4650 midterm

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what are the materials used in HMA?

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___ is produced from burning coal and is fuel resistant.tartar has ___, which means that its physical properties change with temperature.high temperature susceptibilitywhat are the three types of commercial asphalt cement?natural petroleum-based non petroleum-based (sustainable, ex. plant or algae)where can natural asphalt cement be found?island of trinadad bermudez, venezuelawhat is sustainability?meeting the needs of the present without compromising the futurepetroleum-based asphalt properties depends on what two things?refinery options composition of the crude sourcewhat is the classification of crude oil?american petroleum institute (API) gravitya heavy or ___ crude oil has ___ API gravity (API < 25) and a ___ AC content.sour low higha ___ or sweet crude oil has high API gravity, and a ___ AC content. The API must be ___ than 25.light low greatersweet crude has a ___ sulfur content, while sour crude has a ___ sulfur content.low highwhat are four AC components?asphaltenes maltenes resins oilsasphaltenes is a high ___ AC component and has large black, discrete inclusions. contents may ___ from asphalt to asphalt.viscosity vary___ is an AC component that has high temperature susceptibility. fluid when heated, brittle when cold.resins___ is an AC component that allows asphalt to flow.oils___ is an AC component that combines resins and oils.malteneswhat are the three types of asphalt commercially used in flex pavement construction?asphalt cements cutbacks emulsions___ is a strong paving material at an ambient temperature but liquid at 325°F.asphalt cementasphalt is a thermoplastic material (meaning properties change with ___) and a rheological material (meaning properties change with ___ or ___).temperature time frequency of loadingcutbacks are ___ at room temperature and are manufactured by adding or "cutting" asphalt cements with ___.liquid petroleum solventwhat are the three classifications of cutbacks?rapid cure (RC) medium cure (MC) slow cure (SC)RC cutbacks consists of ___ or gasoline, which has ___ volatility. (ex. tack coats, surface treatments)naphtha highMC cutbacks consists of ___, which has ___ volatility. (ex. stockpile patching mix)kerosene moderateSC cutbacks consists of ___, which has ___ volatility. (ex. prime coat, dust control)low viscosity oil low[T/F]: Environmental regulations are increasingly expanding the use of cutbacks.False, limiting the use___ are produced by blending asphalt cements, water, and an ___ (ex. soap) in a high shear colloidal mill.Emulsions emulsifieremulsifier gives ___ to asphalt droplets suspended in water medium.surface chargeanionic emulsifiers is usually an ___, negatively charged, and goes well with positively charged ___.alkaline limestonescationic emulsifiers is usually an ___, positively charged, and foes well with negatively charged ___.acid silica gravelswhat are three types of emulsifiers?cationic anionic nonionicwhat are the three types of settling?rapid settling (RS) medium settling (MS) slow settling (SS)Emulsions are made of ___ (%) AC, ___ (%) emulsifying agent, and ___ (%) water, and it is ___ in color.55-70% 0.5-3% 27-44.5% brownwhat does a flexible pavement structure consist of?AC mixture base subbase subgradewhat does a rigid pavement structure consist of?portland cement concrete base subgrade___ is the variability of repeat measurement under carefully controlled condition.precision___ is the conformity of results to the true value or the absence of bias.accuracy___ us the tendency of an estimate to deviate in one direction from the true value.biaswhat are the five asphalt grading systems?pre-penetration grading penetration grading viscosity grading age residue (AR) viscosity grading performance grading (PG)Penetration grading is based on the penetration test at ___°C. Lower penetrations are used for ___ climates, whereas higher penetrations are used for ___ climates.25 hot coldwhat are the advantages of penetration grading?consistency at avg. service temperature short testing time adaptable to field applications relatively low equipment cost test standards with precision limits available temperature susceptibilitywhat grading system uses penetration index (PI)?penetration gradingwhat are the disadvantages of penetration grading?empirical tests grades overlap with other grading systems high shear rates of test w/ variable, f (AC consistency) no viscosity available at mixing & compaction temperatures (275°F, 135°C) deceptive to performance at higher and lower service temperaturesviscosity grading is based on the ___ AC at 140°F, or ___.original 60°C___ grading is widely used and consists of fundamental units (rather than empirical), Poises.viscosityWhat are the Poises units?1 dyne∙s/cm²in viscosity grading, convert AC-2.5 and AC-40 into poises.250 4000in viscosity grading, the lower the number, the ___ viscous it is.morewhat are three tests under viscosity grading and their service temperatures?penetration test, 25°C viscosity test, 135°C TFOT for viscosity, 60°C for ductility, 25°Cwhat are the advantages of viscosity grading?suitable to a wide range of environments property fundamental (independent of test systems and sample size) test standards available with precision limits based on 60°C temperature susceptibility (VTS) & pen-vis number (PVN)viscosity grading is suitable for pavement temperatures ranging from ___.77-140°Fdisadvantages of viscosity testing: - test system is ___ expensive than others - grading at 140°F is deceptive to ___ and ___ service temperatures - ___ testing time - not adequate to safeguard against ___more low and average longer low temperature crackingage residue (AR) grading is based on viscosity at ___ of the short term AR material and is used in ___ states.60°C westernAR-1000 (at 60°C) = ___ P1000what are the test requirements are age residue grading?minimum penetration , 25°C, on AR minimum viscosity, 135°C, on ARUnlike viscosity grading, AR has no consistency measurements on the ___ binder.originalwhat is one advantage of AR grading?represents asphalt properties after mixingwhat are the disadvantages of AR grading?highly regional requires