While seal coating has been widely used as a cost effective strategy in asphalt pavement preservation, many cities in Minnesota have reported their concerns of the premature stripping of street pavements under seal coating. As a result, there is a growing number of local agencies that are choosing not to use seal coating. The Minnesota Department of Transportation (MnDOT) wants to know if this premature stripping is caused by seal coating. If yes, then what is the mechanism for this? Is seal coating counterproductive in cities in Minnesota? A hypothesis proposed that premature stripping is caused by the high air void pavement, which allows water to intrude and spread, and the low surface breathability, which traps water in the asphalt pavement.
This research will investigate this problem through literature review, field data collection and lab testing. The lab tests include permeability and surface breathability tests, effect of air voids on moisture susceptibility, and effect of seal coating on moisture susceptibility.
The objectives of this research are to: 1) find out the causes of premature stripping of street asphalt pavement under seal coats; 2) investigate possible solutions to address pavement stripping under seal coats; 3) provide recommendations for the preservative strategies of street pavements in Minnesota.
SPONSOR: MICHIGAN DEPARTMENT OF ENVIRONMENTAL QUALITY
PI: Zhanping You
This project will evaluate the feasibility of GTR-emulsion and activated rubber for pavement chip seal. The feasibility study includes the emulsification and performance evaluation of GTR-emulsions, and trial field sections of chip seals for GTR-emulsions and/or activated rubber. The project will be considered successful if the following results are obtained:
(1) GTR-emulsion and ARMA is successfully prepared and its performance is evaluated in laboratory. Its properties meet the requirements of each standard. The comparison between regular-emulsion and modified emulsions is made for performance evaluation.
(2) GTR-emulsion and activated rubber chip seals are successfully prepared and the performance is evaluated through the laboratory paving of chip seals. The life cycle cost analysis of chip seals is used to evaluate the ROI and the comparison between GTR-emulsion chip seal and others will be made.
(3) The road trial sections of GTR-emulsion and activated rubber chip seals are successfully implemented.
The success of this research project can enable MDOT to understand which best practices in other states or countries can be potentially implemented in Michigan. This would help Michigan to improve their pavement system by lowering construction and maintenance cost and extending pavement durability. It is also beneficial for MDOT to update their specifications, manuals and guidelines to be consistent with the development of those innovations in pavement design, pavement materials, construction and maintenance.
The objectives of this research are the following:
• Document best practices nationally and internationally for pavement design, pavement materials selection, construction (workmanship), and maintenance of roadway pavements in wet freeze climates that are similar to Michigan.
• Identify barriers to implementing the best practices presently not used in Michigan.
• Recommend the best practices that could be implemented in Michigan.
SPONSOR: MICHIGAN DEPARTMENT OF ENVIRONMENTAL QUALITY
PI: Zhanping You
This project will conduct comprehensive evaluations on the CRM WMA for pavements in the State of Michigan. The main objective of this project is to develop and apply low emission asphalt pavement technology through the combination of crumb rubber and warm mix asphalt and to evaluate the feasibility of CRM WMA with respect to performance improvement, emission reduction, and cost effectiveness. The performance of CRM WMA will be evaluated through laboratory and field testing. The emission reduction will be assessed through laboratory and plant emission measurements. The environmental impact of the CRM asphalt mixtures will be evaluated through LCA, while the cost effectiveness will be evaluated through LCCA.
The evaluation includes performance improvements, emission reduction, life cycle environmental impact assessment, and life cycle cost analysis. If it shows that the CRM WMA is a feasible option after the evaluation, it is anticipated the CRM WMA can have more applications in the future. And therefore a sustainable market for scrap tires can be developed in Michigan. In this project, we anticipate the CO2 output for the designed materials will be reduced by up to 30% and other volatiles will be reduced by up to 30% as well, while the engineering parameters of the pavement meet or exceed the pavement agency’s goal.
