bluuebunny/crossref_metadata_2025 huggingface dataset:
Internal Stress Measurements of Electroless Nickel Coatings by the Rigid Strip Method
Authors: Parker K
Published: December 2008

Residual macrostresses in electroless nickel (EN) coatings affect critical deposit properties such as hardness and adhesion. Straight thin aluminum, beryllium, and steel strips were plated in hot nickel hypophosphite baths varying in chemistry, pH, and usage. When the nickel-phosphorus (Ni-P) coating was stripped from one side the metal strip assumed either a concave (tensile) or a convex (compressive) arch because of internal stress in the EN coating. The degree of curvature was measured and the residual stress calculated. The total stress consists of an intrinsic component resulting from plating bath chemistry and usage and a thermal stress produced by the difference in thermal expansion coefficients between the EN coating and the substrate. Thus, on aluminum strong compressive stresses are induced by its larger shrinkage, which occurs during cooling from bath (90°C) to room temperature. Annealing decreases the compressive stress. With usage of the EN bath the coatings decrease in compressive stress and after three to five turnovers are tensile stressed and blister because of adhesive failure. On beryllium compressive stress is obtained if the EN coating contains >11% phosphorus. Annealing changes the stress to slightly tensile. On steel the initial low tensile stress increases linearly with bath usage and reaches 180 MPa (28 ksi) after six turnovers, which is moderated by annealing at 200°C. The internal stress of EN coatings depends on the chemistry and usage of the bath, the substrate, and the phosphorus content of the deposit. The plating of thin, rigid metal strips offers a simple, inexpensive method to determine the residual stress of coatings on any metal substrate. The results obtained are in good agreement with contractometer stress measurements of EN coatings.
Thickness of Metal Coatings
Authors: Ogburn F
Published: December 2008

The concept of coating thickness is clear, but surface roughness can confuse the meaning of the term. Thickness is usually not of interest in itself, but it tells us something about the properties of the coating that are really of interest such as the corrosion life or wear resistance. Instead of measuring the property of primary interest, thickness is measured because it can be measured more easily, less expensively, and nondestructively. The commonly used coating thickness instruments do not measure thickness directly but really measure something else (X-ray emmission, for example) that is proportional to the thickness of the coating. Some of the instrument measurements are not proportional to thickness unless variations of the density of the coating material are corrected for.
Measurement of the Thickness of Extremely Thin Inorganic Coatings of Metals
Authors: Bijlmer PFA
Published: December 2008

A measuring method for thin inorganic coatings on metals has been developed, based on the capacitance of the coating, using an electrical conductive rubber probe as the electrode, pressed against the surface and the substrate as the counter electrode. The reciprocal value of the capacitance is displayed in Angstrom units as the dielectric thickness and by multiplication with the dielectric constant the geometrical thickness is found. If calibration samples, with known thickness, are used, the variable resistance is set to the value of the sample. Coatings of equal nature can then be measured in terms of the geometrical thickness. The optimal range of the instrument is between 500 and 5000 Å units. Below 500 Å, the meter tends to indicate higher values than measured by other means like electro microscopy. Coatings in excess of 5000 Å can be measured provided a high dielectric constant of the coating exists. Most of the work was carried out on aluminum samples on which oxide layers of various thickness values were created.

Barrier layer anodic oxide layers could be measured from 50 Å (3.5V), and except for the very low values a good correlation with the expected coating thickness was obtained. The thickness of hydrated oxide layers formed in hot water is a good example of the application of the method, finding the critical temperature and immersion time at which the bondability is affected. Clear conversion coatings in Alodine 1000 has been successfully measured and the influence of concentration, temperature, and process time can be studied without the need of laborous gravimetrical methods. Results of measurements of phosphoric acid anodic oxide coatings and the influence of voltage and time on coating formation are shown. The range above 5000 Å can be used for chromic acid and sulfuric acid anodized material although hydration differences on samples with varying thicknesses will interfere with accurate readings of the geometrical thickness.
Testing of Anodic Coatings on Aluminum Alloys: A Review
Authors: Lacey EA , Sonnino C
Published: December 2008

The test methods will be presented and reviewed for evaluating specific properties and parameters of anodic coatings on aluminum alloys: (1) thickness, (2) hardness, (3) dielectric properties, (4) mechanical continuity, (5) sealing effectiveness, (6) color matching, and (7) color stability. The thickness of the anodic coating is probably considered the most important propety to be determined, because most of the other properties are dependent upon it. The gravimetric, optical, and eddy current methods will be described and discussed. Hardness of çoatings may vary widely; and for many applications involving wear, knowledge of hardness is very important. Hardness tests will be reviewed. Electrical dielectric properties of the anodizing and the determinations of a breakdown voltage of the coating are essential for safety and to insure the proper service conditions and limitations. The testing methods, capable also of determining the leakage existent for elevated voltages, will be discussed.

