Discrete element method-based chip seal application in asphalt pavement maintenance

In recent years, chip seal has gained increasing popularity as one of the pavement preservation techniques. It has been found to be a cost-effective strategy in various projects. However, there are some aspects that remain unclear, such as the precise asphalt application ratio in chip seal and its performance under different conditions. Specifically, the lack of a test method for chip seal\u27s tensile and shear bond performance contributes to this uncertainty. Therefore, the primary objective of this dissertation is twofold: firstly, to develop a laboratory performance evaluation of chip seal, and secondly, to analyze the factors influencing its performance using the DEM (Discrete Element Method) modeling approach. By accomplishing these goals, we seek to shed light on the reasons behind chip seal\u27s performance and identify the factors that significantly impact its effectiveness. This dissertation presents a novel method for assessing the tensile and shear bond performance of both hot rubber chip seal and conventional emulsion asphalt chip seal under various laboratory conditions. The study examines the influence of cyclic load and freeze-thaw cycles on chip seal\u27s shear and tensile bond performance. Furthermore, the evaluation extends to the performance of the chip seal at various application rates using a three-dimensional discrete element model, considering factors such as asphalt thickness, aggregate shape, and azimuth angle. Additionally, the research explores another application of chip seal as a stress absorbing membrane interlayer (SAMI). An assessment is conducted on a resurfacing project that incorporates a rubber modified asphalt mixture with a stress absorbing membrane interlayer. The benefits of chip seal in enhancing cracking resistance as a stress absorbing membrane interlayer are evaluated through the Disc-shaped compact tension (DCT) test. Lastly, the dissertation investigates the use of stress absorbing membrane interlayers in asphalt pavement to prevent pavement cracking. Predictions are made regarding the SAMI layer\u27s effect on pavement cracking performance based on a DEM-FEM coupling model. The rutting resistance and fatigue cracking resistance of the SAMI layer are compared with those of a conventional asphalt overlay to determine the improvement it offers

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

Laboratory evaluation and field demonstration of cold in-place recycling asphalt mixture in Michigan low-volume road

Cold-in place recycling (CIR) is a promising technology for the rehabilitation of asphalt pavements. However, the CIR asphalt pavement constructed in the field often has high air voids due to the presence of moisture during construction, and the moisture susceptibility of the pavement is crucial in determining its service life. Therefore, the objective of this research was to assess the laboratory performance of CIR asphalt mixes under freeze-thaw conditions (The mix prior to being subjected to freezing and thawing is labeled as dry condition , while the mix that was placed in a refrigerator at –18 °C for 16 h and then transferred to a distilled water bath at 60 °C for 24 h is referred to as “post-freeze-thaw”) and forecast in-situ pavement performance through pavement mechanistic-empirical design (PMED). Moisture susceptibility was evaluated by preparing CIR asphalt mixtures under dry condition and freeze-thaw conditions. The Disk-Shaped Compact Tension (DCT) test was utilized to approximate the low-temperature characteristics of the CIR mixture, while the rutting resistance properties were assessed using the Hamburg wheel tracking device (HWDT). The dynamic modulus test was used to assess the elastic deformation characteristics. The asphalt was extracted from the loose material, and the viscoelasticity properties were analyzed using the Dynamic Shear Rheometer (DSR) test and Asphalt Binder Cracking Device (ABCD) test, respectively. Based on the M-E inputs, the projected pavement deterioration was determined through calculations. The outcomes indicated that the dynamic modulus of the asphalt mixture after the freeze-thaw cycle dropped by 11–42 % under varying temperatures and frequencies. The number of wheel passes for the dry condition CIR asphalt mixture was 8.4 % higher than that of the post-freeze-thaw CIR asphalt mixture. The fracture energy dropped by 6 % after freeze-thaw conditions. The emulsion asphalt used in the RAP (reclaimed asphalt pavement) made the binder softer, the fatigue and low-temperature cracking resistance of the material was enhanced, and decreased its resistance to rutting. the results of the M-E pavement design demonstrated that the freeze-thaw condition increased rutting, cracking, and IRI (International Roughness Index) distress. In conclusion, the application of CIR technology in the project enhanced the performance of the asphalt pavement with regard to its resistance to cracking and fatigue. As a result, CIR pavement may be suitable for use in low-traffic road

