Standard Specification FP-03.doc

DIVISION 550

BRIDGE CONSTRUCTION

Section 551. — DRIVEN PILES

Description

551.01 This work consists of furnishing and driving piles. This work also includes furnishing and placing reinforcing steel and concrete in concrete-filled steel shell and concrete-filled pipe piles.

Piles are designated as steel H-piles, concrete-filled steel shell piles, concrete-filled pipe piles, precast concrete piles, prestressed concrete piles, sheet piles, or timber piles. Pile load tests are designated as static or dynamic.

Material

551.02 Conform to the following Sections and Subsections:

Concrete piles 715.03

Grout 725.22(b)

Paint

Pile shoes 715.08

Reinforcing steel 709.01

Sheet piles 715.07

Splices 715.09

Steel H-piles 715.06

Steel pipes 715.05

Steel shells 715.04

Structural concrete

Treated timber piles 715.02

Untreated timber piles 715.01

Construction Requirements

551.03 Pile Driving Equipment. Furnish equipment meeting the following requirements.

(a) Pile hammers.

(1) Gravity hammers. Gravity hammers may only be used to drive timber piles. Furnish a hammer with a ram weighing between 2,000 and 3,500 pounds and limit the drop height to 15 feet. The ram mass shall be greater than the combined mass of the drive head and pile. Provide hammer guides to ensure concentric impact on the drive head.

(2) Open-end diesel hammers. Equip open-end (single acting) diesel hammers with a device, such as rings on the ram or a scale (jump stick) extending above the ram cylinder, to permit visual determination of hammer stroke. Submit a chart from the hammer manufacturer equating stroke and blows per minute for the hammer to be used. A speed versus stroke calibration may be used if approved.

(3) Closed-end diesel hammers. Submit a chart, calibrated to actual hammer performance within 90 days of use, equating bounce chamber pressure to either equivalent energy or stroke for the hammer to be used. Equip hammers with a dial gauge for measuring pressure in the bounce chamber. Make the gauge readable from ground level. Calibrate the dial gauge to allow for losses in the gauge hose. Verify the accuracy of the calibrated dial gauge during driving operations by ensuring that cylinder lift occurs when bounce chamber pressure is consistent with the maximum energy given in the hammer specifications. Do not use closed-end diesel hammers that do not attain cylinder lift at the maximum energy-bounce chamber pressure relationship given in the hammer specification.

(4) Air or steam hammers. Furnish plant and equipment for steam and air hammers with sufficient capacity to maintain the volume and pressure specified by the hammer manufacturer. Equip the hammer with accurate pressure gauges that are easily accessible. Use a hammer with the mass of the striking parts equal to or greater than one third the combined mass of the driving head and pile. The combined mass shall be at least 2,750 pounds.

Measure inlet pressures for double-acting and differential-acting air or stream hammers with a needle gauge at the head of the hammer when driving test piles. If required, also measure inlet pressures when driving production piles. A pressure versus speed calibration may be developed for specific driving conditions at the project as an alternative to periodic measurements with a needle gauge.

(5) Nonimpact hammers. Use nonimpact hammers, such as vibratory hammers, only when permitted in writing or when specified in the contract. If permitted, use such equipment for installing production piles only after the pile tip elevation or embedment length for safe support of the pile load is established by static or dynamic load testing. Control the installation of production piles when using vibratory hammers by power consumption, rate of penetration, specified tip elevation, or other acceptable methods that ensure the required pile load capacity is obtained. On one out of every 10 piles driven, strike with an impact hammer of suitable energy to verify the required pile capacity is obtained.

(6) Hydraulic hammers. Provide a power plant for hydraulic hammers with sufficient capacity to maintain the volume and pressure, specified by the manufacturer, at the hammer under working conditions. Equip the power plant and equipment with accurate pressure gauges that are easily accessible to the CO.

(b) Approval of pile-driving equipment. Furnish pile-driving equipment of such size that the permanent piles can be driven with reasonable effort to the required lengths without damage.

Approval of pile-driving equipment will be based on a wave equation analysis unless the contract specifies the dynamic formula to determine the ultimate driven pile capacity. If the contract specifies the dynamic formula, approval of pile-driving equipment will be based on minimum hammer energy in Table 551-1. The CO will evaluate the proposed equipment and accept or reject the driving system within 14 days of receipt of the pile and driving equipment information.

Use only the approved equipment during pile-driving operations. Approval of the pile‑driving system is specific to the equipment submitted. If the proposed equipment is modified or replaced, re-evaluate and resubmit the analysis and revised data for approval before using. The CO will accept or reject the revised driving system within 14 days of receipt of the revised submittal. Approval of a pile hammer does not relieve the Contractor of responsibility for piles damaged due to driving stress.

(1) Equipment submittal. Submit the following pile-driving equipment information to the CO at least 30 days before driving piles. Include a wave equation analysis for the proposed pile driving system, unless the contract specifies the use of the dynamic formula to determine the ultimate driven pile capacity. Use a professional engineer with at least 3 years experience in wave equation analyses to perform the wave equation analysis. Submit a resume of the engineer for approval.

(a) General. Project and structure identification, pile-driving contractor or subcontractor, and auxiliary methods of installation such as jetting or preboring and the type and use of the equipment.