more test equipments for aging such as RTFO longer testing time no test on original binderpenetration grading was used in the ____, and viscosity grading was used after the ____.1900s 1950s____ grading is based on climate.performance grading (PG)elaborate the PG grade: PG HTG-LTGPG - performance grade HTG - high temp. grade (average 7-day max temperature) LTG - low temp. grade (min. pavement temperature)advantages of PG: - physical properties requirements are ___ - physical properties obtained from binder tests are related to ___ - specifications requires testing to meet ___, ___, & ___ - ___ range at site is considered - specifications developed to minimize binder construction to ___, ___, & ___constant performance handing, aging during construction, aging while in service temperature rutting fatigue cracking low temperature cracking___ relates to any material relating to flow, and it's used to influence pavement performance.rheologywhat is rheology?the study of deformation and flow of matterwhat is a rheometer?an instrument for measuring the deformation of materials with flow characteristicswhat are the seven rheological properties?age hardening penetration ductility viscosity temperature susceptibility shear susceptibility stiffnesswhat are the quantifications of temperature susceptibility?PI PVN VTSwhat is asphalt aging?oxidation of asphalt mixture in flexible pavements (stiffer with age) because asphalt is a hydrocarbonhow does aging influence pavement performance?rutting and crackingthree phases of age hardening: 1. ___ - mixing in the ___ - substantial 2. ___ - storage, transportation, and laydown - minimal 3. ___ - short term: ___ rate for first 2-3 years in service - long term: ___ rate after 2-3 years in serviceproduction - pugmill construction & installation service - slow - very slowthe slower the rate of age hardening, the more ___ the AC is.durablewhat are the age harding contributing factors?(OVPTSS) oxidation volatilization polymerization thixotropy syneresis separationwhat is oxidation?reaction of AC to oxygen due to the rate of temperaturevolatilization is: - [define it] - function of ___ - ___ to long term aging- evaporation of lighter constituents from AC - temperature - not significant___ is the combining like molecules to form larger molecules, and it causes progressive ___.polymerization hardeningthixotropy (steric/reversible) is: - ___ of structure within the AC overtime - causes ___ hardening - destroyed by ___ and ___ the material - associated with pavements that have ___ traffic- formation - progressive - reheating & working - little or nosyneresis is an exudation reaction, which is the act or an instance of ___.oozing forthdescribe the exudation reaction in AC.the thin oily liquids are exuded to the surface of the AC film, and then the AC becomes hard.___ is like forming a skin protecting the material, so there is no damage done.thixotropy___ is the removal of oily constituents or resins from the AC, and it absorbs by ___.separation porous aggregateswhat is the percent retained penetration formula?% retained pen. = (pen. of aged asphalt/pen. of orig. asphalt)×100what is the aging index formula for viscosity?aging index = (visc. of aged asphalt/visc. of orig. asphalt)what are the three phases asphalt goes through?(hard) solid --> maltene --> oil (soft)age hardening is useful for evaluating aging among different ___ and sources, but it's not a good predictor for ___ aging.gradings long termAge hardening includes the ___ and ___ tests, and it allows hardening during ___ only.TFO & RTFO production___ is measured at high stresses and short loading times, and it has a variable shear rate. (*there's a vast storehouse of data on ___ of aged asphalts)penetration (for both)penetration influences overall HMA performances, especially ___, at an avg. yearly service temperature of ___.cracking 25°Cthe objective of penetration on pavement is to use as ___ penetration as possible without reducing ___.high stability___ refers to the distance in ___ that a standard asphalt cement will stretch before breaking when the two ends of the specimen are pulled apart at a specified __ and ___.ductility centimeters speed temperaturewhat is ductility an indicator of?physiochemical state of asphalt colloid systemin pavement performance, good and poor service are from ___ Pen. good service has ___ ductility, and bad service has vice versa.highan extensive crack is less than ___.5cm___ can discriminate between different AC. tests are conducted on highly ___ asphalt at ___ temperatures after further aging of ___ test.ductility stiff low TFOwhat is viscosity? (include formula)it is used to describe resistance of liquid to flow viscosity = shear stress/rate of shear strainat high temperatures, viscosity is a ___ liquid and ___, meaning they're ___ of shear rates.newtonian constant independentat low temperatures, viscosity is a ___ liquid and the ___ affects viscosity.non-newtonian shear strain rate___ asphalt is an example of newtonian fluid, and ___ is an example of a shear thinning fluid.hot warmwhy are viscous fluids sometimes called plastic?once they start flowing, they do not return to its original position (ex. rutting)in a shear thinning fluid, viscosity ___ as shear strain rate ___, also known as ___. (ex. ketchuo, whipped cream, blood, paint)decreases increases pseudoplasticin shear thickening fluid, viscosity ___ as shear strain rate ___, also known as ____.increases increases dilatantwhat type of pavement distress does low viscosity induce at 60°C? & why?permanent deformation (rutting) because of the selection of viscosity gradewhat type of pavement performance does high viscosity induce at low temperatures?low temperature crackingwhat is temperature susceptibility?rate at which the consistency of asphalt changes with a change in temperature___ temperature susceptibility is not desirable.highviscosity at 135°C is ___, and what problem does this cause?low tender mixing problem during compactionviscosity at low temperatures is ___, and what problem does this cause?high low temperature shrinkage cracking___ is based on penetration values at 2 or 3 temperatures.PIwhat is the PI range of most asphalts and high temperature susceptibility?