Fatigue Evaluation of Asphalt Pavement using Beam Fatigue Apparatus

The fatigue resistance of asphalt mixtures is predicted based on material properties and load responses. In this study, four-point bending beam fatigue testing has been used for a typical Michigan Asphalt mixture under various loading frequencies (10Hz, 5Hz, 1Hz, 0.5Hz, and 0.1Hz) and test temperatures (21.3°C, 13°, and 4°C). This study includes evaluation of different fatigue prediction models (Asphalt Institute Model and Shell Model) over wide ranges of laboratory testing conditions. In addition, this paper also provides a linkage between compression modulus and flexural stiffness, this study helps substantiate the concept that compression modulus can be used for evaluating both rutting due to vertical compression and fatigue due to flexural bending. The results in this study showed that there is a strong linear correlation between the flexural stiffness and compression modulus, with the flexural stiffness about 30% lower than the compression modulus

Rheological Evaluation of Foamed WMA Modified with Nano Hydrated Lime

Although the Warm Mix Asphalt (WMA) is gaining popularity very rapidly and becoming a mainstream technique for producing asphalt mixtures, there are many concerns regarding its long-term performance. Over the years, the Regular Hydrated Lime (RHL) has gained considerable recognition as a common additive to bituminous pavements. However, the Nano Hydrated Lime (NHL) (particle sizes 100 nanometer (nm) or less) has not been used as an additive to the asphalt mixtures before. The rheology properties of foamed WMA were studied since the pavement performance is primarily controlled by the rheological properties of asphalt cement. NHL materials with particle sizes of 50 nm and 100 nm were used in this study along with RHL to investigate the effectiveness of the new generation fabricated NHL modification on the rheological properties of the foamed WMA. NHL was added to the asphalt binder at ratios of 20%, 10%, and 5% (by weight). The foamed WMA was produced by adding Advera® at ratios of 3%, 4.5%, and 6% (by weight). The Dynamic Shear Rheometer (DSR) test was used to evaluate the rutting and fatigue cracking of the binders while the Bending Beam Rheometer (BBR) test was used to evaluate thermal cracking of the binders. The overall results reveal that the binder rheological properties can be enhanced successfully by adding small amounts of NHL. The NHL particle size affects the rheological properties of the binders. The application of the RHL with the normal dose (20% by weight of binder) can be replaced by adding almost 5% (by weight) of NHL (50 nm). The outputs of this study can be interesting from a practical point of view since it was proved that the NHL has interesting functionality on the rheological performance of the binders

Ethanol based foamed asphalt as potential alternative for low emission asphalt technology

Foamed asphalt typically relies on water as a foaming agent because water becomes gaseous at elevated temperatures, generating numerous tiny bubbles in the asphalt and causing spontaneous foaming. In this study, ethanol was used as a potential alternative to water as a foaming agent. Ethanol is expected to be a physical blowing agent in the same manner as water, except it requires less energy to foam due to its 78 °C boiling point. This study compares the performance of water and ethanol as foaming agents through the measurements of rotational viscosity, the reduction in temperature during foaming, and volatile loss. The ethanol-foamed asphalt binders were prepared at 80 °C and 100 °C, while the water-foamed asphalt binders were prepared at 100 °C and 120 °C. Additionally, the rolling thin film oven (RTFO) was used to generate short-term aging of the foamed asphalt binders. A rotational viscometer was used to determine the viscosity of the asphalt binders at 80 °C, 100 °C, 120 °C, 140 °C, and 160 °C. Overall, ethanol can function in the same manner as water but requires less energy to foam. It is proven based on the smaller drop in temperature of the asphalt binder foamed using ethanol compared with that prepared with water. This is due to the lower latent heat capacity of ethanol, which requires less energy to vaporize compared with water. Through the rotational viscometer test, ethanol performs better in lowering the viscosity of asphalt binders, which is essential in allowing production processes at low temperatures, as well as a better workability and aggregate coating. Ethanol can be expelled from the foamed asphalt binders at a higher rate due to its lower boiling point and latent heat

Rheological Evaluation of Foamed WMA Modified with Nano Hydrated Lime

Although the Warm Mix Asphalt (WMA) is gaining popularity very rapidly and becoming a mainstream technique for producing asphalt mixtures, there are many concerns regarding its long-term performance. Over the years, the Regular Hydrated Lime (RHL) has gained considerable recognition as a common additive to bituminous pavements. However, the Nano Hydrated Lime (NHL) (particle sizes 100 nanometer (nm) or less) has not been used as an additive to the asphalt mixtures before. The rheology properties of foamed WMA were studied since the pavement performance is primarily controlled by the rheological properties of asphalt cement. NHL materials with particle sizes of 50 nm and 100 nm were used in this study along with RHL to investigate the effectiveness of the new generation fabricated NHL modification on the rheological properties of the foamed WMA. NHL was added to the asphalt binder at ratios of 20%, 10%, and 5% (by weight). The foamed WMA was produced by adding Advera® at ratios of 3%, 4.5%, and 6% (by weight). The Dynamic Shear Rheometer (DSR) test was used to evaluate the rutting and fatigue cracking of the binders while the Bending Beam Rheometer (BBR) test was used to evaluate thermal cracking of the binders. The overall results reveal that the binder rheological properties can be enhanced successfully by adding small amounts of NHL. The NHL particle size affects the rheological properties of the binders. The application of the RHL with the normal dose (20% by weight of binder) can be replaced by adding almost 5% (by weight) of NHL (50 nm). The outputs of this study can be interesting from a practical point of view since it was proved that the NHL has interesting functionality on the rheological performance of the binders

