Construction. Provide safe and environmentally acceptable equipment that can produce a specification pavement.

Transcription

1 Section 502. HOT MIX ASPHALT CONSTRUCTION PRACTICES Description. Prepare the existing pavement and construct hot mix asphalt (HMA) pavements, shoulders, and approaches. Provide a pavement meeting plan requirements, which is uniform in texture, density and smoothness with no measurable segregation Materials. Use materials meeting the following: Hot Mix Asphalt Mixtures Bond Coat, SS-1h, CSS-1h Release agents. Use release agents that do not harm the properties of the mixture, or the environment and is approved by the Engineer. Do not use fuel oil or other distillate derivatives. Construction. Provide safe and environmentally acceptable equipment that can produce a specification pavement. A. Equipment. 1. Cold-Milling Machines. Equipment must consistently remove the HMA surface, in one or more passes, to the required grade and cross section producing a uniformly textured surface. Machines must be equipped with all of the following: a. automatically controlled and activated cutting drums b. grade reference and transverse slope control capabilities c. an approved grade referencing attachment, not less than 30 feet in length. An alternate grade referencing attachment may be used if approved by the Engineer prior to use. 2. Hauling Equipment. Transport trucks must be equipped to completely protect the mixture from the weather and to retard the loss of heat. 3. Pressure Distributor. Pressure distributor must meet the requirements of subsection A Pavers. Each paver must be equipped with a full-width vibratory or tamper bar screed that can spread and finish the HMA to the required cross section and grade. Use a paver that produces a uniformly finished surface free from tearing or other blemishes and free from measurable segregation. 230

2 Equip the paver to provide a uniform head of material ahead of the screed. Install reverse pitch augers or paddles inside both ends of the auger shafts to force the mix to the center of the main screed. Extensions added to the main screed must provide the same vibrating or tamping action and heating capabilities as the main screed. Adjust extensions to the main screed so no longitudinal marks remain on the surface after breakdown rolling. Equip in line screed extensions with a continuation of the automatically controlled spreading augers to within 18 inches of the outside edge. Follow the manufacturer s recommendations for all other screed extensions. Except in certain conditions outlined in subsection.f, equip pavers with an automatically controlled and activated screed with grade reference and transverse slope control. Use an approved grade referencing attachment, 30 feet or more in length, for all lower courses and the first pass of the top course. Secure the Engineer s approval before using any alternate grade referencing attachment. After the first pass of the top course has been placed, a joint matcher or a grade referencing attachment 10 feet or more in length may be substituted for constructing subsequent adjacent passes of the top course, with prior approval of the Engineer. 5. Rollers. Rollers must meet the following requirements. a. Steel-Wheeled Rollers. Steel-wheeled rollers must be selfpropelled vibratory or static tandem rollers or self-propelled static three-wheeled rollers. Provide a steering device that responds readily and permits the roller to be directed on the desired alignment. Equip rollers with wheel sprinklers and scrapers. Provide smooth roller wheels free from openings or projections that will mar the surface of the pavement. Provide vibratory rollers with an automatic shutoff to deactivate the vibrators when the roller speed is less than 0.5 mph. Provide rollers that operate according to the manufacturer s recommended speed, impacts per foot, and amplitude of vibration (dynamic force) for the thickness of HMA being compacted. b. Pneumatic-Tired Rollers. Pneumatic-tired rollers must be selfpropelled. Rollers must be equipped with a minimum of seven wheels spaced on the axles so that the rear group of tires do not follow in the tracks of the forward group but provide a minimum tire path overlap of 1 2 inch. Provide smooth tires that can be 231

