Part 1 — General
1.1 Section Includes
A.Drilled shafts for bridge, overhead sign/VMS, and general structure foundations
B.Integrity testing
1.2 Related Sections
A.Section 03055: Portland Cement Concrete
B.Section 03211: Reinforcing Steel and Welded Wire
C.Section 03310: Structural Concrete
D.Section 03390: Concrete Curing
E.Section 03924: Structural Concrete Repair
1.3 References
A.AASHTO M 31: Deformed and Plain Carbon and Low -Alloy Steel Bars for Concrete Reinforcement
B.ASTM A 706: Deformed and Plain Low -Alloy Steel Bars for Concrete Reinforcement
C.ASTM C 1107: Packaged Dry, Hydraulic -Cement Grout (Nonshrink)
D.ASTM D 6760: Integrity Testing of Concrete Deep Foundations by Ultrasonic Crosshole Testing
E.ASTM D 7949: Thermal Integrity Profiling of Concrete Deep Foundations
1.4 Definitions
A.Contaminated Concrete – Concrete where localized mix proportions have been changed by the placement process, such as with excess water or segregation; or concrete containing unintended materials, such as soil or rock from the excavation.
B.Crosshole Sonic Logging (CSL) – Non-Destructive Testing (NDT) method to measure uniformity and integrity of the concrete in deep foundations through use of measured ultrasonic pulses between parallel CSL pipes.
C.Centralizer – A device attached to the reinforcing steel cage to maintain an offset distance between the reinforcing steel and the wall of the drilled shaft hole.
D.Oversized Drilled Shaft – A drilled shaft foundation that is larger in diameter than the supported column and that has a reinforcing steel cage larger than and independent of the column’s reinforcing steel cage.
E.Shaft Inspection Device (SID) – Instrumentation used to inspect the bottom of drilled shaft hole
F.Thermal Integrity Profiling (TIP) – Non-Destructive Testing (NDT) method to measure uniformity and integrity of the concrete in deep foundations through temperature measurements associated with the heat of hydration generated by concrete as it cures.
G.Thermal Wire Cable – A series of thermal sensors and wires arranged to position sensors at specific depths along the length of the drilled shaft. The cable is connected to a recording apparatus to collect thermal data for reporting.
1.5 Submittals
A.Drilled shaft contractor qualifications for review. Include the following:
1.A list of at least three projects completed in the last three years in which the drilled shaft contractor has installed drilled shafts of a diameter and length similar to those shown, and in similar subsurface conditions
a.Include names and phone numbers of owner’s representatives who can verify the drilled shaft contractor’s participation on the listed projects.
2.Name, contact information, and experience record of the drilled shaft superintendent who will be in charge of drilled shaft operations for this project
a.Include responsibilities as a supervisor on at least three of the listed projects.
3.Drilled shaft contractor’s quality control methods to verify that shafts are installed according to this Section
B.Drilled Shaft Installation Plan for review. Include at least the following:
1.Equipment to be used, such as cranes, drills, augers, bits, tremies, concrete pumps, casings, and inspection devices
2.Construction operation sequence
3.Methods to excavate and clean the shaft holes
a.Provide provisions to verify required final shaft cutoff elevation.
4.Methods to maintain drilled shaft hole stability during excavation and concrete placement
a.Include at least the following where casing is provided: 1) Casing details, size, length, materials, and thickness 2) Description of the method of advancing the casing
b.Provide specifications, procedure, and example inspection report for SID to be used.
5.Details of reinforcing steel placement including support and centralization methods
6.Details of concrete placement, curing, and protection, including concrete placement times
a.Use a concrete mix that is compatible with placement methods.
b.Describe the method to maintain the concrete slump to keep it workable, for example, admixtures such as retarders or high range water reducers.
c.Description of the method to place concrete under water, where encountered
C.Containment and Disposal Plan for review
1.Include the proposed methods to dispose of drilling spoils and to contain and dispose of water if encountered
D.Drilled Shaft Integrity Testing Plan for review, when integrity testing is required. Include at least the following:
1.Method to be used: CSL or TIP
2.Independent integrity testing organization’s qualifications
a.Provide a list of at least three projects completed in the last three years in which the integrity testing organization has tested drilled shafts of a diameter and length similar to those shown, and with the same testing method to be used
3.Testing procedures and equipment specifications
4.Materials, length, and connection details
5.Installation details
E.Construction documentation for information
1.SID inspection reports when SID is required
a.Include recordings from the SID inspections 1) Include the date of recording, shaft number, and camera position in the recording.
