bluuebunny/crossref_metadata_2025 huggingface dataset:
Mixed Waste Solidification Testing on Polymer and Cement-Based Waste forms in Support of Hanford's WRAP 2A Facility
Authors: Burbank DA , Weingardt KM
Published: March 2009

A testing program has been conducted by the Westinghouse Hanford Company to confirm the baseline waste form selection for use in Waste Receiving and Processing (WRAP) Module 2A. WRAP Module 2A will provide treatment required to properly dispose of containerized contact-handled, mixed low-level waste at the U.S. Department of Energy Hanford Site in south-central Washington State. Solidification/stabilization has been chosen as the appropriate treatment for this waste. This work will test cement-based, thermosetting polymer, and thermoplastic polymer solidification media to substantiate the technology approach for WRAP Module 2A.

Screening tests were performed using the major chemical constituent of each waste type to measure the gross compatibility with the immobilization media and to determine formulations for more detailed testing. Surrogate materials representing each of the eight waste types were prepared in the laboratory. These surrogates were then solidified with the selected immobilization media and subjected to a battery of standard performance tests. Detailed discussion of the laboratory work and results are contained in this paper.
Vitrification of Lead Contained in Lead Based Organic Coatings Using Thermal Spray Technology
Authors: Covey SW , Petreanu JP , Kumar A
Published: March 2009

The feasibility of in situ vitrification of lead oxide contained in red lead based organic coatings was investigated. The removal of organic lead based primers and paints has been achieved by a flame spray process that uses a glass/ceramic compound designed for high lead solubility and resistance to devitrification. The two designer glass waste forms that exhibited the best results belong to the lead borosilicate and the lead alkali silicate systems. The glass/ceramic compounds were prepared by fusing, fritting, and ball milling to produce the desired powder. The resulting powder was collected and used to flame spray previously prepared samples containing a commonly used red lead primer. Oxyacetylene flame spray technology was used to apply the glass compound to the steel substrate. The resulting glass waste was collected and analyzed for lead content using X-Ray Spectrometry (XRS) and the lead cation teachability rates using the U.S. Environmental Agency approved Toxicity Characteristic Leaching Procedure (TCLP). Of the alkali silicate glass compositions that were tested, the least lead leached from the glass was 2 ppm of lead. The lowest leachate concentration from the borosilicate glass compositions was 12 ppm of lead.
Critical Parameters and TCLP Performance of the RFP Microwave Solidification System
Authors: Eschen VG , Fenner GS , Splett DM , Sprenger GS
Published: March 2009

Two series of experiments were conducted at Rocky Flats Plant (RFP) to identify the critical operating parameters for microwave solidification and to evaluate the performance of the product against the Environmental Protection Agency's (EPA's) Toxicity Characteristic Leach Procedure (TCLP). A surrogate hydroxide coprecipitation sludge spiked with heavy metals was used in the study. The RFP process uses microwave energy to heat and melt the waste into a vitreous final form that is suitable for land disposal. The results of the study indicate that waste loading and borax content in the glass-forming frit are critical in the treatment of hydroxide sludge. Also, the product will easily satisfy EPA's limitations for land disposal. These results are very encouraging and support RFP's commitment to the use of microwave technology for treatment of various mixed waste streams at the facility.
Property Changes of Cement-Based Waste Forms During Leaching
Authors: Cheng KY , Bishop PL
Published: March 2009

This work investigates the physical property changes of cement-based waste forms before and after leaching in acetic acid solutions. Specimens were prepared in the laboratory with a Type I Portland cement and synthetic metal sludges. The physical properties (water content, densities, and porosity) of the waste forms were examined before and after leaching. The study showed that a leached layer developed on the surface of every leached specimen. The physical properties of the leached layer, which were highly porous and lighter weight in nature, were distinctly different from those of the original material.
Evaluation of Contaminant Leachability Factors by Comparison of Treatability Study Data for Multiple Solidified/Stabilized Materials
Authors: Erickson PM , Barth EF
Published: March 2009

Solidification/stabilization (S/S) technology is widely used in the treatment of hazardous waste and contaminated soil in the U.S. In a project sponsored by the U.S. Navy and the U.S. Environmental Protection Agency (U.S. EPA), treatability test data were compiled into a data base listing contaminant concentration and matrix, binder type and ratio, and effects of S/S treatment on 18 metals. Preliminary analysis showed that S/S treatment achieved substantial reduction in laboratory-measured leachability in the majority of cases involving silver, cadmium, lead and mercury; however, selenium, arsenic, chromium and barium were less readily treatable. Numerical correlations between waste or binder properties and degree of immobilization were not readily apparent, possibly because of gaps in available data. In this study, a subset of the data base was selected and analyzed graphically to elucidate general relationships between waste and binder properties and the effectiveness of S/S treatment. Relationships were examined between the degree of immobilization and such factors as leachable metal concentration in the raw waste, extraction test procedure, binder, binder-to-waste ratio and extract pH. Leachate pH was the best indicator of lead leachability, with very strong trends in a single study and noticeable trends in the larger data base. Overall, however, the existing data do not indicate how to predict S/S performance without conducting treatability tests on new materials being considered for treatment.
Bulk Site Reference Materials
Authors: Barich JJ , Jones RR
Published: March 2009