3 inflated to the pressure recommended by the manufacturer of the roller. Equip the rollers with a mechanism that can smoothly reverse the motion of the roller. Equip the rollers with wheel scrapers and skirting to enclose the wheel area to within 3 inches of the pavement surface. Use a release agent to prevent material from sticking to the tires. Do not leave excessive globules of mixture on the top course pavement during rolling. c. Combination Rollers. Combination pneumatic-tired and steelwheeled rollers manufactured specifically for HMA compaction may be used provided they are equipped with the necessary sprinklers and scrapers described above. 6. Spreaders. Use self-propelled spreaders with sufficient power and weight to push the hauling units. Spreaders must be capable of maintaining the specified width, depth, and slope, without causing segregation of the material. 7. Compressed Air System When a compressed air system is required for cleaning pavement, equip the air compressor with a moisture separator to remove all oil and water from the air supply. Provide a compressor that can produce a minimum pressure of 100 pounds per square inch and continuous 150 cubic feet per minute of air flow. 8. Miscellaneous Equipment. Provide a straightedge (10-foot minimum) and all tools necessary to satisfactorily finish the work. 9. Lights on Equipment. On HMA construction where traffic is being maintained, all equipment working within the project limits, including cold-milling machines, distributors, and rollers, must be equipped with at least one approved flashing, rotating, or oscillating amber light. Pavers must be equipped with at least one such light on each side of the paver. Mount the lights so that the warning signal will be visible to traffic in all directions. Operate the lights while the work is in progress. Hauling units must activate four-way flashers within the project limits B. Preparation of Base. Provide subgrade, subbase, aggregate base course, crushed and shaped base, or rubblized base that meets applicable requirements of Divisions 2 and 3, at the time of placement of the HMA. 232

4 C. Preparation of Existing Pavement. 1. Drainage Structures, Monument Boxes and Water Shutoffs. Temporarily lower and/or adjust catch basin and manhole covers, monument boxes and water shutoffs according to section A. 2. Cleaning Pavement. Thoroughly clean all dirt and debris from the surface of the pavement, and the paved shoulders if applicable, before placing HMA. Use a method approved by the Engineer. Remove loose material from all joints and cracks using compressed air. If the Engineer determines that the compressed air system will not remove detrimental material, removal of this material by a hand or mechanical method approved by the Engineer will be paid for as extra work according to subsection D. Do not place HMA until the Engineer has inspected and approved the condition of the pavement. 3. Removing Existing Pavement for Butt Joints. When a butt joint is specified, remove the existing surface to the thickness of the proposed overlay, for the full width of the joint where the overlay is to end. Uniformly taper the removal up to the original surface over a minimum of 35 feet. 4. Edge Trimming. Where the removal of HMA shoulder material or up to one foot width of HMA pavement is required, first cut the HMA material full depth along the pavement edge or removal line to prevent the tearing of the pavement surface. Cut joints that will be exposed in the completed surface must be cut with a saw or a coldmilling machine or other methods approved by the Engineer. Joints that will be covered by HMA must be cut with a coulter wheel, a saw, a cold-milling machine or other method approved by the Engineer. 5. Cold-Milling HMA Surfaces. Before milling the existing pavement, have an approved mix design and adequate supply of materials to ensure that the first lift of the specified HMA is placed on all milled surfaces. Remove the HMA surface to the depth, width, grade, and cross section specified. Backfill, and compact according to Subsection.C.9, all depressions left by removal of material below the specified grade. All costs associated with this backfill and compaction will be borne by the Contractor. 233

5 Immediately after cold-milling, clean the surface. Dispose of the material removed from the surface according to Subsections and Do not incorporate it into the HMA. 6. Removing HMA Surface. Except as specified in subsection.c.4, removing HMA surface applies to removing HMA overlying a base course that is to remain in place. Joints that will be exposed in the completed surface must be cut in a neat line with a saw or a cold-milling machine. Joints that will be covered by HMA must be cut with a coulter wheel, a saw, a coldmilling machine. Alternate methods for cutting these joints must be approved by the Engineer. When removing HMA overlying a base course that is to remain in place, cut the edges of the surface to be removed along straight lines for the full depth of the HMA surface. When removing by coldmilling, the Engineer may direct that the depth of the HMA surface removed be less than full depth. Cutting the edges and removal and disposal of the HMA material are included in this item of work. 7. Removing HMA Patches. Remove all patches that may cause unsatisfactory performance of the overlay. 8. Joint and Crack Clean out. When joint and crack clean out is called for on the plans use mechanical or hand methods to remove joint sealants to a depth of at least one inch. Remove vegetation, dirt and debris that cannot be removed using methods described in subsection.c.2 from transverse and longitudinal joints and cracks. Use hand patching to fill cleaned joints and cracks that are equal to or greater than one inch wide. 9. Hand Patching. When hand patching is called for in the contract documents, fill holes, depressions, joints and cracks in the existing pavement and replace existing patches. Compact the hand patching material in maximum 3-inch lifts to the adjacent pavement surface grade using a machine vibrator or approved roller. Use top course mixture for hand patching material. 10. Repairing Pavement Joints and Cracks. Repair joints and cracks according to the details shown on the plans and in the proposal. 234

