Asphalt Paving

Start here: ten words every newcomer needs

Overheard on the job

Real-sounding lines from the floor, translated into plain English.

• Mix is coming in fat and the breakdown's checking it, call the hot plant and have them back off the oil.

  TranslationThe mix has too much binder and is cracking under the first roller, so the plant needs to reduce the binder content.

• Stop short and let the paver pick you up, and quit flipping the wings, we've got truck-end seg every load.

  TranslationDrivers should stop before reaching the paver so it can push them without a jolt, and the crew should stop folding the hopper sides, because both habits are causing coarse spots at the end of each load.

• Carry it two and a half loose, match the joint a hair high, and let the raker bump it back for the roller.

  TranslationSet the uncompacted mat at 2.5 inches so it compacts to 2, set the new side slightly above the old pass at the seam, and have the hand crew push the overlap onto the hot side so the roller can compress it.

• Rice came up two hundredths, so that 92 on the nuke is really 91 and change, we're under on density.

  TranslationThe lab's maximum specific gravity went up, so the nuclear gauge reading actually falls below the density minimum.

• Tack's still brown, hold the end dumps, and tell the plant to tarp them, the last one showed up with a crust.

  TranslationThe emulsion has not broken yet, so keep the trucks off it, and make sure loads are covered because the previous truck arrived with a cooled, hardened top layer.

• Burn says 5.0 against a 5.4 JMF, mix looks dry and it's already raveling at the joint.

  TranslationThe ignition oven shows binder content well below the approved recipe, and the lean mix is losing stone at the seam.

• Kick back that cold load and keep the MTV full, I'm not stopping the paver on a smoothness job.

  TranslationReject the truck that arrived below temperature and keep the material transfer vehicle stocked so the paver never stops, since the contract pays on ride quality.

The black glue of the mix: binder grades, emulsions, cutbacks, and the tack and prime coats that hold layers together.

• ACalso asphalt cement, asphalt concrete
  Asphalt cement: the binder itself, and in pavement design talk, shorthand for the asphalt concrete layer.
• Asphalt binderalso binder, asphalt cement
  The black, sticky petroleum cement that glues the aggregate together in an asphalt mix.
• Asphalt emulsionalso emulsion, emulsified asphalt
  Asphalt binder broken into tiny droplets and suspended in water with an emulsifier so it can be sprayed cool.
• Breakalso breaking
  The point when an emulsion's water separates and the asphalt droplets fuse, turning the film from brown to black.
• Cutback asphaltalso cutback, liquid asphalt
  Binder thinned with a petroleum solvent so it flows at low temperature, then hardens as the solvent evaporates.
• Oilalso liquid, liquid AC
  Crew and plant slang for liquid asphalt binder, as in oil content or a load that looks short on oil. Shop talk
• Penetration gradealso pen grade, pen
  A binder rating based on how far a weighted needle sinks into the asphalt at 25 C.
• PGalso performance grade, PG grade
  Performance Grade: the binder rating that names the hottest and coldest pavement temperatures a binder can handle.
• Polymer-modified asphaltalso PMA, modified binder
  Binder blended with an elastic polymer, usually SBS, to resist rutting in heat and cracking in cold.
• Prime coatalso prime
  A low-viscosity asphalt sprayed onto granular base to soak in, seal it and bind loose surface particles before paving.
• Tack coatalso tack, bond coat
  A thin spray of asphalt between layers that bonds the new lift to the surface underneath.

Binder rheology and aging tests, mix performance tests, and the lab shorthand for specimens and results.

