Asphalt Paving

This specification covers the materials, mix design, execution, and quality control for hot-mix asphalt (HMA) flexible pavement constructed on a prepared aggregate base course. Asphalt pavement is a layered, flexible system: each course carries load by flexing slightly and distributing wheel loads downward over an increasing area, so that the stress reaching the subgrade is a small fraction of the contact stress at the tire. The system performs only as well as its weakest layer. A surface course placed over a deficient base, or a properly designed mix compacted to inadequate density, fails prematurely regardless of how good the other elements are. The cost of correcting an asphalt defect after the pavement is opened to traffic — milling, removal, and replacement, plus the disruption of taking a parking lot or drive out of service — vastly exceeds the cost of placing it correctly the first time.

This standard addresses the HMA mixture types and the role of each course in the section, aggregate gradation and nominal maximum aggregate size, the performance-graded binder grade and its climate dependence, the mix design method and volumetric acceptance, prime and tack coats, reclaimed asphalt pavement content, field quality control for density and thickness and smoothness, and the execution of subgrade and base verification, prime and tack application, placement temperature, lift thickness, compaction, and joint construction. Predecessor work — the aggregate base course on which this pavement is placed — is covered by Aggregate Base CourseAggregate Base CourseResolves to the current adopted revision.sync/aggregate-base-course, and the subgrade beneath the base is covered by EarthworkEarthworkResolves to the current adopted revision.sync/earthwork. The Contractor placing asphalt inherits the base surface left by the base course Contractor, and shall not place asphalt over a base that has not been accepted.

All work under this specification shall conform to the pavement section, course thicknesses, limits, grades, and drainage shown on the contract drawings and to the recommendations of the geotechnical report. Where this standard and the geotechnical or pavement-design report conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing. The pavement section thicknesses shown on the drawings are design-specific and are not subject to reduction; the Contractor shall not thin a course to compensate for a high base or to economize on material, because pavement thickness is the single largest determinant of fatigue life.

Materials, mix design, testing, and execution shall comply with the latest adopted edition of the following standards. Where project documents, adopted codes, and referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.

Note on superseded standards: ASTM D3515 (Hot-Mixed, Hot-Laid Bituminous Paving Mixtures) was withdrawn in 2009 and is not a current acceptance basis; mixtures shall be designed and accepted under the Superpave volumetric framework (AASHTO M 323 / R 35) or the Marshall method (ASTM D6926 / D6927) as specified herein. Penetration-graded binder (ASTM D946) is a legacy grading system retained only where a local authority still specifies it; performance-graded (PG) binder per AASHTO M 320 or M 332 is the default.

The Contractor shall submit the following for the Engineer of Record's review before delivering any asphalt mixture to the site. Paving shall not begin until the submittals are reviewed and returned. Submittal review does not relieve the Contractor of responsibility for compliance with the contract documents.

• Job-mix formula (JMF) for each mixture and course, prepared under the specified mix design method, showing the design aggregate gradation against the control points for the specified nominal maximum aggregate size, the design binder content, and the volumetric properties at the design number of gyrations or Marshall blows (air voids, voids in the mineral aggregate, voids filled with asphalt, and dust-to-binder ratio)
• Performance-graded asphalt binder certification (certificate of analysis) for the specified PG grade, traceable to the supply terminal lot, confirming compliance with AASHTO M 320 or M 332
• Aggregate gradation analysis for each aggregate stockpile feeding each mixture, and the combined gradation of the JMF
• Aggregate quality test results: Los Angeles abrasion (ASTM C131/C131M), sulfate soundness (ASTM C88/C88M), and percentage of fractured faces (ASTM D5821) for the coarse aggregate
• Reclaimed asphalt pavement (RAP) characterization where RAP is proposed: source, gradation of the extracted aggregate, recovered binder content, and the resulting blended binder grade
• Prime coat and tack coat material product data and the proposed application rates
• Mix design verification or prior approval letter from the producing plant's certified laboratory, or from the state DOT where the plant holds a current approved-mix listing that matches the specified mixture

Prior to substantial completion the Contractor shall provide the following:

• Field and plant test reports for asphalt content, gradation, volumetrics, in-place density, and core thickness, indexed to lot, course, and location, and signed by the testing technician
• Daily placement records showing tonnage placed by course, ambient and mix temperatures, and the areas paved each day
• As-built record of finished pavement surface elevations and course thicknesses sufficient to confirm conformance with the drawings and with the thickness and smoothness tolerances of this specification
• Material certifications for the binder and aggregate sources delivered, including any source changes during construction
• Manufacturer's and Contractor's warranty documentation as required by this specification

