Section 551 — Driven Piles

Description

551.01This work consists of providing and constructing driven piles and concrete-filled pipe piles.

Material

551.02Conform to the following Sections and Subsections: Coating material 719 Non-shrink grout 701.04(b)(1) Piling 715 Polyester resin grout 725.14(b) Prestressing steel 709.02 Reinforcing steel 709.01 Sandbags 713.14

Construction Requirements

551.03Qualifications. Provide a professional engineer and a pile specialty consultant with experience installing driven piles and provide AWS certified welders when installing steel piles. A t least 30 days before starting driven pile work , submit the following for approval:

(a)Professional engineer. A résumé describing at least 3 years’ experience in wave equation analyses.

(b)Pile specialty consultant. If dynamic load testing is specified, provide a résumé describing at least 3 years’ experience in:

(1)Dynamic load testing and analysis;

(2)Signal matching analysis; and

(3)Wave equation analysis including the initial wave equation analysis.

(c)Welders. AWS certifications.

551.04Submittals. At least 30 days before starting driven pile operations, submit the following according to Subsection 104.06:

(a)Construction s equence. Start date and proposed driven pile construction sequence;

(b)Wave equation analysis report. A wave equation analysis for the proposed pile driving system;

(c)Equipment and analysis. The following pile- driving equipment information:

(1)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;

(2)Hammer. Manufacturer, model, type, serial number, rated energy ( _____ at _____ length of stroke), ram weight, modifications, and 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 i f approved. For closed- end diesel hammers, 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;

(3)Capblock (hammer cushion). Material, thickness, area, modulus of elasticity, and coefficient of restitution; (4) Pile cap. Helmet weight, bonnet mass, anvil block mass, and drivehead mass;

(5)Pile cushion. Material, thickness, area, modulus of elasticity, and coefficient of restitution;

(6)Pile. Pile t ype, length (in leads), mass per linear foot, wall thickness, taper, cross -sectional area, design pile capacity, and tip treatment description;

(7)Test pile details. Location, type, estimated tip elevation, minimum allowable embedment, length, capacity, allow able compressive and tensile stresses;

(8)Subsurface conditions. Soil description, soil damping and quake parameters used in analysis, anticipated driving difficulties (if any);

(9)Bearing graph analysis results. Calculated maximum compressive and tensile stres ses, penetration resistance (blow counts), hammer stroke and energy transferred to the pile for a range of nominal soil resistance values. Provide an inspector’s chart with blow count versus stroke graph for the required nominal capacity;

(d)Splices. Details for pile field splices, pile section lengths, and elevations of splices;

(e)Pile shoes. Details for pile shoes;

(f)Pile installation log. Proposed form for recording installation of piles;

(g)Preboring. Preboring, hole cleaning and preparation, pile placement and equipment, and procedures for the ground conditions expected to be encountered. Include methods and certifications required for penetration of subsurface obstructions. If preboring disturbs the capacity of previously installed piles or structures, submit a plan with procedures to restore the required nominal capacity; and

(h)Static load test. Drawings of the proposed loading apparatus.

551.05Pile Driving Equipment. Provide equipment conforming to the following requirements:

(a)Pile hammers.

(1)Gravity hammers. Gravity hammers may only be used to drive timber piles. Provide a hammer with a ram weighing between 2000 and 3500 pounds and limit the drop height to 12 feet or less. Select a ram mass greater than the combined mass of the drive head and pile. Pr ovide hammer guides to ensure concentric impact on the drive head.

(2)Open- end diesel hammers. Use open -end diesel hammers with pure (B100) biodiesel. Equip open- end (single acting) diesel hammers with a device on the ram to allow visual determination of hamm er stroke.

(3)Closed -end diesel hammers. Use closed -end diesel hammers with pure (B100) biodiesel. Equip hammers with a dial gauge for measuring pressure in the bounce chamber. Ensure the gauge is 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 achieve cylinder lift at the maximum energy -bounce chamber pressure relationship given in the hammer specification.

(4)Air or steam hammers. Provide plant and equipment for steam and air hammers able 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 at least one- third the combined mass of the driving head and pile. Ensure the combined mass is at least 2750 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 with non- petroleum based hydraulic f luids and biodiesel fuels. If specified, use nonimpact hammers, such as vibratory hammers. 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. Strike piles with an impact hammer of suitable energy to verify the required pile capacity is obtained on at least one of every ten piles.

