Mechanistic Analysis and Economic Benefits of Fiber-Reinforced Asphalt Overlay Mixtures

Among the various distresses in flexible pavement structures, rutting and fatigue cracking can be accounted as two of the major distresses that need to be addressed by pavement engineers. Laboratory tests, such as four-point bending beam and flow number are utilized to characterize the rutting and cracking resistance of flexible pavements. Various construction practices are introduced to reduce the effect of fatigue and rutting in pavement structures. One of such methods is applying fibers to the asphalt mixture to prolong the serviceability and the performance of the pavement structures. The use of fibers is applicable to freshly constructed pavements as well as in the pavement rehabilitation and maintenance work, such as overlay. This paper primarily analyses the application of fibers in the overlay of pavements. The two major cases of the pavement with original asphalt overlay and the one with fibers mixed asphalt overlay is considered utilizing a developed testing program where the mechanistic analysis as well as the economic effectiveness is evaluated. 3D move analysis software package is utilized extensively as a means of mechanistic analysis tool. It is found that the fiber mixture pavement overlay had a higher pavement life than the ordinary asphalt overlay. In addition, the cost effectiveness in terms of fatigue and rutting of fiber-reinforced overlay structures were 4.4 and 4.1 times the unmodified mixtures, respectively. The use of fibers in the overlay of pavement resulted in higher pavement life with a high cost effectiveness

CHANGE IN RESILIENT MODULUS OF BASE LAYERS IN ASPHALT PAVEMENT STRUCTURES OVER TEXAS

The properties of materials change over time and the same case happens for the HMA pavement. The various components of HMA pavement such as surface, base, sub-base, and sub-grade have time related functions. In particular, the base layer which is the immediate layer below the surface, comprising of various materials such as crush aggregates and HMA also have a time related function. Among the numerous properties of the base layers which are dependent with time is its resilient modulus. Therefore, this paper correlates the effect of the change in resilient modulus with time including the various varying conditions such as rutting, thickness of base layer, precipitation, traffic, temperature, IRI index, wheel path length cracked, cracking percentage, crack length, liquid limit, plastic limit, optimum moisture content, and % fine passing below 200 sieve. Each individual factor has different effects over the resilient modulus of the base layer, but their effects are more severe when they act at once in a pavement structure

Mechanistic Analysis and Economic Benefits of Fiber-Reinforced Asphalt Overlay Mixtures

Among the various distresses in flexible pavement structures, rutting and fatigue cracking can be accounted as two of the major distresses that need to be addressed by pavement engineers. Laboratory tests, such as four-point bending beam and flow number are utilized to characterize the rutting and cracking resistance of flexible pavements. Various construction practices are introduced to reduce the effect of fatigue and rutting in pavement structures. One of such methods is applying fibers to the asphalt mixture to prolong the serviceability and the performance of the pavement structures. The use of fibers is applicable to freshly constructed pavements as well as in the pavement rehabilitation and maintenance work, such as overlay. This paper primarily analyses the application of fibers in the overlay of pavements. The two major cases of the pavement with original asphalt overlay and the one with fibers mixed asphalt overlay is considered utilizing a developed testing program where the mechanistic analysis as well as the economic effectiveness is evaluated. 3D move analysis software package is utilized extensively as a means of mechanistic analysis tool. It is found that the fiber mixture pavement overlay had a higher pavement life than the ordinary asphalt overlay. In addition, the cost effectiveness in terms of fatigue and rutting of fiber-reinforced overlay structures were 4.4 and 4.1 times the unmodified mixtures, respectively. The use of fibers in the overlay of pavement resulted in higher pavement life with a high cost effectiveness

Rutting Performance of Pavement under Autonomous Vehicle Consideration

Rutting also referred as permanent deformation has always been a concern in the asphalt pavement industry. Prevalence of rutting is the sign of inefficient functioning of the roadways. Various studies are being performed for the rutting analysis and nowadays, rutting related studies are more inclined to autonomous vehicles. The introduction of autonomous vehicles on the prevailing pavements may raise countless questions regarding the distress free functioning of pavement. Lateral as well as longitudinal wandering of the autonomous vehicles are top concerns on the rutting related analysis of the pavement. Therefore, there is a great need for understanding rutting related behavior of pavement when it is loaded with autonomous vehicles. This paper assumes various conditions related to automated vehicles and quantifies the rutting encountered when there is shift from man drive vehicle to autonomous vehicles

Expanding the Concept of Comprehensive Area Ratio Parameter to the South-Central States Towards Simplifying the Structural Evaluation of Flexible Pavements at the Network Level

The surface deflection bowl data collected through Non-Destructive Testing (NDT) has been widely utilized by various Department of Transportation (DOTs) in the South-Central States and other places. The primary purpose of using deflection-based NDTs in network-level assessment is to identify a weak pavement section that requires further analysis at the project level. The falling weight deflectometer (FWD) test is one of the common NDT based tests utilized by highway agencies in assessing the performance of the flexible pavement. However, a robust method to evaluate pavement sections utilizing FWD data from all the sensors are seldom developed. There is always a need for DOTs and highway agencies to have a simplified procedure, which can be directly implemented in agencies’ databases. This study focuses on expanding the concept of previously developed area ratio parameters towards the pavement section of South-Central States (Arkansas, Louisiana, New Mexico, Oklahoma, and Texas) in effectively analyzing the pavement performances. Simulation-based deflections are utilized to develop enhanced deflection-based parameters. The need for extensive FWD testing at the field will be reduced with software-based simulations. 3D-MoveAnalysis and Analysis and Simulation (ANSYS) were utilized to simulate the surface deflection obtained from FWD test. Deflection values obtained through the software simulations were highly correlated with the field test results. Furthermore, ninety-seven pavement sections in these states are considered to implement and validate simplified procedures that will be readily available to various transportation agencies to evaluate their pavement conditions at the network level. Area ratio parameters developed in the study are reliable enough to consider the effect of different drop loads and various pavement sections across the South-Central States. Additionally, a pavement ranking chart is proposed for the five South-Central states, which categorizes the pavement section to very good, good, fair, and poor pavement sections. The chart will be helpful for DOTs and highway agencies to carry out the rehabilitation and maintenance work in time and estimate the budget required in these procedures. Similarly, the remaining fatigue life of the pavement section can be easily predicted utilizing the newly-developed relationship based on comprehensive area ratio parameters and number of cycles to fatigue failure

