Bio-oil recycled asphalt binders in road engineering can help solve the problem of oil shortage and reduce the environmental pollution and sustainability. This paper investigated the road performance of the aged asphalt binder by adding bio-oil so that the aged asphalt binder could be reused to reach purpose of reuse. The residual soybean oil was selected as rejuvenator and blended with aged asphalt binder at 0%, 2%, 4%, and 6%, respectively. The results showed that bio-oil increased the penetration of aged asphalt binder, the penetration of bio-oil recycled asphalt binder with a bio-oil content of 6% reached the standard of 70# matrix asphalt binder. The addition of bio-oil reduced the viscosity, mixing and compaction temperature of aged asphalt binder. As a common knowledge, bio-oil helps to increase the lightweight components of the aged asphalt binder, which diminishes the high-temperature rutting resistance of bio-oil recycled asphalt binders. The high-temperature deformation resistance of bio-oil recycled asphalt binders had not decreased linearly with the bio-oil dosage. Meanwhile, the high-temperature performance of the bio-oil recycled asphalt binder with a 6% bio-oil was superior to matrix asphalt binder. Bio-oil increased the light components of the aged asphalt binder, thus reducing the high-temperature rheological properties of bio-oil recycled asphalt binders as the bio-oil dosage increases. The above test results showed that the bio-oil could restore the aged asphalt binder to the initial level to reach the reuse target.
As more and more oil resources are exploited, their quantity diminishes. Petroleum asphalt binders are essential materials in the road industry, and how to reuse road asphalt is also a problem to be solved. The most common method is to use a regenerating agent to restore the road performance of aged asphalt binders to achieve the objective of regenerating aged asphalt. Road workers explored and investigated different types of regenerating agents, including bio-oil as a cost-effective regenerating agent [
In this article, organic oil was added to aged asphalt to enhance the plasticity of aged asphalt binder, and the rheological properties of bio-oil recycled asphalt binders were studied. Three indexes tested the conventional properties of bio-oil recycled asphalt binders. The viscosity and high-temperature rheological properties of bio-oil recycled asphalt binders were determined through rotational viscosity and DSR tests. In combination with the test results, the rheological properties of high-temperature bio-oil recycled asphalt binders were analyzed with the change in bio-oil content. The test results could provide a scientific basis for preparing excellent high-temperature performance and determination of organic oil content.
In this paper, 70# matrix asphalt was selected as the raw material, and as described in
Property | Test results | Technical specification | Test method |
---|---|---|---|
Penetration index PI | 0.105 | –1.5~+1.0 | T0604-2011 |
Penetration (25°C, 5 s, 100 g) (0.1 mm) | 60.4 | 60~80 | T0604-2011 |
Softening point (°C) | 49.8 | ≥49 | T0606-2011 |
Ductility (5 cm/min, 10°C) (cm) | 27 | ≥15 | T0605-2011 |
Ductility (5 cm/min, 15°C) (cm) | >100 | ≥100 | T0605-2011 |
After RTFOT (163°C, 85 min) | T0609-2011 | ||
Mass loss (%) | –0.078 | ≤±0.8 | T0610-2011 |
Residual penetration ratio (%) | 64 | ≥61 | T0604-2011 |
Residual ductility at 15°C (cm) | 21 | ≥15 | T0605-2011 |
Appearance color | Density (g/mL) | Flash Point (°C) | 60°C Viscosity (mPa · s) |
---|---|---|---|
Yellowish-brown | 0.947 | 209 | 80 |
In this document, in accordance with the AASHTO specification [
In this section, the conventional properties of various bio-oil recycled asphalt binders were tested following the test procedures of JTG E20-2011. The traditional tests include softening point (JTG E20 T0606-2011), ductility at 15°C (JTG E20 T0605-2011), penetration at 25°C (JTG E20 T0604-2011). In this paper, a Brookfield viscometer with a temperature control device was selected to determine the viscosity of various bio-oil recycled asphalt binders. The viscosity of 120°C, 135°C, 150°C, and 165°C was measured at a speed of 20 r/min under AASHTO T 316 [
In this article, a dynamic shear rheometer (DSR) was used to assess the rheology properties of bio-oil recycled asphalt binders. The geometrical shape of the plate was chosen with a 25 mm diameter plate and a 1 mm release plate [
The traditional performance results of bio-oil recycled asphalt are shown in
As a viscoelastic material, asphalt binder is critical to the analysis of its rheological properties. The storage modulus (G’), loss modulus (G’’), and rutting factor of the bio-oil recycled asphalt binders may be achieved by DSR test. The storage modulus and the loss modulus characterize the degree of elasticity and the viscosity characteristics of asphalt binders [
This paper selects the loss factor combined with the storage modulus and loss modulus to analyze the high-temperature rheological properties of bio-oil recycled asphalt binders. The loss factor shall take account of the viscoelastic characteristics of the asphalt. The lower the loss factor, the greater the resilient recovery capacity [
The frequency sweep temperature was 60°C, and the angular frequency range was 0.1–100 rad/s. In combination with the experimental results, the rheological properties of bio-oil recycled asphalt binders were analyzed with different frequencies at 60°C.
The central damage of asphalt pavement is rutting, and the main reason is that the asphalt mixture is too soft. It is necessary to evaluate the high-temperature performance of asphalt [
Bio-oil recycled asphalt binders will change differently depending on temperature fluctuations. In this paper, Ln G*/sin-Ln T is selected for linear fitting; the fitting results are shown in
Asphalt type | |A| | B | R2 |
---|---|---|---|
0% | 7.6724 | 41.559 | 0.99285 |
2% | 7.7548 | 41.322 | 0.99409 |
4% | 7.8183 | 39.734 | 0.99365 |
6% | 7.8496 | 39.235 | 0.99371 |
MA | 7.8541 | 39.990 | 0.99473 |
G*/sin-Ln T is selected for linear fitting; the fitting results are shown in
In this study, four bio-oil recycled asphalt binders were prepared by physical blending. Through conventional performance tests, rotational viscosity and dynamic rheometer shear investigated conventional performance, construction feasibility, high-temperature flange resistance, and temperature sensitivity of various bio-oil recycled asphalt binders. Changes in road performance in bio-oil recycled asphalt binders are examined. The conclusions from the experimental data can be summarized as follows: As a light component, bio-oil was mixed into aged asphalt binder to improve their low-temperature performance by weakening the high-temperature performance. When the bio-oil dosage is 6%, the softening point of the aged asphalt is reduced by 16.4%, but the low-temperature ductility is increased by 8.5 times. In addition, the mixing and compaction temperature decreases with the bio-oil content. Bio-oil enhances the plasticity of aged asphalt by increase the loss modulus relatively. Loss factor analysis can be obtained that storage modulus decreases more than the loss modulus, which causes the viscous component of bio-oil recycled asphalt binders to increase with the bio-oil dosage. A comparison of A3 and MA shows that aged asphalt binder may regain its plasticity when the bio-oil content is 6%. The bio-oil level should be maintained at about 6%. As expected, anti-rutting performance of aged asphalt decreases with the bio-oil content, as does the temperature sensitivity. The effect of bio-oil in weakening the high-temperature performance of aged asphalt decreases as its content increases. To sum up, bio-oil can achieve the goal of regenerating aged asphalt binder, and the amount of bio-oil should be about 6%.
Thanks to Dr. Wu, School of Highway, Chang’an University, for financial support.