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Though the definition of equilibrium moisture content of porous materials is straight forward from the point of view of equilibrium thermodynamics, experimental determination of this quantity may not always be easy. Many factors play their roles from an experimentalist's point of view. Hysteresis, the reference dry state, the initial moisture content, the history of the test specimen, the size of the test specimen, the drying technique and drying temperature - all influence the value that is arrived at by an experimentalist. This paper reports results from several series of measurements on gypsum board, eastern white pine, aerated concrete, and calcium silicate brick using the ASTM Standard C 1498 in the hygroscopic ranges and pressure plate techniques above the hygroscopic range of equilibrium moisture contents. These results show the ambiguities that may surround the experimental definition of equilibrium moisture content. The results presented in the paper demand a few refinements in the existing ASTM Standard C 1498 as well as in the procedure that is used in the pressure plate method. The paper proposes a few refinements for both. The need for the development of an ASTM standard for the pressure plate technique is identified., Also published in Symposium on Heat, Air and Moisture Transport Properties of Building Materials, ASTM, Toronto, Ontario, April 2006, pp. 1-18.

SRI International has prepared dynamically generated silica samples since 1980 for the National Institute of Occupational Safety and Health (NIOSH) and the American Industrial Hygiene Association (AIHA) Proficiency Analytical Testing (PAT) programs. Aerosol-generated samples were developed in 1980 to more closely approximate real world samples and to improve intrabatch precision. Liquid-generated samples may provide tighter control limits, and this method has been reexamined as the generation procedure of choice. Sample preparation procedures have also been investigated to minimize analytical uncertainty and, hence, obtain a true evaluation of the sampling error. Samples were analyzed by SRI, NIOSH, and the Wisconsin Occupational Health Laboratory, using X-ray diffraction or Fourier transform infrared spectrometry (FTIR). Results were plotted and statistically evaluated, then compared to the existing PAT interlaboratory database.

In this experimental study, the effects of vacuum process on mechanical and physical properties of concrete were investigated by comparing mechanical properties of vacuum processed and half vacuum processed concrete specimens with those of control specimens. Vacuum equipment was used to apply vacuum to fresh concrete in order to extract water from floor concrete. Compressive strength and some other test results obtained from both vacuum processed and plain concrete core specimens were evaluated and then compared. Test results have shown that the compressive strength of vacuum processed concrete specimens increased substantially due to the decrease in water/cement ratio by dewatering process. The effects of the process on compressive strength at early ages and on surface placement are much more pronounced. Some of the other properties such as dry density, unit weight, surface hardness, and surface porosity are also improved by vacuum dewatering process.

Bituminous aggregates from a total of 52 sources located in Texas, Oklahoma, Arkansas, New Mexico, and Missouri were evaluated using both Micro-Deval and magnesium sulfate soundness tests. Each aggregate was also characterized using petrography, absorption, and specific gravity. Findings showed that Micro-Deval test is a more repeatable test than the soundness test. Micro-Deval showed a fair to good correlation with soundness and an improved correlation was observed when used along with aggregate absorption values. It is concluded that further research is needed to completely replace soundness tests but the Micro-Deval test could be used as a good quality indicator tool.

Research was undertaken using thin sections and immersion mounts with the objective of using a modified line count procedure for the quantitative petrographic determination of fly ash and ground-granulated blast furnace slag (GGBFS) in hardened concrete and blended cements. The line method used in this study is a variation of standard microscopic point count methods and yields an average number frequency that is a linear function of the weight percent of fly ash or GGBFS of total cementitious materials. Multiple traverses were counted on thin sections of concrete over areas of paste only and in immersion slides of blended cements containing known amounts of fly ash and GGBFS. The average number of particles in a traverse was computed, the traverse length being equal to the width of the field of view of the petrographic microscope. For hardened concrete, only pozzolan particles were counted. For blended cements, all particles were counted and the ratio of pozzolan particles to total particles was determined. A linear relationship between the average number of pozzolan particles for a traverse line and the weight percent of pozzolan makes it possible to estimate the fly ash and GGBFS content of unknowns. Results of the research indicate that the line method is a rapid and accurate method for petrographic determination of fly ash and GGBFS in hardened concrete and blended cements. This technique and variations of it have been used by other researchers and it has the potential to be a standard test procedure.