(6)Hydraulic hammers. Use hydraulic hammers with pure vegetable oil or grape seed oil. 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. Provide pile -driving equipment that allows permanent piles to be driven with reasonable effort and to the required depths and resistances without damage. Approval of pile -driving equipment will be based on a wave equation analysis. Use the approved equipment represented in the wave equation analysis 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. Approval of a pile hammer does not relieve the Contractor of responsibility for piles damaged due to driving stress. The req uired number of hammer blows indicated by the wave equation at the nominal pile capacity is from two to ten blows per inch. Do not allow the pile stresses resulting from the wave equation analysis to exceed the following values:

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

(2)Concrete piles. Limit the tensile (TS ) and compressive ( CS) driving stresses to: TS ≤ 3 f' c 1/2 + EPV CS ≤ 0.85f f'c - EPV where: f'c = The 28-day design compressive strength of the concrete in pounds per square inch EPV = The effective prestress value in pounds per square inch

(3)Timber piles. Limit the compressive driving stress to: σdr = φ da(FCO) where: σdr = limiting driving stress (ksi) φda = resistance factor, drivability analysis FCO = base resistance of wood in compression parallel to the grain (ksi)

(c)Driving appurtenances.

(1)Hammer cushion. Equip 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 starting pile driving at each structure or af ter 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. Provide appropriate drive heads, m andrels, 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. 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. 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 allows proper alignment of battered piles.

(4)Followers . Use followers only if approved. If followers are allowed, drive the first pile in each bent or substructure unit and ever y tenth pile thereafter, full length without a follower, to verify that adequate pile embedment is being achieved to develop the required nominal capacity. Provide a follower of such material and dimensions that allows the piles to be driven to the require d penetration. Hold and maintain follower and pile in proper alignment during driving.

(5)Jetting. Use jetting only if approved. Provide jetting equipment with sufficient capacity to deliver a consistent pressure equivalent to at least 100 pounds per square inch at two ¾- inch jet nozzles. Jet so as not to affect the lateral stability of the final in -place 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 nominal capacity with an impact hammer. Control, treat if necessary, and dispose of 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 starts 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. If specified, provide shoes to protect the pile tip from damage during driving. Fabricate 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 holes, cuts, or caps in treated timber piles with two -brush applications of creosote -coal tar solution according to American Wood Protection Association (AWPA).

551.06Pile Lengths. Provide piles with sufficient length to obtain the required resistance and to extend into the pile cap or footing as indicated in the plans. Increase the length to provide fresh heading and to provide for the method of operation. If test piles are required, provide piles in the lengths determined by the test piles.

551.07Test Piles. Install test piles if specified. 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 after the pile is in leads and take wave speed measurements. 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. Provide 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 nominal capacity at the estimated tip elevation. Allow test piles that do not attain the required nominal c apacity at the estimated tip elevation to set up for 24 hours before re -driving. Warm the hammer before re -driving starts by applying at least 20 blows to another pile. If the required nominal capacity is not attained on re -driving, drive a portion or the remaining test pile length and repeat the set up and re -drive procedure as directed. Splice and continue driving until the required nominal pile capacity is achieved. Conform to the requirements for production piles when test piles are to be used in the completed structure. Remove test piles not incorporated in the completed structure to at least 24 inches below finished grade.

551.08Driven Pile Capacity. Drive piles to the specified penetration and to the depth necessary to achieve the required nominal pile capacity. Splice piles not obtaining the required nominal capacity at the ordered length, and drive with an impact hammer until the required nominal pile capacity is achieved. Use a Saximeter or other approved equipment to record the blow count and stroke versus depth for test and production piles. Determine the nominal pile capacity of the in -place piles using dynamic load test results. If a dynamic load test is not specified use the wave equation to determine nominal pile capacity of the in-place pile.

(a)Wave equation. Adequate penetration is achieved when the specified wave equation resistance criteria are 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. Do not use the dynamic formula to determine driven pile capacity.

