The emergent network structure of the multilateral environmental agreement system

The conventional piecemeal approach to environmental treaty-making has resulted in a 'maze' of international agreements. However, little is known empirically about its overall structure and evolutionary dynamics. This study reveals and characterizes the

Unravelling the maze of multilateral environmental agreements: a macroscopic analysis of international environmental law and governance for the anthropocene

Earth has entered a new geological epoch, the Anthropocene, where humans have become a major driver of global environmental change. Many believe, however, that current international environmental law is a maze of international agreements, and it is unsuitable for navigating the Anthropocene. It is generally agreed that, for global sustainability, this institutional maze needs to be modelled in ways more appropriately aligned with the functioning of the Earth system itself. For the purpose of improving the alignment, this PhD thesis explores the structural and functional dynamics of multilateral environmental agreements (MEAs) as a systemic whole in relation to Earth system dynamics. The thesis begins with a preliminary review of international environmental law through the lens of a specific systems theory called complex adaptive systems. It then provides two parallel empirical studies on the macroscopic structure and function of the MEA system. In terms of the structure, I quantitatively analysed and characterized the topological properties of the dynamic web of 747 MEAs as approximated by 1,001 cross-references found in their texts. This network analysis provided novel insights into how MEAs have self-organized into an interlocking network with complex topology and what the emergent order looks like. In terms of the function, I conducted a qualitative case study on ocean acidification to examine whether the networked system of MEAs is autonom! ously capable of filling the regulatory gap through mutual adjustments. Inherent weaknesses in the polycentric order were observed, which led to the conclusion that a new MEA on ocean acidification is necessary. Despite the interlocking structure, the MEA system is currently limited by its design to a piecemeal approach to global environmental governance. The conceptual and empirical studies provided several implications for the design of international environmental law in the Anthropocene. In particular, the thesis makes a case that the absence of an international environmental grundnorm is preventing a more purposive, systemic continuum of laws, one that would ensure policy coherence across Earth's subsystems. The thesis concludes that international environmental law needs a clearly agreed, unifying goal to which all international regulatory regimes are legally bound to contribute. I suggest that this goal should be about the protection of the integrity of Earth's life-support systems

New Mixture Additives for Sustainable Bituminous Pavements

In an effort to improve mechanical properties of asphalt concrete, an exploratory research using mixture additives was attempted. Two different types of additives on two material scales were used: asphalt concrete (AC) level and binder level. At the start of this study, the effect of natural cornhusk fibers on the resistance of two types of AC mixtures on cracking were tested for hot-mix asphalt (HMA) and cold-mix asphalt (CMA). The results showed slight improvements in cracking resistance in cornhusk reinforced HMA, and in the case of the CMA, marshal flow. Overall, based on the test results, cornhusk-reinforced HMA and CMA may not significantly improve critical mechanical properties given the added cost of fibers. In addition, cornhusk fibers proved difficult to properly disperse in HMA and CMA when mixed in laboratory. However, when fibers were mixed in an asphalt production plant, the fibers appeared to become more distributed. The second part of this study, two different types of carbon nano-fillers (F1 and F2) with different surface properties and sizes were added to two different asphalt binders: the base binder and the polymer modified binder. Also, mastic samples were prepared by replacing parts of the limestone filler by the carbon nano-fillers. It was observed that the nanoscale additives interacted with the binder quite differently. Additive F1 did not show a drastic improvement in the mechanical properties, fatigue resistance, and rutting resistance of the base and polymer modified binder at the mastic and the binder scale; however, additive F2 improved all the above- mentioned properties. From the experimental investigation, it can be inferred that part of the polymer modification can be replaced by additive F2. Although additive F1 showed a minimal change, it could be useful in improving the secondary application of the pavement, such as the electrical conductivity, thermal conductivity, and absorption of radiation for energy storage, which was not the scope of this study but appears worthy to investigate

Evaluation of Dowel Bar Inserter Practices in PCC Pavements with Magnetic Tomography Technology