Laboratory evaluation of the residue of rubber-modified emulsified asphalt

Emulsified asphalt has been widely used in various surface treatment methods such as chip seal for low-volume road preservation. Using modified emulsified asphalt made it possible to use chip seal technology on medium-and even high-volume traffic pavements. The main objective of the study is to quantify the residue characteristics of rubber-modified emulsified asphalt and to assess the effectiveness of using crumb rubber to modify emulsified asphalt binder. The four emulsified asphalt residues used the distillation procedure. Then, the rheology characteristics of emulsified asphalt residue were evaluated. The Fourier transform infrared spectroscopy (FTIR) test analyzed the chemical change of emulsified asphalt during the aging procedure. The results indicate that the evaporation method cannot remove all the water in emulsified asphalt. The mass change during the rolling thin film oven (RTFO) process only represented the component change of emulsified asphalt binder residue. Both the high-temperature and low-temperature performance grade of the two emulsified asphalt binders with rubber were lower. The original asphalt binder adopted to emulsification had a crucial influence on the performance of emulsified asphalt. The rubber modification enhanced the property of the emulsified asphalt binder at low temperatures, and the improvement effect was enhanced as the rubber content in the emulsified asphalt was raised. The C=O band was more effective in quantifying the aging condition of the residue. The findings of this study may further advance the emulsified asphalt technology in pavement construction and maintenance

Reconstruction of Asphalt Pavements with Crumb Rubber Modified Asphalt Mixture in Cold Region: Material Characterization, Construction, and Performance

Dry-processed rubberized asphalt mixture has recently attracted a lot of attention as an alternative to conventional asphalt mixtures. Dry-processed rubberized asphalt pavement has improved the overall performance characteristics compared to the conventional asphalt road. The objective of this research is to demonstrate the reconstruction of rubberized asphalt pavement and evaluate the pavement performance of dry-processed rubberized asphalt mixture based on laboratory and field tests. The noise mitigation effect of dry-processed rubberized asphalt pavement was evaluated at the field construction sites. A prediction of pavement distresses and long-term performance was also conducted using mechanistic-empirical pavement design. In terms of experimental evaluation, the dynamic modulus was estimated using materials test system (MTS) equipment, the low-temperature crack resistance was characterized by the fracture energy from the indirect tensile strength test (IDT), and the asphalt aging was assessed with the rolling thin-film oven (RTFO) test and the pressure aging vessel (PAV) test. The rheology properties of asphalt were estimated by a dynamic shear rheometer (DSR). Based on the test results: (1) The dry-processed rubberized asphalt mixture presented better resistance to cracking, as the fracture energy was enhanced by 29–50% compared to that of conventional hot mix asphalt (HMA); and (2) the high-temperature anti-rutting performance of the rubberized pavement increased. The dynamic modulus increased up to 19%. The findings of the noise test showed that at different vehicle speeds, the rubberized asphalt pavement greatly reduced the noise level by 2–3 dB. The pavement M-E (mechanistic-empirical) design-predicted distress illustrated that the rubberized asphalt pavement could reduce the IRI, rutting, and bottom-up fatigue-cracking distress based on a comparison of prediction results. To sum up, the dry-processed rubber-modified asphalt pavement has better pavement performance compared to the conventional asphalt pavement

Effects of Tire Pressures and Test Temperatures on Permanent Deformation of Direct Coal Liquefaction Residue Mixture

The main objective of this research is to investigate the permanent deformation of asphalt mixtures containing direct coal liquefaction residue (DCLR) under various tire pressures and temperatures. Three types of asphalt mixtures, including control/DCLR/composite-DCLR modified asphalt mixture, were prepared by the Marshall design method. The rutting test was conducted under a tire pressure range of 0.7–1.0 MPa with a 0.1-MPa interval and at a temperature range of 55–70°C with a 5°C interval. Moreover, the dynamic stability and rutting depth of three asphalt mixtures were obtained to evaluate their resistance of permanent deformation. It was found that the rutting resistance of three asphalt mixtures declines with the increased tire pressures and temperatures. The asphalt mixture containing DCLR has a higher dynamic stability and lower rutting depth compared to the control asphalt mixture under the same conditions. Furthermore, the rutting resistance of composite-DCLR modified asphalt mixture is better than that of DCLR modified asphalt mixture. It indicates that the composite-DCLR is favorable for the improvement of rutting resistance of asphalt mixture. Moreover, the analysis of variance was applied, which analysis results showed that the rutting resistance of asphalt mixture is more sensitive to temperature than tire pressure. Based on the least-squares procedure, the relationship between dynamic stability and rutting depth was obtained, and the accuracy of the prediction is acceptable

