663 608- 5 Basis of Payment: The accepted quantities of each type of sign panel designated in the bidding schedule, measured as provided above, will be paid for at the contract unit price per square foot, complete in place, regardless of the type of sheeting or type of character used on the sign panel. Payment shall be made on the total area of each type of sign panel to the nearest square foot. No additional payment will be made for signs with sheeting appl ied to both sides, the cost being considered as included in the contract unit price for the sign panel. No measurement or payment will be made for Route Shields and EXIT ONLY Panels (for installation on sign panels), the cost being considered as included i n the contract unit price for the sign panel. The contract unit price shall be full compensation for furnishing all labor, materials, tools, equipment , and incidentals, and for performing all the work involved in furnishing and installing the sign panels, complete in place, including furnishing and applying all retroreflective sheeting, all fastening hardware, all necessary sign supports, stringers, and post ties, all as shown on the plans and as specified herein. The accepted quantities of graffiti shield, measured as provided above, will be paid for at the contract unit price per square foot, complete in place, as shown in the plans and as described and specified herein. The accepted quantity of Miscellaneous Work will be paid for at the contract lump sum price, which price shall be full compensations for the work, complete in place, as shown on the plans and as described and specified herein. 609- 1 Description: 609- 1.01 General: The work under this section shall include furnishing all materials and constructing reinforced concrete shafts formed within a drilled excavation. Each drilled shaft foundation shall consist of a shaft section with or without casing left in place, as directed or specified, with or without a rock socket or a belled footing, and shall be constructed in reasonably close conformity with the details and dimensions shown on the plans and the requirements of these specifications. TABLE OF CONTENTS INDEX 664 609- 1.02 Certification: The contractor shall be responsible to review all a vailable geotechnical investigation reports, and its signature on the proposal form shall certify that the firm performing the drilled shaft operations, whether the prime contractor or a subcontractor, has completed this review. The geotechnical investigation reports are available on the ADOT Contracts and Specifications Group Current Advertisements website. 609- 1.03 Installation Plan: The contractor shall provide to the Engineer for review and approval a detailed installation plan containing the following information:
drills, augers, bailing buckets, final cleaning equipment, desanding equipment, slurry pumps, sampling equipm ent, tremies or concrete pumps, casing, etc. ;
sequence of shaft construction in bents or groups;
of each shaft excavation;
contractor shall submit Safety Data Sheets, quality control procedures, and disposal details;
centralization methods, lifting equipment, and staging location for tied steel reinforcement cages prior to placement ;
charts;
loss of slump during placement ;
TABLE OF CONTENTS INDEX 665
unforeseen stoppage of work or interruption in concrete delivery occurs; and
The contractor’s installation plan shall be developed with input from subcontractors, material suppliers, and all others with drilled shaft responsibility. The installation plan shall also identify which portion of the drill shaft construction the contractor and each of the subcontractors will be performing. The documentation required above shall be submitted to the Engineer at least four weeks before work on shafts is to begin. The Engineer will review the initial submittal within 10 working days, and subsequent submittals, as necessary, within five working days. A drilled shaft preconstruction meeting will be scheduled following the final approval of the installation plan and prior to commencement of drilling activity. All parties named in the installation plan shall be represented at the preconstruction meeting. No drilled shaft work shall be performed until the contractor's final submittal has been approved by the Engineer and the preconstruction meeting concluded. Such approval will not relieve the contractor of responsibility for results obtained by use of the installation plan, or any of its other responsibilities under the contract. The contractor shall be responsible to submit a modified installation plan each time a change is made to facilitate construction. Unless otherwise specified in the Special Provisions, foundations of less than 4 feet in diameter and 20 feet in length utilized in li ght pole and sign post foundations shall be exempt from the requirement to submit an installation plan, p erform integrity testing, conduct a drilled shaft preconstruction meeting, and construct a confirmation shaft. 609- 2 Materials: 609- 2.01 Concrete: Concrete shall conform to the requirements of Section 1006 of the specifications for the design criteria shown on the plans, with the following additions or modifications:
Where concrete is placed in drilled shaft excavations containing slurry or water, the cement content of the concrete shall be between 660 and 750 pounds per cubic yard.
Maximum nominal aggregate size shall be limited to 1/5 of minimum clear bar spacing (vertical and horizontal), not to exceed 3/4 inch nominal for drilled shafts constructed with a wet method or with temporary casing TABLE OF CONTENTS INDEX 666 (excluding col lar-only casings), and 1 inch nominal for drilled shafts constructed with a dry method.