6 D. Bond Coat. Apply the bond coat uniformly to the clean, dry, surface with a pressure distributor. Obtain the Engineer s approval of the application rate once work has started. Apply the bond coat far enough ahead of the paving operation to allow it to cure before placing the HMA. Do not leave pools of bond coat on the surface. When constructing HMA shoulders or widenings, do not spray the bond coat on the adjacent pavement surface. Apply the bond coat to each layer of HMA and to the vertical edge of the adjacent pavement before placing subsequent layers. E. Transportation of Mixtures. Apply an approved release agent to the hauling units. Excessive use of a release agent will be cause for rejection of the load. Do not place crusted HMA in the paver. Maintain the temperature of the mixture discharged from the hauling unit at the target placement temperature according to Table or as approved by the Engineer. A tolerance of ±20 F from the specified target placement temperature is acceptable. Occasional loads outside ±20 F may be permitted, provided the temperature of the mixture is adjusted back to the specified target placement temperature. The Department will reject all loads having a temperature below 250 F or above 350 F at time of discharge from the hauling unit. Table Target Placement Temperatures Temperature of Rate of Application of HMA Material, the Surface Being lb/syd Overlaid, F < >200 Target Placement Temperatures, F and over

7 F. Placing HMA. Use pavers meeting subsection.a.4 unless placing mixtures for: (1) variable width sections, (2) the first course of a base course mixture on a subgrade or on a sand subbase, (3) base course mixtures for shoulders and widenings less than 10.5 feet in width, or (4) top and leveling course mixtures for shoulders and widenings less than 8 feet wide. Place HMA mixtures in lifts, not to exceed the application rate. When the application rate for a HMA pavement exceeds the maximum rates shown in Table and the edges are not confined, construct the pavement in two or more lifts. Table Maximum HMA Application Rates Maximum Application Rate, Mixture Type Course Application lb/syd 2 Base Base Leveling Leveling, Top Top A Base, Leveling, Top A Leveling, Top 165 2C Base 500 3C Base, Leveling 330 4C Leveling, Top 260 Wedge with HMA when necessary to take out irregularities in the existing road surface. Place and compact any HMA wedging necessary to make corrections to the foundation and allow to cool enough to support construction equipment without causing visible distortion of the mat prior to placing subsequent wedging, base, leveling, or top course mixtures. Place all HMA mixtures to the plan slope and width. Place any subsequent HMA course such that the current vertical edge aligns with the previous course(s) without constructing a ledge. Correct any ledge which results from placing material in excess of the plan width. All costs associated with this corrective action will be borne by the Contractor. 236

8 Place shoulder aggregate and compact flush after each lift of HMA placed. Traffic control devices must be placed according to subsection , at the Contractor s expense, at any location where shoulders are not flush with the pavement upon completion of the day s paving. The shoulder aggregate shall be brought flush the next day. Complete final shaping and compaction of the shoulders after placement of the top course of HMA. When delays slow paving operations such that the temperature of the mat immediately behind the screed falls below 200 F, stop paving and place a transverse construction joint. If the temperature of the mat falls below 190 F before any rolling, remove and replace the mat. All cost associated with this removal and replacement will be the Contractor s responsibility. When placing the uppermost leveling and top course, place the longitudinal joint to coincide with the proposed painted lane lines. If the temperature of the previously placed mat falls below 170 F prior to placement of the adjacent mat, apply bond coat to the vertical edge before placing mixture on the adjacent section. When constructing the lanes with two or more pavers in echelon, match the depth of loose HMA from each paver at the longitudinal joints. Transition the new mat to existing surfaces at the beginning and ending of resurfacing sections and at intersections unless butt joints are used. Transition the new mat to existing surfaces at a rate of approximately 1 inch in 35 feet. Construct transitions only after bond coat has been applied at 0.10 gallons per square yard and properly cured. After compaction has been completed, spray with bond coat, sand, and roll the first 3 feet of the joint and 1 foot of the existing surface. 1. Transverse Construction Joint. When constructing a transverse construction joint, stop the paver and lift the screed before the material falls below the auger shaft; remove the paver and roll through the proposed joint location. Cut a transverse vertical joint and remove the excess HMA. Place burlap, canvas, or paper as a bond breaker ahead of and against the vertical face. Place HMA against the bond breaker and taper from the new mat down to the existing surface. Extend the temporary taper 5 feet for each inch of mat thickness or as directed by the Engineer. Thoroughly compact and cool the temporary taper before allowing traffic on the new surface. Remove the temporary taper before resuming paving. 237

