NS742: Holistic Design and Selection Criteria for Unbound Geomaterials Used in Pavement Systems
Problem
It has been proven that the characteristics of unbound geomaterials used in roadway base layers significantly impact the long-term performance of pavements. In addition to the index properties of aggregates/geomaterials used in such applications, the geomechanical (e.g., shear strength, stiffness) and hydraulic properties (drainage, suction) of these materials are crucially important characteristics that affect the behavior of geomaterials under traffic loading. However, there has been limited consideration of the important requirement to balance design for drainability performance and design for mechanical (stiffness and strength) performance (i.e., well-draining base materials do not always correspond to stiff/strong base materials and vice versa).
Objective
This research will address the lack of holistic and comprehensive approach towards to mechanical and hydraulic properties of base materials predominately used in Minnesota (recycled base, limestone base, virgin glacial and alluvial base, and reclamation bases) considering the crucial role these materials play in overall structural capacity of pavement systems. The research should include a review of the current roadway foundation design practices and guidelines (e.g. MnPAVE and other Midwest states) and performing laboratory and field verification tests to develop a holistic approach/method for base course gradations that improve hydraulic conductivity and water retention properties while maintaining current strength and stiffness characteristics. The research should consider MnPAVE and its approach to the foundation layer, such as modifying the moisture resistance factors and pore suction resistance factors, to increase the implementation potential of the research outcome. Furthermore, preliminary work should be conducted to develop rating factors for material drainage that could be potentially compatible with MnPAVE.
Expected outcomes
- New or improved technical standard, plan, or specification
- New or improved manual, handbook, guidelines, or training
- New or improved decision support tool, simulation, or model/algorithm (software)
Expected benefits
The numbers 1 and 2 indicate whether the source of the benefit measurement is from:
- A specific research task in your project that supports measuring this particular benefit, or
- Implementation of the research findings (anticipating positive results)
- Construction Saving: (2)
- This work will investigate the characteristics of recycled aggregate bases, which decrease material costs and contribute to sustainability when applied.
- Decrease Engineering/Administrative Cost: (1)
- This work should include a task to develop a rating scale, modifying pore suction and seasonal moisture resistance factors for performing geomaterials. This rating scale will assist engineers in following a data-driven decision-making process for pavement design.
- Decrease Lifecycle Costs: (2)
- Implementation of this work is expected to contribute to the longevity of pavement systems by investigating the complex nature of geomaterial behavior and integrating it into the design process, thereby increasing sustainability and achieving longevity.
- Environmental Aspect: (2)
- Implementation of this work is expected to contribute to the longevity of pavement systems by investigating the complex nature of geomaterial behavior and integrating it into the design process, thereby increasing sustainability and achieving longevity. In addition, recycled base materials will be investigated within the scope of the research, which will increase sustainability and decrease the environmental impact of using virgin aggregates.
- Increase Lifecycle: (2)
- Implementation of this work is expected to contribute to the longevity of pavement systems by investigating the complex nature of geomaterial behavior and integrating it into the design process, thereby increasing sustainability and achieving longevity.
- Risk Management: (2)
- Implementation of this work offers a more holistic approach to design and material selection, explicitly considering geomechanical and hydraulic properties, as well as environmental factors.
- Climate change: (2)
- The project is expected to develop a holistic method that considers not only aggregate index properties but also hydraulic properties, which are crucial as climate change causes heavy precipitation and resulting floods.
Technical advisory panel
- Bernard I. Izevbekhai
- Raul Velasquez
- Joseph Podolski
- Terrence Beaudry
- Glenn Engstrom
- Bruce Tanquist