Cold in-place recycling asphalt mixtures: Laboratory performance and preliminary m-e design analysis

Cold in-place recycling (CIR) asphalt mixtures are an attractive eco-friendly method for rehabilitating asphalt pavement. However, the on-site CIR asphalt mixture generally has a high air void because of the moisture content during construction, and the moisture susceptibility is vital for estimating the road service life. Therefore, the main purpose of this research is to characterize the effect of moisture on the high-temperature and low-temperature performance of a CIR asphalt mixture to predict CIR pavement distress based on a mechanistic–empirical (M-E) pavement de-sign. Moisture conditioning was simulated by the moisture-induced stress tester (MIST). The moisture susceptibility performance of the CIR asphalt mixture (pre-mist and post-mist) was estimated by a dynamic modulus test and a disk-shaped compact tension (DCT) test. In addition, the standard solvent extraction test was used to obtain the reclaimed asphalt pavement (RAP) and CIR asphalt. Asphalt binder performance, including higher temperature and medium temperature performance, was evaluated by dynamic shear rheometer (DSR) equipment and low-temperature properties were estimated by the asphalt binder cracking device (ABCD). Then the predicted pavement distresses were estimated based on the pavement M-E design method. The experimental results revealed that (1) DCT and dynamic modulus tests are sensitive to moisture conditioning. The dynamic modulus decreased by 13% to 43% at various temperatures and frequencies, and the low-temperature cracking energy decreased by 20%. (2) RAP asphalt incorporated with asphalt emulsion decreased the high-temperature rutting resistance but improved the low-temperature anti-cracking and the fatigue life. The M-E design results showed that the RAP incorporated with asphalt emulsion reduced the international roughness index (IRI) and AC bottom-up fatigue pre-dictions, while increasing the total rutting and AC rutting predictions. The moisture damage in the CIR pavement layer also did not significantly affect the predicted distress with low traffic volume. In summary, the implementation of CIR technology in the project improved low-temperature cracking and fatigue performance in the asphalt pavement. Meanwhile, the moisture damage of the CIR asphalt mixture accelerated high-temperature rutting and low-temperature cracking, but it may be acceptable when used for low-volume roads

A case study of the comparison between rubberized and polymer modified asphalt on heavy traffic pavement in wet and freeze environment

Ground tire rubber (GTR) usage in asphalt pavement with the dry process has gained more prominence in recent times. The objective of this work is to investigate the pavement performance of GTR-modified asphalt pavement and polymer-modified asphalt pavement on heavy volume of traffic conditions in Michigan\u27s wet and freeze environment. A suite of laboratory tests was done to evaluate the pavement performance of GTR-modified and polymer-modified asphalt mixtures. To reveal the strain and stress relationship under different frequencies and temperatures, the dynamic modulus test was applied. The Hamburg wheel tracking device (HWTD) was used to assess the high-temperature deformation resistance. The disc-shaped compact tension (DCT) test was used to evaluate the low-temperature cracking characteristics. The characteristics of the asphalt binder were assessed by the dynamic shear rheometer (DSR) for high-temperature properties and the asphalt binder cracking device (ABCD) for low-temperature properties. After the construction, a field noise test was conducted. The experimental results stated that the polymer-modified asphalt mixture and GTR-modified asphalt mixture showed higher dynamic modulus and better ability to prevent cracking than the conventional asphalt mixture at low temperatures, as well as better permanent deformation and stripping resistance than the conventional asphalt mixture. The fracture energy of the GTR-modified hot mix asphalt (HMA) is 13–16 % larger than the polymer-modified HMA. The number of passes to the stripping point of GTR-modified was 510–518 % higher than the conventional HMA. When compared to the field core, the lab-compacted HMA offers superior pavement performance. The extracted asphalt binder test results show the GTR-modified asphalt has better rutting resistance and cracking resistance than polymer-modified asphalt, and the results in the noise test demonstrated that the rubber-modified asphalt pavement mitigated the noise level by 2–3 dB on the road at different vehicle speeds. Moreover, the pavement condition was noticeably enhanced after the reconstruction of the surface course. The total number of passenger tires to be used in this project is about 2270. To summarize, better rutting and cracking properties in asphalt pavement are shown by the project\u27s utilization of rubber technology. And the GTR-modified HMA is comparable to polymer-modified HMA. Therefore, it may be appropriate to utilize rubber technology on high-traffic volume asphalt pavement in Michigan\u27s wet and freeze climate