Where the corrosion protection afforded by the anodic coating is essential (as in anodized cans, and so forth) the mechanical continuity of the coating is of paramount importance because any discontinuity will involve very high corrosion current densities, causing extremely rapid failures. The detection of discontinuities is an essential test that will be reviewed. Also essential to optimize the corrosion protection by the anodizing is the effectiveness of the seal extended by the anodic coating. A simple test will be described applicable to finished items and to periodic control of the continuing effectiveness of the sealing. The use of anodizing for a large variety of esthetic applications, from architecture to costume jewelry, dictates that two important parameters must be controlled: color matching and color stability. Appropriate test methods for these exist and will be described and discussed.
Porosity Testing of Metallic Coatings
Authors: Krumbein SJ , Holden CA
Published: December 2008

Porosity tests generally make use of the relative corrosivities of the coating and the substrate to determine the integrity of the former. This paper is concerned with coatings, such as gold, that are cathodic to the substrate. Coatings of this type are usually applied to protect the substrate from the environment and provide a surface having other beneficial properties, such as wear resistance, electrical conductivity, and an attractive appearance. Porosity is detrimental to the intended functioning of such coatings in that it provides openings through which atmospheric corrodants can attack the substrate and degrade the integrity of the plating.

Different methods of evaluating such tests are presented, including laboratory investigations of the critical parameters and interlaboratory (“round robin”) comparison testing. These methods are described with reference to the nitric acid vapor and sulfur dioxide porosity tests, respectively. It will also be shown how results and insights from these programs are incorporated into ASTM test specifications.
Electrostatic Charge Decay for Detecting Contamination on Aluminum Surfaces
Authors: Cibula A , Daech A , Silbert L
Published: December 2008

This paper discusses the theory behind electrostatic charge decay (ECD), parameters that affect the measurements, and how potential primer adhesion problems can be detected before the application of coatings.

ECD, a technique for detecting flaws in dielectric materials, is examined as a method to detect surface cleanliness of aluminum parts before the application of primer coatings. The ECD device was used to measure the contact potential difference (CPD) of a metal. The CPD is the difference in work function of the specimen and that of a gold reference. It is the measure of the ease with which electrons are released from the surface in the absence of external fields. In addition, a corona charger was used to apply 12 kV onto the surface and the rate of electrostatic charge decay (ECD) was monitored. Together, the CPD and ECD measurements can be used to give important information about the metal surface quality.

CPD and ECD measurements are both affected by surface contamination, surface morphology, nature of the oxide film, adsorbed gases and films, as well as the particular metal alloy. Contaminated surfaces exhibit a different electrochemical behavior. Processed 2219-T87 aluminum was examined. By implementing a process delay between acid deoxidation of the aluminum and rinsing, a significant change was seen in the ECD/CPD readings. ESCA/auger surface analysis indicated only small chemical differences. Scanning transmission electron microscopy (STEM), however, showed that the surface profile nearly doubled in depth on the delayed etch panel. Atomic composition remained relatively the same, but the ECD readings reflected the change in morphology. The delay before rinsing expended the deoxidizer, preferentially etching the metal. The deeper profile provided a better surface for paint adhesion.
Lateral Drainage Designs Using Geotextiles and Geocomposites
Authors: Koerner RM , Bove JA
Published: December 2008

Of the available functions that geosynthetic materials possess, their ability to conduct liquids in the plane of their structure is important in a wide class of drainage applications. The thicker geotextiles (usually needled nonwoven types) and a new generation of high drainage composite materials are most suitable for this purpose.

This design-oriented paper gives the necessary theory and required test data and then proceeds to solve three numeric examples illustrating the procedures. They are slope drainage, consolidating foundation drainage, and drainage behind a retaining wall.
Durability Testing
Authors: Hodge J
Published: December 2008

Durability, while an essential requirement for geotextiles, is difficult to predict through testing. Since applications are so varied and field conditions so diverse, it is a formidable task to provide test data that can help the design engineer choose the correct engineering fabric (construction, weight, physical properties, etc.) for the intended application. Virtually all durability tests are “index” tests which allow the design engineer to compare the performance of different engineering fabrics, tested in an identical manner, and from these fabrics to select the geotextile that best meets his requirements.
The Evolution of Asphalt Concrete Mix Design
Authors: Goetz WH
Published: December 2008

The development of mix design procedures is reviewed historically along with the theoretical concepts on which current procedures are based. Durability considerations are included. An evaluation of the strength tests utilized in design procedures is made and the effect of test variables on the selection of a design asphalt content is presented. The currently used standard procedures, while serving a very useful purpose, are shown to be empirically based and lacking from a fundamental and rational point of view. A mix design system is needed that relates engineering properties to mix parameters and translates to design that prevents failure in all of its various modes.
Asphalt-Aggregate Mixtures Analysis System: Philosophy of the Concept
Authors: Von Quintus HL , Scherocman J , Hughes C
Published: December 2008

This paper presents the philosophy of the asphalt-aggregate mixture analysis system (AAMAS) concept and provides a brief discussion on those factors that must be included in the design of optimum paving mixtures based on performance-related criteria. Typically, the structural design of asphalt concrete pavements is based on assumed material properties (layer stiffness coefficients, resilient modulus, and fatigue or permanent deformation constants or both). After the structural design has been completed, materials are submitted and a mixture design is completed. The question then becomes: Does the as-placed material meet the assumptions used in structural design?

