Rheological, fatigue and relaxation properties of aged bitumen

Figures & data

Table 1. Specifications of PEN 70/100 at fresh (unaged) state.

Property	Unit	PEN 70/100
Penetration at 25°C	0.1 mm	70–100
Softening point	°C	43–51
Dynamic viscosity at 60°C	Pa s	160
Complex shear modulus at 1.6 Hz and 60°C	kPa	1.8
Phase angle at 1.6 Hz and 60°C	°	88

Table 2. Ageing programme.

Ageing method	Temperature (°C)	Pressure (atm)	Ageing time (h)
Oven	100	1	20, 40, 80, 160, 320
Oven	50, 150	1	40
PAV	100	5, 10, 15, 20	40

Figure 1. Master curves of PEN 70/100 bitumen with ageing time (oven ageing at 100°C and 1 atm).

Figure 2. Black diagram of PEN 70/100 bitumen with ageing time (oven ageing at 100°C and 1 atm).

Figure 3. Schematic of crossover modulus.

Figure 4. Crossover modulus of bitumen at different ageing conditions.

Figure 5. Ageing index of crossover modulus of bitumen at different ageing conditions.

Figure 6. Complex shear modulus vs number of cycles for bitumen at fresh conditions (unaged state): stress-controlled mode (left) and strain-controlled mode (right).

Figure 7. Fatigue results of bitumen with various ageing time: stress-controlled mode (left) and strain-controlled mode (right).

Table 3. Fitting parameters for fatigue results.

Control mode	Stress-controlled			Strain-controlled
Parameter	$A_{\sigma }$	$B_{\sigma }$	R^2	$A_{\epsilon }$	$B_{\epsilon }$	R^2
Fresh	7.736	−3.298	0.985	88772	−2.054	0.998
20 h	25.581	−3.281	0.994	134938	−2.617	0.998
40 h	72.197	−3.327	0.988	162852	−2.671	0.997
80 h	106.99	−3.725	0.967	229202	−2.678	0.997

Figure 8. Relaxation curves (left) and residual stress curves (right) of PEN 70/100 at different ageing conditions.

Figure 9. Shear stress of PEN 70/100 at 0 and 100 s under different ageing conditions.

Figure 10. Relaxation time at shear stress levels of 50% and 25% of the initial stress.

Figure 11. Ageing index of relaxation of bitumen at different ageing conditions.

Figure 12. Relationship between the crossover modulus $\mathrm{A}{\mathrm{I}}_{\mathrm{C}\mathrm{M}}$ and the stress relaxation $\mathrm{A}{\mathrm{I}}_{R\mathrm{\_}50\text{\%}}$ ageing indices.

Figure 13. Relationship between the crossover modulus $\mathrm{A}{\mathrm{I}}_{\mathrm{C}\mathrm{M}}$ and the stress relaxation $\mathrm{A}{\mathrm{I}}_{\mathrm{R}}$ ageing indices at shear stress levels of 50% and 25% of the initial stress.