(b) Hammer. Manufacturer, model, type, serial number, rated energy ( _____ at _____ length of stroke), and modifications.

(c) Capblock (hammer cushion). Material, thickness, area, modulus of elasticity (E), and coefficient of restitution (e).

(d) Pile cap. Helmet mass, bonnet mass, anvil block mass, and drivehead mass.

(e) Pile cushion. Material, thickness, area, modulus of elasticity (E), and coefficient of restitution (e).

(f) Pile. Pile type, length (in leads), mass per foot, wall thickness, taper, cross-sectional area, design pile capacity, description of splice, and tip treatment description.

(2) Wave equation. The required number of hammer blows indicated by the wave equation at the ultimate pile capacity shall be between 3 and 10 per inch.

Use the following hammer efficiencies in the wave equation analysis unless more specific hammer efficiency information is available:

In addition, the pile stresses resulting from the wave equation analysis shall not exceed the values at which pile damage is impending. The point of impending damage is defined for steel, concrete, and timber piles as follows.

(a) Steel piles. Limit the compressive driving stress to 90 percent of the yield stress of the pile material.

(b) Concrete piles. Limit the tensile (TS) and compressive (CS) driving stresses to:

TS ( 3fc'1/2 + EPV

CS ( 0.85fc' - EPV where:

fc’ = The 28-day design compressive strength of the concrete in pounds per square inch

EPV

= The effective prestress value in pounds per square inch

(c) Timber piles. Limit the compressive driving stress to 3 times the allowable static design stress.

(3) Minimum hammer energy. The energy of the driving equipment submitted for approval, as rated by the manufacturer, shall be at least the energy specified in Table 551-1 that corresponds to the required ultimate pile capacity.

Table 551-1

Minimum Pile Hammer Energy

Ultimate Pile Capacity

(tons) Minimum Rated Hammer Energy (foot-pounds)

(c) Driving appurtenances.

(1) Hammer cushion. Equip all impact pile-driving equipment, except gravity hammers, with a suitable thickness of hammer cushion material to prevent damage to the hammer or pile and to ensure uniform driving behavior. Fabricate hammer cushions from durable, manufactured material according to the hammer manufacturer's recommendations. Do not use wood, wire rope, or asbestos hammer cushions. Place a striker plate, as recommended by the hammer manufacturer, on the hammer cushion to ensure uniform compression of the cushion material. Inspect the hammer cushion in the presence of the CO when beginning pile driving at each structure or after each 100 hours of pile driving, whichever is less. Replace the cushion when its thickness is reduced by more than 25 percent of its original thickness.

(2) Pile drive head. Provide adequate drive heads for impact hammers and provide appropriate drive heads, mandrels, or other devices for special piles according to the manufacturer's recommendations. Align the drive head axially with the hammer and pile. Fit the drive head around the pile head so that transfer of torsional forces is prevented during driving and proper alignment of hammer and pile is maintained.

(3) Leads. Support piles in line and position with leads while driving. Construct pile driver leads to allow freedom of movement of the hammer while maintaining axial alignment of the hammer and the pile. Do not use swinging leads unless permitted in writing or specified in the contract. When swinging leads are permitted, fit swinging leads with a pile gate at the bottom of the leads and, in the case of battered piles, fit with a horizontal brace between the crane and the leads. Adequately embed leads in the ground or constrain the pile in a structural frame (template) to maintain proper alignment. Provide leads of sufficient length that do not require a follower but will permit proper alignment of battered piles.

(4) Followers. Followers are not permitted unless approved in writing. When followers are permitted, drive the first pile in each bent or substructure unit and every tenth pile thereafter, full length without a follower, to verify that adequate pile embedment is being attained to develop the required ultimate capacity. Provide a follower of such material and dimensions that will permit the piles to be driven to the required penetration. Hold and maintain follower and pile in proper alignment during driving.

(5) Jetting. Do not use jetting unless approved in writing. Provide jetting equipment with sufficient capacity to deliver a consistent pressure equivalent to at least 100 pounds per square inch at two 3/4-inch jet nozzles. Jet so as not to affect the lateral stability of the final inplace pile. Remove jet pipes when the pile tip is at least 5 feet above the prescribed tip elevation, and drive the pile to the required ultimate capacity with an impact hammer. Control, treat if necessary, and dispose of all jet water in an approved manner.

(6) Pile cushion. For concrete piles, use a new pile cushion to protect the head of each pile. Cut the pile cushion at least 4-inches-thick and to match the cross-section of the pile top. Replace the pile cushion if it is compressed more than one-half its original thickness or it begins to burn. For steel and timber piles, protect each pile with an approved driving cap. Enclose timber piles with approved collars or bands to prevent splitting or brooming. Replace caps when damaged. Do not reuse cushions or caps.

(7) Pile shoes. When specified, provide shoes to protect the pile-tip from damage during driving. Fabricate all shoes to snugly fit the pile tip. For concrete piles, attach the shoe to the pile using dowels or other approved methods. For steel piles, design and fit the shoe to the steel shape and weld the shoe to the pile so as not to stress the web or the flange. For timber piles, carefully shape the tip to secure an even uniform bearing for the pile shoe. Treat all holes, cuts, or caps in treated timber piles with 2-brush applications of creosote-coal tar solution.