+1 to -1 < -2PI can be estimated from penetration at the ___ test at __.softening point 25°Cwhat problem is associated with PI and the softening point test?variation in the penetration at softening pointwhat is the formula for PI?PI = (20-500A)/(1+50A)what is the formula for the slope, A?A = (log Pen (T₁)-log Pen (T₂))/(T₁-T₂)the lower the __ or ___, the higher temperature susceptibility.PI or PVNwhat temperatures is PVN based on? and where are they obtained?penetration at 25°C viscosity at 135°C or 60°C obtained from existing specification datawhat is the range of PVN?0.5 to -2.0how does PVN change with aging?stays about the samewhat is the formula for PVN at 135°C? include units.PVN = [(L-X)/(L-M)]×-1.50 L = log visc. (V) (cSt) at 0.0 PVN M = log V (cSt) at -1.5 PVN X = log V (cSt) at x PVNwhat number of temperatures is VTS based on? and what is the VTS range?2 or more 3.36 to. 3.98what is the formula for VTS? include units.VTS = [log (log V, T₂)-log (log V, T₁)]/(log T₁-log T₂) **temperature is in Kelvins (K = C+273), and V is in cP**the ___ VTS, the higher the temperature susceptibility.largerwhat is stiffness?it is temperature and time dependent. stiffness = stress/strainfor high temperatures, ___ stiffness is desirable. vice versa for low temperatures.increasedwhat are the types of HMA pavement distresses?ravelling cracking rutting stripping___ is progressive disintegration of HMA layer from the surface downward as a result of the dislodgment of aggregate particles.ravellingwhat are the causes of ravelling?- deficient asphalt binder content - lack of construction compaction (high air voids) - insufficient fine aggregate matrix - excessively aged asphaltwhy do different asphalts age at different rates?higher air voids accelerate aging in the mixturewhat two groups categorize cracking?load & non-load associatedwhat are the four geometric descriptions of cracking?longitudinal transverse polygon (alligator) blockwhat are the three mechanic descriptions of cracking?slippage shrinkage reflectionthe principal class of load associated cracking is ___ cracking.fatiguehow does fracture occur in load associated cracking?it occurs under repeated stress level that is less than the tensile strength of the materialin load assoc. cracking, constant stress (load) tests are suitable for ___ HMA pavements more than 5". A(n) ___ mixture stiffness ___ fatigue life by using ___ penetration and ___ viscosity.thick increased increases lower higherin load assoc. cracking, constant strain (deformation) tests, are suitable for ___ HMA pavements. A(n) ___ stiffness ___ fatigue life by using ___ penetration and ___ viscosity. (*may cause rutting*)thin increased decreases higher lowerwhat is fatigue cracking affected by?asphalt binder aggregates pavement structurelonger fatigue life consists of ___ materials and a ___ stress/strain level, and shorter fatigue life consists of __ materials and a ___ stress/strain level.flexible low stiff highwhat are the two exceptions concerning fatigue behavior?thick pavements non-deflecting support layersthe primary class of non-load assoc. cracking is ___ cracking.low temperature crackingwhat is low temperature cracking? and what is it primarily affected by?it happens when there's rapid chilling at the surface, and stresses/strains are induced by temperature change. asphalt binderWhat improvements can be used for low temperature cracking?use less stiff asphalt binder use asphalt binder less prone to aging construct HMA with proper air voidswhat is rutting?it represents an accumulation of small amounts of deformation that occur each time a load is appliedwhere can rutting occur?in the subgrade, base, or asphalt layerwhat is rutting in the asphalt layer affected by?asphalt binder aggregate___, a moisture induced damage, is the loss of bond between the aggregates and asphalt binder in the presence of water.strippinghow does stripping occur?it begins at the bottom of the HMA layer and moves upward___ mechanisms are based on aggregate's surface affinity for water.strippingin stripping, what can be used to change the surface of the aggregate?additives from hydrophilic to hydrophobicin stripping, the cohesive failure occurs within the ___.ACwhat are the mechanisms of stripping?detachment due to dirty aggregates displacement due to water pore pressure due to trapped water & traffic hydraulic scouring at surface by trafficwhat are the causes of stripping?presence of water physiochemical aggregate property asphalt characteristics (absorption of functional groups) environment/trafficwhy does higher viscosity help stripping?it induces the compaction of aggregates, thus reducing permeable air voids. **it must be limited to fatigue and low temp. cracking**what is the bending beam rheometer (BBR)? and what is it susceptible to?its an equipment that can test and provide fundamental properties at low temp. susceptible to low temp. cracking (thermal cracking)what causes low temp./thermal cracking (TC)?environmental distress stress/strain induced by temperature change one thermal cycle temp. is ≥ T, criticalwhat is T, critical?the limiting stiffnesswhy can't most DSRs be used to reliably measure properties?because of its parallel plate geometrywhat does BBR measure?measures binder deflection (creep) under a constant loadin the BBR test, ____ load stimulates the stresses that ___ in a pavement when temp. ___.creep gradually build up dropswhat are the parameters of BBR tests? explain.creep stiffness (S) - how the asphalt resists constant loading m-value - the measure of how the asphalt stiffness changes as loads are appliedwhat do creep and non-creep loads have in common?constant stress is applied develop elastic strain upon unloading elastic rebound: instaneous recoverywhat is different between creep and non-creep loads?creep is a time dependent strain, and it has full or partial recovery with time.