2.Drilled shaft construction logs
a.Use the “Drilled Shaft Construction Logs” template found at the Department’s website for each shaft. 1) Refer to http://www.udot.utah.gov/go/standardsreferences .
b.Include drilled shaft excavation log and drilled shaft concrete placement log for each shaft.
F.Integrity testing reports for review within seven calendar days, when integrity testing is required 1. Submit report within three calendar days of integrity test if test results identify substandard concrete integrity, anomalies, or are inconclusive.
2.Include at least the following:
a.Test results
b.Drilled shaft location, details, layout of testing equipment, date and time of test
c.Logs showing initial pulse arrival time, and energy/amplitude versus depth for each pipe pair tested for CSL testing
d.Logs showing temperature measurements versus depth for each thermal wire cable, and the average temperature of all thermal wire cables for TIP testing
e.Zones of substandard integrity in the logs
f.Recommendations for additional NDT if test results are inconclusive
3.Provide interpretation and analysis of the recorded measurements by a Professional Engineer (PE) or Professional Structural Engineer (SE) licensed in the State of Utah having at least three years of experience in the interpretation of CSL/TIP results
a.Provide the seal of the PE or SE on the report.
1.6 Acceptance
A.The Department may accept drilled shafts at a reduced price when the concrete compressive strength is less than the specified 28- day minimum compressive strength. Refer to Section 03055.
1.The Department applies the pay factor for 28 -day compressive strength to the measured length of each shaft containing concrete with tested strength less than the specified compressive strength.
B.Drilled shafts will be accepted based on the integrity testing results when required, meeting construction tolerances, and other construction documentation.
1.NDT methods may be used to evaluate possible shaft defects, such as Single- hole Sonic Logging, Gamma- Gamma Nuclear Density Logging, 3D Tomography, and surface Sonic Echo and Impulse Response tests.
a.The Contractor is responsible for the costs of NDT testing
b.Provide a NDT testing firm or consultant experienced and competent in the chosen NDT methods.
2.The Engineer may require coring of the shaft to verify shaft conditions if the integrity testing and NDT results are inconclusive.
a.The Contractor is responsible for coring costs, including grouting of core holes.
Part 2 — Products
2.1 Concrete
A.Class A A(AE) unless shown otherwise. Refer to Section 03055.
1.Provide target slump of at least 6½ inch.
2.Modify as follows when placed under water:
a.Use high range water reducers.
2.2 Reinforcing Steel
A.Vertical bars 1. Overhead sign/VMS structure foundations
a.Use coated bars meeting AASHTO M 31, Grade 60. Refer to Section 03211.
2.Oversized drilled shaft foundations
a.Use uncoated bars meeting AASHTO M 31, Grade 60. Refer to Section 03211.
3.Other foundations
a.Use uncoated bars meeting ASTM A 706, Grade 60. Refer to Section 03211. 1) Bars meeting AASHTO M 31, Grade 60 may be substituted if they meet the ductility requirements of ASTM A 706.
B.Spiral bars
1.AASHTO M 31, Grade 60. Refer to Section 03211.
a.Use coated bars in overhead sign/VMS structure foundations.
b.Use uncoated bars in other drilled shaft foundations.
2.3 Casings
A.Use smooth and clean, non- corrugated steel casings.
B.Provide casing with sufficient strength to withstand handling, driving stresses, and loads from earth and wet concrete.
C.Size the casing to have an inside diameter of at least the diameter of the drilled shaft as shown, but not more than six inches larger.
2.4 Equipment
A.Use drilling equipment capable of drilling holes to the required diameter, location, alignment , and to a depth of at least 10 ft beyond the depths shown, in the type of materials present at the shaft locations.
B.Use equipment capable of installing and removing casing.
C.Use SID capable of providing underwater video inspection to determine cleanliness of bottom of shaft excavation when required. SID must include at least the following:
1.A camera sealed inside a watertight jacket
2.A probe to measure the amount of loose or disturbed material at the bottom of the drilled shaft hole
3.A recording device capable of documenting the SID inspection
D.Use lifting equipment capable of placing the full length of the reinforcing steel cage into the drilled shaft.
E.Use concrete pumping equipment capable of pumping at least 50 yd3/h against a 20 ft head of concrete measured from the discharge end of the pump hose extension of the tremie pipe when placing concrete underwater.
1.Use a rigid steel pipe pump hose extension for the tremie pipe with tight couplings straight to within ½ inch in 10 ft.
a.Length of extension – At least the depth of the shaft.
b.Inside diameter – Greater than or equal to the concrete pump discharge hose but not more than one half the inside diameter of the reinforcing steel cage.
