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1Volumetric Analysis of HMA Mixtures VOLUMETRIC ANALYSIS OF HMA MIXTURES

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2Volumetric Analysis of HMA Mixtures Volumetrics All matter has mass and occupies space Volumetrics are the relationships between mass and volume

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3Volumetric Analysis of HMA Mixtures Specific Gravity, G Mass Volume * w

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4Volumetric Analysis of HMA Mixtures Basic Terms Specific Gravity (G): G xy –x:b = binder s = stone (i.e., aggregate) m = mixture –y:b = bulk e = effective a = apparent m = maximum –Example: G mm = gravity, mixture, maximum (i.e., maximum gravity of the mixture)

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5Volumetric Analysis of HMA Mixtures Basic Terms (cont.) Mass (P) or Volume (V) Concentration: P xy or V xy –x:b = binder s = stone (i.e., aggregate) a = air –y:e = effective a = absorbed –Example: P b = percent binder

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6Volumetric Analysis of HMA Mixtures Volumetric Relationships V mb V sb V ba VbVb V se V mm VaVa VMA

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7Volumetric Analysis of HMA Mixtures HMA Volumetric Terms Bulk specific gravity (Gmb) of compacted HMA Maximum specific gravity (Gmm) Air voids or voids total mix (Va) Effective specific gravity of aggregate (Gse) Voids in mineral aggregate, VMA Voids filled with asphalt, VFA

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8Volumetric Analysis of HMA Mixtures G mb of Compacted HMA AC mixed with agg. and compacted into sample Mass agg. and AC Vol. agg., AC, air voids G mb = V mb

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9Volumetric Analysis of HMA Mixtures Testing Mixing of asphalt and aggregate Compaction of sample Mass of dry sample Mass under water Mass saturated surface dry (SSD)

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10Volumetric Analysis of HMA Mixtures Testing Obtain mass of dry compacted sample

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11Volumetric Analysis of HMA Mixtures Soak in water for 3 – 5 minutes

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12Volumetric Analysis of HMA Mixtures Testing Obtain mass of specimen at SSD

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13Volumetric Analysis of HMA Mixtures Calculations G mb = A / ( B - C ) Where: A = mass of dry sample B = mass of SSD sample C = mass of sample under water

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14Volumetric Analysis of HMA Mixtures Maximum Specific Gravity Loose (uncompacted) mixture Mass agg. and AC Vol. agg. and AC G mm = V mm

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15Volumetric Analysis of HMA Mixtures Testing Mixing of asphalt and aggregate Mass in air Mass under water

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16Volumetric Analysis of HMA Mixtures Testing Loose Mix at Room Temperature

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17Volumetric Analysis of HMA Mixtures Testing Vacuum Pump Residual Manometer Metal Bowl with Lid Shaker Table

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18Volumetric Analysis of HMA Mixtures Calculations G mm = A / ( A - C ) Where: A = mass of dry sample C = mass of sample under water

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19Volumetric Analysis of HMA Mixtures Air Voids Calculated using bulk and maximum specific gravities Air voids (V a ) = 100 * G mm – G mb G mm V mb VaVa

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20Volumetric Analysis of HMA Mixtures Why Are Air Voids Important? Related to Rut Resistance Related to Durability (aging and fatigue)

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21Volumetric Analysis of HMA Mixtures Effective volume = volume of solid aggregate particle + volume of surface voids not filled with asphalt G se = Mass, dry Effective Specific Gravity Effective Volume Absorbed asphalt Vol. of water-perm. voids not filled with asphalt Surface Voids Solid Agg. Particle

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22Volumetric Analysis of HMA Mixtures Effective Specific Gravity G se is an aggregate property Determined from a mix test G se = 100 - P b G mm G b

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23Volumetric Analysis of HMA Mixtures Voids in Mineral Aggregate VMA is an indication of film thickness on the surface of the aggregate VMA = 100 - G mb P s G sb V mb VMA

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24Volumetric Analysis of HMA Mixtures Voids Filled with Asphalt VFA is the percent of VMA that is filled with asphalt cement VFA = 100 x VMA - V a VMA

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25Volumetric Analysis of HMA Mixtures Percent Binder Absorbed P ba is the percent of absorbed asphalt by wt. of aggregate P ba = 100 ( G se - G sb G se G sb ) G b

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26Volumetric Analysis of HMA Mixtures Effective Asphalt Content The effective asphalt content is the total asphalt content minus the percent lost to absorption? P be = P b - P ba 100 PsPs

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27Volumetric Analysis of HMA Mixtures Dust /Asphalt Ratio F % passing No. 200 = A % P be

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28Volumetric Analysis of HMA Mixtures Factors That Influence Volumetric of HMA Asphalt viscosity Mix temperature Time held at elevated temperature

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29Volumetric Analysis of HMA Mixtures Important Considerations Consistent laboratory procedures –Equiviscous mixing temperatures –Mixing times Curing time to simulate field conditions

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30Volumetric Analysis of HMA Mixtures Example Problem