Certainly, asphalt concrete mixture design and analyses need to be related to those factors that affect pavement performance. The AAMAS objective is to predict in-place properties of the asphalt concrete in the laboratory during the mixture design stage to evaluate mixture behavior and performance under traffic and environmental loads. Thus, the focus for the development of AAMAS was to develop new laboratory mixture design procedures or modify existing procedures based on engineering properties, structural behavior and pavement performance, rather than on empirical numbers such as Marshall or Hveem stability.

Specific items addressed in the paper include compaction of laboratory mixtures to simulate the characteristics of mixtures placed in the field, preparation and mixing of materials in the laboratory to simulate the asphalt concrete plant production process, simulation of the long-term effects of traffic and the environment (this includes accelerated aging and densifi-cation of the mixes caused by traffic), and the conditioning of laboratory samples to simulate the effects of moisture-induced damage and hardening of the asphalt.

The AAMAS concept is applicable to hot-mixed asphalt concrete and includes mixture variables such as binders, aggregates, and fillers used in the construction of asphalt concrete pavements. The AAMAS currently excludes such materials or layers as open-graded friction courses and drainage layers.
A Comprehensive Asphalt Concrete Mixture Design System
Authors: Monismith CL , Finn FN , Vallerga BA
Published: December 2008

The design of an asphalt concrete mix consists, essentially, of the following steps: 1. select type and gradation of aggregate, 2. select type and grade of asphalt, with and without modifier, and 3. select proportionate amount of asphalt in asphalt/aggregate blend.

These steps have been incorporated into a general framework for design, which serves as the basis for the mix design procedure presented in this paper.

Essentially, the system consists of a series of subsystems in which the mix components and their relative proportions are selected in a step-by-step procedure to produce a mix that can then be tested and evaluated to ensure that it will perform adequately in the specific pavement section for which it has been formulated. The latter evaluation phase includes the influence of environmental factors, effects of traffic, and the consequence of the anticipated structural cross-section design at the designated site in the following distress modes: fatigue, rutting, thermal cracking, and raveling.

The paper includes a brief discussion of the important factors associated with the various steps of the design process and recommended test procedures to be followed. Information and data are presented to illustrate a procedure that might be followed to ensure that the laboratory method of specimen preparation and fabrication provides specimens with stress versus strain characteristics similar to those obtained by field compaction. The use of the creep test to assist in the design process is illustrated. Some techniques to reduce the amount of testing associated with the methodology described herein are also described.
The Role of Asphalts in Rational Mix Design and Pavement Performance
Authors: Ruth BE , Tia M , Badu-Tweneboah K
Published: December 2008

Conceptually, a rational mix design procedure should provide test parameters for input into mechanistic pavement design methods and analytical procedures to predict high and low-temperature pavement performance. It is suggested that high-temperature evaluation be performed to design asphalt concrete mixtures using a gyratory testing machine (GTM) to simulate (1) field compaction at conventional mix temperatures, and (2) traffic densification at 60°C. This would provide a better indication of mixture behavior and sensitivity to changes in aggregate blend and asphalt content than current mix design methods. The major advantage of this approach is that the changes in the shear response of the mix can be evaluated easily over the range from as-compacted to highly densified. Conventional mix design procedures are essentially one-point tests that do not provide information rate of densification or changes in stability when the mix density changes.

Tentative recommendations are presented for quality control and acceptance testing using gyratory testing of plant-produced hot mix. Advantages of this procedure are its sensitivity to combined changes in gradation and asphalt content, simplicity, and potential for more intensive testing of produced hot mix.

The low temperature (<25°C) properties and behavior of asphalt concrete paving mixtures are controlled by the Theological properties of the asphalt concrete. Therefore, it is essential that specifications for asphalts or mixtures or both be established to minimize the potential for excessive age hardening and pavement cracking. Research investigations have found cracking to be related to thermal contraction, thermal gradients that produce pavement rippling, vehicular loads, and the viscosity of the asphalt binder during cooling of the pavement. A stress analysis is presented to illustrate the combined effect of asphalt concrete moduli, underlying pavement support, and heavy wheel loading on the maximum pavement stresses developed at designated low temperatures.