F.Use core drilling equipment in good condition and capable of delivering a smooth flow of power to the bit, both in rotation and down thrust.
1.Use a positive displacement typ e pump, capable of delivering at least 15 gallons of water per minute at 200 psi. a. Equip pump with a relief valve set to release at a maximum of 200 psi, and equipped with a pressure gauge ranging from 0 psi to 1,000 psi.
2.5 Non- Shrink Grout
A.Refer to ASTM C 1107.
2.5 Concrete Repair Mortar
A.Use ASTM C 928 Type R3 concrete repair mortar according to Section 03924.
Part 3 — Execution
3.1 General
A.Follow the authorized Drilled Shaft Installation Plan and Containment and Disposal Plan. Follow the authorized Drilled Shaft Integrity Testing Plan when applicable.
B.Begin installation of drilled shafts after embankment is placed and compacted.
C.Form drilled shaft to at least 12 inches below finished ground surface where top of shaft elevation is above finished ground surface.
D.Refer to Section 03310 for forms, form removal, and construction joints.
3.2 Drilled Shaft Holes
A.Excavation
1.Drill straight, vertical holes to the tip elevations shown or as determined by Engineer.
2.Do not use slurry or rely on water for drilled shaft hole support during drilling operations.
3.Do not begin drilling for a shaft located three diameters center to center , or closer , to an adjacent completed shaft until at least 48 hours after placing concrete for the completed shaft .
4.Do not begin drilling for a shaft located between three and five diameters center to center from an adjacent completed shaft until at least 24 hours after placing concrete for the completed shaft.
5.Drill hole in a continuous operation without interruption.
a.Notify the Engineer and protect the drilled shaft hole if the excavation operation is stopped. 1) Install a safety cover. 2) Use a temporary casing to protect the safety of the shaft excavation, surrounding soil, adjacent facilities, and stability of the sidewalls. 3) The Engineer will evaluate design impacts to the shaft due to delays in completion.
6.Provide a clean, flat, and level bottom surface.
a.Remove loose material from the bottom of the drilled shaft holes before placing concrete.
b.Use an SID when shown. 1) Remove loose or disturbed material until at least 50 percent of the bottom of each drilled shaft hole has less than ½ inch of loose or disturbed material. 2) The maximum depth of loose or disturbed material at any location is 1 inch.
B.Casing
1.Drill or oscillate casing to provide direct contact with the soil throughout its length
2.Furnish and place temporary casing when necessary to prevent the drilled shaft hole from caving
a.Full length casings are required where groundwater is present
b.Have f ull length casings on site where groundwater is anticipated
C.Spoils
1.Drilling spoils and their disposal are the responsibility of the Contractor.
3.3 Construction Tolerances
A.Plan location
1.Top of shaft within 3 inch horizontally of plan.
B.Alignment
1.Not more than 2 percent (1:50) from vertical .
C.Reinforcing steel cage
1.No more than 2 inch above or below the plan elevation.
3.4 Reinforcing Steel Placement
A.Verify bottom cleanliness in the presence of the Engineer immediately before placement of the reinforcing steel.
1.Use an SID when shown .
B.Rigidly brace the reinforcing steel cage with additional reinforcing steel as needed to retain its configuration during handling and installation .
1.Do not use loose bars.
2.Provide an opening in the center of the cage to allow tremie access.
3.Use centralizers to maintain reinforcing steel cage position in drilled shaft hole.
4.Pick cage in several locations as necessary to maintain cage shape and alignment during placement.
C.Protect integrity testing instrumentation from damage during installation, handling and construction.
1.Do not allow temporary bracing to free- fall when cut loose.
D.Rigidly brace column reinforcing steel cage projecting above the top of drilled shaft, if applicable.
3.5 Miscellaneous Embedded Element Placement
A.Securely position anchor bolts, anchor bolt templates, and conduit, if applicable.
3.6 Concrete Placement
A Dry Hole Placement
1.Place concrete immediately after placing the reinforcing steel cage.
a.Begin concrete placement within 16 hours of completion of drilling the shaft hole.
b.Place concrete in a continuous operation.
2.Use a tremie or spout to prevent concrete from striking the reinforcing steel cage .
a.Do not allow the free- fall of concrete to exceed 5 ft.
3.Vibrate the concrete within at least 10 ft from top of shaft .
4.Remove contaminated concrete from the top of the shaft.
a.Remove and dispose of muck, laitance, and contaminated concrete.
