Results of surface hot-in place recycling (remix) of modified and alternative asphalt mixtures in Finland. Part II: bitumen scale

Figures & data

Table 1. Roads, codes, and conventions of the project.

Site	Road code	Convention
		Short label	After REM	After RUT-REM	Symbol
Ylöjärvi	MT 2773	Ylö	Ylö*		● – Circle
Kilvakkala	KT 261	Kil		Kil*	▴ – Triangle
Riihimäki	MT 2879	Riihi		Riihi*	▪ – Square
Oulu	VT 4 and MT 847	Oulu	Oulu*		♦ – Diamond

Roads and materials after remix/rut-remix are marked with a star (*).

Table 2. Roads and materials of the project.

Ylöjärvi (MT 2773)	Kilvakkala (KT 261)	Riihimäki (MT 2879)	Oulu
REM	RUT-REM	RUT-REM	REM
●	▴	▪	♦
REF	REF	REF	OKTO SMA (VT 4)
ARA	ARA	RAS	OKTO AC (MT 847)
FEP	FEP
KB	KB
PAB	STO

The conventions are consistent throughout the document.

Figure 1. Flowchart of the test plan. Bitumen scale results are presented herein. Mixture scale results are presented in Part I.

Figure 2. Example of gradations of the materials from the project, before and after REM. Notice that the materials labelled OKTO SMA and OKTO AC both follow and SMA-type gradation.

Figure 3. Change in percentage passing (gradations), after REM/RUT. (a) Ylöjärvi, (b) Kilvakkala, (c) Riihimäki, (d) Oulu. Notes. Changes in the AV and RV locations are presented separately for Ylöjärvi, Kilvakkala and Riihimäki. A diagram with the AV/RV locations is presented in Paper I.

Figure 4. Bitumen content of the specimens, before and after REM/RUT, all roads. Ylöjärvi (●), Kilvakkala (▴). The values from Ylöjärvi are linked with a line. Notes: STO before REM is likely lower than presented. ARA bitumen does not contain fibres after extraction.

Figure 5. Change in bitumen content after REM/RUT. Ylöjärvi (●), Kilvakkala (▴). The values from Ylöjärvi are linked with a line. ARA bitumen does not contain fibres after extraction.

Figure 6. Penetration for all bitumens, before and after REM/RUT. Ylöjärvi (●), Kilvakkala (▴). The values from Ylöjärvi are linked with a line. Notice that one bitumen has been compounded per material from the AV and RV specimens. ARA bitumen does not contain fibres after extraction.

Figure 7. Change in penetration after REM/RUT. Ylöjärvi (●), Kilvakkala (▴). The values from Ylöjärvi are linked with a line. ARA bitumen does not contain fibres after extraction.

Figure 8. Softening point for all materials, before and after REM/RUT. Ylöjärvi (●), Kilvakkala (▴). The values from Ylöjärvi are linked with a line. One bitumen has been compounded per material from the AV and RV specimens. ARA bitumen does not contain fibres after extraction.

Figure 9. Change in softening point after REM/RUT. Ylöjärvi (●), Kilvakkala (▴). The values from Ylöjärvi are linked with a line. ARA bitumen does not contain fibres after extraction.

Table 3. Range of temperatures with meaningful DSR results within the tested frequency range, all bitumens, before and after remix/rut-remix.

Ranges after REM/RUT are shaded. Highlighted cells indicate that the phase angle becomes erratic at this temperature, at the high end of the tested frequency range. ARA bitumen does not contain fibres after extraction.

^a Note. The test of Kil-REF produced erratic results at 10 and 20°C. However, the results were consistent at temperatures below and above this range.

Figure 10. Illustrating the process of shifting original data towards a master curve. Notice the shift factors (a_T) and the reference temperature 20°C. (a) Complex shear modulus, (b) phase angle. Bitumen: Kilvakkala ARA* after REM, 8-mm.

Figure 11. Master curves, (a) shear complex modulus and (b) phase angle, for all bitumens before REM/RUT. Left side: 8-mm plate (70 to 0°C). Right side: 4-mm plate (6 to −30°C). ARA bitumen does not contain fibres after extraction.

Figure 12. Master curves, (a) shear complex modulus and (b) phase angle, for all bitumens after REM/RUT. Left side: 8-mm plate (70 to 0°C). Right side: 4-mm plate (6 to −30°C). ARA bitumen does not contain fibres after extraction.

Figure 13. Change in (a) shear complex modulus and (b) phase angle, for all bitumens after REM/RUT. Left side: 8-mm plate (70 to 0°C). Right side: 4-mm plate (6 to −30°C). ARA bitumen does not contain fibres after extraction.