Air entrainment requirements detailed in Section 1006 of the specifications shall be utilized in drilled shaft foundations. 609- 2.02 Reinforcing Steel: Reinforcing steel shall conform to the requirements of Section 1003 of the specifications. Welded splices will not be allowed except as shown on the plans. 609- 2.03 Casing: Casing shall be steel and may be of unit or sectional construction. The casing shall be of sufficient strength to withstand handling and driving stresses, to withstand the pressure of concrete and the surrounding earth and to prevent seepage of water. Steel shall conform to the requirements of AASHTO M 270 (ASTM A 709), Grade A 36, unless otherwise speci fied. Should telescoped casing be used, the contractor shall not allow concrete to overfill any interior casing. Spillage must be removed from the annulus, or the shaft shall be declared deficient. Temporary casing shall be clean, inside and out, prior to placement in the excavation. All casing shall be handled so as to limit distortion to within 2 percent of the diameter. No side shear capacity will be allowed where temporary casing installed becomes permanent. If approved by the Engineer and if conditions permit, temporary casings may be corrugated and non- watertight. The contractor shall be responsible to compensate for loss of frictional capacity in the cased zone if temporary casing is abandoned in the shaft. Such modifications shal l be approved by the Engineer, and shall be at no additional cost to the Department. 609- 3 Construction Requirements: 609- 3.01 General: The methods and equipment used shall be appropriate for the intended purpose and materials encountered. The allowable methods are the dry method, wet method, temporary casing method, or permanent casing method, as defined by the 2017 LRFD Bridge Construction Specifications 4th Edition, Section 5. The most suitable of the listed methods for the conditions recorded in the geotechnical investigation report, or a combination of these methods, shall be used, subject to approval of the TABLE OF CONTENTS INDEX 667 Engineer, to produce sound, durable concrete foundation shafts free of defects. The permanent casing method shall be used only when required by the plans or authorized by the Engineer. If at any time during the construction of the drilled shafts the Engineer determines that the equipment, materials, employees, or procedures are such that defects in the work may occur, the Engineer may stop the work until appropriate changes are made by the contractor. In no case shall the contractor be relieved of its responsibility for constructing acceptable drilled shaft foundations. 609- 3.02 Confirmation Shafts: Unless otherwise specified in the Special Provisions, the contractor shall construct a confirmation shaft to determine the adequacy of the contractor’s equipment, materials, employees, and procedures for completion of the drilled shaft foundations in accordance with the requirements of the plans, specifications, and installation plan. Confirmation shafts may also be waived if approved in writing by the Engineer. Unless otherwise approved by the Engineer, the confirmation shaft shall be the first drilled shaft foundation to be developed. The Engineer will specify the location of the confirmation shaft, unless shown on the plans. The confirmation shaft holes shall be completed in the same manner as other production shafts. The contractor shall revise its methods and equipment as necessary at any time during the construction of the confirmation shaft hole to satisfactorily complete the excavation. When the contractor fails to satisfactorily demonstrate the adequacy of its methods, procedures, or equipment; or when unforeseen conditions require revision, such as the need for slurry; the installation plan shall be revised and the adjacent shaft shall be designated as the confirmation shaft f or the revised installation plan, as approved by the Engineer. When shown on the plans or when directed by the Engineer in writing, the reaming of bells or development of rock sockets at specified confirmation shaft holes shall be required to establish feasibility in a specific soil strata. 609- 3.03 Excavation: The contractor shall perform all excavation required for the shafts, rock sockets, or belled footings, through any material encountered, to the dimensions and elevations shown on the plans or directed by the Engineer. Unless otherwise shown on the plans, the maximum deviation from plumb shall be not more than 1.5 percent. The maximum permissible variation of the design center axis for both the borehole and rebar cage at the top shall be 5 percent of the shaft diameter, not to exceed 3 inches from its project plan location. The contractor shall determine plumbness by plumb lines in dry excavations and by Kelly bar position readings at 10- foot intervals in wet excavations, or as approved TABLE OF CONTENTS INDEX 668 by the Engineer. The contractor shall provide the Engineer with these readings for each drilled shaft constructed to verify plumbness. When bells or rock sockets are required, they shall be excavated so as to form a bearing area of the size and shape shown on the plans. If suitable material is not encountered at plan elevation, the bottom of any drilled hole may be lowered, at the direction of the Engineer. Alteration of plan depth shall be made to satisfactorily comply with design requirements. Reinforcing steel and concrete shall not be placed in the shaft until this final elevation has been established and the Engineer has approved the completed excavation. Raising of the foundation elevation shall require approval by the Engineer. If caving conditions are encountered, no further drilling will be