bluuebunny/crossref_metadata_2025 huggingface dataset:
Normal Glucose Tolerance and Gestational Diabetes Mellitus
Authors: Di Cianni Graziano , Seghieri Giuseppe , Lencioni Cristina , Cuccuru Ilaria , Anichini Roberto , De Bellis Alessandra , Ghio Alessandra , Tesi Federica , Volpe Laura , Del Prato Stefano
Published: June 2007

OBJECTIVE— The aim of this article was to define the metabolic phenotype of pregnant women with one abnormal value (OAV) during an oral glucose tolerance test (OGTT) and to test whether OAV could be considered metabolically comparable to gestational diabetes mellitus (GDM) or a specific entity between GDM and normal pregnancy.

RESEARCH DESIGN AND METHODS— After 100-g 3-h OGTTs, 4,053 pregnant women were classified as having GDM, OAV, or normal glucose tolerance (NGT). Those with OAV were subdivided into three subgroups: fasting hyperglycemia (one abnormal value at fasting during an OGTT), 1-h hyperglycemia (one abnormal value at 1 h during an OGTT [1h-OAV]), or 2- or 3-h hyperglycemia (one abnormal value at 2 or 3 h during an OGTT). As derived from the OGTT, we measured insulin sensitivity (insulin sensitivity index [ISI] Matsuda) and insulin secretion (homeostasis model assessment for the estimation of β-cell secretion [HOMA-B], first- and second-phase insulin secretion). The product of the first-phase index and the ISI was calculated to obtain the insulin secretion–sensitivity index (ISSI).

RESULTS— GDM was diagnosed in 17.9% and OAV in 18.7% of pregnant women; women with GDM and OAV were older and had higher BMI and serum triglyceride levels than those with NGT (all P < 0.05). Women with NGT had the highest ISI followed by those with OAV (−21.7%) and GDM (−32.1%). HOMA-B results were comparable with those for OAV and GDM but significantly (P < 0.01) lower than those for NGT; first- and second-phase insulin secretion appeared progressively reduced from that in women with NGT to that in women with OAV and GDM (P < 0.01). ISSI was higher in women with NGT than in women with either OAV (−34%) or GDM (−51.7%) (P < 0.001). Among OAV subgroups, the 1h-OAV subgroup showed the lowest ISSI (P < 0.05).

CONCLUSIONS— OAV and GDM are clinically indistinguishable, and both groups are different from women with NGT. Women with GDM and OAV showed impaired insulin secretion and insulin sensitivity, although these defects are more pronounced in women with GDM. Compared with other OAV subgroups, 1h-OAV could be considered a more severe condition.
Medical Nutrition Therapy and Lifestyle Interventions
Authors: Reader Diane M.
Published: June 2007

Nutrient intake plays a significant role in the health outcomes of all pregnant women. In a pregnancy complicated by gestational diabetes mellitus (GDM), excellent glucose control is as foundational as appropriate weight gain and adequate nutrient intake.

The controversies in GDM management include the following: how far to manipulate energy intake, dietary composition (carbohydrates and fats), and gestational weight gain. Signs that food restrictions have gone too far include weight loss or lack of weight gain, undereating to avoid insulin therapy, positive urinary ketones, and intentional restriction of healthy foods. If a balance between nutrient needs and glucose control cannot be achieved, then concurrent medication therapy is needed to assist in reducing insulin resistance and supplementing insulin production to provide normoglycemia and improved pregnancy outcomes.

Medical nutrition therapy is a self-management therapy. Education, support, and follow-up are required to assist the woman to make lifestyle changes essential to successful nutrition therapy. Women with GDM are at increased risk for type 2 diabetes; learning to manage GDM with lifestyle change provides an opportunity to affect personal risk factors and the health of the whole family.
Electromagnetic wave propagation through frequency-dispersive and lossy double-negative slab
Authors: Sabah C. , Uçkun S.
Published: June 2007

This study presents the electromagnetic wave propagation through the frequency-dispersive and lossy double-negative slab embedded between two different semi-infinite media. The double-negative slab is realized by using two models, the Lorentz and Drude medium models. The properties and the required equations for the frequency-dispersive and lossy double-negative slab, the Lorentz medium and Drude medium are given in detail. After the construction of the problem, the reflection and transmission coefficients are derived for both TE and TM waves. Then, the reflected, transmitted and loss powers are determined using these coefficients. Finally, in the numerical results, the mentioned powers for TE and TM waves are computed and illustrated as a function of the incidence angle, the frequency and the slab thickness when the damping frequency changes.
Exciton localization behaviour in different well width undoped GaN/Al0.07Ga0.93N nanostructures
Authors: Sabooni M. , Esmaeili M. , Haratizadeh H. , Monemar B. , Paskov P. , Kamiyama S. , Iwaya M. , Amano H. , Akasaki I.
Published: June 2007