___ is the measure of overall resistance to deformation.stiffness___ is the measure of the properties of overall resistance caused by ___ response and ___ response.m-value viscous elasticthe m-value decreases when the temp. ___, and the m-value increases when the loading time ___.decreases increaseswhen m = 0, the binder is ___, and when m = 1, the binder is __.completely elastic (recoverable) completely viscous (non-recoverable)at low temp., material must behave ___; phase angle is ___; and m-value is ___.elastically approaching 0 (for m-value too)when temp. increases, the phase angle and m-value ___.increaseswhat is flexural creep stiffness? provide formula.the ratio maximum bending stress to maximum bending strain S(t) = σ/ε(t)the absolute value m is the rate of change of ___vs. ___.log S(t) vs. log temp.what's the purpose of stiffness and m-values?calculate the thermal shrinkage stresses & used for specification criteriafor the BBR test, constant load is applied to an asphalt beam for ___, and it measures ___.4mins beam center deflectionwhat are the four components of the BBR equipment?loading frame controlled temp. fluid bath computer control and data acquisition system test specimenin the BBR equipment, load is applied to the ___.blunt shaftin BBR tests, what does the fluid in the temp. bath consist of?ethylene glycol methanol waterfor BBR specification, S is ___, and m is ___.≤ 300 MPa ≥ 0.3(BBR) what are the beam dimensions?width = 12.7mm thickness = 6.35mmwhat grading system does BBR & DTT fall under?PGfor DTT specification, S is ___, and m is ___.≤ 600 MPa ≥ 0.3BBR test method determines the ___ parameters that affect TC.rheologicalwhat are the critical factors of the BBR test method?time and temperature dependency physical hardening and conditioning time load levels(BBR) ___ researchers conducted several tests to evaluate the critical factors of the BBR test method. they correlated lab test to field performance at loading time ___, but it's ___ for specification purposes.SHRP 1 to 5.5 hrs too long(BBR) lab test for TC specifications should stimulate ___.field conditionsflow behavior of asphalt could be the same for one hour at ___ and 10 hours at ___.60°C 25°Chigh temp. and short time of loading is equivalent to ___.low temp. & long time of loading(BBR) what principle was used to shorten testing time?Time-Temperature Superposition Principle(BBR) specifications were based on limited testing with a selected loading time of ___.240sat the lowest pavement temperature, the time-temperature superposition shift functions are ___ for many asphalts.similiar(BBR) what is offset temperature? when is a single offset temperature needed in the specifications?10°C above the lowest pavement temp. to estimate the response at long time of loading(BBR) what are the stiffness measurement paramaters? include time and temperature.field stiffness (7200s, LTG) laboratory (60s, 10°C + LTG)(BBR) what is the time measurements of stiffness applied by creep load? (hint: equally spaced on the LOG scale)8, 15, 30, 60, 120, 240 in seconds(BBR) in the specifications, ___ is a measure of thermal stresses developed in HMA pavement as a result of ___, and ___ is the rate of stress relaxation.flexural creep stiffness, S(t) thermal contraction mS(t) and m in TC is analogous to ___ and ___ in ___ and ___ factor.stiffness & visc. rut & fatiguein superpave binder specifications: S(t) is ____ m is ____ t is ____≤ 300 MPa ≥ 0.3 60s(BBR) how are the measurements valid?must be in the viscoelastic region(BBR) in the viscoelastic redion: studies conducted use loads that range from ___. ___ and ___ are independent. load of ___ was selected.20 to 150 grams stress & strain 100g(DTT) what is the formula for failure strain and stress?failure strain (ε_f) = change in length (∆L)/effective gauge length (L_e) stress (σ) = P/A(DTT) what is the rate of load?1mm/minwhat is the purpose of for DDT tests?evaluate strain at peak stress ≥ 1% & stress at failure to determine the low temp. capacity to stretchwhere are the physical properties obtained from in the superpave asphalt binder specifications?DSR, BBR, DTT, & RVwhat are the physical properties of superpave asphalt binder specification?- criteria remain the same - temperature at which criteria achieved varies - measured on aged binderwhy a minimum G*/sin δ to address rutting?we want a stiff, elastic binder to contribute to mix rutting resistance by increasing G* or decreasing δa large rutting factor value means the binder behaves more like ___.an elastic solidfatigue cracking is addressed by ___ temperature stiffness.intermediatefatigue factor is derived from ___ then ___ binders and refers to the ___ part of pavement service life.RTFO PAV laterwhy is a maximum G*×sin δ to address fatigue?we want a soft, elastic binder to sustain many loads without cracking by decreasing G* and δa smaller fatigue factor means ___.a softer elastic materialwhy a minimum m-value and a maximum S to address low temperature cracking?binder will be a soft elastic binder that will relax when stressedwhy a minimum failure strain?to produce a stiffer binder that will stretch without breakingLow temperature cracking is controlled by ___ materials, and what are its S, m, and tensile failure strain specifications?RTFO & PAV aged S ≤ 300MPa m ≥ 0.3 tensile failure strain ≥ 1.0%(superpave asphalt binder spec.) pumping and handling are controlled by ___ or ___ and ___. the viscosity must be ___.rotational or capillary viscometer unaged binder ≤ 3 Pa∙s(superpave asphalt binder spec.) safety is controlled by ___ by COC, and the temperature specification must be ___.flash point ≤ 230°C(superpace asphalt binder spec.) aging during hot mixing and construction is tested by ___ and controlled by ___.RTFO mass loss ≤ !