The asphalt mixture shall be produced by a plant with a current quality-control program and, where the Authority Having Jurisdiction maintains a producer-certification program, a current certification. The plant shall be capable of producing the specified mixture at the specified rate, maintaining mix temperature within the limits specified herein during loading and haul, and providing certified plant test data for each lot. A plant that holds a current state DOT certification and an approved-mix listing matching the specified mixture has demonstrated the relevant capability; absent such certification, the Contractor shall submit the plant's quality-control plan and recent production test history for the Engineer of Record's review.

Each job-mix formula shall be approved by the Engineer of Record before production begins. Approval confirms that the gradation falls within the control points for the specified nominal maximum aggregate size, that the design binder content produces the specified air void content at the design compactive effort, and that the volumetric properties meet the requirements of the specified mix design method. A JMF that was approved on a prior project may be reused only if the aggregate sources, the binder grade, and the RAP content are unchanged; any change in source or RAP fraction requires a new or revised JMF and re-approval, because the volumetrics shift with aggregate shape, absorption, and the stiffness contributed by recovered RAP binder.

Acceptance testing for in-place density, thickness, and mixture properties shall be performed by a qualified independent testing agency retained by the Owner. Testing for acceptance shall not be performed by the Contractor or by an agency under the Contractor's direction, because the testing entity must be independent of the party whose work it accepts. The testing agency shall be experienced in HMA testing, equipped with calibrated nuclear density gauges and a coring rig, and capable of providing results within the reporting times required by this specification.

Before paving begins the Contractor shall participate in a pre-construction conference attended by the Contractor's paving superintendent, the asphalt producer's representative, the testing agency, and the Engineer of Record. The conference shall review the approved job-mix formulas, the pavement section and course sequence, the prime and tack coat materials and rates, the placement temperature and weather limits, the lift thickness and compaction requirements, the density and smoothness acceptance criteria, the joint construction details, the procedure for handling failing density and thickness results, and the lines of communication for field decisions.

Hot-mix asphalt loses heat to the surface it is placed on and to the air, and compaction must be completed before the mat cools below the temperature at which the binder is workable. Placing on a cold base, in cold air, or with wind accelerating heat loss shortens the available compaction window, often to the point that the specified density cannot be achieved before the mat sets. The minimum placement temperature depends on the compacted lift thickness, because thicker lifts retain heat longer and tolerate cooler conditions.

The surface on which asphalt is placed shall be dry. HMA shall not be placed on a wet, frozen, or frost-covered base, because trapped moisture flashes to steam under the hot mat and disrupts the bond, and a frozen base thaws beneath the new pavement to create a low-density layer that propagates as a settlement defect. The Contractor shall measure surface temperature, not just air temperature, before placement.

The surface course is the most sensitive to cold-weather placement because it is the thinnest course and cools fastest. Where the schedule forces base and intermediate courses to be placed in marginal weather, the Engineer of Record may permit deferral of the surface course to a period of favorable weather, with the intermediate course serving as a temporary wearing surface. Deferral shall be documented so that the surface course obligation is not lost at closeout.

Paving shall be suspended at the onset of rain and shall not resume until the base surface is dry. Mix in transit or in the paver hopper at the time rain begins shall be evaluated for temperature loss; mix that has cooled below the minimum compaction temperature shall be wasted rather than placed. High wind accelerates surface cooling and shall be treated as a reduction in the available compaction window, narrowing the conditions under which thin lifts can be placed.

A flexible pavement section is built from the base up, and each course has a distinct function that drives its mixture design.

The asphalt base course (where used) is the lowest asphalt-bound layer, placed directly on the aggregate base. It carries the largest structural contribution per inch of any asphalt course and uses the largest nominal maximum aggregate size, because a coarse, stiff, economical mix is appropriate where surface texture and ride quality are not yet a concern.

The intermediate (binder) course bridges between the base and the surface. It provides structural depth, levels out irregularities in the layer beneath it, and establishes the plane on which the surface course is placed.

The surface (wearing) course is the layer exposed to traffic and weather. It uses the smallest nominal maximum aggregate size to provide a dense, tight, smooth, durable, skid-resistant surface, and is designed for durability and impermeability as much as for structural contribution.