A brief discussion on the selection of asphalts and polymer modification is presented to illustrate the major deficiencies in current test methods and specifications. Most asphalt specifications require only tests at 25°C and higher that neglect behavior at low temperatures. Low-temperature viscosity tests should be incorporated in all asphalt specifications. A comprehensive model asphalt specification is presented that includes viscosity tests at 15 and 25°C. An example is given to demonstrate how the viscosity-temperature relationships enhance our ability to interpret asphalt, polymer modified asphalt, and mix behavior at low temperature.
Asphalt Mix Design and the Indirect Test: A New Horizon
Authors: Baladi GY , Harichandran RS
Published: December 2008

The features of a new indirect tension test apparatus is introduced. Analytical models to reduce the test data and to calculate the structural properties of asphalt mixes are presented and discussed. A summary of the findings along with the resulting statistical equations are also presented. It is shown that the structural properties of asphalt mixes obtained from the indirect tension test using the new apparatus are consistent and the test data are reproducible.
Asphalt Concrete Mix Design in the Caribbean
Authors: Charles R
Published: December 2008

Integration of the asphalt concrete mix design procedure can be achieved through interaction between pavement distress identification, desired mix design parameters and selection of criteria, and territorial constraints including economic, technological, physical, and human resources capabilities. Surveys and investigations in Trinidad and Tobago have identified the critical types of distress as rutting and fatigue cracking, the occurrence of which are dependent on subgrade type and high pavement temperatures. A review and selection of related proven criteria from developed countries has been done to account for them. Structural analysis of full depth asphalt pavement sections has been used to generate strain-stiffness profiles for both types of distress and these profiles were combined with the selected criteria to establish a target mix stiffness. Through trial testing with a selected binder, and use of the Shell Nomograph analysis, it is shown that the target mix stiffness can be converted into stability criteria that can be substituted into Asphalt Institute criteria to provide a complete set of mix design specifications. The procedure has worked well over the past nine months.
Hazardous Waste Reduction Efforts in the Department of the Army
Authors: Pomerleau NM , McCarthy JJ , Bandy JT
Published: December 2008

The Department of the Army generates approximately 102 000 metric tons of hazardous waste each year. Nearly 90% of these wastes are produced by the Army's industrial activities. The typical method of treatment has been land disposal. Because of the costs associated with managing these wastes, both in terms of final disposal and corrective actions, and recent legislation emphasizing waste reduction, the Army began to strengthen its pollution prevention strategy. Beginning in 1984, the Army elevated the management of all wastes to the highest levels; previously, the Army had maintained a decentralized program by individual Army installations. Also, the Army established policy goals for reducing the disposal of solvents, a significant hazardous waste contributor. Similarly, in 1985, Army industrial activities developed waste reduction strategies for all other types of hazardous wastes that also emphasize front-end reduction, using methods such as materials substitution, recycling, and process changes to achieve specific process reduction goals. Hazardous waste audits and economic analyses are also required to identify and rank the appropriate type of reduction options that are economically practicable. Moreover, to develop a strategy for selecting waste management options and to measure progress in achieving program goals, formal committees were established. Committee members represent the various facets of Army activities responsible for the cradle-to-grave management of hazardous wastes.

To further facilitate the Army's hazardous waste reduction objectives, a study is being conducted to assess all hazardous waste reporting requirements, as provided by local, state, Federal, and international regulation and Army policy. The findings and recommendations from this study will support a concurrent study to identify and develop the most appropriate type of computer data base to record the necessary hazardous waste data. This data base will also serve as a useful tool in programming and budgeting for hazardous waste activities. Moreover, two additional studies are being conducted, in concert, to refine a hazardous materials tracking system and to economically evaluate and rank waste reduction options. These studies, in support of on-going waste reduction initiatives, and continuing waste reduction committee forums, will enhance the Army's efforts to meet its hazardous waste reduction objectives and goals.
The Waste Minimization Program at the Feed Materials Production Center
Authors: Blasdel JE , Crotzer ME , Gardner RL , Kato TR , Spradlin CN
Published: December 2008

A waste minimization program is being implemented at the Feed Materials Production Center to reduce the generation of uranium-contaminated wastes and to comply with existing and forthcoming regulations. Procedures and plans are described that deal with process and nonprocess trash, contaminated wood and metals, used metal drums, and major process wastes such as contaminated magnesium fluoride and neutralized raffinate. The waste minimization techniques used include segregation, source reduction, volume reduction, material substitution and waste/product recycling. The importance of training, communication, and incentives is also covered.
Minimizing Waste by Charging the Generator
Authors: Berry JB , Homan FJ
Published: December 2008

