Low Temperature Investigation on the Combined Recycling of Reclaimed Asphalt Pavement and Steel Slag in Asphalt Mixture Ki Hoon Moon Augusto Cannone Falchetto Michael P. Wistuba Gabriele Tebladi Oh Sun Kwon Tokyo, Japan, November 20-21, 2017
Institut für Straßenw esen Outline T U B r a u n s c h w e i g • Introduction • Materials and Experimentation • Results and Analysis • Summary and Conclusions 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 Straßenw esen Introduction T U B r a u n s c h w e i g • Reclaimed Asphalt Pavement (RAP) and Electric Arc Furnace Steel Slag (EAFSS) are commonly used for asphalt pavement construction. • Approximately 70 million tons of RAP are reused for pavement application in US, and 47 million tons of RAP are reused in Europe, making RAP one of the most recycled materials. • Several studies were performed to address the use of EAFSS in asphalt mixtures. • However, not many studies can be found on the combined use of these materials. Augusto | Low temperature investigation on the combined recycling of reclaimed asphalt pavement and steel slag in asphalt mixture| 20 – 21 Nov, 2017 | 3
Institut für Straßenw esen Research Objective T U B r a u n s c h w e i g 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 Augusto | Low temperature investigation on the combined recycling of reclaimed asphalt pavement and steel slag in asphalt mixture| 20 – 21 Nov, 2017 | 4
Institut für Straßenw esen Materials and Testing T U B r a u n s c h w e i g Materials Table 1. Asphalt mixtures Augusto | Low temperature investigation on the combined recycling of reclaimed asphalt pavement and steel slag in asphalt mixture| 20 – 21 Nov, 2017 | 5
Institut für Straßenw esen Materials and Testing T U B r a u n s c h w e i g BBR creep testing • Relaxation modulus, E(t) t t ∫ ∫ = τ ⋅ − τ τ = − τ ⋅ τ τ t E ( ) D t ( ) d E t ( ) D ( ) d 0 0 Figure 1. BBR Device • Thermal stress ξ ε ξ α ∆ t ( ') ( ) d d T ∫ ∫ σ ξ = ⋅ ξ − ξ ξ = ⋅ ξ − ξ ( ) E ( ') d ' E ( ( ) t '( )) t dt ' ξ d ' dt ' −∞ −∞ ξ = t a / reduced time T α coefficient of thermal contraction of asphalt mixture Augusto | Low temperature investigation on the combined recycling of reclaimed asphalt pavement and steel slag in asphalt mixture| 20 – 21 Nov, 2017 | 6
Institut für Straßenw esen Materials and Testing T U B r a u n s c h w e i g SCB fracture testing • Semi-circular shape with diameter of 150mm, thickness of 30mm and straight vertical central notch of 15mm • The sample is placed on a frame consisting of two fixed rollers and having a span of 120mm. The fracture energy, G f : W = f G f A lig W f work of fracture A lig area of ligament Figure 2. SCB Test Augusto | Low temperature investigation on the combined recycling of reclaimed asphalt pavement and steel slag in asphalt mixture| 20 – 21 Nov, 2017 | 7
Institut für Straßenw esen Materials and Testing T U B r a u n s c h w e i g SCB testing The fracture toughness (critical stress intensity factor), K Ic : = ⋅ ⋅ ⋅ π ⋅ ⋅ + ∆ ⋅ K [ P / (2 r t )] a Y ( s / ) r B Ic c I S ( / ) r 0 0 where, K Ic mode I stress intensity factor p eak load P c r radius t thickness Y I normalized stress intensity factor a notch length Δ s 0 geometry parameter B parameter depending on a and r Augusto | Low temperature investigation on the combined recycling of reclaimed asphalt pavement and steel slag in asphalt mixture| 20 – 21 Nov, 2017 | 8
Institut für Straßenw esen Materials and Testing T U B r a u n s c h w e i g Resistance to permanent deformation T = +50 °C • German standard FGSV TP Asphalt -StB, Part 25 A1 (2010). stamp specimen Figure 3a. Stamp test Skid resistance • German Standard TP Gestein-StB, Part 5.4.2 (2010). Figure 3b. Wehner/Schulze machine polishing friction measurement Polierstation Griffigkeitsmessung Augusto | Low temperature investigation on the combined recycling of reclaimed asphalt pavement and steel slag in asphalt mixture| 20 – 21 Nov, 2017 | 9