The number and thickness of courses are set by the pavement design and shown as indicated on the pavement section detail and the paving plan. A typical commercial parking lot uses a single surface course over an intermediate course; a heavy-duty truck or drive lane adds an asphalt base course or increases the intermediate-course thickness.

The nominal maximum aggregate size (NMAS) is the controlling gradation parameter for an HMA mixture. A smaller NMAS produces a finer, denser, lower-permeability surface with better workability and a smoother finished texture, but contributes less structural stiffness per inch and requires more binder. A larger NMAS produces a coarser, stiffer, more economical mix suited to lower courses. The NMAS shall be matched to the course and to the compacted lift thickness: the compacted lift thickness shall be at least three times the NMAS for fine-graded mixes and at least four times the NMAS for coarse-graded mixes, so that the largest particles can reorient under the roller rather than locking and fracturing.

The combined aggregate gradation shall fall within the control points of AASHTO M 323 for the specified nominal maximum aggregate size, and shall avoid the restricted zone guidance such that the mixture is a well-graded, dense mixture rather than a tender, fine-sand-prone gradation. The job-mix formula gradation, once approved, becomes the target, and production gradation shall track the JMF within the production tolerances rather than wandering anywhere within the broad control-point band. A gradation that drifts within the band from truck to truck produces a mat with variable density, variable permeability, and variable durability even though every individual sample is "within specification."

Coarse aggregate shall be crushed, angular, and durable. Angular crushed faces interlock under load and resist rutting; rounded, uncrushed gravel particles roll past one another and the mix shoves and ruts under traffic. The aggregate shall resist mechanical breakdown during mixing, placement, and compaction (Los Angeles abrasion, ASTM C131/C131M) and shall resist weathering breakdown over the pavement service life (sulfate soundness, ASTM C88/C88M).

The performance-graded (PG) binder is designated PG XX-YY, where the first number is the upper pavement temperature the binder must resist without rutting and the second is the lower temperature it must resist without thermal cracking. The grade is selected for the project climate: the high-temperature grade is keyed to the seven-day average maximum pavement temperature, and the low-temperature grade is keyed to the minimum pavement temperature, both adjusted for the desired reliability. Specifying a binder grade that does not match the climate is a common and consequential error — too soft a high grade rutts in summer, too stiff a low grade cracks in winter.

The local climate-appropriate base grade shall be confirmed against the project location; PG 64-22 is the most common grade across much of the temperate United States but is not universal. The Asphalt Institute and state DOT binder maps provide the location-specific base grade.

Where traffic is heavy, slow, or standing — truck drive lanes, loading docks, bus stops, and intersection approaches — the binder high-temperature grade should be increased ("bumped") one or two grades above the climate base grade to resist rutting under the longer load duration. Under the MSCR specification (AASHTO M 332), traffic is addressed by a grade letter (S, H, V, or E for standard, heavy, very heavy, or extremely heavy loading) appended to the base PG grade and verified by the non-recoverable creep compliance (Jnr) from the MSCR test (AASHTO T 350), rather than by bumping the high-temperature number. Either system is acceptable where it is the locally adopted convention.

The Superpave volumetric method (AASHTO M 323 with AASHTO R 35) is the default mix design method and is the dominant method in current US practice. It compacts trial specimens in a gyratory compactor to a number of gyrations selected for the design traffic level, and the mixture is accepted on its volumetric properties at that compactive effort rather than on a stability load. The Marshall method (ASTM D6926 for specimen preparation and ASTM D6927 for stability and flow) is a legacy method that remains in use in some jurisdictions and for some small or specialty mixtures; it compacts specimens with a drop hammer (35, 50, or 75 blows per face) and accepts the mix on stability, flow, and air voids. Marshall shall be used only where it is the locally adopted method or where the project is too small to justify a gyratory design.

The design number of gyrations (Ndesign) for a Superpave mix is selected for the design traffic expressed in equivalent single-axle loads (ESALs) over the design life. Most commercial parking lots and light site roadways fall in the low to medium traffic range; truck routes, bus lanes, and industrial drives fall higher. Selecting too high a gyration count for a low-traffic lot produces a dry, low-binder mix that is durable in theory but brittle and prone to raveling and cracking in practice; selecting too low a count for a heavy-traffic drive produces a rich mix that ruts.

