low temperature investigation on the combined recycling …...low temperature investigation on the...

Low Temperature Investigation on the Combined Recycling of Reclaimed Asphalt Pavement and Steel Slag in Asphalt Mixture

Tokyo, Japan, November 20-21, 2017

Ki Hoon Moon

Augusto Cannone Falchetto

Michael P. Wistuba

Gabriele Tebladi

Oh Sun Kwon

Augusto | Low temperature investigation on the combined recycling of reclaimed asphalt pavement and steel slag in asphalt mixture| 20 – 21 Nov, 2017 | 2

Institut für StraßenwesenT U B r a u n s c h w e i g

• Introduction

• Materials and Experimentation

• Results and Analysis

• Summary and Conclusions

Outline


Institut für StraßenwesenT U B r a u n s c h w e i gIntroduction

• Reclaimed Asphalt Pavement (RAP) and Electric ArcFurnace Steel Slag (EAFSS) are commonly used forasphalt pavement construction.

• Approximately 70 million tons of RAP are reused forpavement application in US, and 47 million tons of RAPare reused in Europe, making RAP one of the mostrecycled materials.

• Several studies were performed to address the use ofEAFSS in asphalt mixtures.

• However, not many studies can be found on thecombined use of these materials.



Experimentally investigate the effect of adding different

amounts of RAP and EAFSS on the creep and fracture

response of asphalt mixtures at low temperature.

Based on:

• Bending Beam Rheometer (BBR) tests

• Semi-Circular Bending (SCB) tests

Quick look at Permanent Deformation and Skid Resistance

Research Objective


Institut für StraßenwesenT U B r a u n s c h w e i gMaterials and Testing

Table 1. Asphalt mixtures

Materials



BBR creep testing

reduced timeα coefficient of thermal contraction

of asphalt mixture

Figure 1. BBR Device

0 0

( ) ( ) ( ) ( )t t

t E D t d E t D dτ τ τ τ τ τ= ⋅ − = − ⋅∫ ∫

( ') ( )( ) ( ') ' ( ( ) '( )) '' '

td d TE d E t t dtd dt

ξ ε ξ ασ ξ ξ ξ ξ ξ ξξ−∞ −∞

∆= ⋅ − = ⋅ −∫ ∫

• Relaxation modulus, E(t)

• Thermal stress

/ Tt aξ =



SCB fracture testing

ff

lig

WG

A=

• Semi-circular shape with diameter of 150mm, thicknessof 30mm and straight vertical central notch of 15mm

• The sample is placed on a frame consisting of two fixedrollers and having a span of 120mm.

The fracture energy, Gf:

Wf work of fractureAlig area of ligament

Figure 2. SCB Test



SCB testing

The fracture toughness (critical stress intensity factor), KIc :

where,KIc mode I stress intensity factorPc peak loadr radiust thicknessYI normalized stress intensity factora notch lengthΔs0 geometry parameterB parameter depending on a and r

0( / ) 0[ / (2 )] ( / )Ic c I S rK P r t a Y s r Bπ = ⋅ ⋅ ⋅ ⋅ ⋅ + ∆ ⋅



Resistance to permanent deformation

• German standard FGSV TP Asphalt -StB,Part 25 A1 (2010).

Skid resistance

Figure 3b. Wehner/Schulze machine

• German Standard TP Gestein-StB,Part 5.4.2 (2010).

Polierstation Griffigkeitsmessungpolishing friction measurement

Figure 3a. Stamp testspecimen

stamp

T = +50 °C


Institut für StraßenwesenT U B r a u n s c h w e i gResults and Analysis

Creep Tests Results

Figure 4. Creep stiffness (left) and m-value (right) mixture results at 60s (lowPG+10ºC)



Thermal stress and critical cracking temperature results

Figure 5. σ(T) comparison (2ºC/h and 20ºC/h cooling rate)

PG 58-28 mixture

PG 58-34 mixture




Table 2. Critical cracking temperature, TCR, comparison (PG 58-28 mixture)

• For 75% EAFSS+25% RAP, and 25% RAP, higher σ(T) and TCR werefound compared to mixtures designed with virgin material for both binder.

• When the aggregate skeleton was entirely (100%) replaced with EAFSS,a very close response to that of mixtures prepared with conventionalaggregates was observed, both in terms of thermal stress and criticalcracking temperature.