allowed until a construction method is employed that will prevent excessi ve caving and which is acceptable to the Engineer. If casing is proposed, the shell shall be clean and shall extend to the top of the drilled shaft excavation. The inside diameter of the casing shall not be less than the specified size of the shaft unless approved by the Engineer. The outside diameter of the shaft shall not exceed plan dimension by more than 6 inches unless use of telescoping casing or surface casing is allowed by the installation plan. Adjacent shafts, unless separated by a minimum of four shaft diameters measured center to center, shall not be drilled until the concrete in the first shaft has been in place for a minimum of 48 hours. Temporary surface casings may be used to aid shaft alignment and position, and to prevent sloughing of the top of the shaft excavation, if approved by the Engineer. Where temporary casing is used to stabilize excavations that include rock sockets, the temporary casing shall be 6 to 12 inches larger than the rock socket diameter and centered on th e rock socket. If the Engineer determines that the amount of caving is within acceptable limits and the contractor elects to drill under the same methods and procedures, the excavation shall be filled with concrete at no additional cost to the Department, regardless of the extent. Any excavation beyond the dimensions shown on the plans where casings are not used shall be filled with concrete at no additional cost to the Department. If the use of drilling slurry is to be employed, either with or without the use of casing, the contractor shall use a method of construction which will allow completion of the drilled shaft in a continuous manner without any mixing of concrete and drilling slurry. Material excavated from shafts and bells and not incorporated elsewhere on the project shall be disposed of by the contractor. TABLE OF CONTENTS INDEX 669 When the plans indicate drilled shafts are to be constructed within embankments, the embankments shall be constructed prior to drilling, except when approved otherwise by the Engineer. After the completion of the drilled shaft excavation and prior to the placement of the reinforcing steel cage and concrete, all loose material shall be machine cleaned from the shaft. A flight auger or other equipment, approved by the Engineer, shall be used for cl eaning dry excavations where slurry or ground water is not present. Where slurry or ground water is present, the excavation shall be cleaned with a clean- out bucket or similar type of equipment, as approved by the Engineer. All open excavations shall be covered at the end of each shift in a manner approved by the Engineer. Prior to concrete placement, final shaft depths will be measured with a weighted tape or other approved method by the Engineer after final cleaning. A minimum of 50 percent of the area of the base of each shaft shall have less than 1/2 inches of sediment. The maximum depth of sediment or any debris at any place at the base of the shaft shall not exceed 2 inches. 609- 3.04 Drilling Slurry:
The contractor is responsible to select, formulate, and implement the use of slurry to facilitate drilled shaft construction. Quality control procedures of the slurry implementation shall be detailed in the contractor’s submitted installation plan. Only co mmercially prepared mineral slurries or polymer slurries shall be employed when slurry is used in the drilling process. Mineral slurry shall have both a mineral grain size that will remain in suspension and sufficient viscosity and gel characteristics to transport excavated material to a suitable screening system. For all slurries the percentage and specific gravity of the material used to make the suspension shall be sufficient to maintain the stability of the excavation and to allow proper concrete placement. During construction, the level of the slurry in the shaft excavation shall be maintained at a level of 5 feet or more above the highest expected piezometric pressure head along the depth of the shaft. Unless otherwise approved in advance by the Engineer, slurry shall be injected into the excavation immediately upon encountering ground water. No further excavation shall be completed until slurry has been introduced into the shaft. In the event of a sudden significant loss of slurry to the hole, the construction of that foundation shall be stopped until either a method to stop slurry loss or an alternative construction procedure has been approved by the Engineer. The slurry shall be premixed thoroughly with clean, fresh water. Adequate time, as pres cribed by the slurry manufacturer, shall be allotted for hydration prior to introduction into the shaft excavation. Slurry tanks of adequate capacity shall be required for slurry circulation, TABLE OF CONTENTS INDEX 670 storage, and treatment. No excavated slurry pits shall be allowed instead of slurry tanks. No mixing of slurry shall be allowed in the drilled shaft excavation. Mineral slurry shall not stand for more than four hours in the excavation without agitation. If this is not possible, excavation sidewalls shall be cleane d to remove filter cake. Mineral slurry density shall be increased by adding barite only when sodium bentonite is the mineral. Desanding equipment shall be provided by the contractor as necessary to control mineral slurry sand content. Desanding will not be required for setting casing. The contractor shall take all steps necessary to prevent the slurry from "setting up" in the shaft. Such methods may include agitation, circulation, and/or adjusting the properties of the slurry. The contractor shall dispose of all mineral slurry off site at an approved disposal site.
