Design and Production Control of SMA Mixes

Transcription

1 Design and Production Control of SMA Mixes

2 SMA Mixture Design Steps Selection of Materials Design Aggregate Structure Design Binder Content Performance Test Test Section

3 Selection of Materials Asphalt Binder Aggregates Mineral Fiber Stabilizer

4 Role of Binder in SMA Stone skeleton carries load Mastic (binder, filler and fiber) fills voids between coarse aggregate structure Mastic must not push aggregate apart Perform under environmental conditions Resist low temperature cracking Adhere to rock in the presence of moisture Polymers and high film thickness help prevent reflective cracking

5 Criteria for Selecting Binder Grades for SMA European Experience Early VA History AASHTO M320 AASHTO M332

6 European Experience SMA initiated in Northern and Central Europe Typically do not have extreme warm temperatures Moderately stiff asphalts Pen Northern Area: Pen (AC 10) Southern Area 65 Pen (AC 20) What s and AC 20?

7 U. S. Experience Initially used AC-20 (PG 64-22) Due to tightening of wheel paths moved to AC-30 (PG 67-22) Mid-Atlantic states: PG PG Southeast: PG VA now 64H-22 or 64E-22

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16 Why is this important? After more than 15 years of PG grades, need to avoid the trap that a PG 64E-22 is going to behave like a PG 76-22, not a PG 64-22

17 Selection of Materials Aggregate Selection

18 SMA Aggregate Composition Example 70% #7 13% #89 10% #810 7% Min. Filler Coarse Aggregate Fine Aggregate Mineral Filler + AC + Fiber

19 Coarse Aggregate Requirements Test Method AASHTO M325 VDOT 248 L.A. Abrasion AASHTO T96 30 max 40 max Flat & Elongated,% 3 to 1 5 to 1 ASTM D4791 (VTM-121) +4 material 20 max 5 max 20 max 5 max Absorption, % AASHTO T85 2 max 2 max Soundness, % Sodium Sulfate Magnesium Sulfate AASHTO T max 20 max NA 15 max Fractured Faces ASTM D5821 One face 100 min 100 min Two faces 90 min 90 min

20 L.A. Abrasion European <20% NAPA/AASHTO <30% Virginia <40% Maryland 30% Georgia <45%

21 Good Rock Bad Rock This is a Catch 22, cubical easier to compact in the field, but cubical tends to result in lower VMA

22 Special Notes VDOT requires two or more coarse aggregates (minimum 10%) Aggregate properties are for each coarse aggregate stockpile except Flat & Elongated Particles (F&E). F&E based on mathematical blend of coarse aggregate stockpiles During production, F&E based on samples SMA

23 AASHTO M325 Fine Aggregate Requirements Test Method Specification Soundness, % Sodium Sulfate Magnesium Sulfate Liquid Limit, % Plastic Index AASHTO T104 AASHTO T89 AASHTO T90 15 max 20 max 25 max Non-Plastic

24 Fine Aggregate must be 100% Crushed! No Natural Sand Allowed! This is both an AASHTO and VDOT requirement

25 RAP - VDOT 248 Table II-26 Mix Type & PG Allowable RAP % in Mix SMA 9.5, 12.5, & 19.0 w/ 64H to 20.0 SMA 9.5, 12.5, & 19.0 w/ 64E to 15.0 What kind of RAP do you want to use in SMA?

26 Selection of Materials Mineral Filler VDOT Section 201 references AASHTO M17

27 What is Mineral Filler? AASHTO M17 Finely divided mineral matter such as rock dust, slag dust, hydrated lime, hydraulic cement, fly ash, loess, or other suitable material. At time of use, it shall be sufficiently dry to flow freely and essentially from agglomerations. Free from organic impurities and have a plasticity index less than percent passing the No. 30 sieve (0.6 mm), 95 to 100 passing the No. 50 sieve (0.3 mm) and 70 percent passing the No. 200 sieve (0.075 mm).

28 VDOT Section 248 Modifications to AASHTO M17 Hydrated lime and fly ash not allowed as mineral filler Hydrated lime allowed as antistripping agent Minimum 55% passing No. 200 sieve

29 Primary Functions of Fill voids Mineral Filler Form a stiff mastic or mortar with the asphalt binder and stabilizing fiber Increased cohesion of the mix will result in significantly increased shear resistance

30 Commonly Used Mineral Fillers Marble dust Fly ash Typically type F Lime Hydrated not quicklime Limestone dust finely ground Agricultural lime, coarse ground limestone Cement kiln dust (mainly calcium silica/alumina oxides) Other stone dust dry de-dusting operations, baghouse fines (?)