551.04 Pile Lengths. Furnish piles with sufficient length to obtain the required penetration and to extend into the pile cap or footing as indicated on the plans. In addition, increase the length to provide fresh heading and to provide for the Contractor's method of operation. When test piles are required, furnish piles in the lengths determined by the test piles.

551.05 Test Piles. Install test piles when specified in the contract. Excavate the ground at the site of each test pile or production pile to the elevation of the bottom of the footing before the pile is driven. Furnish test piles longer than the estimated length of production piles. Drive test piles with the same equipment as the production piles.

Drive test piles to the required ultimate capacity at the estimated tip elevation. Allow test piles that do not attain the required ultimate capacity at the estimated tip elevation to "set up" for 24 hours before re-driving. Warm the hammer before re-driving begins by applying at least 20 blows to another pile. If the required ultimate capacity is not attained on re-driving, drive a portion or all of the remaining test pile length, and repeat the "set up" and re-drive procedure as directed. Splice and continue driving until the required ultimate pile capacity is obtained.

Test piles to be used in the completed structure shall conform to the requirements for production piles. Remove test piles not incorporated in the completed structure to at least 2 feet below finished grade.

551.06 Driven Pile Capacity. Drive piles to the specified penetration and to the depth necessary to obtain the required ultimate pile capacity. Splice piles not obtaining the required ultimate capacity at the ordered length, and drive with an impact hammer until the required ultimate pile capacity is achieved.

Use the wave equation to determine ultimate pile capacity of the in-place capacity of the in-place pile.

(a) Wave equation. Adequate penetration will be considered to be obtained when the specified wave equation resistance criteria is achieved within 5 feet of the designated tip elevation. Drive piles that do not achieve the specified resistance within these limits to a penetration determined by the CO.

(b) Dynamic formula. Drive the piles to a penetration necessary to obtain the ultimate pile capacity according to the following formula:

where:

Ru = Ultimate pile capacity in kips

E = Manufacturer's rated hammer energy in foot·pounds at the ram stroke observed or measured in the field log10(10N) = Logarithm to the base 10 of the quantity 10 multiplied by N e = Hammer efficiency factor

Use: 0.72 for all diesels

0.67 for conventional single acting ECH (external combustion hammers), including rope driven hammers

0.50 for conventional double acting ECH

0.95 for free fall rams or hammers with internally measured impact velocities

N = Number of hammer blows per inch at final penetration

(1) Jetted piles. Determine the inplace ultimate capacity of jetted piles based on impact hammer blow counts (dynamic formula) after the jet pipes have been removed. After the pile penetration length necessary to produce the required ultimate pile capacity has been determined by impact hammer blow count, install the remaining piles in each group or in each substructure unit to similar depths with similar methods. Confirm the required ultimate pile capacity has been achieved by using the dynamic formula.

(2) Conditions for dynamic formula. The dynamic formula is applicable only if all of the following apply:

(a) The hammer is in good condition and operating in a satisfactory manner;

(b) The hammer ram falls freely;

(c) A follower is not used; and

(d) The head of the pile is not broomed or crushed.

551.07 Preboring. Use auguring, wet rotary drilling, or other approved methods of preboring.

In compacted embankments more than 5 feet deep, prebore the pile hole to natural ground. Prebore holes 6 inches greater than the diameter of the pile. For square, rectangular or H piles, make the diameter of the hole equal to the diagonal of the pile cross-section plus 6 inches.

For piles end-bearing on rock or hardpan, preboring may extend to the surface of the rock or hardpan. Seat the pile into the end-bearing strata.

For piles not end-bearing on rock or hardpan, stop preboring at least 5 feet above the estimated pile tip elevation, and drive the pile with an impact hammer to a penetration which achieves the required ultimate pile capacity. Prebore holes smaller than the diameter or diagonal of the pile cross-section while allowing penetration of the pile to the specified depth.

If the subsurface obstructions such as boulders or rock layers are encountered, the hole diameter may be increased to the least dimension adequate for pile installation. After driving is complete, fill all remaining void space around the pile with sand or other approved material. Do not use a punch or a spud in lieu of preboring.

Do not impair the capacity of existing piles or the safety or condition of adjacent structures. If preboring disturbs the capacity of previously installed piles or structures, restore the required ultimate capacity of piles and structures by approved methods.

551.08 Preparation and Driving. Perform the work under Section 208. Make the heads of all piles plane and perpendicular to the longitudinal axis of the pile. Coordinate pile driving to prevent damage to other parts of the completed work.

Drive piles to within 2 inches of plan location at cutoff elevation for cutoff locations above ground and within 6 inches of plan location for cutoff locations below ground. The pile shall not be closer than 4 inches to any cap face. Drive piles so that the axial alignment is within1/4 inch per foot, along the longitudinal axis, of the required alignment. The CO may stop driving to check the pile alignment. Check alignment of piles that cannot be internally inspected after installation before the last 5 feet are driven. Do not pull laterally on piles or splice to correct misalignment. Do not splice a properly aligned section on a misaligned pile.

Place individual piles in pile groups either starting from the center of the group and proceeding outward in both directions or starting at the outside row and proceeding progressively across the group.

Correct all piles driven improperly, driven out of proper location, misaligned, or driven below the designated cutoff elevation in an approved manner. Replace piles damaged during handling or driving. Obtain approval for the proposed method(s) of correcting or repairing deficiencies.