551.09Preboring. Use augering, wet rotary drilling, or other approved methods of preboring. Do not use a punch or a spud instead of preboring. Prebore the pile hole to natural ground in compacted embankments more than 5 feet deep. In natural ground, preboring may extend to the surface of the rock or hardpan for piles end -bearing on rock or hardpan. Seat the pile into the end- bearing strata. 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 nominal pile capacity for piles not end -bearing on rock or hardpan. Prebore holes smaller than the di ameter or diagonal of the pile cross -section while allowing penetration of the pile to the specified depth. Increase the hole diameter to the least dimension adequate for pile installation if subsurface obstructions such as boulders or rock layers are enco untered. Fill remaining void space around the pile with sand or other approved material after driving is complete. 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 nominal capacity of piles and structures by approved methods.

551.10Preparation and Driving. Make the heads of 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 pile heads to within 3 inches of plan location at cutoff elevation for bent caps supported by piles and to within 6 inches of plan location for piles capped below final grade. Locate and dr ive piles at least 4 inches from any edge of the cap. Drive piles so that the axial alignment is no more than ¼ inch per foot along the longitudinal axis of the required alignment. The CO may stop driving to check the pile alignment. Check alignment before the last 5 feet are driven for piles that cannot be internally inspected after installation. 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 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 unless otherwise approved. Obtain approval for the proposed methods of correcting or repairing deficiencies. Submit pile driving records including Saximeter readings at the end of each work shift.

(a)Steel piles. Provide full -length, un- spliced piles where practical. Load, transport, unload, store, and handle steel piles to keep the metal clean and without damage. Do not use piles that exceed the allow ed mill tolerance for camber and sweep. Steel piles damaged during installation are unacceptable unless the minimum tip elevation is achieved and load tests show the bearing capacity is 100 percent of the required nominal. Perform tests on damaged piles. If driving points are required, weld driving points to steel piles according to AWS, Structural Welding Code - Steel D1.1 or AASHTO/AWS, Bridge Welding Code D1.5 as applicable.

(b)Precast and precast prestressed concrete piles. Fabricate precast piles from Cla ss P(AE) concrete and precast prestressed piles from Class P(AE) concrete according to Section 552. Conform to Section 554 for reinforcing steel. Conform to Section 553 for prestressing steel. If lifting anchors are used, maintain at least a 1 -inch clearance from the pile reinforcing steel or prestressing steel. Use metal, plywood, or dressed lumber forms that are watertight, rig id, and true to line. Use a 1 -inch chamfer strip in corners of the forms. Cast piles separately or, if alternate piles are cast in a tier, cast the intermediate piles at least 4 days after the adjacent piles are poured. Separate piles cast in tiers with tar paper or other suitable separating material. Place concrete in each tier in a continuous operation that prevents the formation of stone pockets, honeycombs, or other defects. Leave forms in place for at least 24 hours. Make piles straight so when a line is stretched from butt to tip on any face, the line is no more than 1 inch from the face of the pile at any point. Make the pile surface true, smooth, even, and without honeycombs and voids. Remove lifting anchors to a depth of at least 1 inch below the concrete surface and fill the resulting hole with concrete. Finish each pile with a Class 1 ordinary surface finish according to Subsection 552.14. Cure the piles according to Subsection 552.13 or 553.06 as applicable. If concrete test cylinders are made and tested according to Section 552, do not move piles until the tests indicate a compressive strength of at least 80 percent of the design 28- day compressive strength. Do not transport or drive piles until tests indicate the minimum design 28 -day compressive strength is attained. If concrete test cylinders are not made, do not move piles until they have cured for at l east 14 days at a minimum temperature of 60 °F or 21 days at a minimum temperature of 40 °F. Do not transport or drive piles until cured for at least 21 days at 60 °F or higher or 28 days at 40 °F or higher. If high early strength cement is used, do not move, transport, or drive piles until cured for at least 7 days. Support concrete piles during lifting or moving at the points shown in the plans. Provide support at the quarter points if not specified. Avoid bending the pile or breaking edges when lifting or moving the piles. 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.

(c)Concrete- filled steel pipe piles. Provide and handle the steel pipes according to Subsection 551.10(a) . Cutting shoes may be inside or outside the pipe. Use high- carbon structural steel with a machined ledge for pipe bearing or cast steel with a ledge designed for attachment with a simple weld. Use the class of concrete designated in the plans according to Section 552 . Drive pile pipes before placing concrete in the pipes. Do not drive piles within 15 feet of concrete -filled pile pipe until 80 percent of the design strength is attaine d. Do not drive pile pipe after it is filled with concrete.