31 Fly Ash One initial concern was spherical nature of fly ash particles. 1000x 2100x Fly Ash Slag Dust

32 General Mineral Filler Characterization Tests Specification Requirements ASTM D242 / AASHTO M17 Gradation ASTM D546 or AASHTO T27 Plasticity ASTM D4318 or AASHTO T89 & 90 Additional Testing with Asphalt Binder and Fibers (Mortars) Note: Many fillers that perform well do not meet M17 gradation

33 Filler Consideration Stiffening Effect AASHTO M325 recommends mineral fillers with modified Rigden voids (NAPA IS 127) > 50% not be used in SMA Based on work by Bryant, modified Rigden Voids of hydrated lime and fly ash often exceed

34 Modified Rigden Voids Test method in Appendix of NAPA IS g sample of mineral filler compacted in mold with 25 blows between 2 filter papers Determine bulk volume based on sample height, solids volume using mass and SG from AASHTO T100/ASTM D854

35 Selection of Materials Selection of Stabilizer

36 Primary Function of Stabilizer Prevent Draindown SMA has increased film thickness compared to conventional (dense graded) mixes Stabilizers, typically fiber, create surface area to hold AC during mixing, hauling and placement Most stabilizers do not add significant strength

37 Types of Stabilizers Cellulose Fiber Loose Pellets Mineral Fiber Polymer

38 Cellulose 400 : 1 Fibers Specifications Mineral 400 : 1 Courtesy of John Bukowski

39 In my experience, counting on modified asphalts (polymer or gelled) to prevent draindown can be risky business! VDOT requires a minimum of 0.3% cellulose fibers

40 SMA WITHOUT FIBERS?

41 Thomas Bennert, Ph.D.

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45 RAS in SMA Illinois DOT produced SMA with 5% RAS and no fibers Placed on I-80 in 2011 Monitored under Pooled-Fund Study: Performance of Recycled Asphalt Shingles in Hot Mix Asphalt: TPF-5(213)

46 SMA Mixture Design Steps Selection of Materials Design Aggregate Structure Design Binder Content Performance Test Test Section

47 Design Aggregate Structure Selection Establish trial blends and determine VCA drc for each blend Compact trial blend specimens Evaluate trial blends Select design aggregate structure

48 Gradations - Background Germans typically use three maximum aggregate sizes: 11 mm 8 mm 5 mm FHWA TWG specification is a borderline 12.5/19.0 mm NMAS by Superpave definition

49 Typical German Stone Sizes - Fractionation

50 Evolution of SMA Gradation Specifications

51 German Specifications Sieve Size 11.0 mm % Passing 8.0 mm % Passing 5.0 mm % Passing 11.2 mm mm 75 max mm mm mm Section 4. Splittmastixasphalt German Federal Ministry of Transport 1984 (Revised 1990)

52 General Comments on SMA Gradations German s tend to use smaller maximum aggregate size due to permeability concerns SMA generally does not meet Superpave s definition of Nominal Maximum Aggregate Size (NMAS) U.S. specifications tend to allow wider specifications for % passing coarser sieves due to difficulty blending standard stone sizes Fractionation required to meet tight bands

53 SMA Technical Working Group Model Material Guidelines Sieve Size % Passing 19.0 mm (3/4 in) mm (1/2 in) mm (3/8 in) 75 max mm (No. 4) mm (No. 8) mm (No. 30) mm (No. 50) mm (No. 200) 8-10

54 2012 AASHTO Specifications Sieve Size 19.0 mm % Passing 12.5 mm % Passing 9.5 mm % Passing 25.0 mm (1 in) mm (3/4 in) mm (1/2 in) mm (3/8 in) mm (No. 4) mm (No. 8) mm (No. 30) max. 0.3 mm (No. 50) max mm (No. 200)

55 Sieve Size VDOT Specifications 9.5 mm % Passing 12.5 mm % Passing 19.0 mm % Passing 19.0 mm (3/4 in) mm (1/2 in) mm (3/8 in) max mm (No. 4) mm (No. 8) mm (No. 30) mm (No. 200)

56 Establish Trial Blends Develop three trial blends Recommend a coarse, fine and intermediate blend within allowable range for break point sieve