The design air void content is the volumetric target that governs binder content: the binder content is selected to produce the design air voids at the design compactive effort. Four percent air voids is the long-standing Superpave design target and is appropriate for the great majority of mixtures. Too few design air voids produces a rich mix that bleeds and ruts; too many produces a dry, permeable mix that ages quickly, ravels, and admits water into the section.

The voids in the mineral aggregate (VMA) shall meet the minimum for the nominal maximum aggregate size, because VMA is the space available to hold both the design air voids and enough binder for durability. A mix that meets air voids but fails VMA is starved of binder and will not be durable. The dust-to-binder ratio (the ratio of material passing the No. 200 sieve to the effective binder content) shall fall within the specified range; excess dust stiffens the mix and reduces its fatigue resistance, while too little dust produces a tender mix. These properties are part of mix design approval and are verified in production.

Reclaimed asphalt pavement (RAP) is milled or crushed existing asphalt that is processed and incorporated into new HMA, recovering both the aggregate and the aged binder. RAP reduces material cost and conserves resources, but the recovered binder is oxidized and stiff, so high RAP fractions stiffen the mixture, raise the effective high-temperature grade, and reduce the low-temperature cracking resistance unless the virgin binder grade is softened to compensate. The allowable RAP content shall be limited based on the course, the traffic, and whether the binder grade is adjusted for the RAP contribution.

Where the RAP content exceeds the fraction at which no binder adjustment is required (commonly about 15 to 20 percent of total binder), the virgin binder grade shall be softened one grade on the low-temperature side, or the blended binder grade shall be verified by testing the recovered-plus-virgin blend, so that the in-place mixture meets the specified PG grade. RAP shall be of consistent, characterized source; commingled or unknown-source RAP shall not be used in surface courses.

A prime coat is a low-viscosity asphalt material applied to an untreated aggregate base to penetrate and bind the surface of the base, promote adhesion between the base and the first asphalt course, and limit moisture intrusion before paving. On a tight, dense, well-compacted dense-graded aggregate base, a true penetrating prime often cannot penetrate and a prime coat may be omitted in favor of a tack coat; the need for a prime coat depends on the base type and local practice.

A tack coat is a thin application of diluted asphalt emulsion applied between asphalt courses (and between asphalt and any abutting existing pavement or vertical face) to bond the lifts into a monolithic section. The bond between lifts is essential to flexible-pavement performance: an unbonded interface allows the courses to slip independently, concentrating stress and producing slippage cracking, debonding, and premature surface failure. Tack coat is one of the lowest-cost and most frequently shortchanged elements of asphalt paving — too little, applied unevenly, or contaminated by tracking, and the bond fails.

The application rate is expressed as residual (undiluted) asphalt per square yard; the as-sprayed rate of diluted emulsion is higher in proportion to the dilution. New, clean asphalt surfaces require a lower rate; milled, oxidized, or dusty surfaces require a higher rate. The tack coat shall be allowed to break (the emulsion color shall turn from brown to black) before the overlying course is placed, so that the water has left the emulsion and the residual asphalt is in place to bond. The distributor application rate shall be verified per ASTM D2995. Tracking of tack coat by construction traffic onto adjacent surfaces and out of the paving area shall be controlled; tracked-away tack leaves bare spots that do not bond.

In-place density is the most important single acceptance parameter for asphalt pavement, because the long-term durability of an otherwise sound mix is governed almost entirely by how well it is compacted. Under-compacted asphalt has high in-place air voids; those interconnected voids admit water and air, the binder oxidizes and embrittles, and the pavement ravels and cracks years before its design life. Density is specified and accepted as a percentage of the theoretical maximum specific gravity (Gmm, the "Rice" value) of the mixture, determined per AASHTO T 209 or ASTM D2041, because that reference accounts for the actual mix and binder content of the material in place.

In-place density shall be a minimum of 92 percent of theoretical maximum specific gravity (Gmm) — equivalently, a maximum of 8 percent in-place air voids — for surface and intermediate courses, unless the pavement design or local DOT specification requires a higher value. Most state DOT specifications set the minimum mat density between 92 and 94 percent of Gmm. A density above approximately 97 percent of Gmm (below about 3 percent in-place voids) is also undesirable because it leaves insufficient void space and the mix becomes prone to flushing and rutting; the acceptance range therefore has both a floor and a practical ceiling.