Quality control procedures for utilization of slurry shall be detailed in the contractor’s submitted installation plan. The contractor shall have suitable apparatus available at the site capable of obtaining slurry samples at any depth within the drilled shaft excavation. 609- 3.05 Integrity Testing:
Each drilled shaft foundation completed, unless otherwise noted on the project plans, shall be inspected by means of a cross- hole sonic logging
shaft contractor shall furnish and install 2- inch (inside diameter) Schedule 80 PVC pipes for the surveys. The minimum number of PVC - pipe inspection tubes shall be equal to the diameter of the drilled shaft, measured in feet, and rounded- up to the next whole integer, but not less than four, or as specified in the plans. The inspection tubes shall be approximately even spaced around the inside circumference of the reinforcing steel cage, or as shown on the project plans. To account for any reinforcing cage stabilizing bars installed by the contractor, the maximum clearance from the reinforcing cage’s stirrups to the test tube shall be no more than the size of the vertical reinforcement plus 1 inch. The pipes shall be joined to provide a clean, watertight, and unobstructed opening as specified in Subsection 609- 3.05(B) of the specifications. If any damage to the tubes occurs during the installation they shall be repaired or replaced at no additional cost to the Department. If testing cannot be performed because of blockage of the tubes, the contractor shall core drill or otherwise determine the extent of any potential anomalies in the concrete, as approved by the Engineer, at no additional cost to the Department. CSL and GGL testing shall be performed by a qualified subcontractor selected by the contractor and approved by the Engineer. The subcontractor shall provide the equipment meeting the minimum TABLE OF CONTENTS INDEX 671 requirements listed herein, and shall have at least one year experience in CSL survey and GGL survey evaluation. The subcontractor performing the GGL shall provide proof that it is licensed to possess and use radioactive material in accordance with the Arizona Radiation Regulatory Agency. Recorded measurements shall be interpreted and the required reports shall be prepared and sealed by a licensed professional engineer, registered in the State of Arizona, with at least three years of experience in CSL survey and GGL survey evaluation. Resumes of proposed personnel shall be submitted to the Engineer for approval at least four weeks prior to commencement of work. CSL tests shall be completed within two to four days after concrete placement and GGL tests shall be completed within two to seven days of concrete placement. The CSL survey and the GGL survey requirements shall be as specified in Subsection 609- 3.05(B) of the specifications. Inspection reports containing the acquired raw data, and evaluation reports, shall be provided as specified in Subsection 609- 3.05(B) of the specifications. All reports shall be provided to the Engineer within three days of test completion. If the testing indicates the presence of anomalies, as defined herein, or the Engineer determines that construction defects may have occurred, the contractor shall conduct remedial testing and make repairs, as specified in Subsection 609- 3.05(B)(6) of the specifications, at no additional cost to the Department. Concrete volumetric charts shall be completed for each drilled shaft. A copy shall be delivered to the Engineer with the submittal of the inspection reports of the associated drilled shaft. After the inspection of a shaft has been completed and the shaft accepted, all holes and test pipes in the shaft shall be filled with an approved grout.
The inspection tubes shall have a round, regular, internal diameter free of defects or obstructions, including at any pipe joints, in order to permit the free, unobstructed passage of source and receiver probes from top to bottom. The tubes shall be watertight and free from corrosion, with clean internal and external faces, to ensure passage of the probes and to ensure a good bond between the concrete and the tubes. Standard glue -on PVC couplings shall be used. No compression, rubber, or clamp fittings will be allowed. Care shall be taken during reinforcement installation operations to not damage the tubes or break the fasteners of the tubes. Before placement of concrete, pipes shall be checked to TABLE OF CONTENTS INDEX 672 ensure they are free from blockages, bends, crimps or other impediments to the free passage of the testing probes. Each pipe shall be fitted with a watertight shoe on the bottom and a removable cap on the top. The bottom cap of each tube shall be adequately secured such that it can withstand the hydrostatic pressure for the full depth of the shaft without water leakag e. The pipes shall be securely attached to the reinforcement cage in a straight line, and in a regular, symmetrical pattern. The tubes shall be adequately secured to the reinforcing cage such that the tubes stay in position during placement of the rebar cage and concrete placement. At a minimum, the tubes shall be securely fastened to the inside of the reinforcing cage at least every 10 feet vertically. The tubes shall be as near to vertical and parallel as possible. The tubes shall extend from 1 inch above the bottom of the reinforcement cage to at least 4 feet above the shaft top, or approximately 2 feet above the top of the rebar cage if above the ground. Under no circumstance shall the tubes be allowed to rest on the bottom of the drilled excavation. If the shaft top is below the ground surface, the tubes shall extend at least 2 feet above the ground surface. Any joints required to achieve full length tubes shall be made watertight. The tube tops shall be bare clean pipe (no pipe joints), level cut, and capped to keep debris out of the tubes. If the rebar cage extends above the top of the tubes, the circular or spiral tie- raps shall temporarily be cleared away from 1 foot below the tube top to approximately 3 feet above. After placement of the reinforcement cage, the tubes shall be filled with clean water as soon as possible, immediately before or within 1 hour after concrete placement. Care shall be exercised in the removal of caps or plugs from the pipes after installation so as to not apply excess torque, hammering, or other stresses which could break the bond between the tubes and the concrete. Before the start of testing, the contractor shall:
through the complete length of each access tube t o check for tube blockage;
as the reference zero depth for all cross- hole sonic and gamma- gamma testing. Therefore, the shaft top must be level and, if mud covered, be cleaned before testing ;
equipment within 2 to 3 feet of each access tube;
TABLE OF CONTENTS INDEX 673
from the top of the concrete, and are capped and filled with water all the way to the top;
and capped;
Volt, 1000- Watt power ; and
tube with the shaft designation and tube number. For example, Pier 2 Shaft 3 Tube 4 shall be denoted as P2S3 T4. By definition, Tube 1 is the northernmost tube, with other tubes referenced in a clockwise direction from Tube 1. The contractor shall also provide documentation that the testing equipment has been calibrated and is functioning properly. Changes from the design conditions such as: test tube lengths, shaft diameter and the as- drilled tip elevation shall be noted in the report.