The relationship between unfrozen water content and temperature, which is referred to as the Phase Composition Curve (PCC) in frozen soils, has long been observed. However, this relationship has not been extensively studied and widely used, possibly due to the lack of a physical understanding. Recent studies of the Pl succeeded in obtaining a physical description, a physically-based equation, and a physic-empirical prediction method for this relationship. Based on the common nature of porous materials, it is hypothesized that there is a relationship between unfrozen water content and temperature in all frozen porous materials. This study will experimentally investigate the existence of the PCC in typical porous materials. Optimization analyses will be conducted for the design of a Time Domain Reflectometry sensor. The TOR sensor together with thermal couples, which is suitable for the measurement of the PCC in the selected porous materials, will be fabricated and calibrated. The sensor will be utilized to measure the PCC by strictly following a specially designed procedure. The measured PCCs will be analyzed using the physically-based equation proposed by the PL The parameters in the equation will be obtained by means of curve fitting to the measured results. The values of the parameters for different porous materials will be categorized and compared.
The research will not only offer a definite answer to the wide existence of the PCC, but also obtain the characteristics of that of different porous materials. The research will provide a clear understanding of phase transition of water in porous materials which is currently absent. The resultant conclusions may advance many engineering applications involving the freezing process of porous materials. The research thus will lay down a necessary basis for the exploration in extraterrestrial environments, where both porous materials and the phase change of water or other liquid are very likely to exist. Also, this study will open a new research area for the PI and will answer a key question for preparing a solid proposal which will be submitted to the NSF.
The safety and reliability of space structures such as airplane wings and helicopters can be significantly decreased because of turbulence and vibrations. All frames and elements have a natural frequency associated with their dimensions and material properties. When these natural frequencies resonate in an element, superposition can cause the propagating waves to increase stresses and forces on the elements. Vibrations in space-structures will cause fatigue on the materials, decrease fuel-efficiency by increasing drag forces, and lead to the operation safety issues or even catastrophic failure of aerospace structures.
The vibrations can be decreased by the use of a trailing edge flap actuator. The trailing edge flap actuator is essentially a flap on an aircraft wing that will change the natural frequency of the element to prevent large vibrations. Changing the geometry of an aircraft wing will cause a different distribution of forces, and therefore can counteract the forces that create the vibrations. CmTent designs for controlling and operating the flap require the use of hydraulics; however, the hydraulic systems are susceptible to pressure differentials in the atmosphere. Therefore, research is being conducted on newer technologies that utilize piezoelectric flap actuators and/or shape-memory alloys to activate the flaps.
SPONSOR: MICHIGAN DEPARTMENT OF ENVIRONMENTAL QUALITY
PI: Qingli Dai
The reuse of scrap rubbers in Portland cement concrete has attracted many interests of researchers and practitioners in the recent decade. These practical efforts can reduce the environmental impact and save energy and resources for cement and aggregate production. In addition, the rubber-modified cement concrete have improved mechanical features, reduced weight, increased durability and toughness and decreased brittleness. Especially, the mixed crumb rubbers will introduce the uniformly distributed “elastic particles”, which have similar size-distribution as the air-entrained air voids to reduce internal stress for the improved freeze-thaw durability. In addition, the “green” geopolymer cement will be specially prepared by using alkali-activated reaction of fly ash and recycled glass powder for reduced CO2 emission and improved durability.
This project will develop a two-stage treatment approach for rubber particles to increase the material stiffness and rubber cement or geopolymer paste bonding strength. The developed techniques will facilitate the utilization of scrap rubber as fine particles in Portland cement and geopolymer concrete.
This project integrates research and education to advance the state of knowledge of the mechanism of frost-induced damage in Portland cement concrete under freeze-thaw cycles. The primary objective of this research project is to combine expertise in microstructure-based computational modeling and innovative sensor technologies to study the fundamental mechanisms of frost damage in concrete. Research will include the experimental characterization of concrete microstructure across different length scales, the development of an innovative Time Domain Reflectometry (TDR) sensor to accurately determine the freeze-thaw status, and the formulation and validation of a frost-induced damage model. This research is expected to result in a model that can clearly and concisely describe the damage that frost can inflict in concrete. This model will provide a valuable tool to assess the potential success of various frost damage prevention strategies and products.
