RPF – 17 May 2001 Validation of HMA Design Guidelines Validation of Draft Guidelines for the Design of HMA in SA OBJECTIVES Feedback Status of Validation

RPF – 17 May 2001Validation of HMA Design Guidelines

Validation of Draft Guidelines for the Design of HMA in SA

OBJECTIVES

Feedback

Status of Validation


Scope of Presentation

Design Procedures & Performance Testing

Study of Rut Resistance Testing

Workshops on HMA Design Guidelines


Design Procedures Validated

Selection of Mix Type

Rating of Design Objectives

Volumetric Design Bulk RD & COMPACT Software

Densely Graded Mixes

Stone Mastic Asphalt


Volumetric Design of Densely Graded Mixes

Modified Marshall Compaction

0%

15%

30%

0 75 150No of Marshall Hammer Blows

Voi

ds

In M

ix (

%)

BC 3.9%

BC 4.4%

BC 4.9%

Fld=7.0%

Fld=5.5%

Trf=4.0%

Trf=5.0%


Mod Marshall Compaction Voids Criteria

Traffic Level

Eq. Field Compaction(75 Blows)

Allowable Void Content Range after additional compaction to

simulate trafficking

Min - MaxTotal No of Blows

Void Content

Minimum Maximum

Light 3.5% - 5.5% 75 + 15 3.0% 4.5%

Medium 4.5% - 6.5% 75 + 45 3.0% 5.0%

Heavy 5.5% - 7.0% 75 + 75 4% 5.0%

Very Heavy

5.5% - 7.0% 75 + 75 4% 5.0%


Volumetric Design of Stone Mastic Asphalt (SMA)

Recommended Trial Binder Content BRD 2.75 : BC = 5.5% & BRD < 2.75 : BC = 6.0%

4 Samples Compacted @ 50 blows

VCA Coarse Aggr. Dry Rodded Test

VMA 17.0% & VIM 3.0%

VCAmix (with mastic) < VCAdrc (without mastic)


Study of Rut Resistance Testing

8 Field Mixes Mixes paved on various roads, incl

national and provincial roads and urban streets

Actual designs based on Marshall Method

8 Laboratory Mixes (Experimental) Different Binder Contents

Different Binder & Mix Types


Field Mixes

Mix No

Road Location Aggr. Mix type (Binder)

1 N2-25 Durban Quartzite AC Med (60/70)

2 P111/1 Carletonville Andesite BTB (40/50)

3 N2-21 Harding Dolorite AC Med (60/70)

4 N3-12 Gilloolly’s Quartzite S/O BRASO

5 N3-7X Harrismith Dolorite AC Crs (60/70)

6 N3-7X Harrismith Dolorite SMA (60/70)

7 CK1 Cape Town Hornfels AC Med (60/70)

8 CK2 Cape Town Hornfels AC Med (60/70)

9 CCP Pretoria Norite AC Med (60/70)


Rut Resistance TestsValidated In Study


Gyratory Compaction

Transportek Wheel Track Test (TWTT)

Dynamic Creep Test

Confined Impact Test (CIT)

Axial Loading Slab Test (ALS)



0%

15%

30%

0 75 150No of Mod Marshall Hammer Blows

VIM

N2 - 25AC MedQuartzite

N3 - 12BRASOQuartzite

PretoriaAC MedNorite


Gyratory Compaction

0%

10%

20%

30%

0 100 200 300No of Gyrations

VIM

N2 - 25AC MedQuartzite

N3 - 12BRASOQuartzite

PretoriaAC MedNorite


Comparison of Gyratory and Modified Marshall Compaction

N2-25

P111/1N2-21

N3-12

N3-7X

CK1

CK3CCP

0%

2%

4%

6%

-7.5% -5.0% -2.5% 0.0%Mod Marshall - Slope of Log VIM

VIM

@ 3

00 G

yrat

ions AC Medium

BTB

AC Medium

BRASO

AC Coarse

AC Medium

AC Medium

AC Medium


Transportek WheelTracking Test (TWTT)


TWTT Downward Deformation


Gyratory Compaction vs TWTT

N2-25

P111/1

N2-21

N3-12

N3-7XCK1CK3

050

0010

000

0.0% 2.0% 4.0% 6.0%VIM @ 300 Gyrations

# P

asse

s @

10m

m R

ut

AC Medium

BTB

AC Medium

BRASO

AC Coarse

AC Medium

AC Medium


Confined Impact Test (CIT)