57 VTM-99 Mix Sieve Size, mm Recommended % s Passing for Design Trials SMA , 37, and 45 SMA , 26, and 30 SMA , 20, and 25

58 Coarse Aggregate Fraction NMAS Break Point Sieve 25.0 mm 4.75 mm 19.0 mm 4.75 mm 12.5 mm 4.75 mm 9.5 mm 2.36 mm 4.75 mm 1.18 mm

59 Percent Passing 19 mm Nominal Sieve Size Fine Aggregate Coarse Aggregate Blend 1 Blend 2 Blend Break Point Sieve Sieve Size (mm) Raised to 0.45 Power

60 Note: Always batch up an extra specimen of each blend to run a washed gradation on! You need to be sure you got what you thought you were getting

61 Voids in Coarse Aggregate (VCA) VCA is used to ensure stone-on-stone contact VCA dry rodded condition (DRC) is obtained by compacting blended coarse aggregate fraction according to VTM-99 (similar to AASHTO T19) VCA of compacted SMA sample (VCA mix ) must be less than VCA DRC or mastic may be pushing stone skeleton apart, causing mix instability

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66 VCA (Voids in the Coarse Aggregate) Dry Rodded Condition VCA drc = [(G ca g w - g s )/G ca g w ] x 100 VCA drc where, G ca = Bulk Specific Gravity of the Coarse Aggregate Fraction g w = Unit Weight of Water g s = Dry Rodded Unit Weight of the Coarse Aggregate Fraction Air Coarse Aggregate

67 VCA (Voids in the Coarse Aggregate) Compacted Mixture VCA mix = [(G mb /G mm ) x P ca ] where, G mb = Bulk Specific Gravity of the Compacted Mix G mm = Maximum Specific Gravity of the Mix P ca = Percent Coarse Aggregate in the Mix VCA mix Air Asphalt Fine Aggregate Coarse Aggregate

68 VCA - Continued VCA Mix 100 G G mb CA P CA VCA of compacted SMA sample (VCA mix ) must be less than VCA DRC or mastic may be pushing stone skeleton apart, causing mix instability

69 VCA Ratio & VCA Criteria VCA Ratio VCA mix VCA drc VCA Criteria: VCA Ratio < 1 VCA mix < VCA drc

70 VCA of Mix Avg. VCA of Mix Avg. VCA Dry- Rodded Aggregate % Passing 4.75 mm Sieve

71 Design Aggregate Structure Selection Establish trial blends and determine VCA drc for each blend Compact trial blend specimens Evaluate trial blends Select design aggregate structure

72 Trial Binder Content Minimum specified 6.3% Slightly higher than minimum specified (allows for field adjustment) Experience

73 Laboratory Compaction Effort 50 Blow Marshall worldwide standard for SMA AASHTO 100 gyration; 75 for higher LA Abrasion VDOT specifies 75 gyrations

74 NCHRP 9-8

75 NCHRP 9-8

76 Other Research Studies Prowell et al. (2002) 75 gyrations Virginia James (2005) 70 gyrations Alabama Xie (2006) 65 gyrations FHWA West et al. (2007) 50 gyrations Georgia Missouri (2007) adopted 65 gyrations

77 AAPTP SMA for Airfields Mix Combinations Coarse Aggregate Binde r Grade P Blow 50- Blow SMA 50 Gyr. 65 Gyr. 80 Gyr. 100 Gyr. Diabase L.A.< X X X X X X Granite L.A X X X X X X Gravel; L.A 20-30; 90%2face X X X X X X Limestone; L.A X X X X X X Limestone; L.A X X X Granite; L.A X X X X X X

78 VMA, % Diabase Gravel Columbus Granite Limestone Ruby Granite Equivalent Design Gyrations to Match 50-blow Marshall Diabase Columbus Granite Ruby Granite Gravel Limestone

79 Equivalent Gyrations to Aggregate 50-Blow Marshall LA Abrasion Loss, % % Flat and Elongated Particles > 3:1 Gyrations to Match VMA Diabase Columbus Granite Ruby Granite Gravel Limestone R 2 = 0.99, standard error = 1.23

80 Evaluation of Trial Determine: Blends Bulk Specific Gravity of Mix (G mb ) Maximum Specific Gravity of Mix (G mm ) Calculate: Voids in mineral aggregate (VMA) Air Voids (V a ) Voids in Coarse Aggregate (VCA mix )