Figure 6. Statistical comparison of σ(T)

PG 58-28 mixture

PG 58-34 mixture



Fracture energy and fracture toughnessTable 3. SCB test results

Figure 7. Load vs. LLD curves for PG58-28 and PG58-34 mixtures

Mixture Fracture energy: GF (J/m2) Fracture toughness: KIc (MPa*m0.5) Control E100% E75%+R25% R25% Control E100% E75%+R25% R25%

58-28 mixture 0.446 0.599 0.512 0.381 1.106 1.324 1.234 1.026

58-34 mixture 0.495 0.641 0.567 0.420 1.157 1.383 1.279 1.100



Resistance to permanent deformation

Figure 8. Results of mixture penetration testTP Asphalt -StB, Part 25 A1 (2010)

• A decrease in permeant deformation is achieved for mixturescontaining both RAP and EAFSS.

0.00.10.20.30.40.50.60.70.80.91.0

A B C D E F G H

Pene

trat

ion

dept

h (m

m)

Mixture

PG58-28 PG58-34



Skid resistance

• The results were addressed by measuring the frictioncoefficients after 90,000 and 180,000 polishing cycles.

• An overall decrease was found for larger contents ofEAFSS: from a value of 0.245 and 0.221 for 90,000 and180,000 cycles in the case of virgin material to 0.198and 0.172 for mixture prepared with 100% slags.



• The effect of the combined use of RAP and EAFSSon the low temperature creep and fractureperformances of asphalt mixture was experimentallyinvestigated based on BBR mixture creep SCBfracture test. Eight asphalt mixtures with twodifferent asphalt binder were prepared and tested.

• In addition, a preliminary investigation on permanentdeformation and skid resistance was performed.

Summary and Conclusions



• BBR results indicate that mixture prepared with 100%EAFSS aggregate have similar low temperatureresponse to that of conventional mixtures.

• Mixtures containing a combination of EAFSS (75%)and RAP (25%) shows higher thermal stresses andcritical cracking temperature.

• Better fracture performances were found for EAFSS100% and EAFSS 75%+RAP 25% mixtures.

• Better resistance to permanent deformation and lowerfriction coefficient are exhibited by mixture preparedwith EAFSS.

Summary and Conclusions


Institut für StraßenwesenT U B r a u n s c h w e i gAcknoledgements

Laboratory Team



Topics• Bitumen aging mechanisms and characterization• Chemo-mechanical coupling• Low, intermediate and high temperature behavior• Microstructure and micro-mechanics• Thermal properties• Recycling and rejuvenation• Nanotechnology for bituminous materials• Multiphase analysis of binders

Important DatesNov. 27th, 2017 Submission of paper open

Apr. 10th, 2018 Submission of paper due

Jun. 1st, 2018 Notification of papers acceptance

Sept. 17-18th, 2018 RILEM 252-CMB Symposium

Sept. 19-20th, 2018 RILEM Annual Meeting

RILEM-CMB-SYMPOSIUMBRAUNSCHWEIG, GERMANYSEP TEMBER 17–18, 2018CHEMO MECHANICAL CHARACTERIZATION OF BITUMINOUS MATERIALS



Contributions and Publicationo Authors can submit a short 6-page document per email ([email protected])o Papers must be written and presented in English.o The 20 best contributions will be selected for oral presentation,

out of which 6 papers will be invited to submit an extended versionfor consideration in the International Journal of Road Materials and Pavement Design.

Sponsors and exhibitorsA specific area of the conference venue will bedevoted to sponsors and exhibitors to present the latestproducts, testing equipment and technologyfor asphalt materials characterization and innovation.

mailto:[email protected]



Conference ChairsChair: Lily Poulikakos, EMPA, SwitzerlandChair: Augusto Cannone Falchetto, TU Braunschweig, Germany Co-Chair: Bernhard Hofko, TU Wien, AustriaCo-Chair: Laurent Porot, Kraton, NetherlandsCo-Chair: Hervé Di Benedetto, Université de Lyon, FranceCo-Chair: Michael P. Wistuba, TU Braunschweig, Germany

SecretariatNina Eßmann, Technische Universität Braunschweig,ISBS - Braunschweig Pavement Engineering Centre,Beethovenstraße 51 b,38106 Braunschweig, Germany.Phone: +49 (0)531-391 [email protected]

mailto:[email protected]



Thank you!

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