The minimum equipment requirements for CSL shall be as follows:
capable of producing records with good signal amplitude and energy through uniform, good quality concrete. The probes shall be of a diameter and have cabling such that they descend freely through the 2 inch internal diam eter Schedule 80 PVC pipe for the full depth of the shafts shown on the plans. Probes shall allow a generated or detected pulse within 6 inches of the bottom of the access tubes and the transmitter probe shall generate an ultrasonic pulse with a minimum pulse frequency of 40,000 Hz. The weight of each probe shall in all cases be sufficient to allow it to sink under its own weight in the access tubes. The probe housing shall be waterproof to at least 1.5 times the maximum depth of the testing. The receiver probe shall be of a similar size and compatible design to the transmitter probe, and be used to detect the arrival of the ultrasonic pulse generated by the transmitter probe;
measurement wheel or other suitable measuring device; TABLE OF CONTENTS INDEX 674
based system for analog to digital conversion and recording of data, for display of individual records, and for analysis of receiver responses and printing of logs;
amplification of data and cable systems;
system ; and
the shaft top and not at the bottom of access tubes. In addition, the system shall be able to log both from the top of the shaft to the bottom as well as from the bottom to the top.
The minimum testing procedure r equirements for CSL logging shall be as follows:
All inspection tubes shall be filled with water prior to testing. During testing, the water level in any tube shall not drop below the top of the concrete that is bei ng tested.
Information on the shaft bottom and top elevations, tube lengths and position, along with construction dates, shall be provided by the contractor to the CSL logging subcontractor prior to the logging being performed. All possibl e tube pairs shall be tested. The tests shall be carried out with the source and receiver probes in the same horizontal plane unless test results indicate potential defects, in which case the questionable zone shall be further evaluated with angled tests (source and receiver vertically offset in the tubes). The electronic circuit shall be thoroughly checked. The choice of time base will be such that the “zero signal” and first arrival time are 2 to 3 divisions apart on the horizontal axis. Amplitude shal l be such that the signal fills 2/3 to 3/4 of the screen vertically. Once the slack is taken up out of the cables to provide accurate depth measurements of the logs, the probes shall be pulled simultaneously and TABLE OF CONTENTS INDEX 675 uniformly from the bottom of the tubes over the depth wheel or other measuring device. All slack shall be taken out of the cables before the analyzer is switched on. The rate of ascent shall be the rate recommended by the equipment manufacturer. The cross- hole sonic measurements shall be taken at 2 -inch intervals or less from the bottom to top of shaft.
Anomaly in a drilled shaft shall be determined by evaluating the pulse arrival times and amplitude/energy signals. Zones where the measured sonic velocity is 10 percent or more lower than the local mean measured sonic velocity within a 5- foot interval above and below the suspected anomalous zone shall be reported to the Engineer. The Engineer may require further tests to evaluate the extent of such anomalies. Any such additional testing shall be at no additional cost to the Department.
Results of the CSL completed at a given substructure element shall be submitted to the Engineer in a report(s) within three working days of completion of testing at that given substructure element. The Engineer will review the report within three working days of the contractor’s submittal. The report shall include:
shaft lengths; shaft tip elevations; shaft cutoff elevations; type and size of drilling equipment; type of slurry if used; description of concrete mix; concrete placement method; shaft layout with shaft numbers;
equipment; identification of shaft logged; location of obstructions in PVC tubes; location of PVC couplers; calibration date, data and plot; summary of any unusual occurrences during testing; description and explanation of adjustments made to instrumentation or data (if any); identification of anomalies using the criteria described herein; delineation of affected tubes; vertical location and extent of anomalies; and estimated percentage of anomalous cross- sectional area;
in terms of velocity and pulse amplitude/ energy versus depth. The cross- hole sonic logs shall be presented for each tube pair with all anomalous zones indicated on the logs; TABLE OF CONTENTS INDEX 676
depth, velocity versus depth, and pulse amplitude/energy versus depth;
of the report shall be included; and
The minimum equipment requirements for gamma- gamma logging shall be as follows:
cylinder containing a gamma particle emitting source and a gamma particle detector. The probe shall be suspended by a cable of sufficient design and length that it is safely capable of raising and lowering the gamma -gamma probe within a 2- inch internal diameter Schedule 80 PVC inspection pipe to the desired test depths;
strength and durability to raise and lower the probe safely and at a controlled rate of speed. A winch mechanism shal l be such that it does not damage the cables or compromise data collected in the test. A means of determining and recording probe depth shall be provided;
137 in a sealed source form ;
proven method of gamma detection, such as Geiger Mueller or scintillation- based counters;
that is capable of displaying or recording counts, densities, and sampling duration or probe speed;
density precision of 1.0 pounds per cubic foot ;
radius of detection of 4.0 inches in concrete with density between 140 and 160 pounds per cubic foot. The probe shall have the capability of varying the radius of detection up to 7 inches in concrete with density between 140 and 160 pounds per cubic foot. TABLE OF CONTENTS INDEX 677 The radius of detection is defined as one half of the center to center distance between the source and the detector. The actual radius of detection used in the test shall be subject to the approval by the Engineer ; and
Engineer with the calibration of the gamma- gamma probe and readout unit to correlate count rate and concrete density. The calibration shall not be more than one year old, and shall be performed using the same source and detector combination as that proposed for the GGL testing on the project. Furthermore, the calibration shall have been conducted in an environment (e.g., water -filled, Schedule 80 PVC pipes) similar to the shafts being tested for the project. GGL shall not be performed until the Engineer has approved the calibration records. Upon approval, the contractor shall perform the gamma- gamma tests exactly in the manner as the calibration of the probe and readout unit was performed.