The selection, manufacture and use of Bulk Site Reference Materials (BSRMs) at hazardous waste sites is discussed. BSRMs are useful in preparing stabilization/solidification (S/S) formulations for soils, ranking competing S/S processes, comparing S/S alternatives to other technologies, and in interpreting data from different test types. BSRMs are large volume samples that are representative of the physical and chemical characteristics of a site soil, and that contain contaminants at reasonably high levels. A successful BSRM is extremely homogeneous and well-characterized. While not representative of any point on the site, they contain the contaminants of the site in the matrices of the site. Design objectives for a BSRM are to produce a material that 1) maintains good fidelity to site matrices and contaminants, and 2) exhibits the lowest possible relative standard deviation.
Field Validation of Test Methods for Solidified Waste Evaluation - A Status Report
Authors: Stegemann JA , Caldwell RJ , Shi C
Published: March 2009

Application of solidification/stabilization as a treatment technology for hazardous wastes has been hindered by the lack of a regulatory approval mechanism for solidified wastes. The Wastewater Technology Centre (WTC) has developed a protocol for evaluation of solidified wastes, which uses the performance of a solidified product in twelve laboratory test methods to recommend one of four categories of utilization and disposal. In order to facilitate acceptance of the protocol, a validation study of the test methods has been initiated by the WTC. A 63 m3 field test cell has been constructed using electric arc furnace dust solidified with an activated blast furnace slag binder system. The behaviour of the solidified waste in the field will be investigated by monitoring of leachate and testing of core samples, and compared with properties measured in the laboratory.
Performance Modeling of Concrete/Metal Barriers Used in Low-Level Waste Disposal
Authors: Shuman R , Chau N , Icenhour AS , Godbee HW , Tharp ML
Published: March 2009

Low-Level radioactive wastes generated in government and commercial operations involving nuclear materials need to be isolated from the environment almost in perpetuity (at least for 300 to 500 years or, in some cases, even longer). An increasing number of disposal sites are using concrete/metal barriers (so called “engineered” barriers) to isolate these wastes from the environment. Two major concerns hamper the use of engineered barriers; namely, the lack of ability to predict reliably the service life of these barriers and to estimate the confidence level of the service life predicted. Computer codes (SOURCE1 and SOURCE2) for estimating the long-term (centuries to millennia) service life of these barriers are presented. These codes use mathematical models (based on past observations, currently accepted data, and established theories) to predict behavior into the future. Processes modeled for concrete degradation include sulfate attack, calcium hydroxide leaching, and reinforcement corrosion. The loss of structural integrity due to cracking is also modeled. Mechanisms modeled for nuclide leaching include advection and diffusion. The coupled or linked effects of these models are addressed in the codes. Typical outputs from the codes are presented and analyzed. These results suggest that major efforts (including research) are needed to compare, evaluate, verify, and eventually validate codes (such as SOURCE1 and SOURCE2) for predicting the long-term behavior of engineered barriers.
Effects of Various Additives on the Solidification of Oily Sludges: A Bench-Scale Study
Authors: Kelly DS , Diethelm EC
Published: March 2009

In preparation for closure of a RCRA hazardous waste site in Northern California, the oily impounded sludges will be solidified in situ using a cementitious system in order to support the closure cover. To determine mix ratios of additives to be used to solidify the sludges in the impoundments, treatability testing was completed. The testing consisted of first mixing the sludge with additives in small batches to determine the effect of various types and combinations of additives on the unconfined compressive strength (by pocket penetrometer testing) of the solidified material. Information learned in this testing was used to determine mix ratios to be tested in larger batches to evaluates caling changes and test for unconfined compressive strength by a more reliable method. The appropriate mix ratio determined in the second set of tests will be used as a guide to solidify the impounded sludge in situ.

Data from the impoundment tested indicates the largest observed effect on the final strength of the solidified material was due to varying the amount of fly ash added. Varying the amount of cement had a lesser observed effect on the final strength of the material. The data also indicates an increase in the strength of solidified material with the addition of relatively small amounts of bentonite in addition to other additives. Further increases in the amount of bentonite did not appear to affect the final strength.
Literature Review of the Interaction of Select Inorganic Species on the Set and Properties of Cement and Methods of Abatement Through Waste Pretreatment
Authors: Mattus CH , Mattus AJ
Published: March 2009

It is a well-known fact that many inorganic species that may be present as a component of a complex aqueous waste can have an adverse effect upon the set of cements and subsequent properties of a final waste form product. Chemical species such as sulfates, aluminates, borates, phosphates, and zinc, to namea few, especially when present in combination, can result in false sets, flash sets, and expansive mineral phases along with many other unwanted changes in physical properties.