The Oak Ridge National Laboratory, a multipurpose research and development facility, has implemented a program to include the cost of waste management in product costs. The following steps are being used (1) planning and implementation tailored to institutional constraints, (2) methods for conflict resolution, and (3) administrative structure that places responsibility for minimizing waste on the generators. Changes in waste disposal practices required to meet regulatory requirements increase the cost of waste management and are reflected in the rate structure. Rate structure and changes in waste disposal practices are compared. Rates are dependent on the type of waste handled, compliance with waste acceptance criteria, processing steps required for treatment, and disposal requirements.
Mechanisms of Airway Hyperresponsiveness
Authors: Sheppard D
Published: December 2008

Airway hyperresponsiveness is relevant to air pollution because its presence defines a sensitive segment of the population and because it can be a consequence of pollutant exposure. No unifying explanation for naturally occurring airway hyperresponsiveness can be supported by present experimental evidence. Nonetheless, a good deal has been learned about the normal control of airway narrowing and the derangements in normal control mechanisms that occur in association with airway injury and inflammation. Evidence to date suggests that different mechanisms may be involved in responses to different, and perhaps even to the same, inflammatory stimuli. In human subjects, there appears to be a wide range of sensitivity to the effects of ozone on airway responsiveness, but any physiological, biochemical, or genetic bases for ozone sensitivity remain to be determined.
Exercise and Regional Dosimetry: An Overview
Authors: Miller FJ , McDonnell WF , Gerrity TR
Published: December 2008

Regional respiratory tract dosimetry is an important consideration when examining susceptibility to inhaled gases and particles. In this overview, an orientation is provided on the major anatomical ventilatory and physiologic factors that affect regional respiratory tract dosimetry. The influence of these factors and the physical laws governing deposition exhibit complex relationships for the extrathoracic, tracheobronchial, and pulmonary regions of the respiratory tract. Specific examples of regional dosimetry of insoluble and hygroscopic particles and an oxidant gas are presented to help identify critical issues and research areas related to susceptibility to inhaled pollutants.
Upper Airway Scrubbing at Rest and Exercise
Authors: Kleinman MT , Mautz WJ
Published: December 2008

The upper respiratory tract removes inhaled toxic or infectious substances from inspired air and thus functions as an important element of the lung's defense systems. Two key parameters that influence the efficiency of this upper airway scrubbing are the rate of ventilation and whether air enters via the nose or the mouth. For a gas of relatively low water solubility, such as nitrogen dioxide, scrubbing efficiency decreases as ventilation rate increases during either nasal or oral breathing; the nose is, however a more efficient scrubber than the mouth at any given ventilation rate. Exercise increases ventilation rate and often, in humans, results in a shift from nasal to oronasal breathing. Increased ventilation and degradation of upper airway scrubbing during exercise can result in greater than expected lung doses; exercise at which minute ventilation is doubled along with a switch from pure nasal to pure oral breathing can increase dose to the lung by six-fold.
Aerosol Boluses
Authors: Stahlhofen W , Gebhart J , Scheuch G
Published: December 2008

Three methods for the study of characteristics of the human lungs are introduced based on a special inhalation technique. The technique using an aerosol bolus of defined volume being injected at any moment during inhalation is applied to detect the dispersion of an aerosol bolus in the expired air, to chart human airway dimensions out of the sedimentation of the particles during breath-holding, and to observe the clearance of radioactively labelled particles from defined regions of the lungs. Applications of the methods for diagnostic purpose are given, and the possibilities of their use for the study of human susceptibility for air pollutants are discussed.
Nutritional Status and Oxidants
Authors: Last JA
Published: December 2008

This review examines the relationship between vitamin C, vitamin E, selenium, copper, zinc, and other dietary antioxidants and the so-called antioxidant defense systems of the lung. The effects of severe caloric and protein malnutrition and vitamin B-6 deficiency on lung development will also be reviewed. The animal models of oxidant-induced injury discussed include those for paraquat, ozone, nitrogen dioxide, and oxygen toxicity, as well as selected experiments with in vitro systems. Susceptible human populations at risk for oxidant-induced lung damage by virtue of nutritional deficiencies are identified and discussed.
Evaluating Relationships Among Personal Risk Factors, Ambient Oxidant Exposure, and Chronic Respiratory Illness
Authors: Hackney JD , Linn WS
Published: December 2008

Transient respiratory irritant effects from exposure to elevated levels of ambient ozone are well documented in studies of human volunteers. Individual reactivity to ozone varies greatly, for unknown reasons. From animal toxicologic evidence, one may reasonably hypothesize that repeated ozone exposure increases the risk of developing chronic obstructive pulmonary disease (COPD). Relevant human evidence is sparse and equivocal. To test this hypothesis rigorously, an experiment combining controlled human exposures and epidemiologic surveys may be appropriate. This approach would also help to determine whether ambient ozone exposure acutely exacerbates COPD. Recent controlled human studies suggest that individuals' short-term reactivity to ozone is a persistent phenomenon, but may vary seasonally, probably in response to ambient exposures.
Asthma and Nitrogen Dioxide: A Review of the Evidence
Authors: Utell MJ
Published: December 2008

