Characterization of Evotherm Warm Mix Binder

Transcription

1 Characterization of Evotherm Warm Mix Binder Koichi Takamura, Ph.D. BASF Corporation Charlotte, NC USA

2 Plant Mixing Temperature 17 Plant Mixing Temperature, C Hot Mix Evotherm Harder the asphalt, higher the mixing temperature with Hot Mix Independent on the asphalt hardiness with Evotherm The thin water film acts as the lubricant, as the curling stone slides on the ice PG grading 2

3 Emulsion based Warm Mix Emissions from Stack % 63% 58% McAsphalt Trial in Oct. 4-5, 25 Plant Production Aggregate Asphalt Compaction Hot Mix 155 o C 155 o C 145 o C Warm Mix 125 o C *95 o C 85 o C % * Emulsion temp. Av. Stack Gas Temperature Hot Mix 162 o C Warm Mix 121 o C CO 2 x, % CO, ppm NO x, ppm SO 2, ppm Warm Mix Hot Mix Fuel Oil Consumption Litres/Tonne Hot Mix 11.4 Warm Mix 5.2 Significant reduction in CO, NO x and SO 2 emissions from stack 3

4 Emulsion based Warm Mix CO Emission NO x Emission SO 2 Emission Hot mix (/4/25) 7 Hot mix (/4/25) 16 Hot mix (/4/25) 6 14 Concentration, ppm 8 6 Concentration, ppm Warm Mix(/5/25) Concentration, ppm Warm Mix(/5/25) Warm Mix(/5/25) 2 2 8:4 8:5 9: 9: 9:2 9:3 Time, minute 8:4 8:5 9: 9: 9:2 9:3 Time, minute 8:4 8:5 9: 9: 9:2 9:3 Time, minute 4

5 Residue Recovery Procedure for Warm Mix Asphalt Emulsion

6 Temperature profile of emulsion based Warm Mix Location Temp., C Mixing temperature 13 Discharge temperature In hopper of paver 97 Just behind the screed of paver 92 at edge of mat 87 at center of mat 92 After pneumatic roller 73 Pavement 4 hrs after lay down* 52 *25mm below the surface Recovery Procedure for Asphalt Emulsion Residue Need to represent the mixing and paving conditions 6

7 Evotherm trial by McAsphalt Penetration at 25 C, dmm Base AC Rec'd AC from HMA 63% of original Rec'd AC from WMA 86% Base asphalt had a penetration of 124dmm at 25 C, 5s. Asphalt cement recovered from field core samples Recovered AC from Hot Mix asphalt = 81dmm (63% of original value) Recovered AC from Warm Mix asphalt = 7dmm (86% of original value) Less heat aging of asphalt cement at the mix plant 7

8 Residue recovery procedure Emulsion Residue with 3% SBR Latex m Dry the emulsion at 8 C for 2 hours 8g emulsion in a PAV pan (~ 5g residue) Maintain stable polymer network Recovered residue = Equivalent of RTFOT sample of the hot mix AC RTFOT simulate heat oxidation of AC at the hot mix plant SHRP and other binder characterizations of recovered residue 8

9 Residue recovery procedure Ramada trial Binder characterization 12 86% 89% Penetration at 25 C, dmm % of Base AC Penetration at 25 C, dmm % of Base AC 4 Base AC Rec'd AC from HMA Rec'd AC from WMA Base AC Base after RTFOT Rec'd WM residue The new procedure closely simulate heat hardening of Evotherm warm AC as penetration values 9

10 Residue recovery procedure Emulsion Residue with 3% SBR Latex Recovered residue Residue after PAV Asphalt binder becomes brittle upon oxidation in the field Reduce fatigue and cold fracture resistance of pavement PAV: Laboratory simulation of oxidative aging of asphalt binder C at 2.1MPa pressure for 2 hours Stable polymer network even after the PAV-aging m

11 Before and After PAV (FTIR).6 Absorption COOH R-CO-R' R-CHO R-SO-R'.1 Unmodified After PAV Wavenumber, cm -1 Absorption COOH R-CO-R' R-CHO R-SO-R' Bd % SBR polymer modified After PAV 9 Wavenumber, cm -1 Polymer modification does not prevent asphalt oxidation 11

12 Oxidative Hardening (Base asphalt/unmodified residue) Base asphalt Unmodified Residue Unmodified Residue Complex modulus, MPa 1.1 after RTFOT After PAV Complex modulus, MPa 1.1 after PAV Complex modulus, MPa 1.1 Rec'd residue after PAV Neat asphalt.1 Rec'd residue.1 Base asphalt after RTFOT Temperature, C Temperature, C Temperature, C Base asphalt shows sharp increase in complex modulus, G*, after PAV Less significant hardening with Evotherm warm mix Base asphalt after RTFOT Evotherm warm mix after PAV 12

13 Before and After PAV (Physics) (a) Unmodified residue (b) SBR latex modified.4 Hz Complex Modulus [G*], MPa Oxidative hardening Before PAV After PAV Complex Modulus [G*], MPa After PAV Before PAV Temperature, C Temperature, C Modification with SBR latex-polymer reduces negative effects of hardened asphalt at wide temperature range 13