Generally, the approach is to adjust the type of additives present in a waste form formulation to compensate or sometimes to rely upon raw waste dilution to minimize or mitigate potential problems. Another approach which is discussed in this paper, in addition to a comprehensive literature review, is based upon an understanding of the chemistry of the waste solution and its components: that is, we rely upon pretreatment of the waste solution to prevent interactions during or after solidification. Various types of precipitation options are available for the removal of certain waste species, or we may simply alter them to a stable, more insoluble form. Undesirable reactions in the cementitious solid phase, as well as some of the various waste pretreatment options which are available, are discussed.
In-Situ Stabilization of Mixed Waste Contaminated Soil
Authors: Siegrist RL , Cline SR , Gilliam TM , Conner JR
Published: March 2009

A full-scale field demonstration was conducted to evaluate in situ solidification for stabilizing an inactive RCRA land treatment site at a DOE facility in Ohio. Subsurface silt and clay deposits were contaminated principally with up to 500 mg/kg of trichloroethylene and other halocarbons, but also trace to low levels of Pb, Cr, 235U, and 99Tc. In situ solidification was studied in three, 3.1m diameter by 4.6 m deep columns. During mixing, a cement-based grout was injected and any emissions from the mixed region were captured in a shroud and treated by filtration and carbon adsorption. During in situ processing, operation and performance parameters were measured, and soil cores were obtained from a solidified column 15 months later. Despite previous site-specific treatability experience, there were difficulties in selecting a grout with the requisite treatment agents amenable to subsurface injection and at a volume adequate for distribution throughout the mixed region while minimizing volume expansion. Observations during the demonstration revealed that in situ solidification was rapidly accomplished (e.g., >90 m3/d) with limited emissions of volatile organics (i.e., < 1 wt% of initial Soil VOCs). Grout distribution within the mixed region was not uniform, with marked differences in compressive strength and elemental content with depth. Volume expansion was significant (30% v/v) and the hydraulic conductivity of the solidified soil was greater than that of the undisturbed natural deposit (10-6 cm/s vs. 10-8 cm/s) Leaching tests performed on the treated samples revealed non-detectable to acceptably low concentrations of all target contaminants.
Effects of Adjuvants and Dynamic Surface Tension on Spray Properties Under Simulated Aerial Conditions
Authors: Dexter WR , Huddleston EW
Published: March 2009

The literature on the effects of active ingredients, adjuvants and surface active agents on the droplet size of agricultural sprays is reviewed. The effects of various agricultural adjuvants on the droplet size distributions of a herbicide sprayed in a wind tunnel simulating an aerial application were determined using a Malvern laser diffraction instrument. All adjuvants caused a decrease in droplet size, which varied with adjuvant type and concentration. Measurements of equilibrium surface tension, dynamic surface tension at 20 ms, density, and viscosity were recorded. Droplet size did not correlate linearly with equilibrium surface tension: only at the lowest surface tensions was any significant decrease in droplet size observed. Droplet size correlated better with dynamic surface tension for each adjuvant over most of the surface tension range, but with different slopes for each adjuvant. At high concentrations of surfactant, bubbles of air were observed within captured droplets and the size distribution became bimodal.
Trisiloxane Surfactants — Mechanisms of Spreading and Wetting
Authors: Venzmer J , Wilkowski SP
Published: March 2009

Aqueous solutions of some nonionic trisiloxane surfactants exhibit superior wetting properties on hydrophobic substrates (“superspreading”). Although this phenomenon has received extensive coverage in the scientific literature in recent years, its mechanism and the reason why only some silicone surfactants show this behavior remained unclear. Apart from the characteristic of a low surface tension, which is typical of most silicone surfactants, it is crucial that the surfactants form bilayer aggregates (vesicles, lamellar phases) in aqueous solution. Based on molecular packing considerations, there is a fundamental difference between the behavior at the solid/liquid interface of a micelle-forming surfactant and of a vesicle-forming surfactant. The model presented is supported by measurements of the spreading kinetics.
Deactivated Clay Carrier
Authors: Stein J , Taylor DR , Svidovsky N
Published: March 2009

Pesticides incorporated into granules are a popular formulation option. Ideally, a granule should offer high liquid holding capacity, high resistance to attrition, low dust and chemical inertness. Clay granules offer a formulator all of the above benefits except, on occasion, chemical inertness. Clays possess chemical activity arising from acid sites associated with the clay surface. While this is not always a problem, in some instances a deactivator (e.g. dipropylene glycol) is incorporated into the formulation to counteract the surface activity of the clays. In this paper, a clay granule that has been processed to lower surface activity is described. The physical characteristics of the new granule are contrasted with clay granules processed in the traditional manner. The stability of two phosphate ester pesticides on the new granule is presented. In one instance, the new granule results in a decrease in the amount of deactivator needed for a stable formulation. In the other instance, the new granule results in a formulation that is stable with no deactivator.
Liquid Matrices For Insecticides for “Pour On” Applications In Queous Medium — Amitraz as A Case Study
Authors: Jon DI , Prettypaul DI , Benning MJ , Narayanan KS , Ianniello RM
Published: March 2009