Dowel Bar Inserters (DBI) are automated mechanical equipment that position dowel bars in Portland Cement Concrete (PCC) after concrete is placed. Compared to the alternative approach, which is using dowel baskets, DBIs offer advantages in cost and speed of construction. However, as dowel bars are not anchored to the subgrade similar to dowel baskets, there is a concern about the quality of dowel placement using this equipment. Improper placement of dowel bars can lead to reduced load transfer between slabs, which results in pavement distresses such as faulting and spalling at joints. To determine the accuracy of dowel placement by DBI, the Nebraska Department of Roads has used an MIT Scan-2 device to scan the joints in projects where a DBI was used. This device uses a nondestructive magnetic imaging technique to capture the position of dowel bars inside the pavement. The aim of the this project is to analyze the MIT Scan-2 data of the joints constructed using a DBI, and to compare them with the corresponding field performance data. This will allow us to judge if DBI is a reliable alternative for dowel placement, and to improve Nebraska’s current specifications for dowel placement tolerances. To meet the objectives, the MIT Scan-2 data of scanned joints were initially compared with dowel placement specifications suggested by national agencies. It was observed that the longitudinal translation and rotation of dowels in a portion of scanned joints fell outside recommended tolerances. The longitudinal and vertical translation of the dowels were respectively higher and lower than the average values reported by a similar study (Khazanovich et al. 2009). MIT Scan-2 data and field performance data were then compared to find any linkage between pavement distresses and dowel misalignment levels, enabling us to potentially improve Nebraska’s current specifications as well as conclude if any of the distresses were caused by low placement accuracy of the DBI. No linkage was found between pavement performance and dowel misalignment levels for over 220 joints that were investigated in this study. No transverse cracking was observed during field investigation, and the spalling at joints was likely to be the result of joint saw-cut operations. However, measured distress from joints with missing or completely shifted dowels show that high severity dowel misalignment has an adverse effect on joint performance

Evaluation of Tack Coating Practices for Asphalt Overlays in Nebraska

The strength of the bond between asphalt layers affects the lifespan of pavement structures. It is also a key factor in preventing major pavement distresses, such as slippage cracking and delamination. This research project evaluates and compares the effectiveness and performance of different tack coating approaches to ensure the proper bond strength is achieved in asphalt concrete (AC) interlayers through an experimental study. Various tack coat materials, including different types of emulsified asphalt and asphalt binders, at multiple application rates and dilution ratios were investigated. In the first part of this study, laboratory-prepared samples were used to evaluate the sensitivity and effectiveness of the direct shear testing (DST) method, which was selected for the characterization of the AC interlayers where different tack coats were treated. Then, emulsified asphalts and binders were applied to a field test section by varying application rates. The DST was performed under a monotonic loading condition at three different testing temperatures. Interlayer shear strengths were used to rank the performance of the tack coats. In addition, cyclic DST was conducted to investigate fatigue behavior of the interlayers treated with different tack coats. The parameters obtained from the monotonic DST were compared with the fatigue DST results. In general, the test results showed superior interlayer performance from CFS-1 and CRS-2P at double application rate (i.e., 0.16 gal/yd2 residual application rate) and CFS-1 at the standard application rate (i.e., 0.08 gal/yd2 residual application rate). Moreover, CRS-2P provided the shortest breaking time among all the emulsified tack coats. With regard to the correlation between the monotonic and cyclic DST results, the maximum shear force showed an acceptable correlation with the fatigue test results, and the interlayer bond energy, which can also be determined using a monotonic DST, is a good (or better) predictor of the fatigue-related shear resistance of the tack coats due to its higher correlation with the fatigue test results

Evaluation of Dowel Bar Inserter Practices in PCC Pavements with Magnetic Tomography Technology

Dowel Bar Inserters (DBI) are automated mechanical equipment that position dowel bars in Portland Cement Concrete (PCC) after concrete is placed. Compared to the alternative approach, which is using dowel baskets, DBIs offer advantages in cost and speed of construction. However, as dowel bars are not anchored to the subgrade similar to dowel baskets, there is a concern about the quality of dowel placement using this equipment. Improper placement of dowel bars can lead to reduced load transfer between slabs, which results in pavement distresses such as faulting and spalling at joints. To determine the accuracy of dowel placement by DBI, the Nebraska Department of Roads has used an MIT Scan-2 device to scan the joints in projects where a DBI was used. This device uses a nondestructive magnetic imaging technique to capture the position of dowel bars inside the pavement. The aim of the this project is to analyze the MIT Scan-2 data of the joints constructed using a DBI, and to compare them with the corresponding field performance data. This will allow us to judge if DBI is a reliable alternative for dowel placement, and to improve Nebraska’s current specifications for dowel placement tolerances. To meet the objectives, the MIT Scan-2 data of scanned joints were initially compared with dowel placement specifications suggested by national agencies. It was observed that the longitudinal translation and rotation of dowels in a portion of scanned joints fell outside recommended tolerances. The longitudinal and vertical translation of the dowels were respectively higher and lower than the average values reported by a similar study (Khazanovich et al. 2009). MIT Scan-2 data and field performance data were then compared to find any linkage between pavement distresses and dowel misalignment levels, enabling us to potentially improve Nebraska’s current specifications as well as conclude if any of the distresses were caused by low placement accuracy of the DBI. No linkage was found between pavement performance and dowel misalignment levels for over 220 joints that were investigated in this study. No transverse cracking was observed during field investigation, and the spalling at joints was likely to be the result of joint saw-cut operations. However, measured distress from joints with missing or completely shifted dowels show that high severity dowel misalignment has an adverse effect on joint performance