(a) Timber piles. Do not use piles with checks wider than 1/2 inch. Drive treated timber piles within 6 months after treatment. Handle and care for pressure-treated piles according to AWPA Standard M 4.

(b) Steel piles. Furnish full-length, unspliced piles for lengths up to 60 feet. If splices are required in the first pile driven and it is anticipated that subsequent piles will also require splices, place the splices in lower third of the pile. Splice lengths less than 10 feet are not permitted and only 2 splices per pile are allowed.

Load, transport, unload, store, and handle steel piles so the metal is kept clean and free from damage. Do not use piles that exceed the camber and sweep permitted by allowable mill tolerance. Steel piles damaged during installation are considered unsatisfactory unless the bearing capacity is proven to be 100 percent of the required ultimate capacity by load tests. Perform tests at no cost to the Government.

(c) Precast and prestressed concrete piles. Support concrete piles during lifting or moving at the points shown on the plans or, if not so shown, provide support at the quarter points. Provide slings or other equipment when raising or transporting concrete piles to avoid bending the pile or breaking edges.

Reject concrete piles with reduced strength caused by external defects such as spalls, cracks, or internal defects such as cavities revealed with non-destructive testing.

(d) Concrete-filled pipe or steel shell piles. Furnish and handle the steel shells or pipes in accordance with (b) above. Cutting shoes for shells or pipes may be inside or outside the shell. Use high-carbon structural steel with a machined ledge for shell bearing or cast steel with a ledge designed for attachment with a simple weld.

When practicable, drive all pile shells or pipes for a substructure unit before placing concrete in any of the shells or pipes. Do not drive pile shells or pipes within 15 feet of any concrete-filled pile shell or pipe until the concrete has cured for at least 7 days or 3 days if using high-early-strength concrete. Do not drive any pile shell or pipe after it is filled with concrete.

Remove and replace shells that are determined to be unacceptable for use due to breaks, bends, or kinks.

551.09 Splices. Submit details for pile field splices for approval. Align and connect pile sections so the axis of the spliced pile is straight.

(a) Steel piles. Submit a welder certification for each welder. Use welders certified for structural welding.

Make surfaces to be welded smooth, uniform, and free from loose scale, slag, grease, or other material that prevents proper welding. Steel may be oxygen cut. Carbon-arc gouging, chipping, or grinding may be used for joint preparation.

Weld according to AASHTO/AWS D 1.5 Bridge Welding Code. Weld the entire pile cross-section using prequalified AWS groove weld butt joints. Weld so there is no visual evidence of cracks, lack of fusion, undercutting, excessive piping, porosity, or inadequate size. Manufactured splices may be used in place of full penetration groove butt welds.

(b) Concrete pile splices. Use dowels or other acceptable mechanical means to splice precast concrete or precast prestressed concrete piles. Submit drawings of proposed splices for acceptance.

If dowels are used, cast the dowels into the tip end of the following pile with corresponding holes at the butt end of the driven pile. Serrate the holes to provide a mechanical bond. Separate the ends of the piles by at least 1/2 inch. Clean all surfaces and dowel holes. Grout the dowels in place and allow the grout to cure. Enclose the gap with forms and inject a bonding agent capable of withstanding the impact and driving forces and having the same compressive strength as the pile. Follow the manufacturer’s recommendations regarding the use and curing of grouting and bonding products.

Attach manufactured splices to the concrete piles as recommended by the manufacturer. The splice shall develop strengths in compression, tension, and bending equal to or exceeding the strength of the pile being spliced.

(c) Concrete pile extensions.

(1) Precast concrete piles. Extend precast concrete piles by removing the concrete at the end of the pile and leaving 40 diameters of reinforcement steel exposed. Remove the concrete to produce a face perpendicular to the axis of the pile. Securely fasten reinforcement of the same size as that used in the pile to the projecting reinforcing steel. Form the extension to prevent leakage along the pile.

Immediately before placing concrete, wet the top of the pile thoroughly and cover with a thin coating of neat cement, re-tempered mortar, or other suitable bonding material. Place concrete of the same mix design and quality as that used in the pile. Keep forms in place for not less than 7 days after the concrete has been placed. Cure and finish according to Section 552.

(2) Prestressed piles. Extend prestressed precast piles according to (b) above. Include reinforcement bars in the pile head for splicing to the extension bars. Do not drive extended prestressed precast piles.

(d) Timber piles. Do not splice timber piles.

551.10 Heaved Piles. Check for pile heave during the driving operation. Take level readings immediately after each pile is driven and again after piles within a radius of 15 feet are driven. Re-drive all piles that heave more than 1/4 inches. Re-drive to the specified resistance or penetration.

551.11 Pile Load Tests. Pile load tests are not required unless specified to be performed in the contract.

(a) Dynamic load test. Use a qualified pile specialty consultant with at least 3 years experience in dynamic load testing and analysis to perform the dynamic load test, the case pile wave analysis program (CAPWAP), and the wave equation analysis including the initial wave equation analysis specified in Subsection 551.03(b). Submit a resume of the specialty consultant for approval.

Furnish equipment and perform dynamic load tests according to ASTM D 4945 under the supervision of the CO.