9 2. Longitudinal Joints. Construct either vertical or tapered longitudinal joints. a. Vertical Longitudinal Joint. Plan the work so that at the completion of each day s paving operations, all lanes are resurfaced to within one load of the same point-of-ending. When placing the HMA in a lane adjoining a previously placed lane, place the mixture so that it uniformly overlaps the first lane by 1 to 2 inches. Place at a height above the cold mat equal to the breakdown roller depression on the hot mat. When necessary, use alternative traffic staging to allow for bumping the joint. Bump the overlapping material, using a lute or other device which will give similar results, back onto the hot lane so that the roller will compress the small quantity of excess material into the hot side of the joint. If the overlap is excessive, trim the excess material to leave an edge having a uniform thickness. Discard the excess material, do not spread it across the surface course. When unable to bump the joint, use a tapered overlapping longitudinal joint as specified in subsection.f.2.b. b. Tapered Overlapping Longitudinal Joint. A tapered overlapping longitudinal joint in lieu of a longitudinal vertical joint is allowed. The requirement that all lanes be resurfaced to within one load of the same point-of-ending at the completion of each day s paving operations does not apply when a tapered overlapping longitudinal joint is used. Construct the tapered overlapping longitudinal joint by tapering the HMA mat at a slope no greater than 1:12 and extend the tapered portion beyond the normal lane width. Place a 0.5 to 1 inch notch at the top of the taper on all courses of paving. Construct the tapered portion of the mat using an approved strike-off device that will provide a uniform slope and will not restrict the main screed. Pave the adjacent lane within 24 hours, unless delayed by inclement weather. Apply bond coat to the surface of the taper before the adjacent lane is placed. 238

10 Final density requirements for the entire pavement, including the taper area, will remain unchanged. Compact the initial taper section as near to final density as possible. Apply a weighted roller, as wide as the taper, to the taper section of the pavement 3. Placing HMA Shoulders. Use a self-propelled mechanical paver or spreader to place the HMA. Place shoulder aggregate and compact flush after each lift of HMA placed. Traffic control devices must be placed according to subsection , at the Contractor s expense, at any location where shoulders are not flush with the pavement upon completion of the day s paving. The shoulder aggregate shall be brought flush the next day. Complete final shaping and compaction of the shoulders after placement of the top course of HMA. When placing the top course on new shoulders, or when placing the leveling or top course on existing HMA shoulders 8 feet or more wide, place the mixture using a paver with an automatically controlled and activated screed and strike-off assembly and corresponding grade referencing equipment. Use the grade referencing equipment as directed by the Engineer. Stop shoulder paving at crossroad approaches, auxiliary lanes, commercial driveways and ramps. Paving through these areas is prohibited. 4. Placing HMA Approaches. Place the HMA on an approved foundation of a driveway or crossroad approach. Place approaches in lifts not to exceed the application rate. Do not stop mainline paving of the lane next to the approach to pave the HMA approach. G. Rolling. Compact each layer of HMA to the required density, free of all roller marks. Use a pneumatic-tired roller for initial compaction on the first course placed on a rubblized base or existing pavement. Do not mark or rut the surface or displace the pavement edges with pneumatic-tired rollers. Use tandem steel-wheeled rollers for the final rolling operation on each layer of HMA. Operate vibratory rollers in the static mode when used for finish rolling or pinching the joint. 239