Non-Nuclear Method for Density Measurements

Quality control (QC) and quality assurance (QA) are necessary to ensure fulfillment and compliance to specifications, guidelines, manuals, and programs which outline methods and requirements during construction. Density, an important part of quality control, can be used to evaluate the quality of Hot Mix Asphalt (HMA) and soil compaction. This study investigated new technologies used for QC and QA by comparing the Pavement Quality Indicator (PQI) model 301 with a nuclear gauge and core sample measurements for HMA. For soil QC and QA, non-nuclear technologies—the Electrical Density Gauge (EDG), the Moisture Density Indicator (MDI), and the Light Weight Deflectometer (LWD)—were also investigated against a nuclear gauge and traditional non-nuclear methods of measurement. Overall, the nuclear gauge shows higher accuracy and higher correlation with cores than the non-nuclear gauges tested in this study. A thorough investigation of calibration methods was also performed, both in the lab and on the field, to improve the accuracy of the PQI‘s results. Data analyses showed that the accuracies of the non-nuclear soil gauges are somewhat lower than that of the nuclear gauge. With an improved methodology to create soil models for the EDG and standardized ways to develop the LWD‘s target values, the EDG and LWD could have a similar or better accuracy than the nuclear gauge. With the EDG and the Soil Density Gauge (SDG), both recently ASTM approved, nonnuclear soil technology is the future. Furthermore, the non-nuclear gauges could be a better alternative to a nuclear gauge when the following benefits are considered: (1) economic savings; (2) faster data measurement (PQI); (3) elimination of intense federal regulations and safety concerns; (4) elimination of licensing and intense training

Investigation of DSR Test Methods to Determine Binder Low Temperature Properties

The low temperature rheology of bituminous binders is of great interest because low temperature cracking is one of the primary asphalt pavement failure modes observed in cold-climate places such as Nebraska. Low temperature binder characterization/grading has been primarily conducted using the bending beam rheometer (BBR), while the dynamic shear rheometer (DSR) can alternatively be used to characterize the low temperature properties of binders with the recent advancement of DSR equipment that can cover a wide range of testing temperatures. This study investigates alternative testing-analysis methods using the DSR to determine low temperature asphalt binder properties that have been measured by the BBR. Toward that end, twelve different binders from four sources satisfying three different PG grading criterion common in Nebraska were selected. The binder samples were tested in the frequency domain at temperatures ranging from 60°C to -30°C under PAV-aged conditions using DSR. The 8-mm parallel plate geometry was primarily employed for the testing, while four binders were randomly selected and tested using the 4-mm parallel plate to investigate the influence of geometry on the results. BBR experiments were also performed as a parallel for each binder. Three methods were used to analyze and compare the data from the two different experiments (i.e., DSR and BBR) where each method utilizes a different scheme for converting the frequency domain results to time domain data to compare with the BBR results. The three methods are: (1) Western Research Institute’s (WRI) methodology; (2) NCHRP methodology; and (3) UNL’s mechanistic approach. It was observed that the DSR testing is quite promising, and sample preparation is crucial to obtain reliable-repeatable results. Moreover, in the proposed UNL’s mechanistic approach, it was observed that a single shift factor for creep compliance may account for different testing conditions, differences in physical hardening and temperature-dependent effects. The approach was then extended to seven additional binders to further examine its feasibility, and it was observed that the predictions from the proposed approach match well with the experimental values