Place the piles designated as dynamic load test piles in a horizontal position and not in contact with other piles. Drill holes for mounting instruments near the head of the pile. Mount the instruments, and take wave speed measurements. Place the designated pile in the leads. Provide at least a 4-foot by 4-foot rigid platform with a 3½-foot safety rail that can be raised to the top of the pile.

Drive the pile to the depth at which the dynamic test equipment indicates that the required ultimate pile capacity is achieved. If necessary to maintain stresses in the pile below the values in Subsection 551.03(b)(2), reduce the driving energy transmitted to the pile by using additional cushions or reducing the energy output of the hammer. If nonaxial driving is indicated, immediately realign the driving system.

At least 24 hours after the initial driving, re-drive each dynamic load test pile with instrumentation attached. Warm the hammer before re-driving by applying at least 20 blows to another pile. Re-drive the dynamic load test pile for a maximum penetration of 6 inches, a maximum of 50 blows, or to practical driving refusal, whichever occurs first. Practical driving refusal is defined as 15 blows per inch for steel piles, 8 blows per inch for concrete piles, and 5 blows per inch for timber piles.

Verify the assumptions used in the initial wave equation analysis submitted according to Subsection 551.03(b) using CAPWAP. Analyze one blow from the original driving and one blow from the re-driving for each pile tested.

Perform additional wave equation analyses with adjustments based on the CAPWAP results. Provide a graph showing blow count versus ultimate capacity. For open-ended diesel hammers, provide a blow count versus stroke graph for the ultimate capacity. Provide the driving stresses, transferred energy, and pile capacity as a function of depth for each dynamic load test.

Based on the results of the dynamic load testing, CAPWAP analyses, and wave equation analyses, the order list and production driving criteria may be approved and the required cut-off elevations provided, or additional test piles and load testing may be specified. This information will be provided within 7 days after receipt of the order list and all required test data for the test piles driven.

(b) Static load tests. Perform static load tests according to ASTM D 1143 using the quick load test method except as modified herein. Submit drawings of the proposed loading apparatus for acceptance according to the following:

(1) Have a professional engineer prepare the drawings.

(2) Furnish a loading system capable of applying 150 percent of the ultimate pile capacity or 1,000 tons, whichever is less.

(3) Construct the apparatus to allow increments of load to be placed gradually without causing vibration to the test pile.

When tension (anchor) piles are required, drive tension piles at the location of permanent piles when feasible. Do not use timber or tapered piles installed in permanent locations as tension piles. Take the test to plunging failure or the capacity of the loading system, whichever occurs first.

The allowable axial pile load is defined as 50 percent of the failure load. The failure load is defined as follows:

• For piles 24 inches or less in diameter or diagonal width, the load that produces a settlement at failure of the pile head equal to:

• For piles greater than 24 inches in diameter or diagonal width:

where:

Sf = Settlement at failure in inches

D = Pile diameter or diagonal width in inches

S = Elastic deformation of pile in inches

Determine top elevation of the test pile immediately after driving and again just before load testing to check for heave. Wait a minimum of 3 days between the driving of any anchor or load test piles and the commencement of the load test. Before testing, re-drive or jack to the original elevation any pile that heaves more than 1/4 inch.

After completion of the load testing, remove or cut off any test or anchor piling not a part of the finished structure at least 2 feet below either the bottom of footing or the finished ground elevation.

Based on the results of the static load testing, the order list and production driving criteria may be approved and the required cut-off elevations provided or additional load tests may be specified. This information will be provided within 7 days after receipt of the order list and all required test data for the test piles driven.

551.12 Pile Cutoffs. Cut off the tops of all permanent piles and pile casings at the required elevation. Cut off the piles clean and straight parallel to the bottom face of the structural member in which they are embedded. Dispose of cutoff lengths according to Subsection 203.05(a).

(a) Steel piles. Do not paint steel to be embedded in concrete. Before painting the exposed steel pile, thoroughly clean the metal surface of any substance that may inhibit paint adhesion. Use aluminum colored paint system 2 according to Section 563. Paint piles before driving. Use one prime coat and 2 finish coats on trestles or other exposed piling to at least 4 feet below the finished groundline or waterline. Paint exposed piling above finished groundline or waterline with one field finish coat.

(b) Wood piles. Treat the heads of all treated timber piles which are not embedded in concrete by one of the following methods.

(1) Reduce the moisture content of the wood to no more than 25 percent with no free moisture on the surface. Brush apply one application of creosote-coal tar solution as required in AWPA Standards.

Build up a protective cap by applying alternate layers of loosely woven fabric and hot asphalt or tar, similar to membrane waterproofing, using 3 layers of asphalt or tar and 2 layers of fabric. Use fabric at least 6 inches wider in each direction than the diameter of the pile. Turn the fabric down over the pile and secure the edges by binding with 2 turns of No. 10 galvanized wire. Apply a final layer of asphalt or tar to cover the wire. Neatly trim the fabric below the wires.

(2) Cover the sawed surface with 3 applications of a hot mixture of 60 percent creosote and 40 percent roofing pitch, or thoroughly brush coat with 3 applications of hot creosote and cover with hot roofing pitch. Place a covering of galvanized sheet metal over the coating and bend down over the sides of each pile.