B.Water In Hole Placement
1.Place concrete immediately after placing the reinforcing steel cage.
a.Begin concrete placement within 16 hours of completion of drilling the shaft hole.
b.Place concrete in a continuous operation.
2.Use a tremie to place concrete .
a.Purge the tremie pipe of water. 1) Insert a sturdy plastic ball or equivalent into the top of the pump hose extension before connecting the hose from the concrete pump. 2) The ball must fit snugly into the pump hose extension when the hose is filled. The hose must be strong enough to resist rupture. 3) Prime the hose and pipe with cement slurry .
3.Lower a small diameter pole with an attached flat plate into the hole to determine the top surface of concrete.
a.Mark b oth pole and tremie pipe so that the length of penetration can be immediately determined.
b.Prevent the end of the tremie pipe from becoming plugged with soil from the bottom of the hole.
4.Begin pumping the concrete immediately after setting the reinforcing steel cage and tremie pipe in the hole.
a.Do not begin raising the tremie pipe until the concrete surface is 10 ft above the bottom of the pipe .
5.Keep the bottom of the tremie pipe at least 5 ft below the top of the concrete until the placement is complete.
a.Provide a positive hold down to maintain distance below top of concrete if the pipe floats .
6.Remove casing as the concrete is placed.
a.Keep the bottom of the casing between 5 ft and 8 ft below the top of the concrete surface when withdrawing.
b.Prevent concrete separation when withdrawing the casing.
7.Do the following if the tremie pipe plugs, equipment breaks down or loss of the seal at the end of the tremie pipe occurs:
a.Pull the tremie pipe, reset it 2 ft below the top of the concrete, and purge it.
b.Lower the tremie pipe to at least 5 ft below the top of the placement and continue pumping concrete until all contaminated concrete has lifted to the top of the shaft.
8.Continue pumping concrete until the water and contaminated concrete is expelled.
a.Remove and dispose of muck, laitance, and contaminated concrete.
C.Finishing
1.Remove scum, laitance, loose gravel, and sediment from the surface of the shaft concrete before finishing.
a.Do not permanently cover or impede access to the top of the drilled shaft until authorization of integrity test report is received.
2.Level high spots from the surface of the shaft concrete that would make placement of steel reinforcing as shown more difficult.
3.Cure exposed concrete according to section 03390.
3.7 Integrity Testing
A.Perform integrity testing on drilled shafts as shown.
B.Crosshole Sonic Logging
1.General Requirements
a.Meet the requirements of ASTM D 6760.
b.Conduct CSL testing no sooner than 72 hours after concrete placement and as recommended by the CSL testing organization. 1) The Engineer may require a longer time if special retarders, mix designs, or other factors result in slower -setting concrete.
c.Notify the Engineer immediately if integrity testing indicates substandard concrete integrity or shows inconclusive results .
2.CSL Pipe Preparation
a.Use Schedule 40 steel pipes with an inside diameter of 1½ inch to 2 inch that are compatible with the equipment and methods of the CSL testing organization. 1) Do not use galvanized steel. 2) Provide pipes with a round, regular internal diameter free of defects or obstructions. 3) Provide pipes that are watertight and free from corrosion with clean internal and external faces . 4) Use threaded pipe joints with watertight couplings for pipe extensions. a) Do not wrap joints with tape or other compounds. 5) Fit pipes with a watertight shoe on the bottom and a removable cap on the top.
b.Space CSL pipes equally around the inside of the reinforcing steel cage: 1) Shafts with diameters up to 48 inch a) Install four pipes 2) Shafts with diameters greater than 48 inch a) Install one pipe for each foot of diameter rounding up 3) Position pipes parallel to each other and at least 3 inch clear to longitudinal reinforcing. a) Bundle the CSL tube with the nearest longitudinal reinforcement where the drilled shaft reinforcement prevents this minimum clear spacing, .
c.Attach the pipes securely to the interior of the reinforcement cage. 1) Wire-tie to the reinforcing steel cage at least every 3 ft, or as required for the pipes to stay in position during placement of reinforcing cage and concrete.
d.Extend the pipes from 6 inch above the bottom of shaft to at least 3 ft above the top of shaft, or if the shaft top is subsurface, at least 3 ft above the ground or water surface. 1) Do not allow the pipes to rest on the bottom of the drilled shaft hole.
e.Fill the pipes with clean, potable water as soon as possible after placement of the reinforcing steel (no later than four hours after placement) and cap or seal the pipe tops to keep out debris. 1) Use an ethylene glycol mixture instead of water i f shaft construction occu rs during winter months and the air temperature near the exposed pipe ends is expected to drop below 30 degrees between the time of concrete placement and the authorization of the integrity test report. 2) Avoid excessive torque, hammering, or other stresses which could break the bond between the tubes and the concrete when removing caps or plugs fr om the pipes after concrete placement.