Five hexagonal ducts constructed from AISI 304 stainless steel in the annealed state were removed from rows 8–14 of the EBR-II fast reactor after many years of irradiation to study the effect of atomic displacement rate on void swelling. For this objective it was important to assure that the observed differences in void swelling were not strongly influenced by variations in helium/dpa ratio. The two major contributions to helium production arise from the nickel and boron content of the steel. However, the boron content was unspecified and therefore unknown, but it was determined from an unirradiated archive duct by converting a well-defined fraction to helium and then measuring the helium content using isotopic dilution mass spectrometry. The same technique was used to measure the total helium in the irradiated duct specimens. After separating the boron contribution from the total measured helium it was possible to determine the contribution from various fast and thermal neutron interactions with the other major elements in the steel and compare the helium generation with predicted values. One important conclusion of the study is that the range of He/dpa ratios over the five subassemblies was not very large, allowing the observed changes in swelling to be attributed primarily to variations in displacement rate and temperature.

Significant advances have been made in heavy duty diesel engine technology to meet increasingly stringent environmental regulations for emissions. Today's heavy duty diesel engines are being designed with lighter and softer metals, greater turbocharging, increased combustion controls, and new emission reduction equipment. The cooling systems contained in these vehicles are similarly being impacted by smaller designs, new cooling system configurations, and increased usage of lighter, softer metals. Vehicle thermal loads have significantly increased due to increased power densities, higher engine temperatures, and greater metal-coolant fluxes which places greater emphasis on oxidation/thermal stability, and high temperature corrosion protection performance of the coolant. Other operating conditions (coolant flow rates, turbulence, pressure drops, deaeration) are also becoming more severe calling for improved erosion-corrosion protection, cavitation protection, and elastomer, seal, hose compatibility. This paper reviews the changes in heavy duty diesel engine technology and provides information on coolant performance in 2002-4 emission compliant engines. Predictions are also made on future engine technology and next generation engine coolants.

The suction technique is a method from soil science that is used for the study of moisture storage capacity in porous construction materials at high relative humidity levels (above approximately 93 %). The samples to be studied are placed in a pressurized container (an extractor) on a water saturated ceramic disk or membrane. The pressure corresponding to a certain relative humidity level is established and moisture is expelled from the samples until moisture equilibrium is reached. This paper presents two adjustments to this method and their applicability. The first adjustment is a new procedure for determining the equilibrium moisture content of samples during the experiment. The method (referred to as the balance method) is to simply keep track of all water entering and leaving the system and use these data to estimate the moisture content of the samples. The advantage of this approach is that the experiment does not need to be stopped and restarted for each relative humidity level tested. The main disadvantage of the method is that the estimation of the moisture content in the samples depends on a correct estimation of the moisture content of the ceramic disk. The second adjustment is the development of a pressure regulation system that keeps the pressure constant (±0.015 bar) within an extractor for weeks.

Thermal analysis combined with composition analysis has been used in this work to identify evolved gas when burning household waste. Thermogravimetry (TG) coupled with Fourier transform infrared (FITR) spectroscopy and mass spectrometry (TG-FTIR-MS) offers structural identification of compounds evolved during thermal processes. Carbon, hydrogen, and nitrogen elemental analysis and XRD offers raw materials information. All these combined can help to evaluate the chemical pathway for the degradation reactions by determining the decomposition products. For comparison purposes, emitted species concentrations are measured with multiple-sensors when burning household waste in a lab-scale fluidized bed combustor. There is excellent agreement between the two different approaches. The measured results also provided some insight into burning household waste as an energy source in large-scale incinerators.

Structural silicone sealants have been used since the mid 1960s in the construction industry to attach glass to curtainwall framing systems. Design standards for these sealants have been in practice since the early 1970s and continue to be developed today. Most of these standards require tests that are based on a one-time destructive test of the joint material in tension. The industry established structural silicone design stress is intended to be reached only during the highest windload for the specified return wind period. The existing practice has had great success because the industry guidelines minimize stress on the silicone, and dictate quality assurance procedures that are instituted by curtainwall producers. In real life situations the sealant is additionally fatigued through a cyclic shear mechanism caused by daily thermal movement differences between the glass pane and the aluminum frame. This paper discusses a method for testing the effect of fatigue in sealants used in structural designs and comparing the data to control samples.