We report results from optical spectroscopy such as photoluminescence (PL) and time resolved photo-luminescence (TRPL) techniques from different well width MOCVD grown GaN/Al0.07Ga0.93N MQW samples. There is evidence of localization at low temperature in all samples. The decay time of all samples becomes non-exponential when the detection energy is increased with respect to the peak of the emission. Localization of carriers (excitons) is demonstrated by the “S-shape” dependences of the PL peak energies on the temperature. The time-resolved PL spectra of the 3-nm well multi quantum wells reveal that the spectral peak position shifts toward lower energies as the decay time increases and becomes red-shifted at longer decay times. There is a gradient in the PL decay time across the emission peak profile, so that the PL process at low temperatures is a free electron-localized hole transition.
Planning Roads for Rural Communities
Authors: Plessis-Fraissard Maryvonne
Published: June 2007

The new report Safe, Clean, and Affordable … Transport for Development sets out the World Bank's transport sector priorities for the period 2007–2015. The report indicates key changes in how the World Bank intends to engage with its clients in low- and middle-income countries with respect to its transport lending program. Investment in transport infrastructure and improved transport services are crucial for meeting the millennium development goals. Low-volume rural roads have been, and continue to be, an important component of the World Bank's transport development program. The recently developed rural access index is a useful indicator of the need for improved accessibility. Research has shown the importance of rural roads in stimulating both economic growth and social development. Effective planning and implementation of good rural road projects depend on a combination of adequate planning tools, worthwhile community consultation, a flexible approach to engineering design, and reliable data. New economic planning criteria need to be developed to reflect new thinking in transport appraisal and to capture fully the social and economic benefits of roads. The results-based approach for monitoring and evaluation can be particularly valuable within the roads sector. Similarly, substantial benefits can be gained from adopting a holistic approach to planning rural infrastructure service delivery including a more detailed consideration of rural transport services and the planning of different types of rural infrastructure together. Underfunding and poor organization of rural road maintenance need to be recognized and addressed.
Planning to Determine Low-Volume Road Standards, Long-Term Needs, and Environmental Risks and Trade-Offs
Authors: Dodson Elizabeth M. , Chung Woodam , Mills Keith , Nall Rob , Sessions John , Zartman Greg
Published: June 2007

Inventories of forest roads are used to manage road networks by chronicling existing road conditions and flagging areas that require attention. Tools are needed to integrate the environmental performance of forest roads, as captured in a road inventory, into the management of these roads. This study used a combination of a multicriterion decision analysis tool (Analytic Hierarchy Process) and a timber transportation model (NETWORK 2000) to determine road standards to minimize both environmental and economic costs. This analysis technique is applied to a forest road network in western Oregon.
Log Truck Transportation on Public Roads in New Zealand
Authors: Dowdle L. R. , Douglas Robert A.
Published: June 2007

Industrial forestry within the Southland region of New Zealand is forecast to double over the next 20 years as the availability of wood from production forest plantations increases dramatically. This is generating unprecedented pressure on the public road network. An issue has arisen between government and industry over which should pay for the increasing road upgrading, rehabilitation, and maintenance costs generated by the burgeoning traffic, with the Southland Regional Council proposing a fourfold increase in the road-related rates (tax) charged to the forest industry. In an effort to produce an independent model of the forest industry's use of the road system, regional spatial data sets characterizing the wood supply, demand for wood, and road network were assembled and verified. The transportation geographic information system software package TransCAD was then used to determine the optimum distribution pattern for Southland's wood production. It was confirmed that an accurate model of the current transportation of wood in the region had been created. Distribution patterns under four input scenarios were analyzed. For domestic sawlogs, rearranging supply contracts was predicted to provide transportation savings, measured in annual tonne-kilometers, of just under 40%. On the other hand, there appeared to be no gains to be made in using unconstrained haul routes—the routes in current use are near the optimum. The predictive power of the model was illustrated for the case of chip logs, in which significant changes in traffic patterns were predicted for the 2009 harvest year, along with an order-of-magnitude increase in traffic volumes. The work revealed that the origin of the fourfold rate increase to be charged to forestry is in an arbitrary “perceived damage factor” applied to the numerically modeled traffic flows.
Life-Cycle Economic Evaluation of Alternative Road Construction Methods on Low-Volume Roads
Authors: Gerbrandt Ron , Berthelot Curtis
Published: June 2007