(d)Timber piles. Do not use piles with checks wider than ½ inch. Drive treated timber piles within 6 months after treatment. Handle and care for pressure- treated piles accor ding to AWPA, Standard M4 Standard for the Handling, Storage, Field Fabrication and Field Treatment of Preservative - Treated Wood Products .

551.11Splices. Align and connect pile sections so the axis of the spliced pile is straight.

(a)Steel piles. Splices are allowed when piles lengths exceed 60 feet. Space splices at least 10 feet apart. Use no more than 2 splices per pile. Use welders certified for structural welding. Make surfaces to be welded smooth, uniform, and without loose scale, slag, greas e, 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 AWS, Structural Welding Code - Steel D1.1 or AASHTO/AWS, Bridge Welding Code D1.5. We ld 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 if approved or shown in the plans. Ensure the splice develops the full strength of the pile in compression, tension, and bending. Perform non -destructive examination on splices located in the upper half of the total pile lengt h by performing one of the following tests:

(1)Radiographic testing according to the requirements of AWS, Structural Welding Code - Steel D1.1 or AASHTO/AWS, Bridge Welding Code D1.5.

(2)Ultrasonic testing according to the requirements of AWS, Structural Welding Code - Steel D1.1 or AASHTO/AWS, Bridge Welding Code D1.5. Repair weld defects according to AWS, Structural Welding Code - Steel D1.1 or AASHTO/AWS, Bridge Welding Code D1.5.

(b)Concrete pile splices. Use dowels or other approved mechanical means to splice precast concrete or precast prestressed concrete piles. 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. Clean surfaces and dowel holes. Separate the ends of the piles by at least ½ inch. Grout the dowels in place and allow the grout to cure. Enclose the gap with forms and inject a bonding agent that can withstand the impact and driving forces and ha s the same compressive str ength as the pile. Follow the manufacturer’s recommendations for the use and curing of grouting and bonding products. Attach manufactured splices to the concrete piles according to the manufacturer’s recommendations. Ensure the splice develops strengths in compression, tension, and bending at least 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 bar diameters of reinforcemen t 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 approved bonding material. Place concrete of the same mix design and quality as that used in the pile. Keep forms in place for at least 7 days after the concrete has been placed. Cure and finish according to Section 552.

(2)Precast prestressed piles. Extend precast prestressed piles according to Subs ection 551.11(b) . 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.

551.12Heaved 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 piles that heave more than ½ inch. Re -drive to the specified resistance or penetration.

551.13Pile Load Tests. Perform dynamic load tests at the locations shown in the plans. Static load tests are not required unless specified.

(a)Dynamic load test. Provide equipment and perform dynamic load tests according to ASTM D4945 in the presence of the CO. Mount the instruments according to Subs ection 551.07. Drive the pile to the depth at which the dynamic test equipment indicates that the required nominal pile capacity is achieved. If necessary to maintain stresses in the pile below the values in Subsection 551.05(b)(1) , reduce the driving energy transmitted to the pile by using additional cushions or reducing the energy output of t he hammer. Realign the driving system if nonaxial driving is indicated. At least 2 4 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 3 inches, a maximum of 20 blows, or to practical driving refusal, whichever occurs first. Practical driving refusal is defined as 12 blows per inch for steel piles, 10 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 551.04(b) using signal matching analysis. 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 signal matching analysis results. Provide a graph showing blow count versus nominal capacity. Provide a blow count versus stroke graph for the nominal capacity of open- ended diesel hammers. Provide the driving stresses, transferred energy, and pile capacity as a function of depth for each dynamic load test. Within 3 days of the completion of testing, s ubmit the dynamic load test results according to Subsection 104.06. Based on the results of the dynamic load testing, signal matching analyses, and wave equation analyses, the order list and production driving criteria m ay 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 required test data for the test piles driven.

(b)Static load tests. Perform static load tests according to ASTM D1143 using the quick load test method, except as modified in this Section .

(1)Provide a loading system that can apply 150 percent of the nominal pile capacity or 1000 tons, whichever is less.