The preparation of closed-cell foam insulation test specimens can affect the results of a number of hygrothermal property measurements. In particular, the thickness of the destroyed surface layer affects the measurement of gas diffusion coefficients and thermal conductivity. Multiple specimen preparation methods are in use, as well as multiple methods to measure the thickness of the destroyed surface layer. A ruggedness test, including an interlaboratory comparison, was conducted by an ASTM technical committee to examine the variations due to both of these factors. The results are important in understanding the likely range in values for each preparation technique. The results also demonstrate a sensitivity to the measurement technique.

An investigation was made into the effects of flux formulation and after brazing residue on the pitting potential of the aluminum surface in various types of coolants during laboratory evaluations. Samples of CAB brazed radiator header alloy aluminum, with various flux loadings, were supplied by Behr and the Ford Motor Company. The flux is generally in the form of potassium fluoroaluminate, general formula K1–3AIF4–6.xH2O. The samples in the flux loading study were all passed through the brazing ovens with the following flux loadings: • No flux, • Half the regular amount of flux, • The regular amount of flux, • Double the regular amount of flux, • Regular amount of flux over half of the surface area. The individual coolants used in the flux loading study were 25 % volumes of the following, each with 100 ppm of chloride: • Conventional, • Hybrid (HOAT), • Organic Acid (OAT), • Modified Organic Acid (MOAT). In the flux composition study, different compositions of potassium fluoroaluminate from three different suppliers were evaluated with hybrid type coolant. All the aluminum samples were run according to a Ford Laboratory Test Method (FLTM) BL105-01 “A Rapid Method to Predict the Effectiveness of Inhibited Coolants in Aluminum Heat Exchangers” [1]. The samples were heated and boiled in coolant for 1 h. The temperature was lowered to 70°C and the samples were electrochemically tested by either potentiodynamic polarization or modified Ford FLTM BL105-01. Each coolant at the end of the test was submitted for chemical analysis of fluoride content. The electrochemical results of the flux loading study showed that the higher the flux loading on the aluminum header material, the easier it is to initiate corrosion. Chemical analysis showed the presence of significant quantities of fluoride in the end of test fluids. As the only fluoride-containing component of the system is the flux residue, it was concluded that fluoride leached from the flux residue. The second study showed that not all potassium fluoroaluminate brazing flux is alike. Samples of three fluxes from three different suppliers of the same loading on aluminum were tested with hybrid coolant. When subjected to heating and potentiodynamic polarization, significantly different results were obtained from the three different fluxes.

Identified from a range of European sources and assessed for their Cementation Index, as proposed by Eckel, marls are the subject of this research. Two marls were selected for calcination in a laboratory kiln; one from Lillienfeld in Austria (CI 2.03) and one from Folwark in Poland (CI 1.75). While not revealing precise kiln conditions, analysis of historical documents does suggest that they were such as not to yield complete decarbonation of the calcite. As a result, a series of calcinations was undertaken in which the peak temperature control of the kiln was set in the range 730 degrees Celsius to 1100 degrees Celsius, with residence times in the range 150 to 1250 minutes. The airflow through the kiln was sufficient to maintain a minimum oxygen content of at least 12%. The clinker resulting was ground to comply with the 19th century Austrian Norme. Pastes were produced at w/c = 0.65 and assessed for setting time and strength development (6 h to 1 year). Both parameters were highly dependent upon calcination conditions with both "low" and "high" calcinations producing slower setting and slower strength development than intermediate conditions. Two strength development profiles were identified; one was the expected continuous increase of strength, even though it had a declining rate of increase with time, while the other showed a three-step sequence of high initial strength, a dormant period which could last for many weeks, and a final increase in strength to an age of one year. Comparisons were made of the cements using X-ray diffraction (XRD). Variation of a considerable amount in the composition was noted and related to the calcination conditions. The formation of both α'-belite and β-belite under differing calcination conditions were of particular interest. Also compared using the SEM in back-scattered electron imaging mode were clinker particles, and observations of the development of morphology were made.

