marshal land super pave utah asphalt 2008

8/14/2019 Marshal Land Super Pave Utah Asphalt 2008

1/32

Marshall and Superpave MixDesign Procedures

Pedro Romero, Ph.D., P.E.

The University of Utah


2/32

Why Mix Design?

Determine a cost-effective blend andgradation of aggregates and asphalt

that yields a mix having: Sufficient asphalt to ensure durability

Sufficient stability to prevent rutting

Sufficient voids to prevent flushing

Maximum voids to limit permeability

Sufficient workability to allow placement


3/32

History (Marshall)

Bruce Marshall (Mississippi DOT) late 30s

WES began to study it in 1943 for WWII Evaluated compaction effort

No. of blows, foot design, etc.

Decided on 10 lb. Hammer, 50 blows/side

4% voids after traffic

Initial criteria were established and

upgraded for increased tire pressures andloads


4/32

Marshall Mix Design

Select and test aggregate

Select and test asphalt binder Establish mixing and

compaction temperatures

Develop trial blends Heat and mix asphalt binder

and aggregates

Compact specimen (100 mm

diameter)


5/32

.1

.2

.3

.5

1

10

5

100 110 120 130 140 150 160 170 180 190 200

Temperature, C

Viscosity, Pa s

Compaction Range

Mixing Range

Mixing/Compaction Temps


6/32

Marshall Design Criteria

Light Traffic Medium Traffic Heavy Traffic

ESAL < 104 10 4 < ESAL< 106 ESAL > 106

Compaction 35 50 75

Stability N (lb.) 3336 (750) 5338 (1200) 8006 (1800)

Flow, 0.25 mm (0.1 in) 8 to 18 8 to 16 8 to 14

Air Voids, % 3 to 5 3 to 5 3 to 5

Voids in Mineral Agg.

(VMA) Varies with aggregate size


7/32

Marshall Mix Design Tests

Bulk specific gravity of compactedsample

Maximum specific gravity of loosemix

Stability and flow 60oC water bath (30 to 40 minutes)

50 mm/min loading rate

Maximum load = stability

Vertical deformation = flow


8/32

Marshall Stability and Flow


9/32

Marshall Design

Target optimum asphalt binder content = average

Air Voids, %

Asphalt BinderContent, %

4%

Stability


Unit Wt.



10/32

Marshall Design (Contd)

Use target optimum asphalt binder

content to check if these criteria are met

Flow

Lower Limit

Upper limitOK

Asphalt Binder

Content, %

VMA, %

Minimum

OK

Asphalt Binder

Content, %


11/32

Marshall Design Method

Advantages Attention on voids, strength, durability

Inexpensive equipment Easy to use in processcontrol/acceptance

Disadvantages Impact method of compaction Does not consider shear strength Load perpendicular to compaction axis


12/32

History (Superpave)

Resulted fromStrategic HighwayResearch Program

1987-1993 Combined strengths of

previous methods withEuropean concepts

Based entirely onVOLUMETRICS

Old versus New?


13/32

Superpave Compactor

Simulate fielddensification traffic

climate Accommodate large

aggregates

Measure

compactability

Conducive to QC


14/32

Basis Corps of Engineers Texas Gyratory French operational characteristics

150 mm diameter mold up to 37.5 mm NMAS

Height measurement Gyrations based on traffic

?

?

Superpave GyratoryCompactor

ram pressure

600 kPa

1.25 degrees

30 gyrations

per minute


15/32

AASHTO T 312 Gyratory Compaction


16/32

Ndesign Table

205125< 89.09> 30.0

160100< 89.083.0 to < 30.011575< 90.570.3 to < 3.0

7550< 91.56< 0.3

%GmmGyrations

NmaximumNdesignNinitialTraffic Level

Compaction Level


17/32

Steps of Superpave Mix Design

1. Materials Selection

2. Design Aggregate Structure

3. Design Binder Content


18/32

Step 1: Materials Selection

Choose correct

asphalt binder Choose aggregates

that meet qualityrequirements for

the mix


19/32

Asphalt Binder Specification

The grading system is based on Climate

PG 64 - 28

Performance

GradeAverage 7-day max

pavement temperature

Min pavement

temperature


20/32

Aggregate Consensus Properties

4545100 / 100100 / 100> 30.0404580 / 7595 / 903.0 to < 30.0

404560 / ---85 / 800.3 to < 3.0

404050 / ---75 / ---< 0.3

> 100 mm< 100 mm> 100 mm< 100 mmTraffic Level

Fine AggregateAngularity

Coarse AggregateAngularity


21/32

Step 2: Aggregate Structure

Establish trial aggregate blends

Estimate optimum asphaltbinder content

Manufacture and compact trialblends

Evaluate the trial blends

Select the most promisingblend


22/32

Aggregate Gradation


23/32

Next steps

Sample preparation Select mixing and compaction

temperatures

Preheat aggregates and asphalt

Mix components

Compact specimens

Extrude and determine volumetrics


24/32

Short Term Aging

Allows time for aggregate to absorb

asphalt binder Helps minimize variability in volumetric

calculations

Most volumetric terms change depending onthe amount (volume) of absorbed asphaltbinder


25/32

Compaction


26/32

% Gmm

Log Gyrations

10 100 1000

Nini

NdesNmax

Three Points on SGCCurve


27/32

% Gmm

Log GyrationsLog Gyrations

10 100 1000

increasingincreasing

binderbinder

3.Design Binder Content

96


28/32

% asphalt binder

VFA

Design Asphalt Binder ContentDesign Asphalt Binder Content

%Gmmat Ndes

% asphalt binder

VMA

% asphalt binder

Va

% asphalt binder

DP

% asphalt binder


29/32

Superpave MixtureRequirements

Mixture Volumetrics

Air Voids (Va)

Mixture Density Characteristics Voids in the Mineral Aggregate (VMA)

Voids Filled with Asphalt (VFA)

Dust Proportion

NO STRENGHT TEST


30/32

Requirements in Common

Sufficient asphalt binder to ensure adurable pavement

Sufficient stability under traffic loads Sufficient air voids

Upper limit to prevent excessiveenvironmental damage

Lower limit to allow room for initialdensification due to traffic

Sufficient workability


31/32

Questions?

Asphalt content

compaction

stability


32/32

Panel Discussion

Darin Furnell, SLC Corporation

William Larson, Utah DOT

Jeff Chollar, Staker Parsons

marshal land super pave utah asphalt 2008

Documents