The minimum testing procedure requirements for GGL shall be as follows:
A GGL survey may be performed by an experienced subcontractor using inspection tubes completely filled with water only if the gamma- gamma probe has been calibrated in concrete calibration samples that contained inspection tubes filled with water, and t he radius of detection and density precision calibration have been performed under water and found to be within the prescribed limits. In the event of gamma- gamma testing in water filled tubes, the water level during testing in any tube shall not drop bel ow the top of the tube.
Information on the shaft bottom and top elevations, tube lengths and position, along with construction dates shall be provided by the contractor to the GGL subcontractor prior to the logging being performed. The test shall be started by lowering the probe to the bottom of the access tube. When extracting the probe, the readings shall be taken at depth intervals not exceeding 1.5 inches and within the density precision of 1.0 pounds per cubic foot. The probe shall be extracted at a rate of between 8 to 10 feet per minute, and recorded. TABLE OF CONTENTS INDEX 678 To evaluate the repeatability of the GGL tests, the contractor shall perform one repeat log for each shaft in which GGL tests have been performed. After all the tubes in a given shaft have been GGL tested, the repeat log shall be performed in the first tube that was tested.
The following steps shall be used in the analysis of the GGL data:
the concrete calibration samples to the raw count readings and obtain bulk concrete densities. Verify that the data set contains no logging errors, duplicated data or skipped data points;
densities and record it on each log. A set shall consist of data collected from a single inspection pipe, using the same equipment, within the same time period. Data that shall not be included in the calculation of the mean density are: (1) repetitive data points collected at a single depth,
where the reading(s) were influenced by the gamma detector component exiting the shaft concrete, (3) data collected in the access tube above the top of the drilled shaft, (4) data affected by the anomalous zones of concrete, and
be statistically non- normal ;
overlapping bars) exists in a segment of a drilled shaft that affects the apparent mean, a separate mean shall be generated and utilized as the mean for that portion of the data;
to obtain a data set that reflects the variation from the mean; and
contained within an individual shaft and plot and present that data as (1) a single plot from all tubes, and (2) an individual plot for each tube.
The following steps shall be used in the standard deviation analysis of the GGL data: TABLE OF CONTENTS INDEX 679
compilation of bulk densities. A compilation shall consist of data collected from the test drilled shaft using the same equipment, within the same time period. Data that shall not be included in the calculation of the mean density are: (1) repetitive data points collected at a single depth,
whe re the reading(s) were influenced by the gamma detector component exiting the shaft concrete, (3) data collected in the access tube above the top of the drilled shaft, (4) data affected by the anomalous zones of concrete, and
be statistically non- normal ;
the calculated value is below 2.5 pounds per cubic foot, then 2.5 pounds per cubic foot shall be used in step 3. If the calculated value is above 3.75 pounds per cubic foot, then 3.75 pounds per cubic foot shall be used in step 3; and
step by - 2.0 and -3.0 to obtain values of “Minus Two Standard Deviations” ( -2SD) and “Minus Three Standard Deviations” ( -3SD), respectively.
Anomaly in a drilled shaft shall be determined by evaluating the data points developed by the above processes to the - 3SD deviation criterion as follows:
greater depth interval, all of the density readings have a value less than the determined value for - 3SD ;
the value for -3SD within a 1 foot vertical extent immediately above or below, then that depth shall be considered as anomalous in addition to the depth identified in the previous step; and
one data point within 2 feet vertically above or below the adjacent tube anomaly falls below the value for the - 3SD, then the depth in that tube at TABLE OF CONTENTS INDEX 680 which the anomaly is found is also anomalous, in addition to the depths identified in the previ ous two steps.