Customers challenge sealant formulators to develop high weatherability construction sealants with ever-higher performance. This paper will discuss some of the factors that influence weatherability and durability of sealants, such as binder, pigments, stabilizers, and catalysts. One-component polyurethane and modified silicone sealants will be evaluated. Raw material influences need to be carefully tested and optimized in order to develop high weatherability sealants. Taking these factors into consideration, it is possible to formulate high weatherability sealants that meet customers' demands. These demands are expected to increase in the future.

The predominant hydraulic binder of the 19th century was natural cement, and it has re-emerged as a restoration material in the 21st century. Modern natural cements must be able to be relied upon by engineers, architects, conservators, and owners to meet the same performance criteria as historic cement materials. Natural cement must also provide the working characteristics demanded by contemporary tradespeople, in addition to the performance criteria, as well as the aesthetic results expected in high-quality historic restoration work. A review of historic standards for natural cement is included, as well as a discussion of criteria used in developing the recently reinstated American Society for Testing of Materials (ASTM) C 10 Standard Specification for Natural Cement. There is a presentation of recent research into the effectiveness of set and flow modifying admixtures with natural cement, as well as an overview of producing color matches for natural cement mortars and stuccos.

A number of test methods are available to measure the bulk specific gravity of compacted hot-mix asphalt (HMA). The most commonly used test method, ASTM D 2726 [1], was designed for use with specimens that do not contain open or interconnected air voids such as dense-graded HMA mixtures. Coarse and open-graded HMA mixes are known for their open or interconnected void space. The current method for addressing coarse and open-graded mixes, ASTM D 1188 [2], can lead to erroneous bulk specific gravity measurements. Thus a nondestructive vacuum sealing method (ASTM D 6752) [3] was developed to address HMA mixtures that contain open or interconnected air voids. The objective of this research is to define the point at which the vacuum sealing method (ASTM D 6752) [3] more accurately measures the bulk specific gravity of an HMA specimen as compared to the conventional test (ASTM D 2726) [1] utilizing the saturated surface dry (SSD) method. Permeability (ASTM PS 129-01) [4] measures an HMA mixture's ability to allow moisture to pass through it, which in turn is related to the mixture's connectivity of void space. For this reason permeability was chosen as the fundamental property to investigate. ASTM PS 129-01 [4] is hypothesized as a criterion test for method selection in determining the appropriate bulk specific gravity test for coarse-graded HMA mixtures. One hundred and thirty-four field compacted roadway cores from 28 paving projects throughout the State of Michigan were evaluated using the vacuum sealing method and conventional SSD method of determining the bulk specific gravity of compacted HMA. These cores were then tested using a falling head permeability apparatus. It was determined that the bulk specific gravity of compacted HMA fine-graded mixes using the vacuum sealing method and conventional method are statistically the same. There is a difference in bulk specific gravity measurements when using the two bulk specific gravity tests on coarse-graded mixtures for roadway cores when the air void level is above 5.1 %. Thus the air void/permeability relationship was used to determine the coefficient of permeability at which the vacuum sealing method provides a more accurate measurement of the bulk specific gravity. This value was found to be 3.7×10-6 cm/s.

This paper examines issues related to deflection criteria for masonry beams. Masonry walls supported by beams and lintels act compositely with the beam. As the height of the masonry wall increases, the behavior becomes more like that of a tied arch, with the masonry in compression and the beam acting as the tension tie. Deflection limits are only needed so that sufficient stiffness is provided during construction to prevent serviceability problems, with the suggested limit being I/600. Several methods for determining the deflection of reinforced masonry beams are examined, and a method for the effective moment of inertia of cracked reinforced sections is recommended. Beams and lintels that exceed this deflection do not necessarily have to be increased in size, but rather shores could be used during construction. Masonry beams and lintels with I/d≤8 should not be controlled by deflections. Therefore, it is recommended that the code not require these members to be checked for deflections.