Sprayable low viscosity liquid matrices capable of forming solutions or miniemulsions with insecticides in water medium were successfully formulated. The water based end-use compositions were designed to be applied as ‘pour on’ on animals. The concentrate matrix for water based delivery comprised of ethoxylated castor oil with HLB between 8–16 as the primary emulsifier, ethoxylated sorbitan monooleate and/or long chain (⩾ C8) N - alkyl pyrrolidone as secondary emulsifiers. A prototype concentrate containing 10% amitraz for aqueous delivery on dilution with water at the time of use is provided along with stability data. The stability of the concentrate was considered enhanced by storing on molecular sieves 4A.
Correlation of Adjuvant Physico-Chemical Properties and Glyphosate Efficacy
Authors: Sun J , Singh M
Published: March 2009

Greenhouse experiments were conducted to investigate the effect of adjuvants on glyphosate efficacy. Adjuvants evaluated were Silwet L-77, Kinetic, Dyne-Amic, Impact, Induce, Optima, LI-700, Freeway, X-77, and Agri-Dex. Tested two weed species were redroot pigweed (Amaranthus retroflexus L.) and barnyardgrass [Echinochloa crus-galli (L.) Beauv.]. In most cases, glyphosate, at 0.56 kg/ha, combined with adjuvants resulted equal or better control in both weed species. Optima was most effective for enhancing glyphosate efficacy. However, the combination of glyphosate with either Induce or Freeway showed antagonism.

Correlation of adjuvant physico-chemical properties and glyphosate efficacy was also analyzed. The results showed that contact angle and spreading coefficient had significant effect on glyphosate efficacy 1 week after treatment (WAT). As the time interval increased to 2, 3, and 4 WAT, the significance of the correlation decreased.
The Potential of Corn Syrup as an Adjuvant for Postemergence Herbicides
Authors: Roggenbuck FC , Kells JJ , Penner D
Published: March 2009

Corn marketing organizations and corn processors are interested in increasing the utilization of value-added products from corn. Corn syrup was evaluated as an activator adjuvant with several postemergence herbicides in greenhouse and field studies. The greatest enhancement of herbicide activity was observed with high fructose corn syrup applied in combination with an ammonium sulfate and an effective nonionic adjuvant with anionic herbicides such as glyphosate and glufosinate for control of grass species such as giant foxtail.
Conservation of Cultural Property in Italy: the UNI-NORMAL Committee for the Definition of Technical Standards
Authors: Alessandrini G , LaurenziTabasso M
Published: March 2009

Diagnosis is of the utmost importance as a basis for planning conservation reatments. Reliable, more comparable results are achieved when diagnostic studies are based on the use of standard methodologies. Not always those available in the field of material science are applicable to the specific field of cultural property, because of the specificity and constraints related to the “values” of the property to study. The paper briefly illustrates aim, structure and activity of the Italian UNI-NORMAL Commission, established in the late 1970s by the Ministry of Cultural Property and the National Research Council (CNR). The Commission originally had the task of defining standard methods for the study of the deterioration of both natural and artificial stone materials and their conservation. Only in recent years has the Commission extended its activity to metals; in the next future other materials, such as wood and textiles, are going to be considered. The list of the Documents published so far is given in Appendix.
Drilling Resistance as an Indicator for Effectiveness of Stone Consolidation
Authors: Lotzmann S , Sasse HR
Published: March 2009

The drilling resistance measurement as a minimally destructive test method has been applied for more than ten years in stone conservation. The main fields of application have been to determine the depth of crusts or surface scaling areas and exfoliations. The aim of investigations at IBAC was to find a correlation between the biaxial tensile strength in bending and the drilling resistance for untreated and treated natural stones. The strengthening caused by the polymer impregnation was established by both measurements. The factor of increasing strength was different dependent on the method. The drilling resistance can be used for site application before and after a consolidation to assess the penetration depth and consolidation of the treated areas. The advantage of drill holes of 3 mm diameter compared with drilling cores of 50 mm diameter for investigations into depth is self-explanatory.
Lessons Learned from the Structural Retrofit of a Historic Charleston House
Authors: Willis VL , Schiff SD , Rosowsky DV , Nelson JK
Published: March 2009

An initiative is underway in Charleston, South Carolina, to provide a center for the demonstration of retrofit techniques intended to increase the ability of historic residences to withstand damage caused by natural hazards: hurricanes, earthquakes, and floods. During the retrofit of the center, many structural engineering issues surfaced. Such topics include retrofit for multiple hazards, application of current building codes, identification of load paths in archaic framing systems, use of nontraditional methods and materials, significance of non-structural components, and masonry chimney and foundation stabilization. Attempts to apply current analysis techniques and retrofit methods led to difficulties that had to be overcome to provide workable retrofit solutions. This paper addresses many of these problems, describes some of the solutions developed, and identifies engineering aspects of historic preservation in need of more research and greater consensus regarding proper methods and procedures.
Geotechnical Procedures for at-Risk and in-Distress Structures
Authors: Laefer DF
Published: March 2009

