procedures and the length of coring to maximize recovery and quality of cored material. Provide continuous core sampling. Keep an accurate log of the core and box and properly mark the core according to Publication 222, showing the drilled caisson depth at each interval of core recovery. Submit the core and Field Inspector’s Boring Log within 24 hours of the completion of the coring. If the quality of the caisson, as represented by the core samples, is determined to be acceptable by the Representative, grout the hole using tremie procedures with non-shrink grout having equal to or greater strength than the concrete used in the caisson, before proceeding with further construction. If testing and inspection of cores indicates that concrete meets specifications, coring and grouting will be paid for as specified in Section 1006.4(i). If a defect is confirmed, investigative coring will be at no additional cost to the Department . Submit a corrective action plan for repair for approval. Engineering evaluations and any modifications to the drilled caisson and load transfer mechanisms caused by the repair will require calculations and working drawings stamped by a Professional Engineer registered in the State for foundation elements affected. Do not begin repairs until notified that the proposed corrective action plan is approved by the Representative. Provide test data on the repaired drilled caisson that confirm the integrity of the repair. Perform corrective action engineering, evaluation, design, repairs, and provide test data on the repaired caisson at no additional cost to the Department with no extension of contract time. If this information is not sufficient for a proper judgment, the Representative will reserve the right to order an inspection by other methods either through a separate specialty subcontractor or through the Contractor at no additional cost to the Department with no extension of contract time.

following information:

• Accurate location and dimensions of the excavation.

• Accurate top and bottom elevations.

• Measurement data for plumbness.

• Methods of excavation used.

• Description of materials encountered during excavation.

• Description of groundwater conditions encountered.

• Description of obstructions encountered and whether or not obstruction removal was achieved.

• Description of temporary or permanent casing placed including purpose, length, and wall thickness, and anchorage or sealing methods used, if any.

• Elevation at which the top of rock was encountered and description of rock.

• Elevation at which bearing material was encountered. Description of bearing material. Probe holes made, along with method of probing, rate of drilling in rock, samples taken, tests made, and conclusions reached regarding adequacy of bearing material.

• Shaft, bell footing, and rock socket measurements.

• Downhole camera inspection data.

• Description of clean-out methods, adequacy of initial clean-out, and final clean-out just before concrete placement.

• Record of depth of water in excavation and rate of water infiltration before concrete placement.

• SID inspection data.

• Record of reinforcing steel inspection for position and adequacy.

• Method of concrete placement and casing removal, if any. Record of concrete head and elevation during removal of casing. Record of concrete elevation when vibration started. Also, include when temporary casing was removed from hardened concrete.

• Difficulties encountered including soil inclusion, voids, shaft squeeze-in, and casing collapse.

• Concreting curves showing actual versus theoretical volume of concrete required to fill caisson excavation. Concrete curing details. Concrete strength test results. Include volume of concrete placed to the bottom of permanent casing, top of permanent casing, and top of the drilled caisson.

• Condition of concrete delivered to site including record of slump, density, air content, and other tests. Record of cylinders made for compression testing.

• TIP results.

• CSL results, if applicable.

• Core drilling logs and photographs of core samples.

• Any deviations from the specifications.

1006.4MEASUREMENT AND PAYMENT—

Measured from the shaft top to the top of rock.

Measured from the top of rock to the shaft bottom.

Measured from the shaft bottom to the socket bottom. For uneven rock surfaces, measure length of rock excavation from the rock surface at shallowest depth to the socket bottom.

The Department will measure and pay for temporary casing left in place, as specified in Section 1006.3(i), as permanent casing.

Augering through overburden, from existing ground surface to the elevation at which NW (NX) core boring is to begin (bottom of caisson or rock socket excavation as specified in Section 1006.3(c)), is incidental to this work.

The unit price includes mobilization of drilling equipment.

The unit price for each drilled caisson includes work associated with the TIP test and reporting. Grouting of access tubes is incidental to this item.

The unit price includes drilling, inspection, and reports. HQ coring will only be paid if quality of the caisson, as represented by the core samples, is determined to be acceptable. Grouting of cored concrete is incidental to this item.