81 Volumetric Criteria Air Voids VMA 1 VCA MIX TSR Property Draindown % Requirement 17.0 % min for 19.0 mm 18.0% min for 9.5 and 12.5 mm Less Than VCA DRC 0.80 min max. 1 Production VMA 1% lower

82 Minimum Recommended Asphalt Content AASHTO R46 Aggregate Bulk Specific Gravity Minimum Asphalt Content

83 VMA Criteria Nominal Maximum Aggregate Size Minimum VMA, % 9.5 mm (3/8 ) mm (1/2 ) mm (3/4 ) 17.0

84 VCA Ratio & VCA Criteria VCA Ratio VCA mix VCA drc VCA Criteria: VCA Ratio < 1 VCA mix < VCA drc

85 Select Design Aggregate Structure Select finest blend having at least 18.0 VMA (for 12.5 mm or smaller NMAS) Check stone-on stone contact (VCA ratio) Check air voids (V a )

86 Select Design Aggregate Structure - Example Properties Criteria Trial #1 Trial #2 Trial #3 P bp (%) N/A VMA (%) > VCA drc (%) N/A VCA mix (%) < VCA drc VCA Ratio < V a (%) > Courtesy of Todd Lynn

87 SMA Mixture Design Steps Selection of Materials Design Aggregate Structure Design Binder Content Performance Test Test Section

88 Selection of Design Binder Content Compact design aggregate structure at multiple binder contents (typically 3) Determine V a, VMA, VCA mix (& stability if Marshall) Select design binder content

89 Design Aggregate Structure: Mixture Properties Binder Content V a (%) VMA (%) VCA mix (%) VCA DRC = 42.9% This is an older example where voids were selected at 4%, for VDOT s Specifications, should test 7.0% Courtesy of Todd Lynn

90 Select Design Binder Content Determine Binder Content at 3% V a (mid-point of range) Determine mix properties at selected binder content Compare mix properties to criteria

91 Design Aggregate Structure: Design Mixture Properties Property Criteria JMF P b (%) > V a (%) VMA (%) > VCA mix (%) <VCA drc 38.1 * * VCA drc = 44.2%

92 Is that a good design?

93 Coarse Aggregate Properties Aggregate Source L.A. Abrasion Loss, ASTM C131, % Flat and Elongated Particles ASTM D4791, % 3:1 5:1 Coarse Aggregate Angularity ASTM D5821,% 1FF 1 2FF 1 Voids in Coarse Aggregate DRC, % 2 Diabase Columbus Granite , Ruby Granite Gravel Limestone

94 Example Design Gradations Diabase Columbus Granite Ruby Granite Gravel Limestone Sieve Size, Blend 2 Blend Blend 1 Blend 8B mm 2 Blend 1 Blend

95 Air Voids, % 7.0 Ruby Granite Blend 8-B Outlier AC, % 50-Blow 50 Gyration 65 Gyration 80 Gyrations 100 Gyrations Poly. (50 Gyration) Poly. (100 Gyrations)

96 VMA, % 21.5 Ruby Granite Blend 8-B Outlier AC, % 50-Blow 50 Gyration 65 Gyration 80 Gyrations 100 Gyrations

97 SMA Mixture Design Steps Selection of Materials Design Aggregate Structure Design Binder Content Performance Test Test Section

98 Performance Tests Draindown VTM-100/AASHTO T305 Moisture Susceptibility - AASHTO T283 Rut Test?

99 Draindown VTM- 100/AASHTO T g minutes Temperatures Plant 15 C (27 F) above Criteria - maximum of 0.30%

100 Moisture Sensitivity AASHTO T 283 Measured on proposed aggregate blend and asphalt content VDOT specifies 7 + 1%, some states reduce to 6% for SMA 3 Conditioned Specimens 3 Dry Specimens Vacuum saturate specimens Freeze Cycle for 16 hours Soak at 60 o C for 24 hours Soak at 25 o C for 2 hours

101 Moisture Sensitivity AASHTO T 283 Determine the tensile strengths of both sets of 3 specimens Calculate the Tensile Strength Ratio (TSR) TSR = Avg. wet tensile strength Avg. dry tensile strength Minimum of 80% needed for SMA

102 Why SMA?

103 Virginia Data and Proposed APA Criteria for SMA Property SMA Mean, rut depth, mm 2.25 Std, mm 0.90 No. of Mixes 21 95% Confidence Limit 4.01 Tentative Criteria, mm 4.0