GROUND TIRE RUBBER ASPHALT FOR DURABLE PAVEMENTS ON HEAVY TRAFFIC ROADS IN MICHIGAN\u27S WET-FREEZE ENVIRONMENT

Ground tire rubber (GTR) is a problematic waste material because it is not biodegradable. One possibility for recycling GTR is to use it as a raw material for pavement construction. GTR has attracted much attention from research institutes and the road industry because of the contribution it makes towards reducing improper waste disposal and promoting environmental sustainability. The objective of this thesis is to evaluate the performance of GTR modified asphalt mixture and styrene-butadiene-styrene (SBS) modified asphalt pavement by a dry process and evaluating the long-term aging performance of the GTR modified asphalt mixture. This thesis conducts the mix design of HMA incorporated with scrap tire rubber by dry process in the lab and determine the gradation of aggregate, asphalt binder content, moisture susceptibility results. The high-temperature rutting and stripping performance was estimated through the Hamburg wheel tracking device (HWTD). The low-temperature cracking resistance was evaluated by the Disc-shaped compact tension (DCT) test. The solvent extraction test was used to obtain the GTR-modified asphalt and polymer-modified asphalt, then the high temperature and low temperature of asphalt binder were estimated by the dynamic shear rheometer (DSR) and asphalt binder cracking device (ABCD). The field noise test was conducted after the construction. The long-term aging process for asphalt binder is pressure aging vessel (PAV), and the long-term aging process for asphalt mixture is conditioned at 85 ℃ for 5 days. The predicted pavement distresses were estimated based on the pavement M-E design method. The results showed that the GTR-modified asphalt mixture improve the high-temperature rutting and low-temperature cracking properties compared with the conventional asphalt mixture, after long-term aging, the GTR-modified asphalt still has the best cracking resistance compared with the conventional asphalt mixture and SBS modified asphalt mixture. In summary, the implementation of rubber technology in the project shows better high-temperature rutting and low-temperature cracking performance in asphalt pavement. Moreover, the GTR-modified asphalt mixture has comparability with polymer-modified asphalt mixture. Therefore, it is possibly acceptable to apply rubber technology to asphalt pavement when used for high-volume roads in Michigan\u27s wet-freeze environment

Reconstruction of Asphalt Pavements with Crumb Rubber Modified Asphalt Mixture in Cold Region: Material Characterization, Construction, and Performance

Dry-processed rubberized asphalt mixture has recently attracted a lot of attention as an alternative to conventional asphalt mixtures. Dry-processed rubberized asphalt pavement has improved the overall performance characteristics compared to the conventional asphalt road. The objective of this research is to demonstrate the reconstruction of rubberized asphalt pavement and evaluate the pavement performance of dry-processed rubberized asphalt mixture based on laboratory and field tests. The noise mitigation effect of dry-processed rubberized asphalt pavement was evaluated at the field construction sites. A prediction of pavement distresses and long-term performance was also conducted using mechanistic-empirical pavement design. In terms of experimental evaluation, the dynamic modulus was estimated using materials test system (MTS) equipment, the low-temperature crack resistance was characterized by the fracture energy from the indirect tensile strength test (IDT), and the asphalt aging was assessed with the rolling thin-film oven (RTFO) test and the pressure aging vessel (PAV) test. The rheology properties of asphalt were estimated by a dynamic shear rheometer (DSR). Based on the test results: (1) The dry-processed rubberized asphalt mixture presented better resistance to cracking, as the fracture energy was enhanced by 29–50% compared to that of conventional hot mix asphalt (HMA); and (2) the high-temperature anti-rutting performance of the rubberized pavement increased. The dynamic modulus increased up to 19%. The findings of the noise test showed that at different vehicle speeds, the rubberized asphalt pavement greatly reduced the noise level by 2–3 dB. The pavement M-E (mechanistic-empirical) design-predicted distress illustrated that the rubberized asphalt pavement could reduce the IRI, rutting, and bottom-up fatigue-cracking distress based on a comparison of prediction results. To sum up, the dry-processed rubber-modified asphalt pavement has better pavement performance compared to the conventional asphalt pavement