The province of Saskatchewan has the largest number of public roads per capita in Canada and one of the largest in the world. Over the past decade, pressures on the road network have increased, resulting in accelerated road damage and increased demand to upgrade portions of the highway network. To address transportation infrastructure sustainability issues, Saskatchewan Highways and Transportation (DHT) and Pavement Scientific International, Inc., are researching more cost-effective methods. The research work involves evaluating the technical and economic feasibility of undertaking alternative road construction techniques. A critical component of this research effort is to evaluate the economic feasibility associated with different road construction techniques. The ability to perform whole-life economic analysis associated with long-term infrastructure assets is important to long-term sustainability. By comparing the present value of initial construction and future preservation costs across different road structures and technologies, an accurate assessment of construction and design options is achievable. On the basis of performance predictions and projected structural performance, resource allocation can be optimized more reliably across limited resources and alternative road strengthening systems, providing technically sound solutions that are more economically attractive. With an ability to predict whole life-cycle performance on the basis of future maintenance treatments, road managers can more reliably assess alternative surfacing and structural preservation strategies. The primary focus of this paper is to demonstrate the economic considerations undertaken in evaluating alternative road design and construction methods. This longer-term evaluation approach allows strategic investments in highway infrastructure and allows DHT and other agencies to consider innovative road structural rehabilitation and management strategies more effectively.
Reduced Impact Logging Road Issues in Tropical Forests
Authors: Keller Gordon R. , Berry Jonathan
Published: June 2007

Road design, construction, and maintenance practices need to be significantly improved in many logging operations being undertaken in tropical forests worldwide. Reduced impact logging is a program designed to achieve more cost-effective and sustainable logging practices through good stand inventories, sound silvicultural practices, less waste and damage in the operations, and replanting where necessary. The program also involves design and construction of improved logging roads. Many roads being constructed and used today are poorly built, poorly drained, and poorly maintained. Resulting impacts include unnecessarily high road costs, inefficient logging operations, and significant negative environmental impacts. Little consideration is given to long-term or full life-cycle costs of the roads. These are not new problems. The objectives of this paper are to identify ongoing common problems and recommend practical solutions, reiterate the need for good basic engineering practices, and highlight some of the negative impacts of poor engineering practices. Key problems that appear to cause unnecessarily high road costs and inefficient logging operations include inadequate road surface drainage, excessively wide roads and roads built under inconsistent design standards, inadequate use of available road surfacing materials, inadequate road maintenance, and poor road location and the subsequent need for road reconstruction. A variety of other road drainage, materials, and erosion control issues also need improving. Social and environmental issues related to roads and their access include colonization and development along the road corridor, illegal logging and subsequent deforestation, bush meat hunting and wildlife depletion, spread of diseases, and other land use changes. Road management and access control are needed along with improved design, construction, and maintenance practices.
Development of a Simplified Mechanistic–Empirical Design Procedure for Low-Volume Flexible Roads
Authors: Zhao Yongsheng , Dennis Norman D.
Published: June 2007

Currently, most low-volume roads (LVRs) are designed on the basis of empirical experience or a loose implementation of some design procedure such as that found in the AASHTO guide. Procedures such as that of AASHTO were developed primarily for higher-volume roads and may not provide cost-effective designs for LVRs. A complicating factor in the AASHTO procedure is that it defines resilient modulus, an elastic material property that is expensive to measure, as the primary material property of interest for the design of pavements. This property is used despite the fact that many LVR pavement systems are subjected to nonelastic deformations. There is, therefore, a strong motivation to develop a sound design procedure applicable specifically to LVRs that uses simple soil properties. In this study, correlations to plastic deformation were made by using simple soil index properties. These correlations were based on measurements from more than 500 specimens of 20 Arkansas subgrade soils. Several finite element analyses were conducted to establish stress states in a pavement system from a variety of geometries and vehicle loads, and the information was tabulated. With this design procedure, a designer simply has to enter the design vehicle and some simple index properties to obtain rutting as a function of load repetitions. On the basis of this information, the user could specify a pavement configuration to carry a certain repetition of the design load or, given a pavement configuration, the model could evaluate damage from overloads or establish maximum loads during periods of poor sub-grade performance.
Sustainable Innovative Surfacing Treatments for Low-Volume Roads
Authors: Pidwerbesky Bryan , Waters Jeff
Published: June 2007

All maintenance and construction projects on New Zealand public roads are contracted out. In combination with constrained budgets limiting resurfacing treatment lengths, contracting out has encouraged substantial investment by industry in new developments and innovation to extend the road maintenance budget. A number of cost-effective, innovative surfacing treatments have been developed in New Zealand for low-volume roads. A sample of these innovative surfacing treatments is presented. Ultra-high-pressure watercutting is being used to improve both macro-texture and microtexture of surfacings on low-volume roads, thereby extending the life of those surfacings. Modern computer-controlled sprayers have been developed to apply bitumen at rates that vary transversely across the lane width. These sprayers are also used when chip seal surfaces have insufficient macrotexture in the wheel tracks, as well as a preventive measure for binder rise in the future. Ultrathin textured gap-graded hot mixes are being used in high-stress, high-trafficked areas. The monitoring of the treatments includes skid resistance, texture depth, performance, and safety (numbers of accidents) for 6 years or more. The performance to date of these treatments and strategies is discussed. In addition, a research project under way is aimed at developing more robust guidelines for selecting binder grade on the basis of climatic conditions to improve the performance of surfacings. Interim results of this project are discussed. Combining the wide range of state-of-the-art surfacing treatments with best practice in asset management in a cost-effective sealing and maintenance program has resulted in significant improvements in road safety, reduced accident costs, and improved performance and substantially reduces the potential for accidents.
Low-Volume-Road Lessons Learned
Authors: Worel Benjamin J. , Clyne Timothy R. , Burnham Thomas R. , Johnson David M. , Tompkins Derek M.
Published: June 2007