Comparative study of ethanol foamed asphalt binders and mixtures prepared via manual injection and laboratory foaming device

The consistency of the ethanol foamed binders and mixtures prepared using asphalt binders foamed by the manual injection technique and laboratory foaming device were evaluated and compared in this study. The asphalt binders foamed using both methods was prepared at 120 °C, 130 °C and 140 °C. The performance of ethanol-foamed binders was evaluated in terms of rotational viscosity, expansion ratio, and low temperature cracking. Meanwhile, the performance of foamed WMA mixtures was tested using semi-circular bending (SCB), disk-shaped compact tension (DCT), and tensile strength ratio (TSR) tests. In order to conduct the TSR test, the samples were conditioned using the Moisture Induced Stress Tester (MIST) to simulate the pore pressure and scouring effects due to a tire passing over wet pavement. The foamed WMA mixtures were produced using pre-heated aggregates at 80 °C and 100 °C and foamed asphalt binders produced at 130 °C. The nano-hydrated lime was used as the filler and anti-stripping agent. Overall, the properties of ethanol-foamed binders and WMA mixtures produced via both methods are significantly comparable, except the resistance to moisture damage test result. However, the findings indicate that the ethanol-foamed WMA mixtures prepared using both techniques are having good resistance to moisture damage, based on the TSR values more than 0.8. The foamed WMA mixtures also exhibited a better resistance to cracking, as indicated by a higher tensile strength compared to the control HMA. Additionally, the WMA specimen prepared at 100 °C was less susceptible to rutting than the samples produced at 80 °C

Achievements and prospects of functional pavement: Materials and structures

In order to further promote the development of functional pavement technology, a Special Issue of “Achievements and Prospects of Functional Pavement” has been proposed by a group of guest editors. To reach this objective, articles included in this Special Issue are related to different aspects of functional pavement, including green roads to decrease carbon emission, noise, and pollution, safety pavement to increase skid resistance by water drainage and snow removal, intelligent roads for monitoring, power generation, temperature control and management, and durable roads to increase service life with new theory, new design methods, and prediction models, as highlighted in this editorial

Achievements and prospects of advanced pavement materials technologies

Road transportation is a basic need for mobility and daily life [...

Design and performance of polyurethane elastomers composed with different soft segments

Thermoplastic polyurethane elastomers (TPUs) are widely used in a variety of applications as a result of flexible and superior performance. However, few scholars pay close attention on the design and synthesis of TPUs through the self‐determined laboratory process, especially on definite of chemical structures and upon the influence on properties. To investigate the properties of synthesized modifier based on chemical structure, firstly each kind of unknown structure and composition ratio of TPUs was determined by using a new method. Furthermore, the thermal characteristics and mechanical properties of modifiers were exposed by thermal characteristics and mechanics performance tests. The experimental results indicate that TPUs for use as an asphalt modifier can successfully be synthesized with the aid of semi‐prepolymer method. The linear backbone structure of TPUs with different hard segment contents were determined by micro test methods. The polyester‐based TPUs had thermal behavior better than the polyether-based TPUs; conversely, the low temperature performance of polyether‐based TPUs was superior. Most importantly, it was found that the relative molecular mass of TPUs exhibited a weak effect on the mechanical properties, whereas the crystallinity of hard segment showed a significant influence on the properties of TPUs

Asphalt Mixture with Scrap Tire Rubber and Nylon Fiber from Waste Tires: Laboratory Performance and Preliminary M‐E Design Analysis

Scrap tire rubber and nylon fiber are waste materials that could potentially be recycled and used to improve the mechanical properties of asphalt pavement. The objective of this research was to investigate the properties of scrap tire rubber and nylon fiber (R‐F) modified warm mix asphalt mixture (WMA). The high‐temperature performance was estimated by the Hamburg wheel-tracking testing (HWTT) device. The low‐temperature cracking performance was evaluated by the disk‐shaped compact tension (DCT) test and the indirect tensile strength (IDT) test. The stress and strain relationship was assessed by the dynamic modulus test at various temperatures and frequencies. The extracted asphalt binder was evaluated by the dynamic shear rheometer (DSR). Pavement distresses were predicted by pavement mechanistic‐empirical (M‐E) analysis. The test results showed that: (1) The R‐F modified WMA had better high‐temperature rutting performance. The dynamic modulus of conventional hot mix asphalt mixture (HMA) was 21.8% ~ 103% lower than R‐ F modified WMA at high temperatures. The wheel passes and stripping point of R‐F modified WMA were 2.17 and 5.8 times higher than those of conventional HMA, respectively. Moreover, the R‐F modified warm mix asphalt had a higher rutting index than the original asphalt. (2) R‐F modified WMA had better cracking resistance at a low temperature. The failure energy of the R‐F modified WMA was 24.3% higher than the conventional HMA, and the fracture energy of the R‐F modified WMA was 7.7% higher than the conventional HMA. (3) The pavement distress prediction results showed the same trend compared with the laboratory testing performance in that the R‐F modified WMA helped to improve the IRI, AC cracking, and rutting performance compared with the conventional HMA. In summary, R‐F modified WMA can be applied in pavement construction