superpavetm mix design - university of memphis handouts/14 - superpave mix... · mix and compact...

SuperpaveTM Mix Design

CIVL 3137 3

Superpave Mix Design Steps

1. Select suitable aggregates

2. Select a suitable asphalt binder

3. Select a suitable aggregate structure

4. Mix and compact samples in the lab

5. Analyze mix volumetrics (air voids, etc.)

6. Select the optimum asphalt content

7. Evaluate moisture susceptibility

CIVL 3137 4

Sample Size

SUPERPAVE

Marshall6"

4"4700 gAggregate 1200 g

Aggregate

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Brovold Gyratory Compactor

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Gyratory Compaction

= 1.25º

20 rpm

P = 600 kPa

SuperpaveTM Level 1

Chapter 6‐6.2p. 242‐245

SuperpaveTM Level 1

1. Determine design ESALs, average high air temperature, and NMAS

CIVL 3137 11

AssumeDesign traffic load = 6 million ESALsDesign high air temperature = 35°C

Design NMAS = 19 mm

SuperpaveTM Level 1

2. Select the asphalt binder grade to be used

CIVL 3137 12

767064585246‐4‐10‐16‐22‐28

PG70‐22

PG64‐16

Lowest 1‐dayTemperature

Highest 7‐dayTemperatureHighest 7‐dayPavement

Temperature

Lowest 1‐dayPavement

Temperature

SuperpaveTM Level 1

2. Select the asphalt binder grade to be used

CIVL 3137 13

AssumeBinder grade = PG 58‐22

Binder relative density = 1.02

SuperpaveTM Level 1

3. Select three trial aggregate blends

CIVL 3137 14

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Blend 1

Blend 2

Blend 3

NMAS = 19 mm

SuperpaveTM Level 1

3. Select three trial aggregate blends

CIVL 3137 17

Assume

45% gravel, 35% sand, 20% screenings

Bulk relative density = 2.68

Absorption = 1.1%

Fines content = 3.7%

SuperpaveTM Level 1

4. Select the trial asphalt content (Pb)

CIVL 3137 18

NMAS(mm)

Aggregate Relative Density and Absorption

2.65 / 0.8% 2.65 / 1.6% 2.70 / 0.8% 2.70 / 1.6%

9.5 8.3 8.9 8.1 8.7

12.5 5.0 5.6 4.9 5.5

19 4.4 5.0 4.3 5.0

25 4.1 4.7 4.0 4.6

Interpolate: Pb = 4.6%

Same as Table 6‐12

SuperpaveTM Level 1

5. Determine the appropriate mixing and compacting temperatures

CIVL 3137 19

Temperature‐Viscosity

CIVL 3137 20

SuperpaveTM Level 1

5. Determine the appropriate mixing and compacting temperatures

CIVL 3137 21

AssumeMixing temperature = 164° – 172°C

Compacting temperature = 151° – 158°C

SuperpaveTM Level 1

6. Prepare two 4700‐g aggregate samples for each trial blend

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Mgravel = 0.45 × 4700 = 2115 gMsand = 0.35 × 4700 = 1645 g

Mscreenings = 0.20 × 4700 = 940 gMg = 4700 g

SuperpaveTM Level 1

6. Prepare two 4700‐g aggregate samples for each trial blend

CIVL 3137 23

b bb

g b b

b

M MP 0.046M M 4700 M

M 227 g

SuperpaveTM Level 1

7. Determine Nini, Ndes, and Nmax

Nini = Numberofrevolutionsrepresentingthecompactionofthepavingmixturebythepavingmachine

Ndes = Numberofrevolutionsatwhichthemixvolumetricsmustbemet(suchas4%airvoids)

Nmax = Numberofrevolutionsrepresentingthecompactionofthepavingmixtureattheendofitsdesignlife

CIVL 3137 24

SuperpaveTM Level 1


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Source: NCEES FE Supplied Reference Handbook

SuperpaveTM Level 1


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(UPDATED VALUES)

< 0.30.3 to < 33 to < 3030 +

Source: ASTM D6925 ‐ 06

SuperpaveTM Level 1

8. Heat aggregate and binder to the mixing temperature and mix

CIVL 3137 27

AssumedMixing temperature = 164° – 172°C

SuperpaveTM Level 1

9. Age the mixtures for 4 hours at 135°C

CIVL 3137 28


(UPDATED PROCEDURE)

Age for 2 hours at compaction temperature

SuperpaveTM Level 1

9. Age the mixtures for 4 hours at 135ºC

CIVL 3137 29

Age for 2 hours at compaction temperature

AssumedCompacting temperature = 151° – 158°C

SuperpaveTM Level 1

10. Compact the specimens to Nmax gyrations

CIVL 3137 30

(UPDATED VALUES)

< 0.30.3 to < 33 to < 3030 +


CIVL 3137 31

(Nini , Hini)

(Ndes , Hdes)

7 75 115

(Nmax , Hmax)

This data is from a 1‐million ESAL mixwith Nini = 7, Ndes = 75, Nmax = 115

SuperpaveTM Level 1

10. Compact the specimens to Nmax gyrations

CIVL 3137 32

AssumeHini = 127.1 mmHdes = 115.9 mmHmax = 114.8 mm

SuperpaveTM Level 1

11. Determine mb at Nini, Ndes, Nmax

CIVL 3137 33

max

mb max max mold

After N Gyrations

M @ N H A

ini

mb ini ini mold

After N Gyrations

M @ N H A

Same

SuperpaveTM Level 1


CIVL 3137 34

mb ini ini mold@ N H A mb max max mold@ N H A

maxmb ini mb max

ini

H@ N @ NH

Measured

SuperpaveTM Level 1


CIVL 3137 37

Assume we weighed the compacted specimen in air andin water and found the density after Nmax revolutions to

be 2438 kg/m3.