The Minnesota Department of Transportation built the Minnesota Road Research Project (MnROAD) and its low-volume road (LVR) between 1990 and 1993. The 2.5-mi LVR consists of a two-lane roadway that originally contained gravel, hot-mix asphalt, and concrete test sections designed for low-volume road research. Each of these test sections is trafficked by a controlled five-axle tractor-semitrailer to simulate conditions of rural roads in two load configurations, resulting in the same equivalent axle loads. Over the years, a number of activities and studies have taken place that have used information from MnROAD's LVR. The first 10 years of findings related to the LVR in the areas of facility, hot-mix asphalt, portland cement concrete, aggregate surfacing, seasonal load limits, and non-pavement-related lessons learned are summarized.
Use of Tank Bottom Sludge to Construct and Upgrade Unpaved Roads
Authors: Taha Ramzi , Hassan Hossam , Al-Rawas Amer , Yaghi Basma , Al-Futaisi Ahmed , Jamrah Ahmad , Al-Suleimani Yahya
Published: June 2007

Tank bottoms are the liquids and residue, such as heavy hydrocarbons, solids, sands, and emulsions, that collect at the bottom of the treating vessel or that remain at the bottom of storage tanks after a period of service. Sludge composition is 50% to 65% crude oil, 20% to 35% water, and 5% to 20% solids. Disposal of tank sludge is a significant item of tank maintenance costs. Results are presented on the use of tank bottoms as a binder to construct and upgrade unpaved roads. Various sludge samples were initially characterized for chemical and physical composition, then three mixtures were prepared by using blends of aggregates and tank bottoms. No bitumen was used in the mixes. The mixtures include hot mix (aggregate and sludge were both heated), heated sludge and cold aggregate mix, and cold mix (no heat was applied). The Marshall mix design (ASTM D1559) was followed in the preparation and testing of the specimens. Results indicate that tank bottoms act as a binder to the aggregate and can provide significant strength. Heating both the sludge and the aggregate resulted in the highest stability value of 11.9 kN. An optimum sludge content of 6.5% by total weight of the mixture satisfied the requirements for low (3.3 kN) or medium (5.3 kN) trafficked surfaces or base layers according to Asphalt Institute specifications. Other mix properties, such as flow, air voids, voids in mineral aggregate, and voids filled with asphalt, were acceptable.
Applicability of Existing Gravel-Road Deterioration Models Questioned
Authors: Van Zyl Gerrie , Henderson Mervyn , Uys Robbie
Published: June 2007

Efforts by the Provincial Government of the Western Cape in South Africa to improve all aspects of gravel-road construction and maintenance since 2001 have resulted in such good performance that existing gravel-road performance models are of limited value in predicting future needs and properly evaluating the need for upgrading to surfaced standards. The performance of several well-constructed road sections, representing different age groups, climates, material properties, and traffic spectra, has been monitored since 2003 and compared with the prediction of various internationally accepted roughness and gravel-loss deterioration models. A background summary of the improved processes, a brief summary of the experimental design, and a discussion of existing models are presented, with emphasis on the immediate and potential future impact of results that were obtained over a period of almost 3 years. Improvements to performance models are suggested, and the impact at the project level and on strategic-level analysis and decision making is highlighted. Recommendations are made on periodic maintenance strategies based on potential economic, social, and environmental benefits.
Development of an Economic and Practical Alternative to Traditional Bituminous Surface Treatments
Authors: Overby Charles , Pinard Michael I.
Published: June 2007

In many developing countries, a substantial portion of the road network, typically more than 75%, consists of earth and gravel roads that carry relatively low volumes of traffic. Traditionally, natural gravel materials are used for providing, maintaining, and upgrading such roads. However, most natural gravels have practical limitations on their use—for example, steep gradients and high rainfall, dust generation in dry weather, and slippery surfaces in wet weather. In addition, there is an increasing scarcity of suitable materials, and, moreover, maintenance is seldom carried out effectively in most developing countries. The inherent problems of maintaining unpaved roads can be overcome by paving them. However, even when this solution is economically justifiable, often it is not adopted widely in developing countries because of limited funds. However, a type of surfacing that can provide an economic and practical alternative to traditional surfacings and, by so doing, make better use of limited funds is the graded aggregate (Otta) seal. Otta seal surfacing is presented as an economic and practical alternative to the more traditional bituminous surface treatments, such as chip seals and slurry seals. The origin, properties, design, and construction of the Otta seal are outlined. The effects of its implementation and the various factors that contribute to its sustainability are discussed, and information is provided on global use of the Otta seal, including a case history relating to its introduction in southern Africa.
Strip Sealing and Ultra-High-Pressure Watercutting Technique for Restoring Skid Resistance on Low-Volume Roads
Authors: Gransberg Douglas D. , Pidwerbesky Bryan
Published: June 2007