551.13 Unsatisfactory Piles. Correct unsatisfactory piles by an approved method. Methods of correcting unsatisfactory piles may include one or more of the following:

(a) Use of the pile at a reduced capacity;

(b) Install additional piles;

(c) Repair damaged piles; and

(d) Replace damaged piles.

551.14 Placing Concrete in Steel Shell or Pipe Piles. After driving, clean the inside of shells and pipes by removing all loose material. Keep the shell or pipe substantially water tight. Provide suitable equipment for inspecting the entire inside surface of the driven shell or pipe just before placing concrete.

(a) Reinforcing steel. When reinforcing steel is required, make the spacing between adjacent cage elements at least 5 times the maximum size of aggregate in the concrete.

Securely tie concrete spacers or other approved spacers at fifth points around the perimeter of the reinforcing steel cage. Install spacers at intervals not to exceed 10 feet measured along the length of the cage.

Place the reinforcement cage into the driven shell or pipe when the concrete reaches the planned bottom elevation of the reinforcement. Support the reinforcement so it remains within 2 inches of the required vertical location. Support the cage from the top until the concrete reaches the top of the pile.

(b) Concrete. Construct concrete according to Section 552. Place concrete in one continuous operation from the bottom to the top of the pile. Before the initial concrete set, consolidate the top 10 feet of the concrete pile using approved vibratory equipment.

551.15 Acceptance. Pile material will be evaluated under Subsections 106.02 and 106.03.

Furnish production certifications with each shipment of the following:

(a) Concrete piles;

(b) Sheet piles, steel H-piles, steel shells, and steel pipes; and

(c) Treated timber piles. Stamp each pile with an identification mark and date of inspection.

Driving piles and related work will be evaluated under Subsections 106.02 and 106.04.

Concrete for steel shells or pipe piles will be evaluated under Section 552.

Reinforcing steel for steel shells or pipe piles will be evaluated under Section 554.

Measurement

551.16 Measure the Section 551 items listed in the bid schedule according to Subsection 109.02 and the following as applicable.

When measurement is by the linear foot, measure the length of pile from the cutoff elevation to the tip.

Measure splices required to drive piles deeper than the estimated tip elevation.

Payment

551.17 The accepted quantities will be paid at the contract price per unit of measurement for the Section 551 pay items listed in the bid schedule except the concrete-filled pipe or steel shell pile unit bid price will be adjusted according to Subsection 106.05. Payment will be full compensation for the work prescribed in this Section. See Subsection 109.05.

Payment for concrete-filled pipe or steel shell piles will be made at a price determined by multiplying the unit bid price by an adjusted pay factor (PFa) determined as follows:

PFa = 1 ‑ 0.5 (1‑PF) where:

PF = Pay factor for concrete as determined under Section 552.

Section 552. — STRUCTURAL CONCRETE

Description

552.01 This work consists of furnishing, placing, finishing, and curing concrete in bridges, culverts, and other structures.

Structural concrete class is designated as shown in Table 552-1.

Material

552.02 Conform to the following Subsections:

Air-entraining admixture 711.02

Chemical admixtures 711.03

Coarse aggregate 703.02

Color coating 725.24

Curing material 711.01

Elastomeric bearing pads 717.10

Elastomeric compression joint seals 717.16

Fine aggregate 703.01

Fly ash 725.04

Ground iron blast-furnace slag 725.04

Hydraulic cement 701.01

Joint fillers and sealants 712.01

Latex modifier 711.04

Linseed oil 725.14

Masonry cement 701.02

Silica fume (microsilica) 725.04

Water 725.01

Construction Requirements

552.03 Composition (Concrete Mix Design). Design and produce concrete mixtures that conform to Tables 552-1 and 552-2 for the class of concrete specified. Determine design strength values according to ACI 318. Structural concrete shall also conform to the following ACI specifications.

• ACI 211.1 Standard Practice for Selecting Proportions for Normal, Heavy Weight and Mass Concrete;

• ACI 211.2 Standard Practice for Selecting Proportions for Structural Light Weight Concrete; and

• ACI 211.3 Guide for Selecting Proportions of No-Slump Concrete.

Table 552-1

Composition of Concrete

Class of

Concrete Minimum Cement

Content

(pounds per cubic yard) Maximum

W/C Ratio Slump(1) (inches) Nominal Maximum Aggregate Size (inches)

ADVANCE \d 4(1) Maximum slump is 8 inches if approved mix design includes a high-range water reducer.

(2) Concrete with a water reducing and retarding admixture conforming to AASHTO M 194, type D.

(3) A latex modified concrete with 0.037 gallons of modifier per pound of cement.

(4) Measure the slump 4 to 5 minutes after the concrete is discharged from the mixer.

Table 552-2

Minimum Air Content for Air Entrained Concrete

Nominal Maximum

Aggregate Size As Delivered Minimum

Air Content (1) (%)

(1) These air contents apply to the total mix. When testing these concretes, aggregate larger than 1½ inches is removed by handpicking or sieving, and air content is determined on the minus 1½-inch fraction of the mix. Air content of the total mix is computed from the value determined on the minus 1½-inch fraction.

Submit concrete mix designs on FHWA Form 1608.

