Pavements

The Midwest region of the United States, including Minnesota, has been experiencing an increase in the number of heavy precipitation events. Historical precipitation data confirmed an increasing trend of heavy precipitation in Minnesota in the 21st century. This study focused on assessing the impact of heavy-precipitation events on moisture levels and stiffness of pavement foundation layers at the MnROAD facility. A two-step approach was adopted for predicting changes in saturation and for estimating corresponding resilient modulus values using the resilient modulus prediction equation employed in AASHTOWare Pavement Mechanistic-Empirical (ME) design. PLAXIS 3D, a finite element analysis tool, was used to simulate the movement of moisture within the pavement layer under varying heavy rainfall scenarios. Multiple linear regression models were developed from rainfall simulation data of the PLAXIS 3D model to predict base layer saturation based on rainfall characteristics and hydraulic conductivity of the material. ArcGIS Pro was then used to develop a framework to generate a preliminary vulnerability map showing changes in the resilient modulus of the pavement base layer from rain events. Four regression models were developed and used in ArcGIS Pro to predict changes in resilient modulus for distinct aggregate types under heavy rainfall events, revealing significant reductions in the base layer's resilient modulus. Recycled aggregate (a mix of recycled concrete aggregate and recycled asphalt pavement) emerged as more susceptible, with initial reductions in modulus values higher under heavy rainfall.

This Research Summary is part of Report 2024-01, "Performance Monitoring of Olmsted CR 117 and 104 and Aggregate Base Material Update," published March 2024.

A performance monitoring and forensic study was conducted on several test sections with varying base and pavement characteristics. This report includes the performance data from the current phase, which was extended until pavement reconstruction, with the previously reported data, collected since original construction of the test sections. Each of the three original test sections were prepared with a different combination of base type and asphalt binder type. Three different crushed limestone base types were used in the construction: (Section 1) standard Class 5, (Section 2) permeable aggregate base (PAB), and (Section 3) Class 5 modified. Two different types of asphalt binders, PG 58-28 and PG 58-34, were incorporated to evaluate the effects of cold temperature cracking. All asphalt mixtures were designed according to MnDOT Specification 2350. In addition to the comparisons among sections, each road section was constructed, both with and without transverse sawn-and-sealed regularly spaced joints, to evaluate the relative performance for ride and cracking (both spacing and crack severity) of sawing and sealing (S&S) versus allowing thermal cracking to relieve tensile stress without sawing and sealing (non-S&S). Prior to reconstruction, the severity of cracking in Section 1 was significantly higher than in Sections 2 and 3, with no severe cracking observed in Section 3. This study confirmed previous research efforts on this project, indicating that the combination of PG58-34 binder with Class 5 modified base material (Section 3) and PAB base (Section 2) performed well as compared to the control section. Seasonal trends of reduced stiffness during spring thaw followed by rapid recovery were also observed in the FWD analysis.

This cover letter accompanied the 2023 Legislative Report on Pavement Life-cycle Cost Analyses.

This report is required by Minnesota Stat. § 174.185. The statute requires a life-cycle cost analysis for every project in the reconditioning, resurfacing and road repair funding categories. The LCCA is a comparison of life-cycle costs among competing paving materials using equal design lives and equal comparison periods. A LCCA is required for all projects constructed after July 1, 2011.

This cover letter accompanied the 2022 Legislative Report on Pavement Life-cycle Cost Analyses.

This report is required by Minnesota Stat. § 174.185. The statute requires a life-cycle cost analysis for every project in the reconditioning, resurfacing and road repair funding categories. The LCCA is a comparison of life-cycle costs among competing paving materials using equal design lives and equal comparison periods. A LCCA is required for all projects constructed after July 1, 2011.

This cover letter accompanied the 2021 Legislative Report on Pavement Life-cycle Cost Analyses.

This report is required by Minnesota Stat. § 174.185. The statute requires a life-cycle cost analysis for every project in the reconditioning, resurfacing and road repair funding categories. The LCCA is a comparison of life-cycle costs among competing paving materials using equal design lives and equal comparison periods. A LCCA is required for all projects constructed after July 1, 2011.

This cover letter accompanied the 2020 Legislative Report on Life-cycle Cost Analyses Cover Letter.