Low-volume roads require cost-effective maintenance methods to minimize the amount of money spent on them while maximizing the engineering properties required to furnish the required levels of service. Skid resistance is an engineering property that is important for any road. Because chip sealing is a tried-and-true pavement preservation method, it often is used as the primary maintenance treatment of these roads. Unfortunately, chip seals are prone to flushing in the wheelpaths, which creates a loss of skid resistance. The economics of replacing strip sealing using conventional chip seal in the wheelpaths with the ultra-high-pressure watercutter used in New Zealand are explored. An economic analysis of typical low-volume roads on the basis of case studies found in Texas is conducted to determine the life-cycle costs of using both options on each case study project. The study applies the FHWA pavement life-cycle cost methodology, and the results are reported on a net-present-value basis to permit assessment of both methodologies. The analysis is conducted on two levels. First, a traditional deterministic life-cycle cost analysis is performed, and that is followed by a stochastic analysis of life-cycle cost using a Monte Carlo simulation. It is concluded that the watercutter is an economically viable alternative to strip sealing with the benefit of restoring the macrotexture without exacerbating the condition that caused the loss of skid resistance in the first place. It also allows the desired engineering objective to be achieved without additional consumption of asphalt binder or aggregate, thus making an environmentally sustainable alternative as well.
Development of Scheduling Algorithms for Routine Maintenance of Unsealed Roads in Western Cape Province, South Africa
Authors: Burger A. F. , Henderson Mervyn , Van Rooyen G. C.
Published: June 2007

A pilot study focused on the development of algorithms that can be used to schedule routine maintenance work in maintenance wards of a gravel road network. The study was undertaken as part of the development of a blading optimization module of the gravel management system of the Western Cape Provincial Administration in South Africa. The two algorithms developed take into account the constraints and variables identified by interviewing personnel of the five district municipalities contained in Western Cape Province. The algorithms were tested and evaluated by using a pilot application.
Low-Volume State Highways in Arizona
Authors: Powers Richard L.
Published: June 2007

Maintenance of unpaved roads in Arizona has become a challenge. With strict environmental compliance issues, historical considerations, lack of surfacing materials, cost increases, an extremely dry climate, and other safety concerns, the task of maintaining these roads is increasingly difficult. The Arizona Department of Transportation Globe District has investigated and implemented various techniques to address the maintenance of unpaved roads in an efficient, cost-effective manner. Options are presented, and two case studies of the most successful techniques are outlined. Construction costs and performance of these road treatment strategies are discussed.
Evaluation of Products and Application Procedures for Mitigating Dust in Temperate Climates
Authors: Rushing John F. , Tingle Jeb S.
Published: June 2007

An evaluation of commercial dust palliatives was conducted to determine their effectiveness in mitigating fugitive dust on roads in temperate climates. Several types of dust palliatives were tested, including polymer emulsions, a polysaccharide solution, a calcium chloride solution, and synthetic fluids. Each product was placed in an individual test section; application rates ranged from 1.8 to 3.6 L/m2 with a topical or an admix construction method (grade, spray, till, compact, spray). Water-soluble products were diluted by using one part product and three parts water. Test sections were constructed and observed for 220 days to monitor product performance. Test sections were located along training routes at Ft. Leonard Wood, Missouri, and were subjected to heavy military truck and tracked vehicle traffic. Data from stationary and mobile particle collectors were analyzed to determine the ability of each product to suppress dust for extended periods. Nuclear density tests were performed to monitor soil moisture content and density. Several products are recommended for use on roads in temperate climates as a result of this evaluation.
Stabilization and Dust Control at the Buenos Aires National Wildlife Refuge, Arizona
Authors: Surdahl Roger W. , Woll J. Heather , Marquez H. Rick
Published: June 2007

The objective of this study was to evaluate road stabilizers and dust palliatives on a construction project of FHWA's Central Federal Lands Highway Division for long-term performance and to recommend products with acceptable performance for use on other projects. The evaluation addressed product performance for dust control, rutting, washboarding, raveling, material stabilization, and cost-effectiveness. Roadway stabilization or dust abatement products are classified into the following seven categories: water, water absorbing, organic petroleum, organic nonpetroleum, electrochemical, synthetic polymer, and clay additives. Six soil stabilizers were applied, each on a 1.6-km (1-mi) section to a depth of 150 mm (6 in.) at the Buenos Aires National Wildlife Refuge in south central Arizona, and were monitored at 6-month intervals for 2 years. Visual evaluation included effectiveness in controlling dust, washboarding, and raveling. Physical evaluation included moisture and density, gradation, liquid limit, plastic limit, R-value, California bearing ratio, and silt loading. Analysis included an overall ranking of the six materials and their performance. All products performed well for this semiarid desert location and nonplastic roadway material. The best-performing group had two organic nonpetroleum plus water-absorbing combination products. The second group had one water-absorbing and one organic nonpetroleum product. The third group had two electrochemical products and one synthetic polymer product.
Precast Modified Beam-in-Slab Bridge System
Authors: Konda Travis F. , Klaiber F. Wayne , Wipf Terry J. , Schoellen Thomas P.
Published: June 2007