%(PG spec.) what does the method of selection consist of?geographic area pavement temperature air temperaturehow many weather database stations are in the US and canada?6500 stations(PG spec.) what are the two annual air temperatures to consider in pavement development?hottest seven-day temperature coldest temperatureon the normal distribution curve, average temperature has a ___ reliability, and design temperature has a ___ reliability.50% 98%an average summer as a ___ reliability, and a very hot summer has a ___ reliability?50% 98%pavement temperature is developed over ___.20 yearspavement temperature is developed by environmental data that's obtained by ___.converting historic air temp. to pavement temp.what kind of models are used in pavement temperature development?high & low temp. modelswhat is the high pavement temperature at the surface?T(surf) = T(air) - 0.00618Lat² + 0.2289Lat +24.4what is the high pavement temp at depth, d?T(d) = T(surf)(1 - 0.063d + 0.07d² + 0.0004d³)what is the high pavement temperature 20mm below the surface?T(pav) = (T(air) - 0.00618Lat² + 0.2289Lat +42.4)what is the low pavement temperature at a depth, d?T(d) = T(air) + 0.051d - 0.000063d²what is the rule of 90?PG XX-XX < 90 - probably unmodified PG XX-XX > 90 - probably modifiedwhat are possible improvements offered by polymer modifiers?stiffer mixes at high temp. & vice versa improved fatigue life (durability) reduced life cycle costwhat are two types of polymers?elastomers & plastomerselastomers offer ___ stiffness, but have ___.high flexibilityplastomers offer ___ stiffness, but have ___.high reduced flexibilitythe rutting factor does not capture rutting for ___ system.modifiedMSCRMultiple Stress Creep Recovery- Test of ashphalt binder using Dynamic Shear Rheometer (DSR)Reason for use of Poly modifiers/ Possible improvements offered by polymidifiers- stiffer mixes at high temps -softer mixes at low temps -improve fatigue life -reduced life cycle costPg specs- limitationsG/sin$ does not capture rutting for modified systempg specs -limitations: G, $, viscous mat, polymer-G and $ are measured in vscoeleastic range -For viscous mats: flow is linear even under high stress and strain -For polymer networks: binder response is not linear for high stress and strainMSCR DSR test definitionsstiffness = stress/strain ~> compliance= 1/stiffness ~> compliance = strain /stressTime - independent response to load-No creep -constant stress apllied -develop elastic strain -upon unloading -elastic rebound, instantaneous recoveryTime- Dependent response to load-creep / recovery -constant stress applied -develop elastic strain -followed by time dependent strain: creep -Upon unloading: Elastic rebound, Instantaneous recovery Full or partial recovery w/ timeNon recoverable creep compliance, Jnrindicator of resistance of an asphalt binder to permanent deformation under repeated loading Non- recov creep compliance= non recov strain/ stress -measure of a residual strain specimen after a creep and recovery cycle divided by the applied stressPercent recovery- characterizes elastic response of polymer modified and unmodified asphalt binders - measure of how much a specimen returns to its previous shape after being repeatedly stressed and then relaxed %recovery= [recov strain, yr/ peak strain, yp ]*100What is creep/ recovery? Significance/ Use?creep compliance= strain/stress -Identify the presence of elastic response in a binder -identify the change in elastic response in a binder -determine Recoverable and non recoverable creep compliance of asphalt bindersSpecifications of test methodDSR conducted at specified temp - 25 mm parallel plate geometry -1 mm gap 25 mm dia X 1 mm thickDetermining presence of elastic response in asphalt binderUnder shear creep and recovery -1 cycle = 10 seconds > creep = 1 second >Recovery = 9 seconds Two stress levels: .1 kpa and 3.2 kpa 10 creep and recovery cycles/ stress level aging condition -Short term aging: residue from AASHTO T240 -Rolling thin film oven test (RTFO)Jnr difference-For polymer modified binders, the stress is not linear and sensitive to the stress level of the test - the polymer chain can be rearranged substantially as the stress increases (fluctuates) Jnr diff= [jnr3.2-jnr.1/jnr.1]*100 -Jnr diff < or = 75%Materials used in asphalt mix-Asphalt cement Aggregate" coarse and fine Materials must meet spec requirementsAggregatesPredominant construction material in volume of useAggregates used aloneAlone: used as road base and various types of fillAggregates used as/in binderBinder: asphalt cement or portland cement AC: asphalt cement concrete PC: Portland cement concreteMineral aggregate responsibility for asphalt mixtues- % of mixture: -93-95% by weight or 73-85% by volume - responsible for load supporting capacity of pavent ( aggregate caries the load) -pavement performance influenced by aggregateMineral Aggregate for HMA Definition-any hard, inert mineral materials used for mixing in graduated particles or fragments. It includes sand, gravel crushed stone, slag, and rock dust or powder - usually refers to soil that has in some way been processed or sortedMineral Aggregate for HMALocal supplies of natural rock or imported -Natural rock classification based on geological origin >igneous >sedimentary >metamorphic -Artificialartificial aggregates-lightweight aggregate: (heating clay to very high temp) -Slag: (produced in blast furnace during steel production)Rock classifications by igneous sedimentary metamorphicIgneous: -granite, syenite, deorite -basalt (trap rock) - diabase (trap rock) -gabbro (trap rock) Sedimentary -limestone, sandstone, chert, shale metamorphic -gneiss, schist, slate, quartzite, marble, serpentineAggregate production-Produced in quarry or mine >convert in situ rock into aggregate w/ specified characteristics -rock is blasted or dug from quarry walls then reduced in size using series of screens and crushers >quarries capable of washing the finished aggregatelargest sieve and smallest sieve3/4 inch (19 mm) No. 200 (75 um)Aggregate classification by sizeCoarse aggregate fine aggregate fillercoarse aggregate-retained on No 4 sieve -opening: .187 inch, 4.75 mmfine aggregatePassing No. 4 Sieve -Opening: .187 inch, 4.75 mmFiller- Greater than or equal to >/= 70% passing No.200 sieve - opening: .0029 inch, .075 mmType of aggregates desired for ashpalt - TraffickingCubical, rough texure aggregate is desire - provides more strength than smooth textured aggregateShearing behavior of aggregate: internal friction-Cubical is better becase it has a higher angle of repose = higher internal frictioncohesion- comes from binderSuitability characteristics used to define aggregates for use in asphalt mixtures- Toughness and Abrasion resistance -Durability and Soundness -Particle shape & Surface texture -Cleanliness and Deleterious materials - Size and GradationCleanliness and Deleterious materials-sand equivalent test -Clay lumps & Friable particles -Plasticity indexLos Angeles Abrasion testToughness -degradation during handling, construction, and use -resistance of coarse agg to abrasion by mechanical force -% passing no 12 sieve is a measure of degradation -sample of coarse agg placed in tumbler with