104 Occurence, % Frequency Distribution of Other Mixes SM-12.5D SMA Rut Depth, mm

105 Rutting Susceptibility SMA developed to resist studded tire wear, a form of rutting SMA has been rut resistant in the field even with 1% higher binder content Some laboratory evaluations show SMA to have increased rutting susceptibility as compared to dense graded mixes

106 Hamburg Test Test combines rutting performance with moisture susceptibility Uses a steel wheel 47 mm wide by 204 mm diameter Load = 685 N (154 lb) Full test is 20,000 cycles Temperature - 50 C VTM % Tested under water

107 Rutting Rate, mm/hr Hamburg Rutting Rate Rutting rate for PG times higher than PG P AC,% Gravel Diabase Limestone Columbus Granite

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109 Cycles to Failure Overlay Tester Results 18,000 16, % 14,000 12, % 10, % 8,000 6,000 4, % 2,000 24% 35% 0 Diabase Columbus Granite Ruby Granite Gravel Limestone PG Limestone PG SMA P401

110 SMA Mixture Design Steps Selection of Materials Design Aggregate Structure Design Binder Content Performance Test Test Section

111 Importance of Trial Sections Courtesy of Vince Aurillo

112 Production Control What can go wrong?

113 Coarse Aggregate Issues Communicate with the Aggregate Producer! SMA typically has percent coarse aggregate If using large percentage of one aggregate, split into 2 cold feed bins Consider Fractionation

114 Keep Fibers Dry!

115 Fiber Hopper ~ Loose

116 Fibers - Pellets 100% Fiber Pellets Pellet Fluffer

117 Monitor Loose Fiber Introduction

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119 Issues with Fibers Feed can clog add clear sight glass Introduce loose fiber just after AC introduced otherwise may clog baghouse Feed is typically by mass if the workers lean on the feeder, it will cause surges Fibers must be included in ignition furnace calibration impossible to separate AC and Fiber changes

120 Mineral Fillers Cold Feed Bin is Not the best way, but... Keep Dry!! Silo where Filler is Metered into Production is Best.

121 Fines Weigh Pod at Drum-Mix Facility

122 Courtesy of G. M. Klinefelter

123 Courtesy of G. M. Klinefelter

124 Courtesy of G. M. Klinefelter

125 Handling SMA in the Lab The mix is very sticky therefore Sampling may be difficult Splitting must be done with care Mastic should be scraped off splitting and handling tools Maximum specific gravity (Rice) samples need to be separated into small pieces before it cools Remove gyratory paper sooner than normal

126 One Stone at a Time Courtesy of G. M. Klinefelter

127 Always Clean Your Scoop! Courtesy of G. M. Klinefelter

128 Asphalt Content Determination Solvent extraction very slow due to high fines and fiber content Ignition Furnace Fibers need to be included when determining calibration factor Fluctuation of fibers affects measured AC% Certain fillers (hydrated lime) affect measured AC%

129 Buttering the bowl with SMA is critical LA Contractor reported furnace AC% 0.4 to 0.6% high in production Ignition Furnace Traced to not buttering bowl when preparing calibration samples. Calibration

130 Clean Out Scoop for Burn Courtesy of G. M. Klinefelter

131 Courtesy of G. M. Klinefelt

132 Tare the Drain Down Apparatus.. Courtesy of G. M. Klinefelter

133 And Weigh the Drain Down Sample Courtesy of G. M. Klinefelter

134 Just A Tad Bit Open! Courtesy of G. M. Klinefelter

135 How About the Drain Down Test? Courtesy of G. M. Klinefelter

136 Voids in Coarse Aggregate Indications mix is failing VCA: Evident roll-down after the first roller pass Mix moves under foot after first pair of rollers passes VCA mix > VCA drc (takes time to get this result) Causes of failing VCA: Generally, the mix is too fine on the break point (# 4) sieve Too much mastic

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138 Example No. 1: 16 mm (SMA TWG Specification) SMA, run through batch plant. Attempted to scalp out much of ¾ inch stone from No. 68 s

139 VCA % VCA vs % Passing # VCA drc % Passing #4

140 % VCA %VCA vs % VMA VCA drc % VMA

141 Example No. 2: 16 mm (SMA TWG) produced with drum plant. Design with Marshall, tested with both Marshall and SGC (100 gyrations)