As a means of extending available resources, the Black Hawk County Engineer's Office, Black Hawk County, Iowa, has developed a precast bridge system specifically for low-volume roads with spans up to approximately 40 ft (12.19 m). The design, referred to as the precast modified beam-in-slab bridge (PMBISB), consists of four precast panels, which are fabricated at the county's casting facility, transported to the bridge site, and joined with a cast-in-place concrete joint. The PMBISB design is similar to the modified beam-in-slab bridge (MBISB) system previously developed by the Iowa State University Bridge Engineering Center (ISU BEC). Two defining features of the MBISB, the transverse arched deck and the alternative shear connector (ASC), are both incorporated in the PMBISB. Allowable stress design methods were applied, and the PMBISB is designed to resist an alternative truck loading [five 20-kip (89-kN) axles spaced on 4 ft 3 in.– (1,295-mm) centers], which is representative of local vehicles. An individual panel consists of three longitudinal W-sections that are embedded in a transversely arched concrete deck. Reinforcement within the deck is limited to that required in the ASC and that needed for crack control. All construction is preformed by county forces with existing equipment. The PMBISB system saves Black Hawk County approximately $16,000, or 17% per bridge, compared with conventional designs. ISU BEC load-tested the first PMBISB to determine service-level performance and the behavior of the joined panels. The design has been further refined and five additional PMBISBs have been constructed on the basis of the results and field experience.
Simplified Bid Process for Single-Span Bridge Replacements
Authors: Toohey Amy , Comisford Randy , Zigan Curtis
Published: June 2007

Just Build is an innovative bid–build process that expedites the replacement of deficient bridges with federal money. Its goal is to assist local governments in using federal funds for the replacement of deficient smaller-span bridges. In the past, preliminary engineering costs (design and environmental) have precluded local governments from pursuing federal funds for these structures. The Just Build process is based on criteria that must be met and maintained from the selection of the bridge to the completion of the project and the use of a scope of service document that capitalizes on the Ohio Department of Transportation's standard drawings and AASHTO's low-volume road standards (if applicable) and thus eliminates the need for detailed construction plans. The savings in time and cost comes about through the elimination of detailed plans, construction of a bridge compatible with local traffic needs, and selection of bridges that are environmentally noncomplex. Just Build is an excellent tool that provides an efficient and cost-effective way to replace a great number of deficient bridges with federal funds and comply with the National Environmental Policy Act, Section 106 of the National Historic Preservation Act, and the Clean Water Act. Overall, the savings in design fees ranges from $35,000 to $125,000 per bridge. The savings in project and staff time, the savings in environmental and design costs, and the ability to use AASHTO's low-volume standards represent outstanding benefits to local governments. To date the pilot projects have successfully replaced nine bridges, with two under construction during summer 2006.
Feasibility of Copper Slag–Fly Ash–Soil Mix as a Road Construction Material
Authors: Havanagi Vasant G. , Mathur Sudhir , Prasad P. S. , Kamaraj C.
Published: June 2007

The use of waste materials in the road construction industry is gradually gaining significance in India, considering disposal and environmental problems and the gradual depletion of natural resources. The copper unit located at Dahej, Gujarat, India, produces 1,200 to 1,500 tons of copper slag per day. The large quantity of accumulated slag is dumped and left for the most part unused on costly land within the plant premises. Also, 50 to 100 tons of fly ash are produced per day from the existing captive thermal power plant. The potential use of these materials in road construction was studied initially by evaluating the materials for their physical and chemical characteristics. The waste materials were mixed with local soils in the range of 25% to 75%, and their geotechnical characteristics were investigated. The feasibility of using these mixes in the base course of road pavement was investigated by adopting stabilization techniques. The potential of copper slag as a replacement for fine aggregates in bituminous mixes was also investigated. It was concluded that a mixture of copper slag, fly ash, and soil has the potential for use in embankment, subbase, base, and wearing courses of road pavement. The results of laboratory tests and typical technical design specifications indicating the utility of copper slag, fly ash, and soil in different layers of road pavement are discussed.
Procedure for Evaluating Stabilization of Road Materials with Nontraditional Stabilizers
Authors: Visser Alex T.
Published: June 2007