• BBRalso bending beam rheometer
  Bending beam rheometer: the test that checks how stiff and brittle a binder gets at low temperature.
• Burnalso burn-off
  Lab shorthand for an ignition oven test, or the binder content result that comes out of it. Shop talk
• DSRalso dynamic shear rheometer
  Dynamic shear rheometer: the instrument that measures a binder's stiffness and elasticity by twisting a thin disk of it.
• Hamburg wheel-tracking testalso Hamburg, HWTT
  A lab test that rolls a loaded steel wheel over submerged mix samples to measure rutting and moisture damage.
• Ignition ovenalso burn oven, NCAT oven
  A furnace that burns the binder out of a mix sample to measure binder content by weight loss.
• MSCRalso multiple stress creep recovery
  Multiple stress creep recovery: a high-temperature binder test measuring how much of a deformation the binder recovers.
• PAValso pressure aging vessel
  Pressure aging vessel: the test that ages binder under heat and pressure to simulate years of service on the road.
• Puckalso pill, specimen
  Lab slang for a compacted cylindrical mix specimen, especially one made in the gyratory compactor. Shop talk
• Ricealso Rice test, max gravity
  Lab slang for the maximum specific gravity test on loose mix, and for the Gmm value it produces. Shop talk
• RTFOalso rolling thin-film oven, RTFOT
  Rolling thin-film oven: the short-term aging test that mimics what plant mixing and paving do to a binder.
• TSRalso tensile strength ratio, Lottman test
  Tensile strength ratio: a moisture-damage test comparing the strength of soaked mix specimens to dry ones.

Superpave volumetrics, gradation, recycled materials and the mix types named on plan sheets.

• Air voidsalso voids, Va
  The small pockets of air between binder-coated aggregate in compacted mix, given as a percent of total volume.
• Binder coursealso intermediate course, binder lift
  The intermediate pavement layer placed between the base course and the surface course.
• Blacktopalso hot top, tarmac
  Everyday name for asphalt pavement, used by driveway crews, homeowners and road crews alike. Shop talk
• Dryalso lean, dry mix
  Describes mix short on binder: dull brown, harsh to rake and likely to ravel early. Shop talk
• Fatalso rich, fat mix
  Describes mix carrying too much binder: shiny, slick and prone to bleeding or rutting. Shop talk
• Finesalso P200, minus 200
  The dust-sized part of the aggregate passing the No. 200 sieve, which stiffens the binder into a mastic.
• Gmmalso maximum theoretical specific gravity, max gravity
  Maximum specific gravity of the mix: the density it would have if every air void were squeezed out.
• Gradationalso grading, gradation curve
  The distribution of particle sizes in an aggregate blend, reported as percent passing each sieve.
• Gyratory compactoralso SGC, gyratory
  The lab machine that compacts mix specimens by pressing and tilting them in a rotating mold.
• HMAalso hot mix, asphalt concrete
  Hot mix asphalt: aggregate and binder mixed hot at a plant, hauled hot and compacted before it cools.
• JMFalso job mix formula
  Job mix formula: the approved recipe of gradation and binder content a plant must produce on a project.
• Ndesalso N design, design gyrations
  N design: the number of gyrations a mix specimen gets in the gyratory compactor, set by expected traffic.
• NMASalso nominal maximum aggregate size, nominal max
  Nominal maximum aggregate size: the sieve size used to name a mix, such as a 9.5 mm or 19 mm mix.
• RAPalso reclaimed asphalt pavement, millings
  Reclaimed asphalt pavement: old asphalt milled or crushed and fed back into new mix as aggregate and binder.
• SMAalso stone matrix asphalt, stone mastic asphalt
  Stone matrix asphalt: a gap-graded, binder-rich surface mix built on a stone-on-stone skeleton.
• Superpavealso SP, Superpave mix
  The performance-based system for grading binders and designing asphalt mixes around climate and traffic.
• VFAalso voids filled with asphalt
  Voids filled with asphalt: the share of the aggregate voids occupied by binder rather than air.
• VMAalso voids in mineral aggregate
  Voids in mineral aggregate: the space between aggregate particles available for binder and air.
• WMAalso warm mix, warm-mix asphalt
  Warm mix asphalt: mix produced and placed about 30 to 100 F cooler than hot mix using additives or foaming.

How mix is made, stored and hauled, from the drum and baghouse to the truck backing up to the paver.

