Minnesota Department of Transportation

Transportation infrastructure is susceptible to moisture intrusion and temperature fluctuations, which negatively impact subgrade soil stability. Calcium-based stabilizers like cement and lime are commonly used to enhance soil properties. However, to reduce material consumption and promote long-term efficiency, researchers and engineers are exploring alternative materials or co-additives that offer sustainable and cost-effective stabilization solutions. In this study, lime sludge, a waste material from water treatment plants, was utilized as a co-additive to ordinary Portland cement for stabilizing high-plasticity clay. Laboratory experiments including unconfined compressive strength (UCS), mass loss, volumetric change, plasticity index, linear shrinkage, and free swell strain were conducted on untreated specimens and on those treated with cement alone or cement-lime sludge combinations to evaluate their performance before and after exposure to environmental stressors such as freeze-thaw-wet-dry (FTWD) and wet-dry-freeze-thaw (WDFT). The results showed that treated specimens had significantly enhanced engineering strength and reduced swell-shrink potential compared to untreated specimens. The inclusion of lime sludge further increased the strength of cement-treated specimens. In addition, specimens subjected to FTWD cycles demonstrated slightly better performance than those under WDFT cycles. Among the treatments, a combination of 8% cement and 4% lime sludge was able to withstand environmental stressors, with a residual strength of about 1,200 kPa (180 psi) after the eighth cycle. These findings provide preliminary evidence that lime sludge can be used as a sustainable co-additive to cement for stabilizing expansive soils, while also aiding in more efficient lime sludge waste management.

Throughout the United States, storms and floods cause widespread damage, disruption, hardship, and economic burdens when transportation systems are disrupted. Extreme rainfall threatens infrastructure in riverine environments through mechanisms such as flooding, landslides, and erosion. Both intense short-duration and long-duration rainfall events are especially challenging in mountainous terrain where road and rail corridors often encroach on rivers and concentrate floodwater flow and increase velocity. Both historically and recently, extreme flood events throughout the nation have resulted in dramatic landscape changes with consequential damage to infrastructure, including bridges, rail and roadway embankments, utilities, as well as residences, businesses, and other facilities. Mountainous areas, because of the topography, often lack redundant networks, increasing the need for resilient transportation corridors to ensure the ability to rapidly respond and recover after flood events. Transportation agencies are exploring ways to improve resilience, identify risk, prioritize investments, and systematically explore ways to lessen the severity of impacts or shorten recovery times to restore transportation corridors to serviceable conditions. While technical strategies to reduce risk exist, they are often not implemented in a systematic, and well-funded, way. These slopes are not explicitly included in transportation asset management plans, so State Departments of Transportation (DOTs) have a wide range of approaches to handling their monitoring and repair. Multidisciplinary efforts will be essential to develop vulnerability assessments and integrated solutions addressing both complex technical challenges and asset management planning and funding through risk-based approaches.

In 2022 the construction initiative that was undertaken at MnROAD was the largest to take place since the initial construction of MnROAD in 1993 on the Mainline of I-94 WB (a 3 mile stretch of interstate), a segment of I-94 WB that runs parallel and North of the original I-94 WB built during the early 1970s. The focus of the construction initiative towards rigid pavement materials was sustainability and resiliency, i.e., reducing the carbon footprint from material use, and mix design optimization while still performing well. As part of this construction in 2022, 18 new rigid pavement test sections were built, of which 6 test sections dealt with the use of carbon dioxide for sustainable and resilient concrete pavements. This work will discuss the flexural and compressive strength-maturity trends observed in each of these 6 mixes. The general form of the Nurse-Saul equation appeared valid for the carbon dioxide injected mixtures as well as their controls. The low level of injected carbon dioxide as well as the use of inter-ground limestone may have reduced the overall effect. However, the results indicated a clustering of the various factorials of the carbon dioxide mixtures and the controls on the basis of the model constants derived from the Nurse-Saul equation. Nevertheless, maturity method was proven to be a reliable and sustainable alternative to time-consuming production and elaborate testing of cylinders and beams for compressive and flexural strength.

A new, multi-fiber, expanded beam optical ferrule, with state-of-the-art IL<0.7 dB (typical 0.34 dB), RL>55 dB for single mode (1310 nm), and IL<0.3 dB (typical 0.14 dB), RL>40 dB for multimode (850 nm), is reported.

ABSTRACT Establishing relationships between the results of laboratory mechanical tests and field performance of the asphalt concrete layer is a necessary step prior to the test implementation at the mix design stage or during production. The objective of this study is to confirm the relationship between the Uniaxial Thermal Stress and Strain Test (UTSST) results and measured field cracking data for test sections at the Minnesota Road Research Project (MnROAD). The interpretation of UTSST results, conducted on reheated plant specimens, highlights the considerable effect observed for the asphalt binder grade on performance; whereas the long-term aging data set suggests a dominant effect of the amount of recycled materials in the mixture. Several UTSST parameters resulted in robust relationships with the mix Bending Beam Rheometer (BBR) and Semi-Circular Bending (SCB) test parameters, including the UTSST cracking resistance index (CRIEnv ) with the mix BBR strain at failure. The UTSST parameters exhibited the most significant correlations with load and non-load field cracking data. Some of the prominent relationships observed corresponding to the shoulder cracking data with the UTSST glassy temperature and Δ T m i x U T S S T , suggest an improved resistance to non-load related cracking due to a delayed transition of the asphalt mixture to the glassy stage.