In response to the need to find cost-effective stabilizers, a large number of chemical products are being marketed as potential solutions. Traditional laboratory tests have not been able to predict the performance of these materials satisfactorily. A solution is for suppliers to construct experimental sections several hundred meters long. However, that becomes an expensive exercise, since each type of soil in a region would have to be used. An evaluation technique has been developed that allows test panels to be constructed in the field at low cost with a range of soils and stabilizers and that takes into account local environmental conditions and traffic. The aim of this paper is to present this evaluation technique and the results with a range of stabilizers and soils. The paper describes construction of the 1- × 3-m test panels and the subsequent testing protocol. Several materials, ranging from sandy to clayey, were tested with different generic stabilizers, such as polymers, enzymes, and ionic soil stabilizers. Control panels without additives were also constructed. The testing regime conducted over 8 months included regularly measuring the following: the in situ California bearing ratio with a dynamic cone penetrometer, both at the in situ moisture content and after soaking for 2 h; density and moisture; and permeability. Visual observations about performance were also noted. The test panel procedure is a cost-effective solution for evaluating the potential strength gain of stabilizers with a range of soils. As is known, stabilizers must be tailored to soil properties, because stabilizers do not all have the same effect.
Laboratory and Field Evaluation of Fluid Bed Combustion Fly Ash as Granular Road Stabilizer
Authors: Thenoux Guillermo , Halles Felipe , Vargas Angeles , Bellolio Juan Pablo , Carrillo Hector
Published: June 2007

This paper presents the result of laboratory and field research on soil stabilization using fluid bed combustion fly ash. This type of ash is the result of the combustion of petroleum coke and limestone in an electric power generation plant (Petropower, located in the south of Chile), which makes it different from other types of ash used regularly in soil stabilization. The ash differs from the traditional ash used in soil stabilization, particularly because of (a) a high concentration of lime that may produce cementing compounds and (b) the presence of sulfates that may produce a secondary reaction such as the formation of gypsum and ettringite, resulting in a different level of expansion in some types of soils. The main objectives of the research were to characterize fluid bed combustion fly ash from the Petropower plant and to evaluate the technical feasibility of using this ash as a soil stabilizer. The laboratory and field research showed that this type of ash improves the mechanical properties and water susceptibility of most types of soils. Although laboratory experimentation proves that the secondary reaction produces soil expansion in clayey soils, field experimentation indicates that the secondary reaction that produces soil expansion may be controlled by an adequate laboratory design and an appropriate dose of fly ash.
Chloride Stabilization of Unpaved Road Aggregate Surfacing
Authors: Monlux Stephen , Mitchell Michael
Published: June 2007

There are few alternatives for improving long-term performance of aggregate surfacing materials in dry climates other than annual dust abatement treatments. In-place stabilization of properly graded aggregate with chloride additives is cost-effective and provides performance and intangible benefits. Similar results are achieved by mixing additives with aggregate during crushing. This 2-year study identifies conditions in which chloride-stabilized roads have a projected life of 10 years or more if properly maintained. The greatest benefits are realized in projects with high aggregate surfacing replacement costs and average daily traffic volumes that exceed 100. Stabilization provides a higher standard of road surface performance by improving ride quality and reducing dust, corrugations (washboarding), and raveling (loose aggregate). Other intangible benefits include reduced sedimentation in streams, reduced aggregate resource depletion, reduced health hazards from dust, and increased road-user safety. This project developed guidelines for chloride stabilization of various aggregate surfacing materials in semiarid to arid environments. Performance and cost-effectiveness of chloride stabilization were measured on 12 projects and monitored for two seasons in four western states; monitoring included construction and maintenance costs, road surface deterioration, traffic, weather conditions, environmental effects, and materials testing. Treated surfaces needed blading after 25,500 vehicles, whereas untreated surfaces needed blading after only 3,200 vehicles. Environmental effects on trees, streams, and roadside soils were insignificant. Many tools were developed to assist in the proper implementation of chloride stabilization of road surface aggregates.
Stabilization of Surficial Slides Using Recycled Plastic Reinforcement
Authors: Loehr J. E. , Fennessey T. W. , Bowders John J.
Published: June 2007

Surficial slope failures, or nuisance slides, constitute a significant economic and manpower burden for many transportation agencies because of the frequent and recurring nature of the slides. TRB recently estimated that annual costs for stabilization of nuisance slides exceed the costs for repair of major landslides; this estimate suggests that annual costs for repair of nuisance slides on the National Highway System alone exceed $100 million. Recent work has shown the feasibility of using slender recycled plastic members for in situ reinforcement of surficial slides in slopes and embankments. This paper describes the activities performed to evaluate the technique and the results and conclusions derived from the work. Topics covered include the description of five instrumented field test sites, material properties of the recycled plastic members used, construction equipment and techniques used to install the members, general performance observed at the field test sites, and the costs of the technique as compared with other methods.
Geotextile Separators for Dust Suppression in Unbound (Gravel) Roads
Authors: Freeman Elisabeth , Bowders John J.
Published: June 2007