steel balls. tumbling causes abrasion b/w particles and b/w steel balls and particlesLA abrasion results-%change in original wt -LA abrasion = [wt passing no 12/total wt]*100 Ex. 5000 gm of blend, 1500 gm passing no 12 sieve -LA abrasion= [1500/5000]*100= 30%L.A. Abrasion valueshard, igneous: 10 soft limestones and sandstones: 60 basalt: 10-17 dolomite: 18-30 gneiss: 33-57 granite: 27-49 limestone: 19-30 quartzite: 20-35Micro DevalToughness -resistance of coarse aggregate to abrasion - abrasion loss in presence of water and damage through abrasionMicro deval procedure/ results-conducted on coarse agg -obtain wt initial: retained on no 4: 1500 gm -obtain wt final: retained on no 16: 1400 gm -%loss=[wt no 4- wt no 16/wt no 4]*100= 6.7Soundness Test-estimates resistance to weathering -simulates freeze-thaw process -repeated submerging an agg sample in saturated solution of sodium or magnesium sulfate -salt crystals will form in agg pores which simulates ice crystal formationSoundness tets procedure-immerse sample in solution and sit at constant temp for 18 hrs -dry sample to constant weight at 110C +/- 5C (230F+/- 9F) -repeat 5 times, wash sample to remove salt -determine weight loss for each sieve - max loss values range between 10-20% for evry 5 cyclesParticle shape and surface texture: Shape-workability and strength -cubical vs flat, thin or elongatedShape: Desired aggregate-Cubical -not flat, thin or elongatedRound aggregate-provides better workability -requires less compaction -lower structural capacity -natural gravel and sandsSurface Texture-Workablility and strength -rough vs smoothRough texture-sand paper like -increases mixture strength: high degree of internal friction -requires additional AC to overcome loss of workability -higher voids space in compacted mass: this provides extra space for AC >the increase in amount of AC provides a stronger mechanical bondParticle shape and texture test- Ia=1.25(V10)-.25(V50)-32---(in-lb) -Each layer: 10 tamps :V10=% voids in agg compacted w/ 10 blows per layer 50 tamps+V50shape and texture test proceduremeasures change in voids as the agg sample is compacted in mold agg sample divided up in to specific size fractions -each size fraction goes in container in 3 layers, repeat process twice -first time, each layer tamp 10 blows, second 50shape and texture test resultsIa is computed as a weighted avg of the individual size fraction Ia based on the size fraction weights -Ia=6-7 for round, smooth Ia=15-20 for cubical, rough -Higher Ia is betterDeleterious Material: Clay lumps and friable particles-Deleterious material is the mass percent of contaminants in the blended agg --soak for 24 hr, each particle rubbed -wash sieve over several scrrens -percent loss is reported as the % clay or friable particlesPerformancePerformance grade of HMA's is influenced by agg propertiesIncrease in agg angularity and texture-increase in strength and stability of HMAs -rutting: agg propertiesAngularity influence on HMA performance-fine aggregates: greater influencebinder affectslow temperature crackingSpecific gravityprovides a relationship b/w mass and volume - constant per specific materialSG weight indicatorLight weight < 2.4 Normal 2.4-2.8 Heavy >2.8SG useSG used as a tool to bridge b/w mass and volume -Used to compute aggregate volume in Asphalt mis designBridge between mass and volume equationG = (mass solid/volume)/(mass water/volume)Sg formulasg= weight of a unit volume of material/ weight of an equal volume of water at approximately 25C G= mass/(volume*yw)DensityDensity = (yw) GEach agg is made of-mass -Solid volume >Pores: may or may not be accessible to waterVolume of agg particle-Apparent volume(Vapp): volume of the solid mater and non accesible pores in the particle -Bulk volume(Vbulk): Apparent volume plus the volume of the water accessible capilary poresMass of aggregate particles-varies with moisture content -stage of moisture contentStages of moisture contentWet -aggregate is well soaked -capillary pores saturated w/ water -surface contains free moisture Saturated Surface dry (SSD) -aggregate is well soaked -capillary pores saturated w/ water -surface is dry (moisture wiped off) air dry -capillary pores are partially saturated Oven dry (OD), (Dry) -Capillary pores are dry -place aggregate in oven to dry to constant weightWeight of agg: SSD & Oven dryWssd: Weight of the aggregate particle in the SSD condition Wod: Weight of agg particle in oven dry conditionGxy-x: indicates s for stone -y indicates the volume type -a: apparemt -b:bulkMass Volume typesMssd Mod Vbulk VappGsb(OD) Gsb(SSD)Gsb(OD)=Wod/Vbulk Gsb(SSD)=Wssd/VbulkGsa(OD) Gsa(SSD)Gsa(OD)=Wod/Vapp Gsa(SSD)=Wssd/VappWater units1gm = 1 cm^3 yw=1 g/cm^3 yw=62.4 lb/ft^3volume measurements-Volume is determined by volume of water it displaces -Mass of water displaced by sample. Since 1 g water= 1 cm^3 water, this value also represents volume of water displaced by sample Vbulk=(Wssd-Wsubmerged)/yw Vapp=(Wod-Wsubmerged)/ywAbsorption- absorption is single event -Absorption%=(Wssd-Wod)/Wod*100If absorption = 0-There are no permeable pores -Volumes are the same -Gsb=Gse=GsaMoisture-Moisture content is variable -Moisture content%=(Ww-Wod/Wod)*100Absorption/Moisture case 1Mc> Abs -There is a free surface moisture -Free surface moisture= MC- AbsCase 2Mc<Abs -The aggregate is in air dry condition -Free moisture= (-) or <0Case 3MC=Abs -Free moisture =03 types of agg SG: All have same mass, Bulk specific gravity (Gsb)Gsb -Bulk Volume -Vbulk=Overall volume of agg particle + the volume of permeable pores filled with water -smallest GEffective SG, GseGse -Effective volume -excludes absorbed asphalt volumeApparent SG, Gsa-Apparent Volume -Volume of aggregate particle -Excludes absorbed water volumeBulk SG-SSD level: reached when the permeable pores are saturated and the surface is dry -Gsb=(Dry mass/bulk vol)/1 g/cm^3 -=Ws/[Vs+Vpp] ywapparent SG-App volume = volume of solid agg particle only -Gsa=(drymass/App vol)/1g/cm^3 -Gsa=Ws/([Vs]yw)effective SG-Eff vol=solid volume + volume of water permeable pores not filled with asphalt Gse=Drymass/Eff vol/1g/cm^3 -Gse=Ws/{Vs+Vpp-Vap}*ywSg tests for aggs: Two test-Specific gravity of coarse aggregate: retained on 4.75 mm sieve -SG of fine agg: Passing the 4.75mm