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  1. In cold regions, the soil temperature gradient and depth of frost penetration can significantly affect roadway performance because of frost heave and thaw settlement of the subgrade soils. The severity of the damage depends on the soil index properties, temperature, and availability of water. While nominal expansion occurs with the phase change from pore water to ice, heaving is derived primarily from a continuous flow of water from the vadose zone to growing ice lenses. The temperature gradient within the soil influences water migration toward the freezing front, where ice nucleates, coalesces into lenses, and grows. This study evaluates the frost heave potential of frost-susceptible soils from Iowa (IA-PC) and North Carolina (NC-BO) under different temperature gradients. One-dimensional frost heave tests were conducted with a free water supply under three different temperature gradients of 0.26°C/cm, 0.52°C/cm, and 0.78°C/cm. Time-dependent measurements of frost penetration, water intake, and frost heave were carried out. Results of the study suggested that frost heave and water intake are functions of the temperature gradient within the soil. A lower temperature gradient of 0.26°C/cm leads to the maximum total heave of 18.28 mm (IA-PC) and 38.27 mm (NC-BO) for extended periods of freezing. The maximum frost penetration rate of 16.47 mm/hour was observed for a higher temperature gradient of 0.78°C/cm and soil with higher thermal diffusivity of 0.684 mm 2 /s. The results of this study can be used to validate numerical models and develop engineered solutions that prevent frost damage. 
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  2. The structural capacity of pavement foundation is altered by moisture conditions. Reliable moisture monitoring of geomaterials throughout pavement service life is critical for asset management by transportation agencies. Improved moisture sensing enables transportation officials and practitioners to better understand performance of complex recycled materials under frequent extreme rain events. Although moisture sensing for geomaterials has improved significantly, there are still challenges when using sensors in recycled materials that may contain unhydrated cement, aged asphalt, or both. Challenges include the development of calibration functions that account for the presence of recycled materials and robust installation procedures, as technology was developed mostly for agricultural practices. In this study, a series of experiments were conducted to suggest improvements for installation techniques and data interpretation of soil moisture and water potential sensors. Suggested installation guidelines minimize wash-out and erosion potential at the soil–sensor interface. Experimental results indicate a strong bilinear relation between dielectric of recycled materials and water content, with a region of relatively small change governed by dielectric permittivity of air and a region of rapid change controlled by dielectric permittivity of water. Moreover, it was found that dielectric permittivity is not significantly affected by aggregate internal structure as dielectric for a specific moisture content for different compaction degrees is relatively similar. Furthermore, soil water characteristic curves obtained using the water potential sensor and improved installation technique compare reasonably well with laboratory results obtained with traditional equipment. Reliability of both moisture and water potential sensors was improved with the suggested guidelines. 
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  3. Frost action in soils causes a significant effect on the performance of roadways. This effect is more pronounced in the regions that are experiencing seasonal subfreezing temperatures as the soil undergoes multiple freeze-thaw cycles. Apart from the subfreezing temperature, the frost action is also affected by the soil type as the void ratio and hydraulic conductivity of soils control the presence and movement of water for the growth of ice lenses. Frost heave is mainly attributed to silty soils, but significant frost heave can also occur in clay and sandy soils under favorable environmental conditions. For the present study, frost heave and thaw settlement of clayey and sandy soils, subjected to a one-dimensional freeze-thaw cycle, is investigated to determine how the frost action varies with soil types. Soil specimens were subjected to ten freeze-thaw cycles. Total heaving, heave rate, and water intake were measured as a function of time during testing. The moisture content of the soils after ten freeze-thaw cycles was also measured. The amount of pore water and external water supply affects the total heave during freeze-thaw cycles. Therefore, the effect of moisture availability during the freeze-thaw cycles was also investigated by comparing the results of specimens with or without an external water supply. Results of the study suggested that significant frost heave occurred in both clay and sandy soils. In addition, the application of ten freeze-thaw cycles provided a better estimation of the total heave than that observed with two freeze-thaw cycles (typical/standard numbers of freeze-thaw cycles). The maximum heave (40.9 mm) and heave rate (5.01 mm/day) were found to be higher in clay soil. The presence of an external water supply contributed to the frost action, and total heave was seven times higher in soils with an external water source. Soil with a free water supply showed 1.1–1.7 times higher moisture content after ten cycles compared to the soils with no external water supply. These results were used in estimating the frost heave potential of soils in different environmental conditions. 
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  4. Anne Lemnitzer, Ph.D. ; Armin W. Stuedlein (Ed.)
    Selected papers from sessions of Geo-Congress 2022, held in Charlotte, North Carolina, March 20–23, 2022. Sponsored by the Society of Exploration Geophysicists and the Geo-Institute of ASCE. This Geotechnical Special Publication contains 66 peer-reviewed papers on geosynthetics, innovative geomaterials, and soil improvement techniques. Topics include: rigid inclusions and stone columns; soil stabilization; bio-grouting and bio-inspired solutions; geosynthetics; and innovative geomaterials and methods. GSP 331 will be valuable to practitioners and researchers working in the area of soil improvement. 
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  5. Anne Lemnitzer ; Armin W. Stuedlein (Ed.)
    Selected papers from sessions of Geo-Congress 2022, held in Charlotte, North Carolina, March 20–23, 2022. Sponsored by the Society of Exploration Geophysicists and the Geo-Institute of ASCE. This Geotechnical Special Publication contains 66 peer-reviewed papers on geosynthetics, innovative geomaterials, and soil improvement techniques. Topics include: rigid inclusions and stone columns; soil stabilization; bio-grouting and bio-inspired solutions; geosynthetics; and innovative geomaterials and methods. GSP 331 will be valuable to practitioners and researchers working in the area of soil improvement. 
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  6. Anne Lemnitzer, Ph.D. ; Armin W. Stuedlein (Ed.)
    Selected papers from sessions of Geo-Congress 2022, held in Charlotte, North Carolina, March 20–23, 2022. Sponsored by the Society of Exploration Geophysicists and the Geo-Institute of ASCE. This Geotechnical Special Publication contains 56 peer-reviewed papers on monitoring and sensing and embankments, dams, and slopes. Topics include: monitoring and remote sensing for geo-systems; geotechnics of resilient infrastructure; pavements; geotechnical engineering education; and data and software in geotechnical engineering. GSP 336 will be valuable to practitioners and researchers working in the areas of pavements and remote sensing and monitoring of geo-systems. 
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  7. Christopher L. Meehan ; Miguel A. Pando, Ph.D. ; Ben A. Leshchinsky ; Navid H. Jafari (Ed.)
    Proceedings of sessions of Geo-Extreme 2021, held in Savannah, Georgia, November 7–10, 2021. Sponsored by the Geo-Institute of ASCE. GSP 330 contains 37 peer-reviewed papers on infrastructure resilience, big data, and risk. Topics include: geo-materials under extreme loading; cold regions and the Arctic; decision making and planning for extreme events; big data and modeling; and risk management. This GSP will be of interest to geotechnical engineers, climate scientists, emergency managers, insurance professionals, and policy makers working to address a wide variety of extreme events. 
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