Over the last ten years the United States has begun to adopt a wide variety of protective and corrective European and Asian ground treatment and intervention methods both to minimize the risk to vulnerable structures during adjacent construction and to stop on-going settlement of existing buildings. This paper introduces the basics of two of the most popular techniques (micropiles and jet grouting), outlines their usefulness around historic properties, and emphasizes the need for standards for these methods.
Toward Structural Safety Standards for Historic Wooden Buildings in Japan—An Attempt through Experiments and Analyses
Authors: Sakamoto I , Nishizawa H , Hidaka K , Fujita K
Published: March 2009

Japanese historic wooden buildings are distinctive regarding the aspect of their material (timber), and of their frequent exposure to natural hazard (earthquake and typhoon). This paper introduces the state-of-the-art of the structural and technical aspects for conservation of the historic wooden buildings in Japan. Damage caused by natural hazards, structural interventions that have been tried, and structural experiments that are being performed are discussed.
Instrumentation for Monitoring Buried Pipe Behavior During Backfilling
Authors: McGrath TJ , Selig ET , Webb MC
Published: March 2009

An extensive instrumentation plan was devised to monitor buried pipe behavior, soil behavior and pipe-soil interaction during backfilling. The emphasis of the instrumentation plan was to monitor these parameters under different installation techniques without impeding construction operations.

Different types and sizes of pipe were selected for installation in trenches excavated in undisturbed in situ soil conditions. Installation variables included in situ soil conditions, trench widths, backfill material (including controlled low strength material), haunching effort, and compaction methods. A total of fourteen tests, each including reinforced concrete, corrugated steel, and corrugated HDPE, were conducted. Eleven of the installations were conducted with 900 mm inside diameter pipe and three with 1500 mm inside diameter pipe. The pipes were buried to a cover depth of 1.2 m.

Measurements of pipe shape, pipe strains, pipe-soil interface pressures, soil density, soil stresses, and soil strains were collected. Pipe shape changes were measured by a custom built profilometer. Custom designed bending beam pressure transducers were used in the steel pipe to measure interface pressures.

Most of the instrumentation performed well and measured results were within the range expected. Pipe-soil interaction effects were effectively measured with the instruments selected. Pipe shape changes were a very valuable parameter for investigating pipe-soil interaction.
Monitoring Pavement Response and Performance Using In-Situ Instrumentation
Authors: Chen D-H , Bilyeu J , Hugo F
Published: March 2009

The purpose of this paper is to present the effectiveness of in-situ instrumentation on diagnosing the pavement layer conditions under full-scale accelerated traffic loading. The test section is an in-service pavement (US281) in Jacksboro, Texas. Multi-Depth Deflectometers (MDDs) are used to measure both permanent deformations and transient deflections, caused by accelerated traffic loading and Falling Weight Deflectometer (FWD) tests. Four different FWD loads of 25, 40, 52, and 67 kN were applied in close proximity to the MDDs at various traffic loading intervals to determine pavement conditions. It was found that the majority of rutting occurred in the newly recycled asphalt mix. The aged (> 40 years) underlying base and subgrade layers contributed less than 30% to overall rutting. Only the top recycled asphalt layer underwent notable deterioration due to traffic loading. Up to 1.5 million axle repetitions, the test pad responded to FWD load almost linearly, not only over the whole pavement system but also within individual layers. However, under higher FWD loads, the percentage of total deflection contributed by the subgrade increased.
A Comparison of Portable and Permanent Landfill Liner Leak Detection Systems
Authors: Taylor SB , White CC , Barker RD
Published: March 2009

Monitoring of the integrity of electrically non-conductive geomembrane liners installed at waste sites using electrical geophysical techniques has been carried out for a number of years using above-liner leak location surveys and, more recently, below-liner monitoring systems. We compare the theoretical response of both types of survey to a hole in a liner and then compare with measurements made in the field. The theoretical leak response indicates that above-liner surveys are sensitive to leaks over a greater area, though both responses result in comparable leak detectability. However, field data suggest that in practice, measurements made on a sparse grid below the liner have the greater sensitivity to certain leaks. This may be due to the differing leak geometries and background conditions present above and below the liner.