Assessing the Performance of High-RAP Mixtures Incorporating Crude Vegetable Oils and an Antioxidant from Mechanical, Environmental, and Economic Perspectives

Utilization of mixtures with high amounts of reclaimed asphalt pavement (RAP) in the pavement industry is limited because of the adverse effects of aged materials in recycled asphalt materials. To date, numerous approaches have been used to reduce the adversity of RAP in mixtures. One such approach is the use of recycling agents (RAs) from various sources, such as petroleum and bio-oil. However, the current need is to maximize the use of RAP by adopting a sustainable source of RAs. Therefore, this study uses two RAs based on vegetable oils (crude soybean oil and crude corn oil) with high-RAP mixtures of 65%. In addition, owing to the aging susceptibility of vegetable-based oil, simultaneous use of an antioxidant (ZnDEC) was performed. The mechanical performance of high-RAP mixtures with or without a recycling agent and antioxidant was assessed in terms of cracking, rutting, and moisture resistance. Apart from that, environmental testing was performed using leaching test procedures. Life cycle cost analysis and life cycle impact analysis (LCCA and LCIA) were performed to understand the long-term cost performance and overall life-cycle impact of each mixture. The results obtained from various test matrices showed that using vegetable-based recycling agents enhanced the cracking performance of the RAP mixture while having minimal effect on the rutting and moisture susceptibility. ZnDEC had a beneficial effect on reducing the aging susceptibility of high-RAP mixtures with vegetable oil without significantly affecting the rutting and moisture susceptibility. In addition, the cost analysis and environmental analysis showed that these additives don\u27t harm the environment, and cost benefits are obtained in the long run when these additives are used with a high-RAP mixture. Overall, this study focused on a multi-aspects analysis procedure to understand the effect of the use of a high-RAP mixture modified by RAs and an antioxidant that can provide useful information on the choice of materials to be used in the asphalt industry. Advisor: Hamzeh Haghshenas Fatmehsar

Research on High-RAP Mixtures with Rejuvenator - Field Implementation

The use of Rejuvenating Agents (RAs), as Recycled Asphalt Pavement (RAP) modifiers, has been increasing over the past years. However, the field performance of asphalt mixtures containing high-RAP materials and modified with RAs has raised some concerns regarding the long-term performance of RAs. This study evaluated the laboratory and field performance of high-RAP mixtures with and without bio-oil RA. Three sets of plant-produced specimens were collected: 1) laboratory-compacted; 2) field-compacted and cored after paving; and 3) field-compacted and cored after one and two years. The Hamburg Wheel Tracking (HWT) test was used to evaluate the specimens\u27 resistance to rutting and moisture damage. The Semi-Circular Bending (SCB) fracture test was performed to examine the specimens\u27 resistance to cracking. The results showed that using the bio-oil RA resulted in an increase in cracking resistance and a decrease in rutting and moisture damage resistance of the RAP-blended mixtures compacted in the laboratory. However, after one and two years of exposure to the environmental conditions and traffic loads, the effect of RA on moisture and rutting susceptibility of the mixtures reduced. The cracking resistance of specimens, estimated by Flexibility Index (FI) and Cracking Resistance Index (CRI), and Tukey\u27s Honestly Significant Difference (HSD) test results implied that the bio-oil RA used in this study could not provide long-term improvement for the RAP-blended mixtures in the laboratory-aging and field-aging conditions. The field performance observations showed that the use of the bio-oil RA in the second layer might have indirectly resulted in more cracks (fatigue and thermal) and ruts in the surface layer

Expanding the Concept of Comprehensive Area Ratio Parameter to the South-Central States: Towards Simplifying the Structural Evaluation of Flexible Pavements at the Network Level

The surface deflection bowl data collected through falling weight deflectometer (FWD) test is utilized by highway agencies in assessing the performance of the flexible pavement. However, a robust method to evaluate pavement sections utilizing FWD data from all the sensors is seldom developed. There is always a need for DOTs and highway agencies to have a simplified procedure, which can be directly implemented in agencies\u27 databases. This study focuses on expanding and validating the concept of previously developed area ratio parameters towards the pavement section of South-Central States (Arkansas, Louisiana, New Mexico, Oklahoma, and Texas) in effectively analyzing the pavement performances. Simulation-based deflections are utilized to develop enhanced deflection-based parameters and to reduce the need for extensive FWD testing in the field. Ninety-seven pavement sections in these states are considered to implement and validate simplified procedures that will be readily available to various transportation agencies to evaluate their pavement conditions at the network level. Due to this purpose, a pavement ranking chart is proposed for the five South-Central states, which categorizes the pavement section into very good, good, fair, and poor pavement sections. Eventually, load-induced effects concerning developed parameters are effectively analyzed to predict the remaining service life of the flexible pavement structures. The developed methodologies will be helpful for DOTs and highway agencies to carry out the rehabilitation and maintenance work in time and estimate the budget required in these procedures