Results of the GGL completed at a given substructure element shall be submitted to the Engineer in a report(s) within three working days of completion of testing at that given substructure element. The Engineer shall review t he reports within three working days of the contractor’s submittal. The report shall include:
shaft lengths; shaft tip elevations; shaft cutoff elevations; type and size of drilling equipment; type of slurry i f used; description of concrete mix; concrete placement method; shaft layout with shaft numbers;
equipment; identification number of shafts logged; location of obstructions in PVC tubes; location of PVC couplers; calibration date, data and plot; summary of any unusual occurrences during testing; description and explanation of adjustments made to instrumentation or data (if any); identification of anomalies using the criteria described herein; delineation of affected tubes; vertical location and extent of anomalies; and estimated percentage of anomalous cross- sectional area;
and the values of - 2SD and - 3SD. The plots shall indicate these points and values at all depths. Utilize symbols or line formats that permit lines corresponding to - 2SD and - 3SD to be distinguishable from data points; and
If the testing indicates the presence of anomalous zones, as identified by both the sonic cross -hole and gamma- gamma tests in the drilled shaft foundation, or if the Engineer determines that construction defects may have occurred, the contractor shall conduct three- dimensional tomographic surveys of the anomalies, at no additional cost to the Department. The results of the tomographic surveys shall be presented in the form of concrete velocity images in two- dimensions (2- D) between TABLE OF CONTENTS INDEX 681 each pair of tubes, and in three -dimensions (3- D) for the anomalous zone.
Should the Engineer determine that the anomalous zones reveal defects; the contractor shall submit a plan to repair, replace, or supplement the defective work in a manner approved by the Engineer. After review and acceptance by the Engineer, the contractor shall perform the work specified in the approved plan at no additional cost to the Department. 609- 3.06 Reinforcing Steel , Cage Construction , and Placement: The reinforcing steel cage for the drilled shaft, consisting of longitudinal bars and spiral hooping or lateral ties shall be completely assembled and placed into the shaft as a unit. All reinforcing steel intersections shall be tied as specified herein. The reinforcing steel unit shall be placed in the shaft no sooner than two hours prior to the start of concreting operations, and shall be placed in accordance with the details shown on the plans. If approved in writing by the Engineer, bundling of vertical or horizontal reinforcing steel may be allowed if necessary to maintain a minimum bar spacing equal to five times the maxi mum nominal aggregate size of the concrete. Bundling of spiral reinforcing will not be allowed. A maximum of three bars may be bundled. Bundled vertical or horizontal steel shall be spaced uniformly. The contractor shall also make the necessary modifications, in accordance with the appropriate ACI specifications, to the splicing and tying details for the reinforcing steel, and submit these to the Engineer for approval along with the contractor's request for bundling of steel. The reinforcing cage shall be adequately supported and anchored from the top to prevent movement from the required location during and for four hours after completion of concrete placement. If temporary casing is used, the reinforcing cage shall be supported prior to removing casing, and for four hours following removal of the casing. The rebar cage shall be kept plumb. The rebar cage shall not rest directly on the bottom of the excavation. The minimum number of spacers shall be equal to the diameter of the drilled shaft, measured in feet, and rounded- up to the next whole integer, but not less than four. The spacers shall be approximately even spaced along the outside circumference of the reinforcing steel cage. Spacers shall be placed at a maximum vertical spacing of 15 feet. For all drilled shafts, unless otherwise shown on the plans for pedestrian bridges or light pole and sign post foundations, the spacers shall provide for a minimum of 6 inches of concrete cover between the reinforcing steel and the excavation wall. Only smooth plastic roller spacers, with a minimum width of 1- 1/2 inches approved by the Engineer will be allowed. Rollers shall be installed per the manufacturer’s recommendations. In no case TABLE OF CONTENTS INDEX 682 shall “dobies”, other rectangular “blocks” or ben t rebar tied to the reinforcing steel be used in the excavations. If the shaft is lengthened and the plans indicate full depth reinforcement, the Engineer shall be notified to determine if extension of the reinforcement is needed. The Engineer will provide details for additional reinforcing if required. Such additional reinforcing will be paid for in accordance with Subsection 109.04 of the specifications. The contractor shall submit a written request to the Engineer for approval of any variation from the splices for reinforcing steel specified in the contract documents. All reinforcing cages shall be fabricated and supported to avoid damage during the lifting and placing. Any temporary bracing and supports shall be removed prior to final placement. Equi pment used for lifting reinforcing cages shall have adequate capacity and boom length to lift the cage clear of the ground. Reinforcing cages shall not be dragged while being moved. Reinforcing cages shall be placed with splices in the lowest possible position within the excavation. 609- 3.07 Concrete Placement:
The contractor shall begin placement of concrete within 24 hours after the completion of the drilled shaft excavation. All concrete shall be placed in accordance with Section 601 of the specifications and as specified herein. If slurry excavation is used, concrete shall be placed the same day the excavation is completed. Unless otherwise specified in the project documents, or as directed by the Engineer, the slump shall be 4 to 7 inches for dry, uncased excavations. For all others, the concrete slump shall be 7 to 10 inches at the time placement begins. Prior to concrete placement, the contractor shall make all necessary arrangements to assure the uninterrupted delivery of concrete so that all drilled shaft foundations will be constructed without cold joints. During concrete placement, from start to fini sh, the rate of rise of the top of concrete in the drilled shaft shall be at least 40 feet per hour. Tremie downpipes and pump pipes shall be made of steel; no aluminum shall be allowed. The inside diameter of the tremie pipe shall be at least 10 inches f or all drilled shafts 4 feet or greater in diameter. The inside diameter of the pump pipe shall be at least 5 inches. The concrete mix shall remain in placement for at least two hours before obtaining the initial set as determined in AASHTO T 197 (ASTM C403). TABLE OF CONTENTS INDEX 683
For placement in dry excavations, concrete may be placed by free fall except in fragile, cohesionless soils where bottom scour is likely to occur, or where other caving conditions exist. The contractor shall prevent concrete from striking either the reinforcing cage or excavation side walls during free fall. Where free fall cannot be used, concrete shall be placed through a suitable clean downpipe. Concrete vibration for the full height of the shaft is not necessary to achieve proper consolidation of the concrete. However, the shafts shall be vibrated in the top 10 feet. If temporary casing is used, the vibration shall occur after the casing has been removed. To be considered a dry shaft, the maximum depth of water in the bottom of a drilled shaft excavation at the time of concrete placement shall be no more than 3 inches.