The nuclear gauge (ASTM D2950/D2950M) is the standard production method because it is fast and non-destructive, but it shall be correlated to pavement cores tested for bulk specific gravity (Gmb) per AASHTO T 166 at the start of production and periodically thereafter, because the gauge reads a calibrated estimate and drifts. Where nuclear and core results disagree, the core result governs.

The longitudinal joint between adjacent paver passes and the transverse joint between a day's work and the next are the most common locations of low density and the first places a pavement fails. The joint shall be compacted to a density not more than 2 percent below the specified mat density. Confined (hot) longitudinal joints, made by paving the adjacent lane while the first is still hot or by overlapping a hot lane against a freshly placed one, achieve better density than cold joints made against a cooled, cut edge.

Each course shall be placed to the compacted thickness shown on the pavement section. Thickness is verified by cores or by survey of top-of-course elevations against the accepted surface beneath. Deficient thickness reduces the structural capacity of the section in direct proportion and is not correctable except by removal and replacement or by an additional overlay; the Contractor shall not place a deficient lift in the expectation of making up thickness in the next course.

The finished surface shall be smooth and true to grade and cross slope, checked with a 10-foot straightedge laid in any direction. Beyond ride quality, smoothness governs drainage: a wavy surface ponds water, and standing water on asphalt accelerates stripping of the binder from the aggregate and creates a hydroplaning and icing hazard. The pavement shall drain positively to the inlets and outfalls as indicated on the grading and drainage plan with no birdbaths that hold water deeper than 1/4 inch after a rain.

The asphalt binder content of the produced mixture shall be verified against the job-mix formula by the ignition method (ASTM D6307) or by extraction, with the recovered aggregate gradation checked against the JMF. The theoretical maximum specific gravity (Gmm) shall be determined per AASHTO T 209 / ASTM D2041 on production samples to establish the density reference and to confirm that the in-place air voids fall in the acceptable range. Production binder content, gradation, and volumetrics shall track the approved JMF within the production tolerances; drift beyond tolerance is cause to suspend production and recover the mix to target.

Minimum acceptance-testing frequencies, in the absence of a more stringent project or DOT requirement, shall be:

• One in-place density lot per day's production per course, with cores or nuclear readings at the frequency required to characterize the lot (commonly one test per 250 tons or one per defined sublot)
• One asphalt content and gradation test per 500 to 750 tons of mixture produced, or one per day per mixture, whichever is more frequent
• One theoretical maximum specific gravity (Gmm) determination per day per mixture, and whenever the JMF or source changes
• Core thickness verification at the locations and frequency directed by the Engineer of Record, with a minimum of one core per defined paving area per course
• Smoothness checked over the full paved area

When an acceptance test fails — low density, deficient thickness, out-of-tolerance binder content, or excessive surface deviation — the Contractor shall stop placing additional pavement in the affected area, determine the cause, and remediate before proceeding. Low-density mat that has cooled cannot be re-compacted and shall be removed and replaced; the binder is no longer workable and rolling a cold mat only crushes aggregate at the surface. Deficient thickness shall be corrected by removal and replacement or by an approved overlay. The Contractor shall not conceal failing results; a pattern of unreported failures discovered at closeout requires coring, density verification, and removal and replacement at the Contractor's expense.

The Contractor shall verify that the aggregate base course has been placed, compacted, proof-rolled, and accepted in accordance with Aggregate Base CourseAggregate Base CourseResolves to the current adopted revision.sync/aggregate-base-course, and that the subgrade beneath it was prepared in accordance with EarthworkEarthworkResolves to the current adopted revision.sync/earthwork, before placing any asphalt. The base surface shall be at the correct elevation and cross slope within the surface tolerances of the base course specification, shall be clean and free of loose material and standing water, and shall be dry and unfrozen. Defects in the base telegraph directly into the asphalt; the Contractor placing asphalt accepts the base condition by paving over it and shall report any deficiency rather than paving over it.

Where a prime coat is required, it shall be applied to the accepted base at the specified rate and allowed to cure and penetrate before the first asphalt course is placed. Tack coat shall be applied uniformly to the underlying asphalt course (and to any vertical faces, abutting existing pavement, curbs, gutters, and structures the new asphalt will contact) at the specified residual rate, and shall be allowed to break before the overlying course is placed. The tacked surface shall be protected from contamination and tracking until the overlying mat covers it. Curbs, gutters, manhole frames, and structures within the paving area shall be protected from overspray.