Institut für Straßenw esen Results and Analysis T U B r a u n s c h w e i g Creep Tests Results Figure 4. Creep stiffness (left) and m -value (right) mixture results at 60s (lowPG+10ºC) Augusto | Low temperature investigation on the combined recycling of reclaimed asphalt pavement and steel slag in asphalt mixture| 20 – 21 Nov, 2017 | 10
Institut für Straßenw esen Results and Analysis T U B r a u n s c h w e i g Thermal stress and critical cracking temperature results PG 58-28 mixture PG 58-34 mixture Figure 5. σ ( T ) comparison (2ºC/h and 20ºC/h cooling rate) Augusto | Low temperature investigation on the combined recycling of reclaimed asphalt pavement and steel slag in asphalt mixture| 20 – 21 Nov, 2017 | 11
Institut für Straßenw esen Results and Analysis T U B r a u n s c h w e i g Thermal stress and critical cracking temperature results Table 2. Critical cracking temperature, T CR , comparison (PG 58-28 mixture) For 75% EAFSS+25% RAP, and 25% RAP, higher σ ( T ) and T CR were • found 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 conventional aggregates was observed, both in terms of thermal stress and critical cracking temperature. Augusto | Low temperature investigation on the combined recycling of reclaimed asphalt pavement and steel slag in asphalt mixture| 20 – 21 Nov, 2017 | 12
Institut für Straßenw esen Results and Analysis T U B r a u n s c h w e i g Thermal stress and critical cracking temperature results PG 58-28 mixture PG 58-34 mixture Figure 6. Statistical comparison of σ( T) Augusto | Low temperature investigation on the combined recycling of reclaimed asphalt pavement and steel slag in asphalt mixture| 20 – 21 Nov, 2017 | 13
Institut für Straßenw esen Results and Analysis T U B r a u n s c h w e i g Fracture energy and fracture toughness Table 3. SCB test results Fracture energy: G F (J/m 2 ) Fracture toughness: K Ic (MPa*m 0.5 ) Mixture Control E100% E75%+R25% R25% Control E100% E75%+R25% R25% 58-28 0.446 0.599 0.512 0.381 1.106 1.324 1.234 1.026 mixture 58-34 0.495 0.641 0.567 0.420 1.157 1.383 1.279 1.100 mixture Figure 7. Load vs. LLD curves for PG58-28 and PG58-34 mixtures Augusto | Low temperature investigation on the combined recycling of reclaimed asphalt pavement and steel slag in asphalt mixture| 20 – 21 Nov, 2017 | 14
Institut für Straßenw esen Results and Analysis T U B r a u n s c h w e i g Resistance to permanent deformation 1.0 0.9 PG58-28 PG58-34 Penetration depth (mm) 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 A B C D E F G H Mixture Figure 8. Results of mixture penetration test TP Asphalt -StB, Part 25 A1 (2010) • A decrease in permeant deformation is achieved for mixtures containing both RAP and EAFSS. Augusto | Low temperature investigation on the combined recycling of reclaimed asphalt pavement and steel slag in asphalt mixture| 20 – 21 Nov, 2017 | 15
Institut für Straßenw esen Results and Analysis T U B r a u n s c h w e i g Skid resistance • The results were addressed by measuring the friction coefficients after 90,000 and 180,000 polishing cycles. • An overall decrease was found for larger contents of EAFSS: from a value of 0.245 and 0.221 for 90,000 and 180,000 cycles in the case of virgin material to 0.198 and 0.172 for mixture prepared with 100% slags. Augusto | Low temperature investigation on the combined recycling of reclaimed asphalt pavement and steel slag in asphalt mixture| 20 – 21 Nov, 2017 | 16
Institut für Straßenw esen Summary and Conclusions T U B r a u n s c h w e i g • The effect of the combined use of RAP and EAFSS on the low temperature creep and fracture performances of asphalt mixture was experimentally investigated based on BBR mixture creep SCB fracture test. Eight asphalt mixtures with two different asphalt binder were prepared and tested. • In addition, a preliminary investigation on permanent deformation and skid resistance was performed. Augusto | Low temperature investigation on the combined recycling of reclaimed asphalt pavement and steel slag in asphalt mixture| 20 – 21 Nov, 2017 | 17
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