There exist significant gaps in our understanding of human health effects resulting from inhalation of low-level nitrogen dioxide. Controlled clinical studies provide an important approach for examining acute effects in potentially sensitive subgroups. Although the evidence is inconclusive in linking nitrogen dioxide (NO2) exposure with enhanced bronchoconstriction in asthmatics, a more consistent data base is emerging. As evaluation techniques improve, it is predicted that more significant changes in the range of 0.30 ppm NO2 will be found.
Techniques for Measurement of the Thermal Expansion of Advanced Composite Materials
Authors: Tompkins SS
Published: December 2008

Techniques available to measure small thermal displacements in flat laminates and structural tubular elements of advanced composite materials are described. Emphasis is placed on laser interferometry and the laser interferometric dilatometer system used at the National Aeronautics and Space Administration (NASA) Langley Research Center. Thermal expansion data are presented for graphite-fiber reinforced 6061 and 2024 aluminum laminates and for graphite fiber reinforced AZ91 C and QH21 A magnesium laminates before and after processing to minimize or eliminate thermal strain hysteresis. Data are also presented on the effects of reinforcement volume content on thermal expansion of silicon-carbide whisker and paniculate reinforced aluminum.
Modeling Continuous Fiber Metal Matrix Composite as an Orthotropic Elastic-Plastic Material
Authors: Sun CT
Published: December 2008

An orthotropic plasticity model for describing the elastic-plastic behavior of metalmatrix composites is reviewed. This plasticity model is derived based on a plastic potential function which is a quadratic form in stresses. Simple uniaxial loading on off-axis specimens is used to determine the parameters in the model. A boron-aluminum composite is used in the experimental validation of the model.
Strain Intensity Factor Approach for Predicting the Strength of Continuously Reinforced Metal Matrix Composites
Authors: Poe CC
Published: December 2008

A method was previously developed to predict the fracture toughness (stress intensity factor at failure) of composites in terms of the elastic constants and the tensile failing strain of the fibers. The method was applied to boron/aluminum composites made with various proportions of 0° and ±45° plies. Predicted values of fracture toughness were in gross error because widespread yielding of the aluminum matrix made the compliance very nonlinear. An alternate method was developed to predict the strain intensity factor at failure rather than the stress intensity factor because the singular strain field was not affected by yielding as much as the stress field. Far-field strains at failure were calculated from the strain intensity factor, and then strengths were calculated from the far-field strains using uniaxial stress-strain curves. The predicted strengths were in good agreement with experimental values, even for the very nonlinear laminates that contained only ±45° plies. This approach should be valid for other metal matrix composites that have continuous fibers.
Strength Predictions for Metal Matrix Composites
Authors: Harmon DM , Saff CR , Graves DL
Published: December 2008

A multistage analysis routine for prediction of metal matrix composite strength and life has been developed. It uses micromechanics to predict material stresses, strains, and crack initiation under load. It uses macromechanics for load redistributions caused by geometry, local failures, and crack growth. This routine can be used to predict lamina and laminate stiffnesses, stresses about a notch and through the net section, laminate strength (notched or unnotched), crack initiation lives, crack growth, and residual strength. The routine is user-friendly and emphasizes rapid analysis techniques, which allow the program to be run interactively. The purpose of this routine is to provide quick and accurate strength and life predictions for metal matrix composites based on limited test data.
The Soliroc Process in North America: A Stabilization/Solidification Technology for the Treatment of Metal-Bearing Wastes with Reference to Extraction Procedure Toxicity Testing
Authors: Ezell D , Suppa P
Published: December 2008

The Soliroc Process is a proven European stabilization/solidification technology which is used in the treatment of liquid wastes containing heavy metals. Tricil has carried out laboratory-scale studies of the Soliroc Process at three of its North American waste treatment facilities and also has contracted an independent consultant to carry out similar studies.

Waste samples at each facility were treated, using the Soliroc technology, and then subjected to the Extraction Procedure Toxicity Test (EP Tox). In all the lab tests, identical waste samples were also treated using a conventional lime precipitation process and compared with the Soliroc results. The results indicated superior performance of the Soliroc process to lime precipitation with respect to the EP Tox test. In addition, chelating agents were found not to adversely affect the EP Tox results of the Soliroc process.
Development of a Composite Polyethylene—Fiberglass-Reinforced-Plastic High-Integrity Container for Disposal of Low-Level Radioactive Waste
Authors: Lowenberg H , Shaw MD
Published: December 2008

Bondico Nuclear (Los Angeles, California) has initiated a program to develop a high-integrity container (HIC) for handling, transportation, and disposal of low-level radioactive wastes. The HIC, made of a composite material, consists of an inner layer of polyethylene bonded to an outer casing of fiberglass-reinforced plastic.