The results indicate that a sparse below-liner monitoring grid, with its long-term monitoring capabilities, combined with above-liner surveys to pinpoint leaks accurately offer a successful approach to ensuring liner integrity throughout the lifetime of a lined waste site.
Field Measurement of Water Contents and Densities by Nuclear Methods in Clay Deposits
Authors: Silvestri V
Published: March 2009

In recent years natural water content and density determinations have been carried out in the stiff clay deposits on Montreal's Island by means of nuclear depth probes. The probes are lowered down aluminum access tubes that are permanently inserted into the ground, thus providing a means of measuring the volumetric water content and the density of the soils surrounding each tube, at any convenient time and depth. Access tubes have an external diameter of 50.9 to 57 mm and a wall thickness of 1.3 to 1.9 mm, and are sealed at the bottom to prevent entry of water. The tubes are pushed into holes of the same diameter which have been reamed out of the soil by a mechanical auger. Tubes have been inserted to a maximum depth of 6 m. Readings in each access hole are taken at 100–200 mm depth intervals along the length of the tube. Values of volumetric water contents and densities are determined by using field calibration curves. The paper gives the results obtained on several projects, reports on the precision of the predicted values and presents typical problems which were encountered during installation of the access tubes and the long-term (up to 8 years) monitoring programs. It is also shown that factory calibration curves furnished with the nuclear probes cannot be used in high-water content clay soils. It is further indicated that even though the water content calibration curves show a high degree of correlation, the neutron scattering technique will not effectively detect changes in soil water content for periods ranging from a few days to about one week. Finally, it is shown that voids around the access tubes adversely affect the nuclear gage readings.
Data Management System for Organic Soil
Authors: Stinnette P
Published: March 2009

A Data Management System for Organic Soil (DMSOS) has been developed that enables the acquisition, management and analysis of organic soil data as well as the presentation of results to be conducted effectively through a common interface. This development was in response to the data management needs of research investigating the engineering properties of organic soil and its extension to the stabilization of organic soil through dynamic replacement (DR). It is shown how the above functions are implemented efficiently using Windows-based software to perform comprehensive data management and analysis of data gathered from both laboratory and field tests. When the engineering properties of a given organic soil deposit are needed, a built-in Computer Advisor for Organic Soil Projects (CAOSP) predicts the properties from DMSOS based correlations. A unique and useful feature of the CAOSP is its ability to estimate the anticipated ultimate settlement of an organic soil deposit given the loading conditions and the moisture or organic content. Also incorporated in the DMSOS is a quality control system that utilizes computerized data acquisition/data management techniques in order to evaluate the degree of improvement of an organic soil layer at a given stage of treatment using DR.
A Software Framework for Two-Dimensional Mixed Mode I/II Elastic-Plastic Fracture
Authors: James MA , Swenson D
Published: March 2009

We present a new two-dimensional software framework for predicting curvilinear elastic-plastic crack growth and residual strength. The framework is an extension of the existing FRANC2D/L software. The crack tip opening displacement (CTOD) is used as the fracture criterion, and the near-tip maximum tensile stress is used as the direction criterion. In some cases, crack tip constraint is modeled using a mixed state of stress, with elements near the crack tip kept in a state of plane strain and elements away from the crack tip in a state of plane stress. A mapping algorithm transfers state variables during remeshing as the crack propagates. Comparisons are made with numerical and experimental results for straight cracks in compact tension and middle crack tension specimens. Further comparisons are made with experimental results for curved cracks in ARCAN Mode I/II specimens. The analyses predict residual strength within 10% of experimental data. For tensile dominated fracture behavior, predicted crack paths are generally in agreement with experimental results; as expected, the maximum tensile stress criterion does not predict the appropriate crack propagation direction for materials that exhibit shear dominated cracking under Mode II loading.
Mixed-Mode Fracture Behavior of Silica Particulate Filled Epoxide Resin
Authors: Kishimoto K , Notomi M , Kadota S , Shibuya T , Kawamura N , Kawakami T
Published: March 2009

Silica particulate filled epoxide resins are used as encapsulant materials in semiconductor packaging. In the present paper, fracture behavior of the epoxide resin, containing 70 wt% silica particles, have been studied at room temperature and high temperature, that is, 250°C. The three-point and four-point bending tests were performed to obtain Mode I and mixed-mode fracture toughness, respectively. The specimen fractured in a brittle manner under room temperature conditions, and the results obeyed the maximum hoop stress criterion. On the other hand, the results at high temperature showed a relatively low dependency on Mode II stress intensity factors. Fracture surface were observed in a scanning laser microscope. Finite element analysis, taking into account the microstructure of the material, have been conducted in order to investigate the influence of temperature on mixed-mode fracture behavior. Local fracture criteria were considered for the silica particles and the epoxide resin. The material constants in criteria were estimated from the bending strength and the Mode I fracture toughness of the material. Good agreement between experimental and numerical results was obtained for the fracture boundary curves on the Mode I and Mode II stress intensity diagram.
Polycrystal Orientation Effects on Microslip and Mixed-Mode Behavior of Microstructurally Small Cracks
Authors: Bennett V , McDowell DL
Published: March 2009