Figure 14. Complex modulus and Phase angle at Glover-Rowe conditions, all bitumens, (a) before and (b) after REM/RUT. Notice the names of the areas to the right. ARA bitumen does not contain fibres after extraction.

Figure 15. Change in modulus and phase angle after REM/RUT at Glover-Rowe conditions, all bitumens. ARA bitumen does not contain fibres after extraction.

Figure 16. Summary of results of the MSCR test for the bitumens before and after remix/rut-remix, at five temperatures: 50, 52, 58, 60, and 70°C. ARA bitumen does not contain fibres after extraction.

Figure 17. Summary of results of the MSCR test for PAB, before and after REM, at temperatures 20, 22, 28, 30, 34, and 40°C before REM, and 28, 30, 34, 40, 46, and 50°C after REM.

Figure 18. Change in non-recoverable creep compliance after remix/rut remix, i.e. percent change in J_nr(3,2). ARA bitumen does not contain fibres after extraction.

Table 4. Summary of comments on performance. Bitumen scale.

Property	Bitumen scale
	Comments
FT-IR	The quality in DCM extraction was considered acceptable for most bitumens. A peak was apparent in the spectra of two bitumens: Kil-KB and Ylö-REF*. The FT-IR spectra of the bitumens decreased (i.e. rejuvenation). This was the case for all materials except Ylö-FEP* and Oulu-OKTO AC*, whose spectra did not change after REM. Distinctive polymer peaks were observed for KB and OKTO SMA, and softer peaks for FEP and RAS.
Gradations	There was no apparent difference between the gradations of OKTO AC and OKTO SMA as originally expected. The change in gradation during REM/RUT was established. Most materials became finer, except PAB, OKTO SMA and OKTO AC. The sieves in the range 1–11 mm experienced the largest changes (increase) in percent passing during the treatments.
Bitumen content	Bitumen content changed between ±0.6%, after REM/RUT. There was relatively high consistency in the bitumen content among materials and AV/RV locations. Asphalt content may increase or decrease after REM/RUT. After RUT-REM, the asphalt content of most materials increased to one side of the rut. Larger amounts of bitumen may have been added during RUT-REM.
Traditional tests	Penetration increased and the softening point reduced after REM/RUT for most materials, except PAB and Riihi-REF (the softest bitumens). These were also the only materials to increase their softening point after REM/RUT. The penetration of KB remained almost constant after REM. Overall, RUT-REM caused more pronounced increases in penetration and decreases in softening point.
DSR	Overall, REM/RUT tended to reduce the complex modulus and to increase the phase angle of the bitumens. However, this was not the case for the softest bitumens (PAB and Riihi-REF). The materials under RUT-REM experienced more critical reductions in modulus and increases in phase angle than under REM. REM/RUT may affect the high temperature performance of non-soft bitumens. Soft bitumens are more likely to lose low-temperature performance. At high temperatures, REM affected the complex modulus and phase angle of OKTO SMA and OKTO AC the most. At low temperatures, the most affected materials were FEP, OKTO AC, and ARA. At high temperatures, RUT-REM affected the complex modulus and phase angle of FEP, KB, and ARA the most. At low temperatures, the most affected materials were FEP and ARA. STO performed well at high and low temperatures under RUT-REM. At low temperatures, ARA increased its phase angle importantly after REM, and even more after RUT-REM. There was good compatibility of the test results from the perspective of both plate sizes (8-mm and 4-mm plates), especially for the phase angle. Moderate differences appeared on the interface between both data sets for the modulus master curves. REM/RUT may increase the susceptibility to rutting of the bitumens (the effect was opposite at mixture scale: see Part I), but at the same time improve the susceptibility to fatigue. Using the Glover-Rowe parameter, the effect of rejuvenation was more evident for Kil-FEP and Kil-KB (RUT-REM).
MSCR	RUT-REM increased the non-recoverable creep compliance (susceptibility to permanent deformation) of the bitumens more than REM. OKTO SMA was importantly affected by REM, followed by KB and OKTO AC. Ylö-REF, ARA and FEP were similarly affected by REM, but FEP was considerably more affected by RUT-REM. STO performed well under RUT-REM. It may have some susceptibility to permanent deformations (it does not have the lowest Jnr), but in contrast with other materials, the susceptibility changes only little after RUT-REM. Riihi-REF had the highest susceptibility to permanent deformations, before and after RUT-REM (this was observed as well at the mixture scale). The creep compliance of PAB decreased after REM. REM/RUT reduced the percent recovery of the materials (except PAB and Riihi-REF), especially OKTO SMA. Ylö-REF, ARA and FEP were less affected by REM, and STO was the least affected by RUT-REM. KB still behaved as a polymer-modified bitumen after remix.