(2)Construc t the loading apparatus to allow increments of load to be placed gradually without causing vibration to the test pile. Perform test at least 5 days after test pile was driven unless approved. If tension (anchor) piles are required, drive tension piles at the location of permanent piles. 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 nominal bearing resistance is defined as 50 percent of the failure load. The failure load is defined as follows: For piles no more than 24 inches in diameter, length of side for square piles or diagonal width, the load that produces a settlement at failure of the pile head equal to: Sf = S + (0.15 + 0.008D) For piles greater than 24 inches in diameter, length of side for square piles or diagonal width: 𝑈𝑈𝑓𝑓 = S + D where: Sf = Settlement at failure (in) D = Pile diameter or diagonal width (in) S = Elastic deformation of pile (in) Determine top elevation of the test pile immediately after driving and again immediately before load testing to check for heave. Wait at least 3 days between the driving of anchor or load test piles and the start of the load test. Before testing, re -drive or jack t o the original elevation piles that heaves more than ¼ inch. After completion of the load testing, remove or cut off test or anchor piling not a part of the finished structure at least 24 inches below either the bottom of footing or the finished ground elevation. Within 7 days of the completion of testing, s ubmit the static load test results according to Subsection 104.06. 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 required test data for the test piles driven.

(c)No load test. If no load test is specified, drive each pile to the minimum tip elevation as shown in the plans or to practical driving refusal. Practical driving refusal is defined as 12 blows per inch for steel piles, 10 blows per inch for concrete piles, and 5 blows per inch for timber piles.

551.14Pile Cutoffs. Cut off the tops of permanent piles and pile casings at the required elevation. Cut off the piles clean and straight and parallel to the bottom face of the structural member in which they are embedded. Dispose of cutoff lengths according to Subsection 203.07. Treat the heads of treated timber piles which are not embedded in concrete by one of the following methods:

(a)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 three layers of asphalt or tar and two 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 two 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.

(b)Cover the sawed surface with three applications of a hot mixture of 60 percent creosote and 40 percent roofing pitch, or thoroughly brush coat with three 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.

551.15Unsatisfactory Piles. Correct unsatisfactory piles by an approved method. Methods of correcting unsatisfactory piles may include one or more of the following:

(a)Use the pile at a reduced capacity.

(b)Install additional piles.

(c)Repair damaged piles.

(d)Replace damaged piles.

551.16Placing Concrete in Steel Pipe Piles. Clean the inside o f pipe piles by removing material to the depth of limits of concrete fill shown in the plans. If a soil plug leaves a void deeper than the limits of concrete fill, fill to that depth using concrete or a bentonite grout mix batched in the proportions shown in Table 551-1 or other approved mix. Table 551-1

Pipe Pile Fill

Material Quantity

Cement 94 lb Bentonite 25 lb Water 30 gal Remove water before placing concrete or place the concrete using a tremie when water is present in the pile. Dispose of water according to Federal, state, and local rules and regulations. Provide suitable equipment for inspecting the entire inside surface of the driven pipe immediately before placing concrete.

(a)Reinforcing steel. Make the spacing between adjacent cage elements at least five times the maximum size of aggregate in the concrete when reinforcing steel is required. Securely tie concrete spacers or other approved spacers at fifth points around the perimeter of the reinforcing steel cage. Install spacers at intervals no more than 10 feet measured along the length of the cage. Place the reinforcement cage into the driven 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. Consolidate the top 10 feet of the concrete pile using approved vibratory equipment before the initial concret e set.

551.17Acceptance. Pile material will be evaluated under Subsections 106.02 and 106.03. Provide production certifications with each shipment of the following:

(a)Concrete piles;

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

(c)Treated timber piles. Driving piles will be evaluated under Subsections 106.02 and 106.04. Concrete will be evaluated under Section 552. Prestressing steel will be evaluated under Section 553. Reinforcing steel will be evaluated under Section 554.

Measurement

551.18Measure the Section 551 pay items listed in the bid schedule according to Subsection 109.02 and the following as applicable: When measuring piles by the linear foot, measure the length of pile from the cutoff elevation to the tip. When measuring preboring by the linear foot, measure from the ground surface to the base of the prebored pile hole. Measure splices required to drive piles deeper than the estimated tip elevation.

Payment

551.19The accepted quantities will be paid at the contract price per unit of measurement for the Section 551 pay items listed in the bid schedule. Payment will be full compensation for the work prescribed in this Section. See Subsection 109.05 .