• Baghousealso bag house, dust collector
  The fabric-filter dust collector that cleans the exhaust from an asphalt plant's dryer.
• Batch plantalso pugmill plant, batch mix plant
  An asphalt plant that weighs and mixes each load in separate batches in a pugmill.
• Belly dumpalso bottom dump, belly
  A trailer that unloads mix through gates in its floor, laying it in a row on the road ahead of the paver. Shop talk
• Blue smokealso blue haze
  Bluish haze rising off the mix that signals overheated binder and premature hardening. Shop talk
• Cold loadalso cold truck
  A truckload of mix that arrives below the minimum temperature or with cold, crusted chunks. Shop talk
• Drum plantalso drum mix plant, drum mixer
  A continuous asphalt plant that dries the aggregate and mixes it with binder in one rotating drum.
• End dumpalso tri-axle, dump truck
  A dump truck or trailer that raises its bed and unloads out the tailgate, the standard way to feed a paver. Shop talk
• Hot plantalso plant, asphalt plant
  Field slang for an asphalt production plant, of either drum or batch type. Shop talk
• Live bottomalso Flow Boy, live floor
  A haul trailer with a conveyor floor that unloads mix out the back without raising the bed. Shop talk
• Load ticketalso ticket, scale ticket
  The printed slip that travels with every truck showing mix type, tonnage, time and plant data for that load.
• Release agentalso bed release, release
  A spray applied to truck beds and tools so hot mix does not stick, used in place of diesel fuel.
• Tarpalso tarping, tarp up
  To cover a loaded haul truck with a tarp to hold in heat and keep the mix from crusting over. Shop talk

The paver, screed and rollers, the crew jobs around them, and the joint and thickness work behind a smooth mat.

• Breakdown rolleralso breakdown, lead roller
  The first roller behind the paver, which does most of the compaction while the mat is still hot.
• Bumpalso bumping the joint, bump back
  To push excess mix off the old side of a joint back onto the hot mat with a lute so the rollers can pinch it in. Shop talk
• Dump manalso dumpman, truck dumper
  The paving crew member who guides trucks to the paver, signals the dump and collects load tickets. Shop talk
• Featheralso feathering, feather edge
  To taper new asphalt down to nearly zero thickness to tie it into an existing surface. Shop talk
• Head of materialalso head, material head
  The amount of mix carried in front of the screed by the augers, which must stay level and constant.
• Joint matchingalso matching the joint
  Setting the screed so the new mat overlaps the old edge slightly and sits just high enough to roll down flush. Shop talk
• Liftalso course, layer
  One layer of mix placed and compacted in a single pass of the paver.
• Longitudinal jointalso long joint, centerline joint
  The seam running lengthwise between two adjacent paving passes, the usual weak spot in an asphalt road.
• Lutealso asphalt rake, lute rake
  A flat-bladed rake used by paving crews to move, level and smooth hot mix by hand.
• Matalso fresh mat
  The freshly laid strip of asphalt behind the paver, before and during rolling.
• Mill and fillalso mill and overlay, mill and pave
  A resurfacing job where the old surface is milled off and repaved with new mix, often the same day. Shop talk
• Millingalso cold planing, grinding
  Grinding off the top of an existing pavement with a rotating cutter drum before repaving.
• MTValso material transfer vehicle, shuttle buggy
  Material transfer vehicle: a machine between the trucks and the paver that remixes hot mix and feeds it nonstop.
• Paveralso laydown machine, finisher
  The self-propelled machine that receives hot mix, spreads it to width and lays it as a smooth, partly compacted mat.
• Pickupalso picking up, tire pickup
  Mix sticking to roller tires or drums and tearing out of the mat, leaving pockmarks behind. Shop talk
• Pneumatic rolleralso rubber-tire roller, pneumatic
  A rubber-tired roller whose offset tires knead the mat, closing surface voids during intermediate rolling.
• Pullalso pass, run
  One continuous paving pass from the start to the end of a run, or the lane width paved in that pass. Shop talk
• Rakeralso lute man, luteman
  A paving laborer who works behind the screed with a lute, fixing joints, edges and handwork. Shop talk
• Roll-downalso rolldown, roll down
  The amount a loose mat drops in thickness as the rollers compact it. Shop talk
• Rolling patternalso roller pattern, pattern
  The planned number, order and coverage of roller passes needed to reach density across the full mat.
• Screedalso floating screed
  The heated, floating plate assembly at the back of a paver that levels and pre-compacts the mat.
• Screwmanalso screw man, screed operator
  Crew slang for the screed operator, who sets mat thickness, slope and width at the back of the paver. Shop talk
• Skialso averaging ski, averaging beam
  Crew name for the long averaging beam on a paver that gives the grade sensor a smoothed reference. Shop talk
• Tender mixalso tender
  Mix that shoves and moves under the rollers instead of compacting, often within a certain temperature range.
• Tow pointalso tow arm pivot
  The point on the paver frame where the screed's side arm pivots, raised or lowered to control mat thickness.
• Windrowalso row
  A continuous row of hot mix dumped on the road ahead of the paver, usually by belly-dump trailers.
• Wingsalso hopper wings, flipping the wings
  The folding side walls of a paver hopper, and the habit of folding them to dump leftover mix onto the conveyors. Shop talk