The mixture shall arrive at the paver, and shall be placed, within the temperature range established by the producer for the specified binder grade and mix, typically in the range of about 275°F to 325°F at placement for unmodified PG binders, higher for polymer-modified binders. Mix delivered below the minimum placement temperature shall be rejected, because cold mix cannot be compacted to density and tears and segregates under the screed. Hauling units shall be insulated and tarped to retain heat, and the haul shall be scheduled so that mix is not held so long that it cools or the binder ages.

Each course shall be placed in a compacted lift thickness appropriate to its nominal maximum aggregate size, with the compacted lift at least three to four times the NMAS so that the aggregate can reorient under the roller. Thicker lifts retain heat and compact more readily but are limited by the paver and screed capability and by the course thickness shown on the drawings; thinner lifts cool fast and are difficult to compact in cold or windy conditions. Where the total course thickness exceeds the maximum single-lift thickness, the course shall be placed in multiple lifts, each compacted before the next is placed, with a tack coat between lifts.

Compaction shall begin as soon as the mat will support the roller without excessive displacement and shall be completed before the mat cools below the lower compaction temperature limit. Breakdown rolling immediately behind the paver achieves most of the density; intermediate rolling follows; finish rolling removes roller marks. Vibratory steel-wheel rollers and pneumatic-tired rollers are the primary equipment; the roller pattern (number of passes, vibration on or off, sequence) shall be established by a test strip at the start of paving and adjusted to achieve the specified density consistently. The Contractor shall not over-roll a cooling mat, which crushes surface aggregate and decompacts the mat, nor allow the mat to cool before the specified density is reached.

Longitudinal joints (between adjacent paver passes) and transverse joints (between a day's work and the next) shall be constructed to achieve density and a tight, durable bond. Longitudinal joints shall be offset between courses so that the joints in successive lifts do not stack vertically, and shall be located on lane lines or pavement-marking lines as indicated on the striping plan rather than in a wheel path. Transverse joints shall be formed by a transverse bulkhead or by sawcutting and removing the tapered cold end of the previous day's mat to expose a full-depth vertical face, which is then tacked before paving resumes.

Where a joint sealant is specified at the asphalt-to-concrete interface (against curbs, gutters, structures, or adjacent rigid pavement) or at constructed cracks, the sealant shall be a hot-applied joint and crack sealant conforming to ASTM D6690 of the type matching the project's service temperature range. On well-constructed confined hot longitudinal joints in a new asphalt lot, a separate sealant is generally not required.

Asphalt mixture is a perishable, time-and-temperature-sensitive product. It shall be delivered in clean hauling units, insulated and covered to retain heat, and shall be discharged into the paver before it cools below the minimum placement temperature or the binder ages from prolonged holding. Loads that have crusted, segregated, or cooled below the minimum temperature shall be rejected. The bed of each hauling unit shall be coated with an approved non-petroleum release agent; diesel fuel and other solvents shall not be used as a release agent because they dissolve the binder and contaminate the mix.

Bulk asphalt binder at the plant shall be stored at the producer's recommended temperature; overheating or prolonged storage ages the binder and shifts its grade. Emulsion for prime and tack coats shall be stored above its minimum storage temperature to prevent the emulsion from breaking in storage, and shall be circulated or agitated per the manufacturer's instructions so that it does not separate. Aggregate stockpiles at the plant shall be managed to prevent segregation, cross-contamination between stockpiles, and excessive moisture, because wet aggregate requires additional burner energy to dry and ages the binder during mixing.

The Contractor shall warrant the asphalt paving, including achievement of the specified mixture properties, in-place density, course thickness, smoothness, and joint construction, for the project warranty period beginning at substantial completion. Warranty obligations include correction of raveling, rutting, shoving, slippage cracking, premature fatigue cracking, debonding between lifts, and surface drainage defects (birdbaths) attributable to non-conforming materials or workmanship.

The warranty does not relieve the Contractor of liability for concealed non-conforming work discovered after the warranty period expires. Distress that develops after the warranty period and is traceable to inadequate compaction, deficient thickness, out-of-tolerance mixture, omitted or deficient tack coat, or undocumented failing tests may constitute a latent defect extending the Contractor's responsibility beyond the warranty term. Normal weathering, oxidation, and routine maintenance such as crack sealing and seal coating are Owner maintenance obligations and are not warranty items.