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31Volumetric Analysis of HMA Mixtures - Example Problem - Let’s assume we have a compacted HMA mixture with the following properties. Bulk Specific Gravity of the Mixture - G mb = 2.425 Theoretical Maximum Specific Gravity - G mm = 2.521 Asphalt Binder Specific Gravity - G b = 1.015 Asphalt Content - P b = 5.0 % (by mass of total mix) Percent passing No. 200 = 5.3%

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32Volumetric Analysis of HMA Mixtures - Example Problem - Let’s also assume that three stockpiled aggregates were used to manufacture this HMA mixture. The percent of each aggregate and the Bulk Specific Gravity (G sb ) for each is as follows: Aggregate % of Total Aggregate G sb 2.695 2.711 2.721 ABCABC 50 % 25 %

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-Example Problem – Based on the information given for this problem, the following steps should be followed: –Calculate the bulk specific gravity of the combined aggregate –Calculate the effective specific gravity of the aggregate –Calculate the percent absorbed asphalt for the mixture –Calculate the percent effective asphalt for the mixture –Calculate the percent voids in total mix for the mixture –Calculate the percent voids in mineral aggregate for the mixture –Calculate the percent voids filled with asphalt for the mixture –Calculate the dust to asphalt ratio

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-Example Problem – Bulk Specific Gravity of the Combined Aggregate - G sb G A G B G C ( P A + P B + P C ) P A P B P C = 2.705 Where:P A, P B & P C = Percent by Mass of Each Aggregate in Blend G A, G B & G C = Bulk Specific Gravity of Each Aggregate Based on the information given: G A = 2.695 G B = 2.711 G C = 2.721 P A = 50% P B = 25% P C = 25% G sb = 2.695 2.711 2.721 ( 50+ 25 + 25 ) 50 25 25 G sb = + + + +

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35Volumetric Analysis of HMA Mixtures Effective Specific Gravity of Aggregate - G se G mm G b 100 - P b 100 P b = 2.735 Where: P b = Percent Asphalt Binder by Total Mass of Mixture G mm = Theoretical Maximum Specific Gravity of Mixture G b = Specific Gravity of Asphalt Binder P b = 5.0 % G mm = 2.521 G b = 1.015 G se = 2.521 1.015 100- 5.0 100 5.0 G se = - - -Example Problem – Based on the information given:

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36Volumetric Analysis of HMA Mixtures Percent Absorbed Asphalt Binder - P ba (100 * G b ) (G se - G sb ) G se * G sb = 0.4 % Where: G b = Specific Gravity of Asphalt Binder G se = Effective Specific Gravity of Aggregate G sb = Bulk Specific Gravity of Aggregate G b = 1.015 G se = 2.735 G sb = 2.705 P ba = ( 100 * 1.015 ) (2.735 - 2.705 ) ( 2.735 * 2.705 ) P ba = -Example Problem – Based on the information given:

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37Volumetric Analysis of HMA Mixtures Percent Effective Asphalt Binder - P be ( P ba * P s ) 100 Where: P b = Percent Asphalt Binder in Total Mix P ba = Percent Absorbed Asphalt Binder in Total Mix P s = Percent Aggregate in Total Mix P b = 5.0 % P ba = 0.4 % P s = 95.0 % P b - = 4.6 % P be = ( 0.4 * 95.0 ) 100 5.0 - P be = -Example Problem – Based on the information given:

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38Volumetric Analysis of HMA Mixtures Percent Voids in Total Mix - Va ( G mm - G mb ) G mm Where: G mm = Theoretical Maximum Specific Gravity of Mix G mb = Bulk Specific Gravity of Mix G mm = 2.521 G mb = 2.329 = 3. 8 % Va, % = 100 * (2.521 - 2.425 ) 2.521 Va = 100 * -Example Problem – Based on the information given:

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39Volumetric Analysis of HMA Mixtures Percent Voids in Mineral Aggregate - VMA ( G mb * P s ) G sb Where: G mb = Bulk Specific Gravity of Mix P s = Percent Aggregate in Total Mix G sb = Bulk Specific Gravity of Aggregate G mb = 2.329 P s = 95.0 % G sb = 2.705 = 14.8 VMA, % = 100 - ( 2.425 * 95.0 ) 2.705 VMA = 100 - -Example Problem – Based on the information given:

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40Volumetric Analysis of HMA Mixtures Percent Voids Filled with Asphalt - VFA ( VMA - Va) VMA Where: VMA = percent Voids in Mineral Aggregate Va = percent Voids in Total Mix VMA = 14.8 % Va = 3.8 % = 74 % VFA, % = 100 * ( 14.8 - 3.8 ) 14.8 VFA = 100 * -Example Problem – Based on the information given:

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41Volumetric Analysis of HMA Mixtures Dust /Asphalt Ratio F % passing No. 200 = A P be Given: P -200 = 5.3% F 5.3 A 4.60 = = 1.15

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42Volumetric Analysis of HMA Mixtures Example Problem - Volumetric Equations Summary G sb = 2.705 G se = 2.732 P be, % = 4.6 % P ba, % = 0.4 % Va, % = 3.8 % VMA, % = 14.8 % VFA, % = 74 % F/A = 1.15