CIT – Measurement of Deformation

TEST SPECIMEN AFTER TESTING

TOP OF SPECIMENBEFORE TESTING

B B

A


CIT – Performance Ratings

Rating of Rutting

Resistance

CIT Deformation after 680 blows with Marshall

Hammer

Very Good < 3 mm

Good 3 – 10 mm

Medium 10 – 14 mm

Poor > 14 mm


CIT – Field Mixes

0

2

4

6

8

10

0 170 340 510 680

No of Automated Marshall Blows

Def

orm

atio

n (

mm

)

N2 - 25AC MedQuartziteN2 - 21AC MedDoloriteN3 -7XAC CoarseDoloriteCape CK1AC MedHornfels


Dynamic Creep vs TWTT

N2-25

P111/1

N2-21

N3-12

N3-7XCK1

CK3

050

0010

000

0 20 40 60 80

Dynamic Creep Modulus (MPa)

# P

asse

s @

10m

m R

ut AC Medium

BTB

AC Medium

BRASO

AC Coarse

AC Medium

AC Medium


Experimental Laboratory Mixes

Mix No

Binder Content

Binder Type

Mix type

1 Optimum 60/70 Pen AC Medium

2 Opt + 1.0% 60/70 Pen AC Medium

3 Opt – 0.5% 60/70 Pen AC Medium

4 Optimum 60/70 Pen Gap Graded

5 Optimum 80/100 + SBS

AC Medium

6 Optimum 60/70 Pen SMA

7 Optimum 60/70 + EVA AC Medium

8 Optimum 60/70 + SBR AC Medium


Comparison of Rut Resistance ofLaboratory Mixes


Gyratory Compaction

Transportek Wheel Track Test (TWTT)

Dynamic Creep Test


Influence of Binder Content: Modified Marshall Compaction

0%

15%

30%

0 50 100 150No of Hammer Blows

Voi

ds

In M

ix (

%)

Opt BC

+1% BC

-0.5% BC

Window


Influence of Binder Content: Gyratory Compaction

0%

10%

20%

30%

0 100 200 300No of Gyrations

VIM

Opt BC

+1% BC

-0.5% BC


Influence of Binder Content: Transportek Wheel Track Test

1

10

100

0 2000 4000 6000 8000No of Load Cycles

Def

orm

atio

n (m

m) Opt BC

+1% BC

-0.5% BC


Influence of Binder Type: Modified Marshall Compaction

0%

15%

30%

0 50 100 150No of Hammer Blows

Voi

ds

In M

ix (

%) Opt BC

SBS Mod

EVA Mod

SBR Mod

Window


Influence of Binder Type: Transportek Wheel Track Test

1

10

100

0 2000 4000 6000 8000 10000No of Load Cycles

Def

orm

atio

n (

mm

) Opt BC

SBS Mod

EVA Mod

SBR Mod


ConclusionsValidity of Rut Resistance Tests

Modified Marshall Compaction Good Indicator of Workability & Stability

Gyratory Compaction Good Correlation of Terminal VIM with Rut

Resistance

Transportek Wheel Tracking Test Best Prediction of Rut Resistance


ConclusionsValidity of Rut Resistance Tests

Dynamic Creep Test Not Applicable to Stone-Skeleton &

Modified Sand-Skeleton Mixes

Confined Impact Test Validity Questionable


ConclusionsInfluence of Mix Composition

Binder Content Higher Binder Contents Lower Rut

Resistance

Binder Type SBS Mod Mix Highest Rut Resistance SBR Mod Mix Lower than SBS Mod, but

still Very Good EVA Mod Mix Similar to Non-modified

Mix


Conclusions – Workshops on HMA Design Guidelines

Cape Province Venue: University of Stellenbosch Date: Tuesday, 12th June 2001

KwaZulu Natal Venue: Roads Dept. Pietermaritzburg Date: Wednesday, 13th June 2001

Gauteng Venue: University of Pretoria Date: Thursday, 14th June 2001

Time: 08:00 17:00

Documents

RPF – 17 May 2001 Validation of HMA Design Guidelines Validation of Draft Guidelines for the Design of HMA in SA OBJECTIVES Feedback Status of Validation