11 Keep the surface of the steel roller wheels completely moist with water when rolling. Start rolling longitudinally at the extreme sides of the lanes and go toward the center of the pavement, overlapping on successive trips by at least half the width of the drive wheel of the roller. Vary the lengths of alternate passes of the roller. When compacting an adjoining lane, and not restricted by traffic, roll the vertical longitudinal bumped joint first with the roller supported on the cold lane with only 2 to 6 inches of the roller extending onto the freshly placed HMA mixture. H. Smoothness Requirements. After final rolling, the Engineer may test the surface longitudinally and transversely using a 10-foot straightedge at selected locations according to MTM 722. Construct the surface to the following limits. All costs associated with correcting variations more than the specified limits will be borne by the Contractor. Base Course Mixtures: Lower Courses: Top Course: 3 4 inch 3 8 inch Leveling and Top Course Mixtures: Multiple Course Construction: Lower Courses: 1 4 inch Top Course: 1 8 inch Single Course Construction: 1 4 inch I. Weighing Loads. Weigh each load of HMA accepted by the Department to the nearest 20 pounds on an approved scale having an automatic point out system. The a scale and print out system for platform and suspended scales must meet subsection G. J. Weather and Seasonal Limitations. Do not place HMA or apply bond coat when precipitation is imminent or when moisture on the existing surface will prevent satisfactory curing. Unless otherwise approved by the Engineer in writing, temperature and seasonal requirements for placing HMA will be according to Table or as stated below. The Department will not allow paving below these minimum temperatures, nor when frost is on or in the grade or on the existing surface. 240

12 Seasonal Limitations for placing HMA are as follows: 1. June 1-October 15 for the Upper Peninsula 2. May 15-November 1 for the Lower Peninsula north of M May 5-November 15 for the Lower Peninsula south of M-46. K. Protection of Structures. Protect bridges, curbs, gutters, driveways, sidewalks, barriers, and other appurtenances to prevent their surfaces from being discolored during the application of bond coat or HMA material to the road surface. All costs associated with removing material from these appurtenances as directed by the Engineer, will be borne by the Contractor. L. Aggregate Shoulders. On resurfacing projects, scarify the existing aggregate shoulder surfaces before placing new aggregate material. Maintain the shoulder as a satisfactory surface for vehicles to travel on while passing the construction equipment. If Contractor s operations or traffic disturb the area between pavement edges and the right-of-way lines, restore it to a condition satisfactory to the Engineer. All costs associated with this restoration will be borne by the Contractor. M. Monument Boxes. Place or adjust monument boxes according to section Measurement and Payment. Contract Item (Pay Item) Pay Unit Pavt for Butt Joints, Rem...Square Yard Edge Trimming... Foot Cold Milling HMA Surface...Square Yard, Ton HMA Surface, Rem...Square Yard HMA Patch, Rem...Square Yard Joint and Crack, Cleanout... Foot Hand Patching...Ton Pavt, Cleaning... Lump Sum Pavt Joint and Crack Repr, Det... Foot HMA, (type)...ton HMA, (type), inch...square Yard HMA Approach...Ton A. Pavt for Butt Joints, Rem includes removing and disposing of concrete or HMA materials. 241

13 B. Edge Trimming will be measured along the cut edge and includes the cutting, removing, and disposing of the excess HMA material. C. Cold Milling HMA Surface includes removing, loading, hauling, weighing, and disposing of the cold milled material. When paid for by the ton, the cold milled material must be deposited directly from the cold milling machine into the hauling units and weighed on a scale meeting the requirements in subsection G prior to placment in a stockpile or a disposal area. Material picked up by cleaning after cold milling will not be weighed or considered for payment. D. Pavt, Cleaning will be measured as a unit including paved shoulders and approaches and widened areas. The work includes cleaning the foundation, joints, and cracks. The work also includes sweeping shoulders, base courses, and leveling courses, if necessary. If additional hand or mechanical methods are required by the Engineer, this work will be paid for as Joint and Crack, Cleanout if this pay item is included in the contract. Otherwise, this work will be paid for as extra work according to subsection E. Joint and Crack, Cleanout will be measured along the joint and crack cleaned. F. Hand Patching includes the HMA placed by hand, or other methods, and compaction of the material. G. HMA will be measured and paid by weight when in tons, or by area when in square yards. Refer to contract documents for details. H. Removing HMA Surface. 1. Removal of HMA surface, 12 inches or less thick, overlying a material to remain in place, will be measured and paid for as HMA, Surface, Rem. 2. Removal of HMA surface, greater than 12 inches thick, overlying a material to remain in place, will be measured and paid for as Pavt, Rem according to subsection