SuperpaveTM Level 1


CIVL 3137 38

maxmb ini mb max

ini

3

H@ N @ NH

114.8 2438 2202 kg m127.1

SuperpaveTM Level 1


CIVL 3137 39

maxmb des mb max

des

3

H@ N @ NH

114.8 2438 2415 kg m115.9

SuperpaveTM Level 1

12. Determine mm (or Gmm) for this mix

CIVL 3137 40

Assume we ran a Rice Test (ASTM D‐2041) to find the maximum (zero‐air‐voids) density of the mix and it came out

to be 2522 kg/m3.

SuperpaveTM Level 1

13. Calculate AV, VMA and VFA at Ndes

CIVL 3137 41

mb des

mm

3

3

@ NAV 1 100%

2415 kg m1 100% 4.2%2522 kg m

SuperpaveTM Level 1


CIVL 3137 42

mb des b

agg

3

3

@ N 1 PVMA 1 100%

2415 kg m 1 0.0461 100% 14.0%

2.68 1000 kg m

SuperpaveTM Level 1


CIVL 3137 43

AVVFA 1 100%VMA

4.2%1 100% 70%14.0%

SuperpaveTM Level 1

14. Estimate the asphalt content (Pb) that will produce 4% air voids

CIVL 3137 44

b bP @4% P 0.4 4% AV

CIVL 3137 45

1

2

3

4

5

6

3.5 4.0 4.5 5.0 5.5 6.0 6.5

Asphalt Content (%)

Air V

oids (%

)

Marshall Mix Design

0.4

1

SuperpaveTM Level 1

14. Estimate the asphalt content (Pb) that will produce 4% air voids

CIVL 3137 46

b bP @4% P 0.4 4% AV

4.6% 0.4 4% 4.2% 4.7%

SuperpaveTM Level 1

15. Estimate VMA and VFA at 4% air voids

CIVL 3137 47

If AV < 4.0%

VMA@4% VMA 0.1 4% AV

If AV > 4.0%


SuperpaveTM Level 1


CIVL 3137 48


14.0% 0.2 4% 4.2% 14.0%

SuperpaveTM Level 1


CIVL 3137 49

4%VFA@4% 1 100%VMA@4%

AVVFA 1 100%VMA

SuperpaveTM Level 1


CIVL 3137 50

4%VFA@4% 1 100%VMA@4%

4%1 100% 71.4%14.0%

SuperpaveTM Level 1

16. Check VMA and VFA for compliance

CIVL 3137 51



SuperpaveTM Level 1

16. Check VMA and VFA for compliance

CIVL 3137 52

ReplacesTable 6‐15

SuperpaveTM Level 1

17. Check specimen density at Nini and Nmax for compliance

CIVL 3137 53


SuperpaveTM Level 1


CIVL 3137 54

mb mbmm

mm mm

G%G 100% 100%G

SuperpaveTM Level 1


CIVL 3137 55

3

mm ini3

3

mm max3

2202 kg m%G 100% 87.3% @ N2522 kg m

2438 kg m%G 100% 96.7% @ N2522 kg m

SuperpaveTM Level 1


CIVL 3137 56


SuperpaveTM Level 1

18. Test material for moisture susceptibility

CIVL 3137 57

TSR= 80%

TensileStrengthofConditionedSpecimenTensileStrengthofFreshSpecimen

CIVL 3137 58

Indirect Tension Test

Source: http://www.cait.rutgers.edu/prp/equipment/idtt.php

SuperpaveTM Level 1

19. Check “dust content” for compliance

CIVL 3137 59


BE

% passing #200FINENESS-TO-EFFECTIVE ASPHALT RATIOP

SuperpaveTM Level 1

19. Check “dust content” for compliance

CIVL 3137 60

BE

% passing #200 3.7%Dust Content 0.92P 4.0%

BAAbsorption 1.1%Assume P 0.55%

2 2

BE B BAP P P 4.6% 0.55% 4.0%

SuperpaveTM Level 1

20. If any of the mix volumetrics criteria were not met, repeat with new blends

CIVL 3137 61

All of the criteria have been met.

SuperpaveTM Level 1

21. Make specimens at four asphalt contents:

CIVL 3137 62

Pb @ 4% air + 1.0%

Pb @ 4% air + 0.5%

Pb @ 4% air = Pb – 0.4 (4% – AV)

Pb @ 4% air ‒ 0.5%

CIVL 3137 64

Asphalt Content Determination

Pb @ 4% air + 1.0%Pb @ 4% air + 0.5%Pb @ 4% air voidsPb @ 4% air ‒ 0.5%

superpavetm mix design - university of memphis handouts/14 - superpave mix... · mix and compact...

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