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 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.
Sponsor: Michigan Department of Environmental Quality (MIDEQ)
PI: Qingli Dai
In the recent decade, the resuse of scrap tire rubbers in concrete has attracted much interests of researchers and practitioners. The practical efforts can reduce the environmental impact. In general, the rubber-modified concrete can improve static and dynamic fracture toughness and decrease brittleness. Particularly, the mixed rubber particles (mesh size #10-#30) will introduce the uniformly distributed “elastic entrained particles”, which can release internal expansive stress due to freeze-thaw damage and chemical attack for improved durability. In addition, the surface-treated rubber particles have good bonding strength with cement paste. Continue reading “Fiber-reinforced High Performance Rubber Concrete for Concrete Structure Construction and Repair”
The objective of this collaborative research project is to advance the smart blade system through innovations in areas of advanced computational models of fluid-structure interactions, sensors and actuators. Wind energy, an important source of clean and renewable energy, is becoming a major component of the U.S. energy portfolio. The interest in large capacity wind turbines as an economical way to harvest wind energy has significantly increased in recent years. Wind turbine blades are over 100m in length and the trend of increasing the size of the blades continues. However, increases in the size of wind turbine blades means that aerodynamic vibrations need to be managed to prevent catastrophic failures. The collaborative project team takes an innovative perspective to advance the smart turbine blade technology. The hypothesis of this research is that aerodynamic vibrations in wind turbine blades can be effectively mitigated with bio-inspired strategies for flow sensing, surface morphological change and fluid-structure interactions. The specific goals of this research project are 1) to understand blade vibration dynamics with advanced modeling of fluid-structure interactions; 2) to study the mechanism of bio-sensing for flow turbulence determination and to implement a feasible sensor design strategy; and 3) to understand and emulate the functions of “smart fins” and “smart denticles” for aerodynamic vibration reductions. A systematic approach will be undertaken by combining modeling, sensing and actuation strategies. The smart blade system performance will also be validated via simulation-based virtual testing and reduced-scale model experiments. All of these aim to advance the state of art in the smart wind turbine blades.
This project presents a great opportunity to advance smart blade technologies, which include intelligent components for blade vibration reduction. A unique bio-inspired strategy will be pursued to prevent catastrophic failures of wind turbine blades by effectively mitigating the aerodynamic vibrations. The strategy will also improve the operational efficiency of the wind energy system. All of these advances will have important impacts on the safe and efficient production of wind energy.
Sponsor: Michigan Tech Transportation Institute (MTTI)
PI: Zhen Liu, Qingli Dai
The air void size distribution has significant impacts on mechanical, thermal and transport properties of concrete and long-term durability such as freeze-thaw resistance. Measuring the characteristics of air voids in concrete (especially at early-ages) is thus very important in assessing its long-term durability. Nondestructive ultrasonic technique will be developed for potential concrete mixture quality control both in lab and field applications.
1. Develop ultrasonic air void size distribution measurement techniques for hardened air-entrained concrete and evaluate the accuracy with ASTM C 457 measurements
2. Develop ultrasonic air void size distribution measurement techniques for early-age air-entrained concrete and evaluate the accuracy with the ASTM C 457 measurements
3. Develop the testing procedures and data processing tools for potential field applications
1. Prepare air-entrained concrete samples with/without internal curing reservoirs (using light-weight fine aggregates) for air void distribution measurements
2. Design the ultrasonic measurement system for both hardened and early-age concrete sample measurements and develop the signal processing programs for the air void distribution evaluation of both types of samples
3. Evaluate the measurement accuracy by comparing with RapidAir ASTM C 457 and propose the testing procedures for potential field mixture quality control