Concrete shall be placed by tremie methods or by pumping. Care shall be taken to ensure that all the fluid and suspended solids are expelled from the excavation during concrete placement. If concrete is placed by pumping, it shall be in accordance with the req uirements of Subsection 601- 3.03(C) of the specifications. The contractor’s installation plan shall demonstrate the procedures used to determine when the tremie pipe is to be raised during concrete placement. The procedure shall assure that the opening of the tremie pipe will be deeper than 5 feet below the surface of the concrete at all times for shaft diameters less than 6 feet, and deeper than 10 feet below the surface of the concrete for shaft diameters 6 feet and larger. A rapid raising or lowering of the tremie will not be permitted. In order to prevent contamination of concrete placed initially, the lower end of the pump or tremie pipe shall be provided with either a valve, sealable cap, or a plug ("pig"). The discharge end shall be placed at the bottom of the excavation prior to commencement of concrete placement. If a plug is used, it shall be inserted at the top after the pipe has been set in place. Concrete shall then be placed by pushing the plug ahead, separating the concrete from the drilling fluid. Only when the tremie pipe is completely filled shall the open end be lifted off the bottom. The concrete flow that comes to the top of the shaft shall be displaced out of the shaft excavation in a continuous flow until clean, fresh concrete is expelled. Slurry ejected during concrete placement may be reused provided that it is screened to remove gravel chips or other granular materials, and providing the slurry meets acceptance criteria. Slurry to be discarded shall be disposed of in a manner ap proved by the Engineer. TABLE OF CONTENTS INDEX 684 Concrete placed under slurry or water shall not be vibrated, except that the top 5 feet of the shaft shall be vibrated after the slurry or water and contaminated concrete have been totally expelled from the shaft. If temporary casi ng is used, the vibration shall occur after the casing has been removed. 609- 3.08 Casing Removal: During removal of any casing, a sufficient head of not less than 10 feet of fluid concrete in the tremie pipe shall be m aintained above the level of concrete in the shaft (outside the tremie pipe), except at the top of the shaft. All contaminated concrete shall be removed from the shaft. Temporary casings shall be removed while the concrete slump is a minimum of 4 inches. The contractor shall maintain a minimum 5- foot head of concrete for shaft diameters of less than 6 feet, and a minimum 10-foot head of concrete for shaft diameters 6 feet or greater, in the casing as it is being removed. Movement of the casing by exerti ng upward pressure and tapping to facilitate extraction, or extraction with a vibratory hammer will be permitted. Casing extraction shall be at a slow, uniform rate with the force in- line with the shaft axis. The removal method shall prevent the intrusion of water, grout, and soil into the excavation, displacement of the reinforcing steel, and lifting of the concrete. Due care shall be exercised to prevent upward movement of the shaft concrete and reinforcing steel during casing extraction. Upward movement beyond 1 inch, excluding movement due solely to tension on the top anchoring system, may indicate serious concrete separation or necking problems at the bottom of the casing. The contractor shall be responsible for corrective action which may include l eaving the casing in place and compensating for the loss of frictional capacity in the resulting cased zone. 609- 4 Method of Measurement: Drilled shafts will be measured to the nearest linear foot from the top elevation of the shaft to the top elevation of the rock socket stratum, if required, or to the actual bottom of the shaft, as shown on the plans, or as determined in the field by the Engineer. Rock sockets, when specified, will be measured to the nearest linear foot from the top elevation of the rock socket stratum to the actual bottom of the shaft, as shown on the plans, or as determined in the field by the Engineer. Bell sections will be measured by the unit for each type of foundation constructed. TABLE OF CONTENTS INDEX