Effects of Specimen Compaction on Performance ... of Specimen Compaction on Performance...

TECHNISCHE UNIVERSITTECHNISCHE UNIVERSIT ÄÄTT

CAROLOCAROLO --WILHELMINAWILHELMINAzu Braunschweigzu Braunschweig

ISBSInstitut für Straßenwesen

Effects of Specimen Compaction on Performance Characteristics:

Results of Triaxial tests on AC

Konrad Mollenhauer

Update of progress at ISBS




Compaction methods at ISBS

Roller Sector Gyratory Marshall




Compaction of Asphalt mix

Goal: Vm = 4 %




Preparation of specimens

French Roller




Triaxial Tests: EquipmentLV

DT

(ra

dial

)

LVD

T (

radi

al)

LVDT (axial)

LVDT (axial)

rubber membrane hydraulic oil(radial loading)

axial loading

specimen




Triaxial Test: Loading (EN 12697-25)

Axial Stress

Radial Stress

• Sinusoidal axial stress:σa = 0.3 MPa; σb = 0.15 MPa; frequency: f = 10 Hz

• static radial stress:σrad = 0.15 MPa

• Temperature: +50°C• Specimen dimensions:Diameter: 100 mm (MPK: 101.4 mm)Height: 60 mmd/H: 0.6




Triaxial test: Results

• Course of cumulatedaxial strain εax(N):

• creep rate fc,ax(N=1,000)

fc,ax






• creep rate fc,ax(N=1,000)Bε1000,calc

fc,ax

εax = A · NB

ε1000,calc






• creep rate fc,ax(N=1,000)ε1000,calc

• Course of cumulatedradial strain εrad(N):fc,rad(N=1,000)

εax = A · NB

ε1000,calc

εrad

fc,ax

fc,rad




Triaxial Test: Results

( ) axaxaxradrad

axradradax

2 ε⋅σ−ε−ε⋅⋅σε⋅σ−ε⋅σ=µ

εrad

εax

here:σax: axial mean stressσc: radial (confining) stressεax: fc,ax

εrad: fc,rad




Triaxial Tests: cumulated axial strains

French Roller

German Sector

Gyratory

Marshall




Triaxial Test: creep rate fc,1000

French Roller

German Sector

Gyratory

Marshall




Triaxial Test: strain after 1000 cycles ε1000,calcFrench Roller

German Sector

Gyratory

Marshall




Triaxial Tests: cumulated radial strains

French Roller

German Sector

Gyratory

Marshall




Poisson‘s ratio µ




Compaction method or void content?

Further Tests necessary:• Further specimens

available:Marshall: Vm = 2,0 %Gyratory: Vm = 1,6 %

• New specimens- Roller Sector (Vm: 1.5 & 3.5)

(2 new slabs: 25 kg mix)- French Roller with varied

compaction energy?




Comparative test program „Segment Roller Compaction”

Scope:• Roller Sector Compactor Devices are commonly used Europe-

wide• Compaction Procedure varies considerably Objective:• Analysation of impact of given compaction procedure on

mechanical properties of asphalt specimens• Evaluation of reproducibility of Roller Sector compaction Participants:

ISBS (Germany), ISTU (Austria), TUDD (Germany), UVT (Hungary); ifbGauer (Germany); TUD (Netherlands)





AC 11 (bitumen 50/70)

2.476maximum density [g/cm³]

6.0binder content [mass-%]

52softening point Ring & Ball [°C]

50/70binder type

C90/1content of crushed aggregate

53.0 %> 2.0 mm

37.5 %> 0,09 mm & < 2.0 mm

9.5 %< 0.09 mm

[%]

2.698maximum aggregate density [g/cm³]

0,25 0,71 2 5 11,28 160,090

10

20

30

40

50

60

70

80

90

100

Sieve [mm]

pass

ing

[%]

Asphalt Mixture: AC11

Each laboratory uses 2 compaction procedures:1. Common procedure (according German Standard)2. Laboratory standard procedure




German Standard Compaction Procedure

00,10,20,30,40,50,60,70,8

-20 -10 0 10 20 30 40 50

Number of compaction cycles

For

ce p

er c

m

slab

wid

th [k

N/c

m]

Force [kN/cm] Pre-Compaction

Force [kN/cm] Main-Compaction

5

6

7

8

9

10

Hei

ght o

f as

phal

t sla

b [c

m]

Slab height during pre-compaction

Slab-height during main compaction

Pre-Compaction Main-Compaction

Force = 0,1 kN/cm slab width

+0,5 cm / cycle

5 cycles ± 0

-0,5 cm / cycle

Force = 0 kN





Test program:

• Slab compaction: January/February

• Specimen preparation (cores) February/March• Mechanical Tests (Triaxial tests)March/April

• Presentation of Results: May




ATCBM pre-conference workshop

Laboratory compaction of asphalt mixtures for the preparation of specimens for performance-based test methods

Topics:Impact of specimen compaction

- on aggregate structure- on performance properties

Comparability with site compacted asphalt




ATCBM pre-conference workshop

Laboratory compaction of asphalt mixtures for thepreparation of specimens for performance-based test methods

Tuesday, May 26th8 presentations about 20 min (selection accordingsubmitted 2 page abstract)

Deadline for abstract submission: February 15thNotice of Acceptance until March 31st

Effects of Specimen Compaction on Performance ... of Specimen Compaction on Performance...

Documents

Transcript of Effects of Specimen Compaction on Performance ... of Specimen Compaction on Performance...