Verify mixture design with trial mixes prepared according to ACI 318 from proposed source(s) or with previous concrete production data for the mixture design submitted from proposed source(s). Submit written concrete mix designs for approval at least 36 days before production. Each mix design submittal shall include all of the following:

(a) Project identification;

(b) Name and address of Contractor and concrete producer;

(c) Mix design designation;

(d) Class of concrete and intended use;

(e) Material proportions;

(f) Name and location of material sources for aggregate, cement, admixtures, and water; and

(g) Type of cement and type of cement replacement if used. Fly ash, ground iron blast-furnace slag, or silica fume may partially replace cement in any mix as follows:

(1) Fly ash.

(a) Class F. Not more than 20 percent of the minimum mass of portland cement in Table 552-1 may be replaced with class F fly ash at the rate of 1.5 parts fly ash per 1 part portland cement.

(b) Class C. Not more than 25 percent of the minimum mass of portland cement in Table 552-1 may be replaced with class C fly ash at the rate of 1 part fly ash per 1 part portland cement.

(2) Ground iron blast-furnace slag. Not more than 50 percent of the minimum mass of portland cement in Table 552-1 may be replaced with ground iron blast-furnace slag at the rate of 1 part slag per 1 part portland cement.

(3) Silica fume (microsilica). Not more than 10 percent of the minimum mass of portland cement in Table 552-1 may be replaced with silica fume at the rate of 1 part silica fume per 1 part portland cement.

For concrete exposed to deicing chemicals, fly ash will constitute no more than 25 percent and silica fume no more than 10 percent of the total replacement weight. Additionally, fly ash, slag, and silica fume will constitute no more than 50 percent of the total replacement weight.

The water/cement ratio for modified concrete is the ratio of the mass of water to the combined masses of hydraulic cement and cement substitute.

(h) Cement content in pounds per cubic yard of concrete.

(i) The saturated surface dry batch mass of the coarse and fine aggregate in pounds per cubic yard of concrete.

(j) Water content in pounds per cubic yard of concrete.

(k) Water/cement ratio.

(l) Dosage of admixtures. When requested by the CO, provide a qualified person from the admixture manufacturer to help establish the proper dosage. Do not mix chemical admixtures together in a mix unless they are compatible. Furnish supporting documentation of compatibility from the manufacturers. Do not use high range water reducers for bridge decks.

(1) Air-entraining admixtures. Entrained air may be obtained with either an air entraining hydraulic cement or an air entraining admixture.

(2) Set accelerating admixtures. Do not use chloride accelerators. Do not use set accelerating admixtures with class P (prestressed) concrete.

(3) Hydration stabilizing admixtures. Hydration stabilizing admixtures may be used to extend the allowable delivery time for concrete. Base the dosage on the time needed to delay the initial set of the concrete for delivery and discharge on the job. Include the design discharge time limit in the dosage submittal. The maximum allowable design discharge time is 3.50 hours.

(m) Sieve analysis of fine and coarse aggregate.

(n) Absorption of fine and coarse aggregate.

(o) Bulk specific gravity (dry and saturated surface dry) of fine and coarse aggregate.

(p) Dry rodded unit mass of coarse aggregate in pounds per cubic foot.

(q) Fineness modulus (FM) of fine aggregate.

(r) Material certifications for cement, admixtures, and aggregate.

(s) Target values for concrete slump with and without high-range water reducers.

(t) Target values for concrete air content. Include the proposed range of air content for concrete to be incorporated into the work. Describe the methods by which air content will be monitored and controlled. Provide acceptable documentation that the slump and compressive strength of the concrete are within specified limits throughout the full range of proposed air content.

(u) Concrete unit mass.

(v) Specified design strength (f’c) and required average strength (f’cr) for the concrete mixture at 28 days based on ACI 318. When insufficient data is available, select (f’cr) from Table 552-3. Pending 28-day strength results, a mix design may be approved on the basis that 7-day compressive strength results meet or exceed 85 percent of the required average strength (f’cr) at 28 days.

Table 552-3

Required Average Strength

Specified Design Strength (f’c)

(pounds per square inch) Required Average Strength (f’cr)

(pounds per square inch)

(w) Compressive strengths test results at 7 and 28 days. Each compressive strength test consists of two or more cylinders tested according to AASHTO T 22 at the same age.

(x) Material samples if requested.

Begin production only after the mix design is approved.

Furnish a new mix design for approval if there is a change in a source of material or when the fineness modulus of the fine aggregate changes by more than 0.20.

552.04 Storage and Handling of Material. Store and handle all material in a manner that prevents segregation, contamination, or other harmful effects. Do not use cement and fly ash containing evidence of moisture contamination. Store and handle aggregate in a manner that ensures a uniform moisture content at the time of batching.

552.05 Measuring Material. Batch the concrete according to the approved mix design and the following tolerances:

A calibrated volumetric system may be used if the specified tolerances are maintained.

552.06 Batching Plant, Mixers, and Agitators. Use a batching plant, mixer, and agitator conforming to AASHTO M 157. Continuous volumetric mixing equipment shall conform to AASHTO M 241.

552.07 Mixing. Mix the concrete in a central-mix plant or in truck mixers. Operate all equipment within manufacturer's recommended capacity. Produce concrete of uniform consistency.

(a) Central-mix plant. Dispense liquid admixtures through a controlled flowmeter. Use dispensers with sufficient capacity to measure, at one time, the full quantity of admixture required for each batch. If more than one admixture is used, dispense each with separate equipment.