3.Maintain the CSL pipes until sealing is authorized
a.Replace the removable cap after testing as the integrity test report may identify need for further testing or testing after repair of identified defects.
4.Sealing CSL pipes
a.Remove the tops of CSL pipes a fter the integrity test report has been authorized, required repair of defects has been completed, and the shaft has been repaired to the Engineer’s satisfaction, as follows: 1) Shafts where the supported structure provides at least 3 inch of permanent concrete cover over the top of the shaft across its full diameter a) Cut off the CSL pipes flush with the top of the drilled shaft. 2) Shafts where the supported structure does not provide at least 3 inch of permanent concrete cover over the top of the shaft across its full diameter a) Remove the tops of the CSL pipes to 3 inch below the top of the drilled shaft.
c.Dewater and fill the CSL pipes with non- shrink grout to 3 inches from the top of the pipe. 1) Mix grout to a flowable consistency according to the manufacturer’s instructions.
d.Use concrete repair mortar to provide 3 inch permanent cover over the cut end of the CSL pipe after the grout sets . 1) Place mortar to the level of the concrete surface + 1/8 inch. 2) Follow the manufacturer’s recommendations for finishing and curing.
C.Thermal Integrity Profiling
1.General Requirements
a.Meet the requirements of ASTM D 7949, Method B: Embedded Thermal Sensors.
b.Conduct TIP testing near the time of peak temperature in the concrete, usually between 12 hours and 4 calendar days after concrete placement , and as recommended by the TIP testing organization.
c.Notify the Engineer immediately if integrity testing indicates substandard concrete integrity or shows inconcl usive results .
2.Embedded Thermal Sensors
a.Space thermal wire cables equally around the inside of the reinforcing steel cage and parallel to the longitudinal reinforcing steel. 1) Shafts with diameters up to 48 inch a) Install four cables 2) Shafts with diameters greater than 48 inch a) Install one cable for each foot of diameter rounding up b) An additional cable may be added to establish an even number of cables to simplify interpretation of results 3) Extend cables to 6 inch from the bottom of shaft. 4) Provide 10 ft of cable length above the top of the shaft. 5) Arrange sensors in a straight line with each sensor spaced at 20 inch or less and at approximately the same elevation as sensors along other thermal sensor wire cables. a) Install top most sensor within the top 20 inches of the shaft.
b.Attach the thermal sensor wire cables to the longitudinal reinforcing steel using nylon zip- ties. 1) Space zip ties at 12 to 20 inch spacing, located midway between sensors along each cable. 2) Do not leave segments of unsecured cable which can be snagged and damaged by movement of the rebar cage or concrete placement.
c.Verify each thermal sensor is functioning after placement of reinforcing steel cage and before concrete placement.
d.Connect each thermal sensor wire cable to a recording apparatus shortly after concrete placement . 1) Document which cable is connected to which recording apparatus . 2) Attach the recording apparatus to a secure location well above the top of the concrete.
3.8 Core Drilling of Drilled Shaft Concrete
A.Take core samples from each defective shaft to the extent necessary to fully identify the anomaly and determine a course of action when directed by the Engineer .
B.Use a new diamond set bit having at least four waterways for each hole.
1.Use a drill bit size HW or larger.
C.Use core barrel size HW or larger, M series, double- tubed, with a chromed inner barrel.
1.Replace the bit or core barrel at any time inspection indicates excessive wear or loss of diamonds.
D.Set the core drill machine so that the drill force will be vertical and so that there will not be more than 5 ft of laterally unsupported drill rod between the bottom of the drill spindle (chuck) and the top of the shaft concrete when the hydraulic feed is in the up position.
1.Use braced casing or rigidly braced guides to prevent lateral whip when longer laterally unsupported sections of the drill stem are necessary.
E.Keep an accurate cor ing log.
1.Place the cores in a suitable wooden crate marked showing the shaft depth at each interval of core recovery.
2.Provide the cores and two copies of the coring log of inspection and testing.
F.Grout the core hole in the shaft when quality of the concrete in the shaft, as represented by the core samples, is determined to be sound, and notification to continue construction is given by the Engineer .
1.Use non- shrink grout .
a.Mix grout to a flowable consistency according to the manufacturer’s instructions .
2.Completely g rout the core hole without voids .
Source: Utah Standard Specifications for Road and Bridge Construction, 2026 Edition. Pages 342–356 of 1,331.