sieve -Combine G's: weighted average =p1+p2+p3/(p1/G1+P2/G2...ASTM C127 coarse agg-5kg on +no 4 -Dry agg to constant weight, soak in water 24 hours -Determine weight under water= C -use damp towel to get SSD condition -Determine weight of SSD agg in bucket= B -Dry to constant weight -Determine oven dry mass= ACoarse agg spec gravityG=wt/V*yw Gsb(Od)=A/(B-C) A=weight of oven dry sample, gm B=wt of sample in ssd condition C=wt of SSD sample submerged in water, gmFine Agg SG: ASTM C128A=wt of oven dry samp, gm B=wt of pycnometer filled w/ water C=wt of pycnometer, SSD aggregate, and water calibration to mark, mg S=SSD agg wtASTM C128: dry agg until reaches SSD point-dry mat slumps too much (<SSD) -mat at SSD point will slump slightly -Wet material does not slump at allwhat are the three asphalt mixture stages?laboratory design -small scale (100 lbs) production -large scale (400,000 lbs/hr) constructionwhat are the five asphalt cement categories?consistency durability purity safety others___ describes the viscosity or degree of fluidity of AC at a specified temperature, and it measures hardening, or ___.consistency agingwhat are four consistency tests?penetration viscosity (absolute & kinematic) softening point ductility testabsolute viscosity tests are tested at ___ because its the max pavement temperature. It relates to the prevention of ___.60°C ruttingkinematic viscosity tests are tested at ___ because thats when the newtonian fluid becomes independent of the rate of loading (mixing and laydown temperature)135°Cpenetration tests are tested at ___ because thats the average pavement surface temperature.25°C (or 4°C for larger loads/longer duration)___ test measures the resistance to flow of a fluid using vacuum capillary viscometers.absolute viscositywhat is the formula for viscosity?viscosity = applied shear stress/rate of shearAbsolute viscosity is measured Poises, and 1 Pa∙s = ___ Poises (P)10 Pwhat is the range of specifications in Poises of absolute viscosity?0.036-200,000 P___ liquid is shear stress over shear rate. shear rate is ___ proportional to shearing stress.newtonian directly___ liquid has a non-constant ratio.non-newtonian___ test measures the resistance to flow of a liquid under gravity. it's the ratio of the ___ to the ___ of a fluid.kinematic viscosity viscosity densitykinematic viscosity is measured in ___.stokes (St)___ test measures the time it takes for a fixed volume of asphalt binder to flow through a capillary viscometer under closely controlled conditions of head and temperature.kinematic viscositywhat is the equation for kinematic viscosity (cSt)?cSt = K (calibration factor)×time (s)what is the equation for absolute viscosity (P)?P = St (k. viscosity)×specific gravity___ test evaluates in-place material and evaluate damage due to overheating.penetration___ test measures the temperature at which an AC cannot support its own weight and starts flowing; in other words, evaluates the temperature at which the phase change occurs.softening point___ is the empirical measure of the consistency of AC as determined by measure how far a truncated No. 2 sewing needle penetrates into an asphalt sample under specified conditions of ___, ___, and ___.penetration test time load temperature1 penetration unit = ___0.1mm___ tests analyzes the ability of a specimen to stretch without breaking.ductilitywhat are the three ductility tests temperatures?77°F, 60°F, and 39.2°Fin the ductility tests, samples are pulled at ___ cm/s at 77°F and ___ cm/s at 39.2°F.5 1___ evaluates a measure of tensile properties, compatibility of blends, and effects of ___. it relates to the prevention of ___.ductility heat/aging low temperature cracking___ measures the solubility of asphalt in trichloroethylene (TCE).solubility testwhat is the equation for solubility?% soluble (purity) = [(mass of sample-mass of insoluble materials)/mass of sample]*100percent soluble must be above ___ %.99___ measures the temperature at which AC gives off enough vapor which can ignite in the presence of a spark or open flame, known as the ___.safety test flash pointwhat are three durability tests?thin film oven test (TFO) rolling thin film oven (RTFO) pressure aging vessel (PAV)TFO is a short term aging test that is heated to ___ over a duration of ___ at the speed of ___.325°F or 163°C 5 hours 5-6 RPMfor the TFO, the max percentage loss is ___. it tests the ___ from the consistency tests and the ___ from % loss.1% property changes volatilityRTFO is a short term aging test that is heated to ___ over a duration of ___.325°F or 163°F 75 minutesRTFO is used to indicate ___ and ___ in a conventional HMA plant and as a basis for ___. the max % loss must be ___.volatility property changes asphalt residue (AR) viscosity grading 1%___ stimulates long term aging of the binder during service.pressure aging vessel (PAV)PAV tests at the temperature of ___, ____, and ___. it's tested at pressure of ___ over a duration of ___.90°C, 100°C, & 110°C 2070 kPa or 300 psi 20 hourswhat are the other tests?specific gravity and spot test___ is the ratio of the mass of a given volume of a material to the mass of the same volume of water at the same temperature.specific gravity___ test uses a pycnometer.specific gravityspecific gravity test is used for converting ___ to units of mass and ___.volume mix design analysis___ test indicates whether the asphalt was thermally cracked (molecules split) during manufacture.spotthe spot test is a method for analyzing complex mixtures by ___ from which they are made of.separating them into chemicalswhat are the specifications of the spot test?uniformly brown --> test negative (OK) darker area at the center --> test positivelimitations of pre-superpave binder grades: - viscosity (uses ___ effects only) - penetration (uses ___ measure of viscous and ___ effects) - testing temperature (penetration at ___ & visc. at ___) - no ___ temp. properties measured - ___ aging considered (includes ___ (2) tests) - problems with ___ - specification proliferation- viscous - empirical, elastic - 25°C & 60°C - low - long term, RTFO & TFO -modified asphalt characterizationwhat is SHRP and Superpave?strategic highway research program superior performance asphalt pavementswhat are the specifications of physical properties in