superpavetm mix design - university of memphis handouts/14 - superpave mix... · mix and compact...
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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
CIVL 3137 7
Brovold Gyratory Compactor
CIVL 3137 8
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
CIVL 3137 16
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
CIVL 3137 22
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
7. Determine Nini, Ndes, and Nmax
CIVL 3137 25
Same as Table 6‐13
Source: NCEES FE Supplied Reference Handbook
SuperpaveTM Level 1
7. Determine Nini, Ndes, and Nmax
CIVL 3137 26
(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
Source: ASTM D6925 ‐ 06
(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
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(UPDATED VALUES)
< 0.30.3 to < 33 to < 3030 +
Source: ASTM D6925 ‐ 06
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
11. Determine mb at Nini, Ndes, Nmax
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
11. Determine mb at Nini, Ndes, Nmax
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
11. Determine mb at Nini, Ndes, Nmax
CIVL 3137 38
maxmb ini mb max
ini
3
H@ N @ NH
114.8 2438 2202 kg m127.1
SuperpaveTM Level 1
11. Determine mb at Nini, Ndes, Nmax
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
13. Calculate AV, VMA and VFA at Ndes
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
13. Calculate AV, VMA and VFA at Ndes
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%
VMA@4% VMA 0.2 4% AV
SuperpaveTM Level 1
15. Estimate VMA and VFA at 4% air voids
CIVL 3137 48
VMA@4% VMA 0.2 4% AV
14.0% 0.2 4% 4.2% 14.0%
SuperpaveTM Level 1
15. Estimate VMA and VFA at 4% air voids
CIVL 3137 49
4%VFA@4% 1 100%VMA@4%
AVVFA 1 100%VMA
SuperpaveTM Level 1
15. Estimate VMA and VFA at 4% air voids
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
Source: NCEES FE Supplied Reference Handbook
Same as Table 6‐14
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
Source: NCEES FE Supplied Reference Handbook
SuperpaveTM Level 1
17. Check specimen density at Nini and Nmax for compliance
CIVL 3137 54
mb mbmm
mm mm
G%G 100% 100%G
SuperpaveTM Level 1
17. Check specimen density at Nini and Nmax for compliance
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
17. Check specimen density at Nini and Nmax for compliance
CIVL 3137 56
Source: NCEES FE Supplied Reference Handbook
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
Source: NCEES FE Supplied Reference Handbook
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%