Preliminary handmade prototype units containing about 0.22 m3 called HIC-7, have been fabricated and exposed to some of the most demanding U.S. Nuclear Regulatory Commission (NRC) and state tests. The HICs withstood over twice the external pressure from maximum burial conditions and twice the Type A package internal pressure requirements. In addition, free drops on compacted soil and an unyielding surface showed no deleterious effects.

The composite material has been tested for mechanical properties, such as tensile, com-pressive, and bond shear strengths, creep, thermal expansion, and hardness. In addition, specimens have been exposed to environments including thermal cycling, gamma and ultra violet radiation, biodegradation from fungi and bacteria, and internal and external chemical corrosion followed by mechanical testing. Prototype production units have been tested to the full range of NRC and state requirements. A topical report showing how this HIC meets all NRC and state requirements has been submitted to the NRC.
A Critical Review of Evaluation Procedures for Stabilization/Solidification Processes
Authors: Poon CS
Published: December 2008

The leaching procedures for evaluation of cement-based stabilization/solidification processes are considered. The difficulties in obtaining a consensus test method are discussed. The relative merits and shortcomings of the equilibrium and dynamic leaching test approaches are underlined, and various leaching models are considered.

Although mass transport and diffusion models have been generally used to describe the leaching behavior of soluble species, the use of these models to describe the cement-solidified heavy metal waste is questioned. This is based on theoretical consideration of the interaction between cementitious materials and waste and experimental evidence of the leaching characteristics. An alternative approach toward modeling the leaching behavior of the solidified waste is presented.

Because the performance of the solidified material is also dependent on the physical properties of the waste form, a physical test procedure in conjunction with an appropriate leach test is proposed as necessary to evaluate the quality of the solidified waste. A tentative approach to formulate such a combined test method is suggested.
Leaching Characteristics of Selected Elements from Coal Fly Ash as a Function of the Acidity of the Contact Solution and the Liquid/Solid Ratio
Authors: de Groot GJ , Wijkstra J , Hoede D , van der Sloot HA
Published: December 2008

To estimate the environmental consequences of the storage and utilization of coal fly ash, in the Netherlands a standard leaching test has been developed. In this test, leach conditions are used which aim at close approximation with field conditions. The standard test consists of three main parts: a column leaching test, a serial batch leaching test, and a test for the determination of maximum leachability. As a time scale the liquid/solid ratio (LS) is used, where LS is the ratio between the total quantity (L) of liquid used for leaching and the weight (kg) of the leached material. The relation between this relative time scale and the actual time scale depends on the time required for a given LS ratio to be reached in the actual situation.

In recent years, 50 ashes from a wide variety of sources were analyzed. Five different ashes were submitted to the complete standard leaching test described. All ashes show common leaching characteristics for several groups of elements. The elements present in the form of anionic species (for example, arsenic, antimony, selenium, molybdenum, tungsten, and vanadium) behave similarly. In contrast with literature information, limited solubility of anions at high pH (>11) has been observed. The metals lead, copper, cadmium, and zinc show minimum solubility at high pH, whereas major elements like aluminum and silicon show two minima in the pH range 7 to 9 and at pH values higher than 11. The latter was related to the formation of new mineral phases (for example, ettringite). To verify the pH dependence of the element concentrations leached, experiments with an artificial fly ash solution, containing all major elements normally found in fly ash extracts at pH 4 and LS ratio 5, have been performed. By stepwise increase of the pH, by adding calcium oxide, the relation between pH and element concentrations in the solution has been established. The results are in good agreement with the concentrations found in normal fly ash extracts. The experimental data of all batch experiments are summarized in three-dimensional graphs relating element concentration in solution, pH, and LS ratio. It shows that pH is the main factor in controlling the leachability.

The leaching behavior of trace elements in products containing fly ash has also been determined. After grinding, the materials were subjected to the standard test described. The leaching data retrieved from the products agreed well with the results from the pure ash/water system, indicating a consistent solubility control in solution. To what extent this information on ash/water mixtures can be used for other waste materials remains to be answered.
Development of a Liquid Release Tester
Authors: Swanstrom CP
Published: December 2008

The 1984 Amendments to the Resource Conservation and Recovery Act (RCRA) specify that bulk liquid wastes which have been stabilized /solidified for land disposal must not release the liquid under the mechanical pressures experienced in a landfill. How to determine this property has not yet been specified. In response to the need for a simple, yet highly effective test device to evaluate the tendency of a stabilized waste to release liquid, the author's company has developed a test apparatus and a test procedure. This simple tester distinguishes between stabilized wastes which will release liquids under pressure on a pass/ fail basis.

The tester utilizes a 100-g sample that requires only minimal sample preparation. The test duration is 5 min. The only expendables are readily available paper filters, and the system requires only a balance and compressed air for operation.