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Volumetric Analysis of HMA Mixtures 43 Classroom Exercise

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44Volumetric Analysis of HMA Mixtures - Classroom Exercise 1 - Let’s assume we have a compacted HMA mixture with the following properties at 25 o C. Bulk Specific Gravity of the Mixture - G mb = 2.413 Theoretical Maximum Specific Gravity - G mm = 2.501 Asphalt Binder Specific Gravity - G b = 1.025 Asphalt Content - P b = 4.3 % (by mass of total mix) Percent Passing No. 200 = 4.8%

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45Volumetric Analysis of HMA Mixtures - Classroom Exercise 1 - Let’s also assume that four stockpiled aggregates were used to manufacture this HMA mixture. The percent of each aggregate and the Bulk Specific Gravity (G sb ) for each is as follows: Aggregate% of Total AggregateG sb 2.650 2.661 2.675 2.697 ABCDABCD 45 % 15 % 25 % 15 %

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46Volumetric Analysis of HMA Mixtures - Classroom Exercise 1 - Based on the information given for this problem, the following steps should be followed: –Calculate the Bulk Specific Gravity of the combined aggregate –Calculate the Effective Specific Gravity of the aggregate –Calculate the Percent Absorbed Asphalt for the Mixture –Calculate the Percent Effective Asphalt For the Mixture –Calculate the Percent Voids in Total Mix for the Mixture –Calculate the Percent Voids in Mineral Aggregate for the Mixture –Calculate the Percent Voids Filled with Asphalt for the Mixture –Calculate the Dust/AC Ratio

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47Volumetric Analysis of HMA Mixtures - Classroom Exercise 1 - Bulk Specific Gravity of the Combined Aggregate - G sb G A G B G C G D ( P A + P B + P C + P D ) P A P B P C P D Where: P A, P B, P C & P D = percent by mass of each aggregate in blend G A, G B, G C & G D = Bulk Specific Gravity of each aggregate Based on the information given: G A = G B = G C = G D = P A = % P B = % P C = % P D = % G sb = + + +

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48Volumetric Analysis of HMA Mixtures - Classroom Exercise 1 - Effective Specific Gravity of Aggregate - G se G mm G b 100-P b 100 P b Where: P b = percent asphalt binder by total mass of mixture G mm = Theoretical Maximum Specific Gravity of mixture G b = Specific Gravity of asphalt binder Based on the information given: P b = % G mm = G b = G se = -

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49Volumetric Analysis of HMA Mixtures - Classroom Exercise 1 - Percent Absorbed Asphalt Binder - P ba (100 * G b ) (G se - G sb ) G se * G sb Where: G b = Specific Gravity of asphalt binder G se = Effective Specific Gravity of aggregate G sb = Bulk Specific Gravity of aggregate Based on the information known: G b = G se = G sb = P ba =

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50Volumetric Analysis of HMA Mixtures - Classroom Exercise 1 - Percent Effective Asphalt Binder - P be ( P ba * P s ) 100 Where: P b = percent asphalt binder in total mix P ba = percent Absorbed Asphalt Binder into aggregate P s = percent aggregate in total mix Based on the information known: P b = % P ba = % P s = % P b -P be =

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51Volumetric Analysis of HMA Mixtures - Classroom Exercise 1 - Percent Voids in Total Mix - VTM ( G mm - G mb ) G mm Where: G mm = Theoretical Maximum Specific Gravity of mix G mb = Bulk Specific Gravity of mix Based on the information known: G mm = G mb = Va, % = 100 * Va =

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52Volumetric Analysis of HMA Mixtures - Classroom Exercise 1 - Percent Voids in Mineral Aggregate - VMA ( G mb * P s ) G se Where: G mb = Bulk Specific Gravity of mix P s = percent aggregate in total mix G se = Effective Specific Gravity of aggregate Based on the information known: G mb = P s = % G se = VMA, % = 100 - VMA =

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53Volumetric Analysis of HMA Mixtures - Classroom Exercise 1 - Percent Voids Filled with Asphalt - VFA ( VMA - Va) VMA Where: VMA = percent Voids in Mineral Aggregate Va = percent Voids in Total Mix Based on the information known: VMA = % Va = % VFA, % = 100 * VFA =

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54Volumetric Analysis of HMA Mixtures Dust /Asphalt Ratio F % passing No. 200 = A Pbe P-200 = Pbe = Pbe = = Based on the information known: F

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55Volumetric Analysis of HMA Mixtures - Classroom Problem 1 - Summary G sb = G se = P ba, % = P be, % = Va, % = VMA, % = VFA, % = F/A =

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Volumetric Analysis of HMA Mixtures 56 Classroom Exercise 2

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57Volumetric Analysis of HMA Mixtures Classroom Exercise 3 Given –G mm = 2.474 –Asphalt Content = 4.5 % –Bulk Sp. Gravity of Aggregate = 2.603 –Bulk Sp. Gravity of Asphalt = 1.020 Determine G mm at 5.0, 5.5 & 6.0 %

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58Volumetric Analysis of HMA Mixtures

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59Volumetric Analysis of HMA Mixtures Questions – does it all make sense?

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