Gauge and core density, smoothness, and the statistical tests that decide what the contractor gets paid.

• Control stripalso test strip, test section
  A short test section paved at the start of a job to set the rolling pattern and density target.
• Corealso core sample, plug
  A cylinder of pavement drilled out of the finished mat and sent to the lab for density and thickness.
• Densityalso in-place density, percent compaction
  How tightly a compacted asphalt layer is packed, reported as a percentage of its maximum theoretical density.
• IRIalso International Roughness Index
  International Roughness Index: a measure of ride quality in inches per mile, collected with a laser profiler.
• Joint densityalso longitudinal joint density
  The density measured at a longitudinal joint, often specified separately because joints compact poorly.
• Nuclear gaugealso nuke gauge, nuke
  A portable instrument with a radioactive source that estimates asphalt density in about a minute without cutting a core.
• Pay factoralso pay adjustment, price adjustment
  A multiplier applied to the contract price for a lot of asphalt based on its test results.
• PWLalso percent within limits
  Percent within limits: a statistical measure of how much of a lot falls inside the specification limits.
• QC/QAalso quality control, quality assurance
  Quality control and quality assurance: contractor testing to run production and agency testing to verify it.
• Shootalso shooting, shoot density
  To take a reading with a nuclear gauge or infrared gun, as in shooting density or shooting a load's temperature. Shop talk

How asphalt fails, from ruts and alligator cracks to segregation and potholes, and how crews patch it.

• Birdbathalso bird bath, ponding
  A low spot in finished pavement that holds a puddle of water after rain. Shop talk
• Bleedingalso flushing
  Free binder rising to the pavement surface, leaving shiny, sticky black patches that turn slick when wet.
• Center streakalso centerline streak, gearbox streak
  A narrow strip of coarse, open mix running down the middle of the mat behind the paver's auger gearbox. Shop talk
• Checkingalso checks, check cracking
  Short, closely spaced hairline cracks across the mat that open up under the rollers during compaction.
• Fatigue crackingalso alligator cracking, gator cracking
  Interconnected cracks in the wheel paths caused by repeated bending under traffic, known as alligator cracking.
• Hot boxalso hotbox, asphalt hot box
  A heated, insulated hopper on a truck or trailer that keeps mix hot all day for patching. Shop talk
• Potholealso chuckhole
  A bowl-shaped hole through the pavement surface where pieces of asphalt have broken out.
• Ravelingalso ravelling
  Loss of aggregate from the pavement surface as the binder lets go of the stone.
• Reflective crackingalso reflection cracking
  Cracks in an overlay that mirror the cracks or joints in the old pavement underneath.
• Ruttingalso ruts, wheel path rutting
  Channel-shaped depressions that form in the wheel paths as the pavement deforms under repeated loads.
• Segregationalso seg, truck-end segregation
  Separation of coarse and fine aggregate, or of hot and cold mix, that leaves open, low-density spots in the mat.
• Shovingalso shove
  Localized bulging and sliding of the asphalt surface where traffic brakes, turns or accelerates.
• Strippingalso moisture damage, stripped
  Loss of the binder's bond to the aggregate surface, caused by moisture working into the mix.
• Tearingalso drag marks, screed tearing
  Rough, open streaks pulled into the mat surface by the screed as the paver moves forward.
• Thermal crackingalso transverse cracking, low-temperature cracking
  Transverse cracks across the lane caused by the pavement shrinking and snapping in very cold weather.
• Throw and roll
  The quick pothole fix of shoveling patch mix into a hole and compacting it with the truck's tires. Shop talk

Frequently asked questions

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