There are two sources of mode mixity—on a macro level (combined loading situation), and on the micro level—that affect the propagation of small crystallographic cracks. This work explores mode mixity on the micro level by utilizing a computational model to simulate microstructural influences on driving forces for the formation and growth of small cracks. Two-dimensional computational cyclic crystal plasticity calculations are conducted to study the distribution of cyclic slip and critical plane-type fatigue parameters in a material with nominal stress-strain characteristics of 4340 steel. Cases of applied cyclic tension-compression and cyclic shear are analyzed at strain amplitudes below macroscopic yielding. Emphasis is placed on stress state and amplitude dependence of the distribution of these parameters among grains. The role of anisotropic plasticity is isolated by assuming the elastic behavior of grains to obey homogeneous, isotropic linear elasticity. All grains are of equal dimension and are assigned a random orientation distribution. It is found that the distribution of the Fatemi-Socie critical plane fatigue parameter among grains is Weibull-distributed, and it is argued that it forms an improved linkage to cyclic crack tip displacement for microstructurally small cracks. We also present computed crack tip opening and sliding displacements as a function of maximum applied tensile strain (from well below to just above nominal yielding) for small cracks within surface grains surrounded by a nearly random orientation distribution of grains. Multiple realizations of the local microstructure are examined for each crack length for sub-grain size cracks, with results normalized to the ratio of crack length to grain size. Key results include a very strong role of the free surface on crack tip displacement, with opening displacement being much greater than the sliding for suitably small crystallographic cracks in the surface grains. There is also a strong effect of the orientation of the next grain ahead of the crack on local mode mixity of the crack tip displacements, which plays an increasingly influential role as the crack tip approaches the first grain boundary.
A Dispersion Strengthened Co-Cr-Mo Alloy for Medical Implants
Authors: Wang KK , Berlin RM , Gustavson LJ
Published: March 2009

A dispersion strengthened version of forged Co-Cr-Mo alloy, GADS Vitallium® alloy, was developed to improve fatigue strength after sintering (1300°C), a required thermal cycle treatment for porous coated products. GADS alloy was made using a powder metallurgy process to create fine dispersed oxides in the alloy. The dispersed fine particles strengthen the alloy and prevent grain growth so that the alloy retains fatigue strength almost twice that of the standard forged alloy (ASTM F-799, Standard Specification for Cobalt-28 Chromium-6 Molybdenum Alloy Forgings for Surgical Implants) following porous coating sintering. The processing development, grain structures, fatigue properties, and corrosion resistance of the gas-atomized dispersion strengthened (GADS) alloy are reported here.
The Development of Surface Coatings for Co-Cr-Mo Alloys Based on Quaternary AlSiFeMn Intermetallic Compounds
Authors: Flores-Valdés A , Castillejos-Escobar AH , Acosta-González F , Escobedo-Bocardo JC , Toscano-Giles A
Published: March 2009

During the development of Co-Cr-Mo as implant alloys, a higher surface hardness is required, in order to avoid the cracks originated by the presence of the chromium or molybdenum carbides in the alloys. Many different methods have been developed, being the surface coating with suitable intermetallic compounds. Surface coatings based on quaternary intermetallic compounds of the AlSiFeMn type have been successfully developed, taking advantage of the fact that chromium diffuses through the boundary layer of the intermetallic alloy, forming a well developed interface. The coatings obtained possess a high microhardness, apart from being continuous and well matched to the base alloy. This paper presents and discusses the methodology that was implemented to produce such coatings at temperatures in the range of 873 to 1123 K, under an applied stress. The coatings were characterized by the use of microprobe analysis, having determined the compositional effects of diffusion of the multiple elements on the coating quality.
Granulation Without a Drying Step Using Dielectric Heating of Binding Polymers
Authors: Beestman GB , Freeman RQ , Mehdizadeh M
Published: March 2009

Dry granules that rapidly disperse into water for spray applications are a popular type of formulation for pesticides. Melt granulation processes that do not require a drying step offer lower cost manufacturing of these formulations. Heat activated binding (HAB) granulation processes produce granules without drying by the steps of: heating a powder under tumbling conditions above the melting point of unique water-soluble binding polymer particles, cooling to solidify the binding polymer, and collecting the granules. External heating of large vessels to affect HAB granulation must be done very slowly to avoid hot spots that melt the binding polymer onto the vessel walls leading to caking. Cautious external heating greatly lengthens the process time of HAB granulation. This paper describes dielectric heating of the binding polymer so that granules can be produced continuously, without heating the equipment, and without significant temperature build-up in the powders being granulated.
Attapulgite as a Suspension Control Agent and Rheology Modifier in Flowables
Authors: Ginez A
Published: March 2009

Attapulgite, a naturally occurring mineral known also as palygorskite, is a 2:1 clay mineral (hydrous phyllosilicates). Attapulgite has a crystal lattice with a net negative charge causing the mineral to absorb cations in water or organic molecules to balance the charge deficit. The ability to bind organic and inorganic cations gives this mineral some of its special features, which led to commercial applications such as thickeners and organic sorbents.