142 % VCA % VCA vs % VMA VCA drc % VMA

143 % VMA VMA vs % Passing # % Passing #4 M - VMA SGC VMA

144 % VTM AC% vs Voids AC % Marshall SGC

145 % VTM VTM Comparison Sample Number Marshall SGC

146 VMA Comparison % 17.5 A M 17 V Sample Marshall SGC

147 Example No. 3: 9.5 mm SMA produced with drum plant. Designed with 100 gyrations SGC

148 Gradation Comparison Sieve Size Standard VDOT SMA VDOT Design MD Spec. GA Spec mm mm mm 75 max mm mm mm

149 Job Mix Formula Property Design MD Spec. GA Spec. AC% min Air Voids, % VMA, % min NA VFA, % 78 NA VCA Mix, % 31.7 NA NA VCA DRC, % 43.1 NA NA

150 VCAMix, % VCA Mix vs % Passing Break Point Sieve % Passing 2.36 mm vs VCA% 2.36 mm % Passing 4.75 mm vs VCA% 4.75 mm R 2 = VCA Mix Calculated Based on 4.75 mm 35.0 Note: VCA DRC based on 2.36 mm = 43.1% VCA DRC based on 4.75 mm = 42.6% R 2 = VCA Mix Calculated Based on 2.36 mm Percent Passing, % VTM-99 specifies 2.36 mm Sieve for 9.5 mm SMA

151 Asphalt Pavement Analyzer (APA) Test Protocol Temperature 64 C 533-N (120 lb) vertical load 830-kPa (120 psi) hose pressure 8,000 cycles Beams tested at 7% air voids Rut depth = difference between preand post test readings Criteria VA: 4 mm at 49 C GA: 5 mm at 49 C

152 APA Rut Depth, mm APA Rut Depth vs Break Pt. VCA Ratio mm BP VCA Ratio, PG mm BP VCA Ratio, PG mm BP VCA Ratio, PG VCA Ratio, 2.36 mm PG mm BP VCA Ratio, PG VCA Ratio, 4.75 mm PG VCA Ratio, 2.36 mm PG VCA Ratio, 4.75 mm PG VCA Ratio

153 APA Rut Depth, mm APA Rut Depth vs AC% PG PG Linear (PG 70-22) Linear (PG 76-22) R 2 = R 2 = Design Asphalt Content Asphalt Content, %

154 VCA, % at 75 Gyrations VCA Mix at 75 and 100 Gyrations y = x R 2 = Line of Equality Note: VCADRC = 43.1% VCA, % at 100 Gyrations

155 75 Gyrations Air Voids at 75 and 100 Gyrations y = 1.099x R 2 = Line of Equality Gyrations

156 Field Density Control

157 Density Measurement - SMA Cores are required for determining the density of SMA Corelok can be a better method for determining core density Nuclear gauge may be used for QC if properly calibrated Due to macro texture, manufacturers recommend sanding sites Keep gauge bottom clean

158 Potential Problem with SSD Coarse Gradations Conventional Gradations Equal Air Volumes (% VTM) - Coarser Gradation -Larger Sized Voids -(more chance for interconnected voids) - Finer Gradation -Smaller Sized Voids -(Less chance for interconnected voids)

159 Corelok Process

160 Bulk Specific Gravity ~ AASHTO T166 Comparison of Corelok and T166 Methods ~ SMA Gradations Gyrations 50 Gyrations 100 Gyrations Bulk Specific Gravity ~ Corelok Method

161 Standard Deviation Precision Based on Difference Analysis SSD W/L Corelok W/L SSD B/L Corelok B/L CG 15 CG 50 CG 100 FG 15 FG 50 FG 100 SMA 15 SMA 50 SMA 100 Average

162 Gauge Density, lb/ft3 Density Comparison ~ SMA 9.5 mm PG R 2 = 0.89 Nuclear PQI Avg R 2 = 0.61 Linear (Nuclear) Linear (PQI Avg. 3) Core Density, lb/ft3

163 Effect of NMAS on Permeability

164 Permeability Due to Lack of Density

165 Rutting in 25 Year Old Base Mix Due to Moisture Damage SMA Permeable

166 Joint Failure in SMA

167 Percent Passing, % Project Gradations mm 19.0 mm 25.0 mm Sieve Size (Raised to 0.45 Power), mm

168 Permeability, E-5 cm/sec Affect of NMAS on Permeability mm 19.0 mm 25.0 mm R 2 = mm R 2 = mm R 2 = mm In-Place Air Void Content, %