14 Before and After PAV (a) Unmodified (b) 3% SBR Latex T g =-16 C T g =-11 C T g =-23 C T g =-18 C.4 Hz Loss Moulus (G"), MPa After PAV Loss Modulus (G"), MPa After PAV Temperature, C Temperature, C 7 C reduction in T g with 3% SBR latex polymer 5 C increase in T g after PAV, both unmodified and modified residues 14

15 Cold Fracture Resistance: Stiffness with BBR -18 C Creep Stiffiness, MPa Base Asphalt after PAV: m-value =.31 Rec'd Residue after PAV: m-value =.35 Base Asphalt after RTFOT: m-value =.38 1 Time, s Improved Cold Fracture Resistance with Evotherm warm mix Base asphalt after RTFOT Evotherm warm mix after PAV 15

16 Bending Beam Rheometer -18 C Creep Stiffness, MPa Unm odified residue Base Asphalt All binder samples are after the PAV-aging Even unmodified residue is lower creep stiffness than the base asphalt used to make the emulsion 3% SBR modified residue SBR latex polymer further reduce the stiffness, thus maintain low temp. flexibility 1 Time, s 16

17 Fatigue Resistance under Repeated Stresses Unmodified Binders Base AC, after RTFOT Unmodified Residue Unmod. Res., after PAV 1% strain 7 C Complex modulus, MPa 1 5% strain % strain % strain Complex modulus, MPa 1 1% strain 5% strain % strain % strain Complex modulus, MPa Cumulative time, minutes Cumulative time, minutes Cumulative time, minutes Base asphalt after RTFOT Evotherm warm mix after PAV 17

18 SBR Polymer Modified Residue 1.5% SBR modified 1.5% SBR, After PAV 3.% SBR, After PAV 1% strain 7 C Complex modulus, MPa 1 Complex modulus, MPa 1 5% strain Complex modulus, MPa 1 2% strain.1 % strain Cumulative time, min Cumulative time, min Cumulative time, min. Evotherm with 3.% SBR latex maintains excellent fatigue resistance even after PAV --- Extended service life with >2% latex 18

19 Pavement Longevity 4, 2, 44 and 94 hours PAV-aging FTIR for Chemistry DSR for rheological measurements Binder samples were too brittle to do the BBR measurements after 44 hrs PAVaging 19

20 Accelerated oxidative aging test (PAV) McAsphalt PG58-28, Unmodified Evotherm Residue.3 Absorption.2 R-COOH R-CO-R' R-CHO 24 hr PAV 44 hr 94 hr R-SO-R' Neat asphalt Wave number, cm -1 McAsphalt PG58-28, 3% SBR Latex Modified Residue.3 Butadiene Absorption.2 94hr 44hr 6hr PAV Neat asphalt Wave number, cm -1 SBR polymers remain even after 94 hrs PAV 2

21 Accelerated oxidative aging test (PAV) After 94hrs PAV-aging McAsphalt PG58-28, Unmodified Evotherm Residue Absorption.3.2 R-COOH R-CO-R' R-CHO 24 hr PAV 44 hr 94 hr R-SO-R' Neat asphalt 18 5 m Wave number, cm McAsphalt PG58-28, 3% SBR Latex Modified Residue Absorption hr PAV 16 94hr 15 Neat asphalt 14 44hr Butadiene 9 Wave number, cm -1 SBR polymers remain even after 94 hrs PAV-aging 21

22 Pavement Longevity: Ergon/Valero in Texas Complex Modulus [G*] at 25 C, MPa Base Asphalt Unmod. Residue 3% SBR Mod. Residue SHRP Procedure Phase Angle, degree Valero PG Hours in PAV-aging 25 1 Hours in PAV-aging Reduced Oxidative hardening of SBR latex modified residue. 22

23 Pavement Longevity: McAsphalt in Canada Complex Modulus at 19 C, MPa Base asphalt Unmod. Residie 3% SBR Mod. Residue 1 Hours in PAV-aging Phase angle, degree McAsphalt PG Hours in PAV-aging Reduced Oxidative hardening of SBR latex modified residue, even after >2 years of service 23

24 Pavement Longevity: Shell China 2 Base Asphalt 65 Complex Modulus at 13 C, MPa 15 5 Unmodified Residue 3% SBR Mod. Residue Phase Angle at 13 C, degree Shell China PG64* Hours in PAV-aging Hours in PAV-aging Reduced Oxidative hardening of SBR latex modified residue Consistent conclusion with 3 widely different asphalt 24

25 Conclusions Potential Pavement Longevity with Warm Mix System Reduced oxidative hardening of asphalt binder during the mixing and paving processes D. Newcomb, the Vice President-Research & Technology, National Asphalt Pavement Association, states Binder aging is directly related to the production temperature of the mixture. The majority of binder hardening due to aging takes place in the hot-mix plant. If the plant temperature is reduced, the oxidative hardening of the binder will be reduced. Less hardening of the binder during construction could mean more flexibility and resistance to cracking in service

26 Reference Davidson, J.K., Lubbers, C., Takamura, K., Proc. Canadian Technical Asphalt Assoc. 52, (27) Takamura, K., Road Materials and Pavement Design 9, 87-2 (28) 26

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