This research will help develop durable concrete and benefit the industries involved with concrete design and construction in cold regions. The durability of concrete plays a central role in the sustainability of the whole infrastructure system on which such regions depend for their development. In this project, research and educational activities will be integrated to promote teaching, training, and learning for the K-12 students and teachers, undergraduate and graduate students in engineering and science, and professional engineers. Additionally, the methodology developed in this project for understanding the frost damage mechanisms of concrete will be applicable for solving other durability issues such as salt scaling and chemical reaction.
The short-term goals of this integrated research and education activities within the project period include: 1) development of a microstructure-based discrete element modeling approach to characterize asphalt materials; 2) implementation of the model to evaluate asphalt material response and performance to improve pavement structural design; 3) integration of the proposed research activities into the educational programs for high school students, K-12 educators, and undergraduate and graduate students, and; 4) dissemination of the research results through publications, conferences, and professional development for practicing professionals. The long-term goals are to: 1) establish a multi-user research and education center for asphalt material and virtual testing by integrating the proposed advanced modeling approach, and; 2) implement advanced technologies into pavement materials, locally through the Michigan Department of Transportation, and broadly through research collaborators and industry partners. This project will: 1) advance the understanding of asphalt pavement materials and pavement structures; 2) increase collaboration among researchers at many leading institutions and industries; 3) enhance scientific and technological understanding of micromechanical aspects of pavement infrastructure, and; 4) significantly reduce the cost of pavement infrastructure construction and maintenance. The development and application of the microstructure-based discrete element model in asphalt materials will enhance understanding by correlating material behavior to pavement performance.
The research will translate directly into improved asphalt mixture design and pavement thickness design. This in turn should create substantial cost savings. A one-percent decrease in asphalt concrete life-cycle cost would amount to approximately $500 million in U.S. Federal government savings alone. Activities are planned to advance discovery and understanding of asphalt pavement infrastructure materials while promoting teaching, training, and learning through specific activities for K-12 students and teachers, undergraduate and graduate engineering and science majors, and practicing engineers.
This award supports the participation of an American researcher, graduate student and undergraduate students in the planning visit which will take place in Malaysia. The visit will enable Professor Zhanping You in the Civil Engineering Department at Michigan Technology University to meet with Professor Meor Othman Hamzah in the School of Civil Engineering at the University Sains Malaysia (USM) in Penang. Their proposed project will involve: 1) increasing multidisciplinary collaboration among researchers in Michigan and Malaysia at their leading institutions; and 2) discovering the mechanism of rutting and fatigue distresses by using advanced micromechanics based discrete element models through the collaborative effort. The team will visit USM?s Asphalt Laboratory to work with the Malaysian professors and students to study and evaluate the feasibility of using cubical aggregated in pavement to reduce rutting potential. The students will also have an opportunity to participate in the testing of samples with/without cubic-stone materials on dynamic modulus and resilient modulus testing. The U.S. students will receive the testing results in order to use the data for discrete element modeling. The discrete element model will be further refined to study the various material phases (aggregates and mastic/asphalt) of pavement materials in order to determine the rutting and fatigue performance of asphalt pavements.
There is sufficient overlap of interests between researchers at the two universities to indicate that the researchers can successfully pursue the activities proposed, and the interaction will benefit both sides. This collaboration will advance discovery and understanding of cubic-stone materials micromechanics, while promoting teaching, training, and learning through the specific activities planned for the students. It is anticipated that the inclusion of the students in this visit will provide them unique training and educational opportunities by providing them a global research experience. These early collaborations between the scientists and students from each country will likely lead to long-term collaborations that will benefit both institutions.