Attapulgite gel grades are processed in a different manner than the attapulgite sorptive grades to produce very different properties from the same mineral making these products valuable in very different applications. The gel products are characterized for imparting thixotropic viscosity to liquid systems, both solvent- based and water- based. Attapulgite as a mineral is a very hydrophilic material and, therefore, able to be dispersed easily in water systems. High shear is usually desirable to obtain the best performance. for solvent-based systems, the addition of a cationic surfactant becomes necessary in order to assure proper gel development. The ratio of attapulgite to surfactant is also critical and the optimum ratio should be determined for any particular system. Gel products have found application as suspending agents and rheology modifiers for coatings, inks, adhesives, caulking compounds; animal feed supplements, wet flowable pesticides, etc. Attapulgite thickeners were compared to xantham gums in a water-based system and showed higher viscosity development efficiency and lower cost.

The sorptive grades are characterized for their capability of absorbing organic liquids and come in either granular grades or powder grades. They have infinite applications including but not limited to carrier for pesticides, wettable powders, dry flowables or water dispersible granules and filtration products.
Validation of Disinfectants Used in Biotechnology Facilities
Authors: Richter SG
Published: March 2009

Disinfection validation is a FDA Good Manufacturing Practices (GMP) requirement. Quality assurance departments are required to determine the effectiveness of given disinfectants using standard test strains under controlled conditions, per the protocol published by the Association of Official Analytical Chemists (AOAC). This protocol is used by manufacturing for in-house disinfection validation. Disinfectant selection can be based upon microbial populations found at the facility. High, intermediate, and low level disinfectants are used in most aseptic processing areas. Validation of the selected disinfectant is based upon repetitive testing under laboratory conditions with concomitant microorganisms. Test conditions for validation processes are based upon the standard AOAC Hard Surface Carrier Method. The procedure is a qualitative carrier test, using glass carriers and standardized bacterial cultures. This paper will concentrate on the selection and validation of disinfectants for biotechnology clean rooms and equipment. The emphasis here will be on developing a standardized testing program that will meet the intent of the FDA GMP's. The main objective of this paper is to instruct the reader on validating disinfectants used in clean room areas. Disinfectants must be challenged under actual shelf life and use conditions. Suitable microbiological challenge methods will be discussed along with appropriate validation protocols. Quality control methods for in-process disinfectant testing will emphasize original data from appropriate indicator organisms and inactivators.
Dynamic Initiation Fracture Toughness of a Pressure Vessel Steel in the Transition Region
Authors: Link RE , Graham SM
Published: March 2009

The dynamic fracture toughness of an ASTM A533, Grade B steel plate was determined at several temperatures in the ductile-brittle transition region. Crack-tip loading rates ranged from approximately 103 to 105 MPa√m/s. The fracture toughness was shown to decrease with increased loading rate. The dynamic fracture toughness was compared with results from previous investigations and it was shown that the decrease in toughness due to increased loading rate at the highest test temperature was not as severe as reported in previous investigations. It was also shown that the reference temperature, T0, was a better index of the fracture toughness vs. temperature relationship than the nil-ductility temperature, RTNDT for this material.
Effects of Finite Element Mesh on Numerical Prediction of Ductile Tearing
Authors: Skallerud B , Zhang ZL
Published: March 2009

Presently, there is still no generally accepted way of calibrating material models accounting for ductile damage, and calibrating the finite element model with this material in order to obtain a representative length scale via the smallest element size. Roughly, one may identify two approaches. One is based on computational cells, where the cells accounting for damage growth are put in a layer in the prospective crack growth direction. The cell size, D, and initial void volume fraction,f0, are argued to be microstructurally based. The simulations are calibrated against a fracture test. The second approach is to a larger extent based on metallurgical observations, and is more in accordance with the objective that the material model is calibrated with simple test specimens (smooth tensile specimens). But also with this method the finite element mesh has to be calibrated against a fracture test. Hence, the finally chosen element size introduces the required length scale. The present study corresponds to the second approach. It focuses on one set of material parameters established in an earlier study. The material is a typical structural steel in the medium strength range. Results from a purely numerical study are presented for a plane strain three point bend specimen. Effects of finite element type, mesh size, mesh irregularity, and damage material layers are considered. These results illustrate the effects of mesh on ductile tearing prediction. Then 3D analyses of a 3PB test are carried out in order to compare a calibrated element size against the sizes applied in the plane strain study.
Stress-Level-Dependent Stress Ratio Effect on Fatigue Crack Growth
Authors: Sunder R , Porter WJ , Ashbaugh NE
Published: March 2009

Fractographic measurements of fatigue crack growth rate for small cracks reveal stress-ratio effects even when fatigue crack closure is absent. These effects are restricted to low fatigue crack growth rates and become significant with increase in net stress levels. To characterize the effect, experiments and analyses were conducted on notched coupons of an Al alloy at stress levels producing inelastic conditions on initial loading. As a reference, fatigue crack growth rates were obtained for a long crack tested under fully elastic loading well below yield stress. The results indicate that for fatigue growth associated with low applied stress intensity range, minor changes in stress ratio can cause substantial variation in crack growth rate. A model is proposed for the small crack fatigue growth rate as a function of applied stress intensity and stress ratio. The model is based on crack growth rates obtained under several stress levels with crack size as small as 0.03 mm.