PG binder tests?must remain constant (temp. may vary) must be obtained from binder tests (related to performance) -spec require testing to minimize binder contribution to rutting, fatigue and low temp crackingPG binder test specifications requires test to meet: 1. ___ : transportation, storage, etc. 2. ___ : short term aging (STA) of the binder 3. ___ : LTA aging of the binderhandling production in servicewhat are the superpave asphalt binder testing equipments?RTFO PAV RV DSR BBR DTT___ stimulates binder aging (hardening) during HMA production and construction. it is resistant to aging (durability) during ___.RTFO production___ stimulates binder aging (hardening) during HMA service life. it is resistant to ____ during service life.PAV aging (durability)what are the purpose and parameters of RV tests?measure binder properties at high construction temperatures concerns handling and pumpingwhat are the purpose and parameters of DSR tests?measure binder properties at high and intermediate service temperatures it's resistant to rutting and fatigue cracking___ and ___ tests measure binder properties at low service temperatures, and it is resistant to thermal cracking.BBR & DTT___ and ___ tests produces aged specimen for further testing.RTFO & PAV___ stimulates short term aging (STA) of HMA, and ___ refers to long term aging (LTA).RTFO PAVwhat are the features and testing time of RTFO?exposes binder to heat and air continuously has rolling action, materials dispersal, & modifiers no skin formation 75 minsin RTFO tests, the STA specimen is used in ___ (3) tests and has ___ mass loss.DSR, BBR, & DTT volatilewhat is the formula for percent mass loss in RTFO?mass loss (%) = [(orig. mass - aged mass)/orig. mass]×100in PAV tests, the LTA ranges from ___ years.5-10what are the features of PAV tests?aging is accelerated without high temp. limited loss of volatiles sufficient aged binderthe LTA binder of PAV tests are used in ___ (3) tests.BBR & DTT DSR (for fatigue cracking)specifications of PAV tests: - temperature - pressure - time - test material- 90, 100, 110°C - 2070 kPA (300 psi) - 20 hrs - RTFO residuein RV tests, ___ is related to viscosity, and it's tested at ___ and ___.torque 135°C & 165°Ctorque is needed to maintain a constant rotational speed of ___ merged in asphalt at ___.spindle sub 20 RPMRV tests produces ___ at 135°C and ___ at 165°C.viscosity viscosity temp. chart for mix design___ tests develop ___ relationship in mixture design.RV temp/viscDSR tests compute ___.shear modulus, |G*| & phase angle, δwhat is the formula for shear modulus?G* = G' + iG" G' = elastic/storage modulus G" = viscous/lost moduluswhat is torsion?the twisting action on a section of a body with respect to a contiguous sectiontorque may vary from ___ of the axis of twist to a maximum at the ___. (look at ppt for those misc. formulas)zero extreme fiberswhat represents deformation in torsional loading?angle of twist (Φ)what is the strain formula (including Φ)?Υ= (rΦ)/Lwhat would an ideal DSR test evaluate?time & temp.what devices can be used in DSR tests?dynamic shear rheometer oscillatory shear rheometer dynamic shear rheometerwhat does the DSR test measure?complex shear modulus & phase angle of asphalt at high and intermediate temp.what is complex shear modulus?the measure of the overall stiffness of the binder under dynamic shear loadingwhat is a phase angle?the measure of relative proportions of visc. and elastic behaviorwhen δ = 0°, the binder is ___.completely elastic (recoverable)when δ = 90°, the binder is ___.completely viscous (non-recoverable)what is the typical δ for asphalt?60-85___ is the vector sum of the storage and viscous modulus.complex modulusin a DSR test, a plate with ___ in diameter with a ___ gap tests original binder and RTFO residue.25mm 1mm high tem so large geometry STa >46cin a DSR test, a plate with ___ in diameter with a ___ gap tests, RTFO residue, and PAV residue.8mm 2mm LTA intermediate temp 4-40Cin DSR tests, provide the following formulas: - stress - strain - stiffness- τ = (2T)/(πr³) - γ = (Θr)/h - G = τ,max/γ,maxwhat is an example of soft materials in high temp. DSR tests? & what is the range of shear strain?unaged binder RTFO residue 10-12%what is an example of hard materials in moderate temp. DSR tests? & what is the range of shear strain?PAV residue 1%in the DSR test, the rut factor is ___ (formula) and is determined in ___ stiffness.G*/sin δ high temp.in the DSR test, the fatigue factor is ___ (formula) and is determined in ___ stiffness.G*×sin δ intermediate temp.in DSR tests, the rut factor must be ___ for original binders and ___ for RTFO residue, and the fatigue factor must be ___ for PAV residue.≥ 1.0 kPa ≥ 2.2 kPa ≤5000 kPastiff binders has higher ___, and elastic binders has lower ___. these properties can be altered to resist ___.G* Φ ruttingDSR test measures the minimum values of ___ and ___.original binder RTFO residuewhat happens to the pavement after work is done due to load application?it can either be recovered by the elastic rebound at the surface and/or be dissipated by permanent deformation or heatwhat is the work formula at a constant stress?W = (πσ²)×[1/(G*/sin δ)]in DSR tests, low stiffness results in low ___ and deforms without ___, and increased elasticity results in low ___. both properties can be manipulated to prevent ___.G* stress build up δ fatigue crackingin DSR tests, the fatigue factor is tested with ___ binders.original & PAV___ pavements are stress controlled phenomenons, and ___ pavements are strain controlled phenomenons.thick thinwhy were the specifications established in DSR tests?it's established to minimize binder contributions to pavement distresseswho developed the DSR specifications?FHWA aphalt binder expert tasks group (ETG)why is the rutting factor testing the original binder performed at 60°C?the temp. was representative of the temp. where AC-10 was common and provided reasonable performancethe rutting factor is tested by unaged binder at AC-___ at the rate of ___.10 10 rad/swhere did the specifications of fatigue factor come from?the fatigue factor was initially limited to 3000 kPa, but 50% of the 42 asphalts tested exceeded the limit. the limit was finally set to be 5000 kPa after only 15% of the samples exceed the limit.