Charge the coarse aggregate, one third of the water, and all air entraining admixture into the mixer first, then add remainder of the material.

Mix for at least 50 seconds. Begin mixing time after all cement and aggregate are in the drum. Add the remaining water during the first quarter of the mixing time. Add 4 seconds to the mixing time if timing starts the instant the skip reaches its maximum raised position. Transfer time in multiple-drum mixers is included in mixing time. Mixing time ends when the discharge chute opens.

Remove the contents of an individual mixer before a succeeding batch is charged into the drum.

(b) Truck mixer. Do not use mixers with any section of the blades worn 1 inch or more below the original manufactured height. Do not use mixers and agitators with accumulated hard concrete or mortar in the mixing drum.

Add admixtures to the mix water before or during mixing.

Charge the batch into the drum so a portion of the mixing water enters in advance of the cement.

Mix each batch of concrete according to AASHTO M 157.

552.08 Delivery. Produce and deliver concrete to permit a continuous placement with no concrete achieving initial set before the remaining concrete being placed adjacent to it. Deliver, handle, and place concrete in such a manner as to minimize rehandling of the concrete and prevent any damage to the structure.

Do not place concrete that has developed an initial set. Never re-temper concrete by adding water.

If a hydration stabilizing admixture is approved for use in the concrete mix, deliver and place the concrete within the approved design discharge time limit. Limit the slump loss to no more than 2 inches during the stabilization period. An approved and compatible hydration activator may be used at the discharge sit to ensure proper placement and testing.

(a) Truck mixer/agitator. Use the agitating speed for all rotation after mixing. When a truck mixer or truck agitator is used to transport concrete that is completely mixed in a stationary central construction mixer, mix during transportation at manufacturer's recommended agitating speed.

If the concrete has not obtained an initial set, water and admixtures in the approved mix design may be added one time at the project to obtain the required slump or air content. The total of all water in the mix shall not exceed the maximum water/cement ratio of the approved mix design. Remix the concrete and added water or admixtures with 30 revolutions at mixing speed. After the initial introduction of mixing water to cement or cement to aggregates, complete the remixing within the time specified in Table 552-4. After the beginning of the addition of the cement, complete the discharge of the concrete within the time specified in Table 552-4.

Table 552-4

Concrete Remixing and Discharge Time Limits

Time Limit (hour)

(1) AASHTO M 85, type III.

(b) Nonagitating equipment. Nonagitating equipment may be used to deliver concrete if the concrete discharge is completed within 20 minutes from the beginning of the addition of the cement to the mixing drum. Use equipment with smooth, mortar tight, metal containers capable of discharging the concrete at a controlled rate without segregation. Provide covers when needed for protection.

552.09 Quality Control of Mix. Submit and follow a quality control plan according to Sections 153 and 154 as applicable and the following.

(a) Mixing. Designate a competent and experienced concrete technician to be at the mixing plant in charge of the mixing operations and to be responsible for the overall quality control including:

(1) The proper storage and handling of all components of the mix;

(2) The proper maintenance and cleanliness of plant, trucks, and other equipment;

(3) The gradation testing of fine and coarse aggregates;

(4) The determination of the fineness modulus of fine aggregate;

(5) The measurement of moisture content of the aggregates and adjusting the mix proportions as required before each day's production or more often if necessary to maintain the required water/cement ratio;

(6) The computation of the batch masses for each day's production and the checking of the plant's calibration as necessary; and

(7) The completion of batch tickets. Include the following information:

(a) Concrete supplier;

(b) Ticket serial number;

(c) Date and truck number;

(d) Contractor;

(e) Structure or location of placement;

(f) Mix-design and concrete class;

(g) Component quantities and concrete total volume;

(h) Moisture corrections for aggregate moisture;

(i) Total water in mix at plant;

(j) Time of batching and time at which discharge must be completed;

(k) Maximum water that may be added to the mix at the project; and

(l) If a hydration stabilizing admixture is used, record the slump at the plant after adding the stabilizer.

Provide equipment necessary for the above tests and controls. Furnish copies of work sheets for (3), (4), (5), and (6) as they are completed.

(b) Delivery and sampling. Designate at least one competent and experienced concrete technician to be at the project and be responsible for concrete delivery, discharge operations, and sampling that include the following:

(1) The verification that adjustments to the mix before discharge comply with the specifications.

(2) The completion of the batch ticket, the recording of the apparent water/cement ratio, and the time discharge is completed. Furnish a copy of each batch ticket at the time of placement.

(3) The furnishing of all equipment and the performing of temperature, unit mass, air content, slump, and other tests to verify specification compliance before and during each placement operation.

If hydration stabilizing admixture is used, determine the slump before placement. Do not use concrete with a slump loss of more than 2 inches as compared to the slump recorded at the batch plant.

Sample every batch after at least 0.25 cubic yards are discharged and before placing any of the batch in the forms. When continuous mixing is used, sample approximately every 10 cubic yards. Test the air content according to AASHTO T 152 or T 196.

Test unit mass, slump, and temperature according to Subsection 552.19.

If 3 successive samples are tested and compliance to the specifications is indicated, screening tests may be reduced to an approved frequency.