The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.

American Society for Testing and Materials

The Environmental Protection Agency (EPA) provides access to information on a variety of topics related to the environment and strives to inform citizens of health risks. The EPA also has an extensive library network that consists of 26 libraries throughout the United States, which provide access to a plethora of information to EPA employees, scientists, and researchers. The EPA implemented a reorganization project to digitize their materials so they would be more accessible to a wider range of users, but this plan was drastically accelerated when the EPA was threatened with a budget cut. It chose to close and reduce the hours and services of some of their libraries. As a result, the agency was accused of denying users the “right to know” by making information unavailable, not providing an adequate strategic plan, and discarding vital materials. This case study explores the background of the digitization project, the practices implemented, and the critiques of the project.

/pdf/the-environmental-protection-agency-3gx4opzrjm.pdf

The Environmental Protection Agency

Artificial neural networks (ANNs) constitute a class of flexible nonlinear models designed to mimic biological neural systems. In this entry, we introduce ANN using familiar econometric terminology and provide an overview of ANN modeling approach and its implementation methods. † Correspondence: Chung-Ming Kuan, Institute of Economics, Academia Sinica, 128 Academia Road, Sec. 2, Taipei 115, Taiwan; ckuan@econ.sinica.edu.tw. †† I would like to express my sincere gratitude to the editor, Professor Steven Durlauf, for his patience and constructive comments on early drafts of this entry. I also thank Shih-Hsun Hsu and Yu-Lieh Huang for very helpful suggestions. The remaining errors are all mine.

Artificial neural networks

Highway Capacity Manual改訂の動向--テイラ-教授の講演より

Dynamics of structures

Two sections at the Virginia Smart Road were instrumented and constructed to quantify the effectiveness of a geocomposite membrane as a moisture barrier and as a strain energy absorber. Results of ground penetrating radar (GPR) surveys and time domain reflectometer (TDR) moisture sensors validated the effectiveness of the geocomposite membrane in abating water infiltration into the subbase layer even in the event of heavy rain. The potential of the geocomposite membrane to mitigate the reflection of cracks was theoretically investigated using the finite element (FE) analysis approach. A model was developed to simulate a cracked pavement structure by creating a singularity at the crack tip. Four contour lines were simulated around the crack to calculate the path-independent integral. Analysis of results indicates that the geocomposite membrane is effective in dissipating a large amount of energy around the cracked region. This has been verified by field cores and falling weight deflectometer (FWD) data analyses. The study showed that a soft interlayer system might increase the number of cycles for crack initiation by several orders of magnitude. For the covering abstract see ITRD E117244.

Analytical modeling and field performance testing of geocomposite membrane in flexible pavement systems

Fine-graded (F-G) asphalt concrete mixtures are composed of an aggregate structure in which the fine fraction controls the load-carrying capacity of the mix. Other states have reported benefits in using F-G mixtures, including improved compaction, lower segregation, and lower permeability—resulting in longer life. Rutting concerns have been mitigated through the use of manufactured sand. This study investigates the feasibility of using F-G mixtures for IL 19.0 mm (3/4 in) asphalt binder courses in Illinois. A careful laboratory investigation, including mix designs guided by the Bailey Method, was conducted, then followed by extensive laboratory performance testing. Performance tests indicated that the F-G mixtures had equivalent or superior rut and crack resistance to a reference coarse-graded (C-G) control mixture. Limited field trials demonstrated the F-G mixtures were easier to compact, led to higher pay factors, and had significantly lower permeability than traditional C-G mixtures, while being similar in cost. Whether designing a coarse- or fine-graded mixture, optimum asphalt content will be the same when using the same materials and targeting the same voids in mineral aggregate (VMA) and voids level, provided asphalt absorption remains constant. Limited full-scale accelerated pavement tests also demonstrated similarity in rutting resistance between the C-G and F-G mixtures investigated. Recommendations for implementation of F-G mixtures are provided, along with a revised draft specification for 19.0 mm mixtures. The revised specification provides upward adjustments to the lower side of the gradation band at the primary control sieve to lessen the likelihood of designing segregation-prone binder mixtures and raises the upper band to permit F-G mixtures to be designed. These principles apply to surface course mixtures as well.

https://rosap.ntl.bts.gov/view/dot/28816/dot_28816_DS1.pdf

Designing, producing, and constructing fine-graded hot mix asphalt on Illinois roadways.

This chapter reports on the long-term weathering of 12 bituminous sealants that contain thermoplastic elastomers, namely block copolymers of polystyrene and polybutadiene. The goal of the work was to determine the rate and mechanisms of sealant weathering so that future accelerated aging tests could be developed. By means of physico-chemical analysis, much weathering was found to occur in the early years of service. Weathering pathways were found to be mass loss, oxidation, and copolymer degradation. Specific mechanisms include the loss of aromatics with time, the formation of sulphoxides, sulphones, and their acids, ketones, and carboxylic acids. Block copolymer degradation occurs mainly through a scission between polystyrene and polybutadiene blocks, and the crosslinking of polybutadiene fragments. The chapter ends with a brief discussion of the suitability of current accelerated aging tests to simulate the natural weathering of elastomeric sealants.

Natural weathering of styrene–butadiene modified bitumen

The use of life-cycle assessment (LCA) to assess the environmental impacts of pavement systems has become more prevalent in recent years. When performing an LCA study, a series of methodological ch...

Effect of Methodological Choices on Pavement Life-Cycle Assessment:

This paper discusses an investigation conducted to evaluate the frictional properties of seven wearing surfaces used at the Virginia Smart Road Variations in the International Friction Index (IFI) measurements due to hot-mix asphalt (HMA) design characteristics and testing conditions (tire, test vehicle speed, and grade) were analyzed The mixtures studied were five different SuperPave mixtures, a stone mastic asphalt (SMA), and an open-graded friction course (OGFC) Surface characteristics were periodically monitored using a locked-wheel trailer, a British Portable Tester, and laser texture measuring devices HMA properties were measured from both field cores and lab compacted samples The effect of specific mixture properties on the International Friction Index was studied, including voids in the mineral aggregate, total voids in the mixture, percentage passing the number 200 sieve, and binder type and content

Imad L. Al-Qadi

Papers

Analytical modeling and field performance testing of geocomposite membrane in flexible pavement systems

Designing, producing, and constructing fine-graded hot mix asphalt on Illinois roadways.

Natural weathering of styrene–butadiene modified bitumen

Effect of Methodological Choices on Pavement Life-Cycle Assessment:

Effect of hma design properties on pavement surface friction