Dust is a health concern because of its potential to contain respirable particles, especially particles less than 10 microns in diameter (PM10). It is also a nuisance issue for residents living in the vicinity of unbound, unsealed (gravel) roads. Numerous techniques are used in attempts to reduce the dust generated from unbound roads, but all have limitations. Anecdotal evidence suggests that dust from unbound roads can be reduced for roads that incorporate a geotextile separator. A program to document the effect of the geotextile separators quantitatively is under way, with several test sections in central Missouri. A test section including a nonwoven, needle-punched geotextile; a non-woven, spun-bonded geotextile; and a new aggregate-only layer was installed; dust measurements were made over a 6-month period, during which the road experienced more than 3,600 vehicle passes. Dust levels were lowest immediately following the placement of new aggregate for the unbound layer and increased with time (traffic passes). Initially the sections containing a geotextile separator produced slightly less dust than the control (no geotextile) section. After 6 months of service, dust levels from the geotextile and control sections were similar, but the percentages of fines in the unbound layer above the geotextiles were about one-half that in the control section. Geotextile separators are likely to reduce dust for unbound roads when the source of particulate is fines migrating from the subgrade into the unbound layer. When the fines are developed because of degradation of the aggregate in the unbound layer, geotextile separators may be less effective in reducing dust from the roadway.
Kimberlite Tailings
Authors: Swami R. K. , Pundhir N. K. S. , Mathur Sudhir
Published: June 2007

Kimberlite tailings are waste materials left after the recovery of diamond from diamond source rock. The material has a particle size ranging from 20 mm to 75 microns and can be categorized as a soft aggregate. It contains mainly silica, alumina, iron oxide, and magnesia. In the absence of a proper outlet, it accumulates around the diamond mines and causes environmental and disposal problems. With a view to assessing the potential use of kimberlite tailings in road works, the Central Road Research Institute engaged in a detailed laboratory study. Kimberlite tailings were characterized to determine their physical engineering properties. Results indicate that kimberlite tailings are a marginal material and possess adequate strength for use in the construction of rural roads. The feasibility of utilizing this material for the construction of various layers of road pavement by adopting stabilization techniques was investigated. A study was also undertaken to assess the suitability of this material for use in bituminous mixes. The laboratory studies indicate that kimberlite tailings can be used in subbase and base course layers in a road pavement. They can also be used in bituminous macadam as the base course and in premix carpet as a wearing course. A 1-km-long road was constructed near the diamond mine using kimberlite tailings, and its performance was monitored during a period of 1 full year. The road's performance was found to be satisfactory. It was concluded that the use of kimberlite tailings would not only conserve precious material resources, which are quickly being depleted, but also lead to considerable savings in construction costs.
Failure Mechanism and Design Criterion for Low-Volume Roads Subgrade Widening
Authors: Ling Jianming , Qian Jinsong , Huang Qinlong
Published: June 2007

During the past decade, a large number of low-volume roads have been rebuilt in China to accommodate a sharp increase in traffic volume. An in situ investigation of highway reconstruction found cracking, a pattern typical of deterioration in pavements related to subgrade widening. The cracking is caused by the development of differential deformations between the widened subgrade and the existing subgrade. On the basis of finite element analysis and full-scale simulation laboratory tests, characteristics of subgrade differential deformation and its impact on pavement performance were studied. For typical asphalt pavements with a semirigid base course, three kinds of cracking modes related to subgrade widening were noted: shear cracking, bottom-up cracking under wheel loads, and top-down cracking induced by subgrade differential deformations. Finally, on the basis of the sensitivity of pavement cracking to change in horizontal slope, a design criterion for pavement subgrade widening was proposed.
Use of Naturally Occurring Pozzolans for Road Construction in Tanzania
Authors: Onyango Mbaki , Macha Innocent , Busch Christian
Published: June 2007

A pilot study has been conducted in Tanzania to investigate the possibility of using naturally occurring pozzolan materials as a sand stabilizing agent for road base and subbase construction. The pozzolan material investigated was to be used in the coastal area of Tanzania, which lacks good road construction materials that meet material specification requirements. The coastal area produces mainly sand and some poor-quality limestones that are not particularly suitable for road construction. Pozzolan samples collected from different parts of Tanzania were investigated. The collected pozzolan samples were mixed with lime to stabilize sand that could be used in a base or subbase course. Laboratory tests were done to determine properties of individual pozzolans and lime–pozzolan–sand mixtures. The compressive strength and split tensile tests were performed to determine the pozzolan mixtures' strength development and their suitability for road construction. Tanzanian experience with natural pozzolanic materials resulting from the Dar–Mlandizi road project will be discussed. The Dar–Mlandizi road was constructed by using sand stabilized with blast furnace slag as the base course material. The paper highlights the availability and preliminary testing of natural pozzolans in Tanzania, which resulted in follow-up testing of natural pozzolans in Denmark and the construction of a test road section in Tanzania. The pilot study can be considered an example of successful research in investigating the use of local materials for low-volume road construction.