The effects of test pressure, test duration, and sample cure time were evaluated. Results may be compared with other test procedures for evaluating stabilized waste.
Metal Immobilization by Solidification of Hydroxide and Xanthate Sludges
Authors: Bricka RM , Hill DO
Published: December 2008

The U.S. Department of the Army (DA) is responsible for the treatment and disposal of heavy metal wastes generated at DA facilities. Heavy metal wastewaters are gen erally treated by hydroxide precipitation. An alternative technique uses xanthates to precipitate the heavy metals. Both of these processes produce a sludge defined as hazardous by the Resource Conservation and Recovery Act (RCRA). One method proposed for treating such materials is solidification/stabilization (S/S). S/S renders a waste less toxic by chemically immobilizing the hazardous constitutes in a solid matrix.

This study evaluated the ability of cellulose and starch xanthate to immobilize heavy metals and compares the results with the metal immobilization capability of hydroxide precipitation. Solidified and unsolidified sludges resulting from starch xanthate, cellulose xanthate, and hydroxide precipitation processes were tested for their physical and chemical characteristics. Sludges were prepared using either cellulose xanthate, starch xanthate, or calcium hydroxide to treat a synthetic waste solution containing four heavy metals (cadmium, chromium, nickel, and mercury) in a laboratory-scale study. Sludges were solidified with portland Type I cement. Physical tests performed on the solidified and unsolidified xanthate and hydroxide sludges included unconfined compressive strength and the cone penetration tests. Chemical leaching characteristics of the unsolidified sludges were determined using the U.S. Environmental Protection Agency's extraction procedure test and a serial graded batch extraction procedure. Results from this study indicated that the solidified materials reduced the concentration of metals in the leachate when compared to the unsolidified sludges. The solidified sludges also developed unconfined compressive strengths as high as 2000 kPa.
Strategy for Management of Mixed Wastes at the West Valley Demonstration Project
Authors: Englert JP , Roberts CJ , Smeltzer EE
Published: December 2008

The evolution of regulations covering the disposal of low-level radioactive wastes (10 CFR 61) and hazardous wastes (40 CFR 260–265) has created a dilemma for generators of wastes that are both radioactive and hazardous, that is, mixed wastes. Because these regulations were developed independently, compliance with one set of regulations may create conflicts with the requirements of the other regulations. The challenge confronting mixed-waste generators is to develop waste management programs that eliminate these conflicts.

The West Valley Demonstration Project is employing cement solidification on several characteristic mixed-waste streams to remove the final waste form from the hazardous waste universe and simplify the regulatory requirements for subsequent storage and disposal. This paper discusses the regulatory basis for specific waste management practices and illustrates their application to a corrosive mixed-waste stream and a radioactive-waste stream that is hazardous based on the extraction procedure (EP) toxicity characteristic.
Large-Scale Demonstration of Low-Level Waste Solidification in Saltstone
Authors: McIntyre PF , Oblath SB , Wilhite EL
Published: December 2008

The saltstone lysimeters are a large-scale demonstration of a disposal concept for decontaminated salt solution resulting from in-tank processing of defense waste. The lysimeter experiment has provided data on the leaching behavior of large saltstone monoliths under realistic field conditions. The results also will be used to compare the effect of capping the waste form on contaminant release.

Three saltstone lysimeters were installed in December 1983 and January 1984, each containing a buried monolith formed from 9500 L of decontaminated salt solution solidified with a blended cement. The decontaminated salt solution was produced using actual Savannah River Plant waste. One lysimeter has a gravel cap and another has a clay cap placed over the buried monolith. The monolith in the third lysimeter is uncapped. Each lysimeter has provision to collect leachate from a sump below the buried monolith and soil moisture samplers for gathering samples adjacent to the waste form.

Biweekly monitoring of sump leachate from all three lysimeters has continued on a routine basis for approximately three years. The uncapped lysimeter has shown the highest levels of nitrate and 99Tc release. The gravel-and-clay-capped lysimeters have shown levels equivalent to or slightly higher than background rainwater levels.

Mathematical model predictions are compared with lysimeter results and are applied to predict the impact of saltstone disposal on ground-water quality.
In Situ Grouting of Shallow Landfill Radioactive Waste Trenches
Authors: Spence RD , Tamura T
Published: December 2008

A backfilled trench containing low-level radioactive waste was grouted with a particulate grout. The accessible void volume of the waste zone was estimated to be 20% or 28 m3, but 30.6 m3 of grout was injected into the trench. Part of the grout forced a path outside the trench. The water permeation into the trench from monitoring wells was reduced by two orders of magnitude. Site characterization and monitoring costs were outside the scope of this paper, so the only costs presented are the grouting costs. The grout costs only $0.055/L; but most of the cost was in manpower, 1220 man-hours for this demonstration.