One of the primary factors in determining the life and performance of turbine oils is its oxidation stability. Oxidation can cause a host of problems for in-service turbine oils, such as sludge, deposits, lacquer, and varnish formation. There is limited published research on the performance of turbine oils once oxidation begins. This paper presents data on the relationship between several turbine oil characteristics during the oxidation process by focusing on the measurable physical and chemical changes that occur. Five turbine oils were chosen, each employing different antioxidants and base oil refining technologies to represent a typical selection of commercially available turbine oils. A 49-day experiment was completed in which the oils were subjected to a controlled and accelerated oxidative process under laboratory conditions. Throughout the testing period, samples were drawn and a range of chemical, physical, and performance tests were performed. The data obtained from this experiment identify several correlations that relate to the performance of each oil. These data are useful in understanding the relationship between turbine oil oxidation and fluid performance and will help end-users in selecting and optimizing their turbine lubricant.

Cyclic loading of a solid material induces a cyclic temperature fluctuation. The thermal cycle is asynchronous with the loading cycle when the strains are elastic. This is commonly known as the thermoelastic effect. In differential thermography, a sensitive infrared camera is used to measure this temperature variation; typically of the order of a few tens of milliKelvin. Since the magnitude of the temperature variation is proportional to the dilational strain, values of the surface elastic stress can be derived. Recent advances in infrared camera technology and data processing algorithms have enabled values of effective stress intensity factor ranges and the location of fatigue cracks to be determined from temperature fluctuations around the crack tip on the specimen surface. Careful observation in the region near a crack tip reveals deviations from the asynchronous behavior of the photon signal relative to the load cycle. Phase shifts up to π/8 are commonly observed. The spatial distribution of these phase shifts exhibits characteristic features which are described and discussed. The features in this distribution appear to be associated with high elastic strain gradients, regions of plasticity and contact between the crack faces. Interpretation of the phase shift and its spatial distribution may lead to a better understanding of the mechanics of fatigue crack growth.

A cascade of probabilistic mechanisms is proposed to better understand the 72 ft-lbs mechanical impact in liquid oxygen ignition threshold sensitivity testing of polymeric and polymer matrix composite materials. This model teams the well established and understood mechanisms of Hertzian fracture and kinetic friction. In conjunction they explain the mechanical fracturing of the specimen and the very rapid transformation of the test's mechanical energy into temperature rising heat energy. The model also provides the first explanation for the random probabilistic occurrence or nonoccurrence of ignitions in tested materials.

The evolution of global and local stress/strain conditions in test fasteners under test conditions is investigated using elastic-plastic, time-dependent finite element analyses (FEA). For elastic-plastic response, tensile data from multiple specimens, material heats and test temperatures are integrated into a single, normalized flow curve from which temperature dependency is extracted. A primary creep model is calibrated with specimen- and fastener-based thermal relaxation data generated under a range of times, temperatures, stress levels, and environments. These material inputs are used in analytical simulations of experimental test conditions for several types of fasteners. These fastener models are constructed with automated routines and contact conditions prescribed at all potentially mating surfaces. Thermal or mechanical room temperature preloading, as appropriate for a given fastener, is followed by a temperature ramp and a dwell time at constant temperature. While the amount of thermal stress relaxation is limited for the conditions modeled, local stress states are highly dependent upon geometry (thread root radius, for example), preloading history and thermal expansion differences between the test fastener and test fixture. Benefits of this FE approach over an elastic methodology for stress calculation will be illustrated with correlations of stress corrosion cracking (SCC) initiation time and crack orientations in stress concentrations.

The electrical conductivity of polymers can be increased by the addition of conductive fillers, including forms of carbon fibers and carbon black. The resulting composites can be used in applications where metals have typically been the materials of choice. The advantages of using these materials include lighter weight, resistance to corrosion, and the ability to be readily adapted to the needs of a specific application. One of the most significant applications for conductive polymer composites are conductive carbon-polymer composite electrodes. As many properties such as conductivity, mechanical integrity, low permeability, electrochemical activity, and stability in the electrolytes are required of materials to be used as electrodes, so “material selection” plays a crucial role in fabricating these materials. In this work it was found that high density polyethylene (HDPE)/ethylene-propylene-diene monomer(EPDM) blend ratio (70/30) has lower percolation threshold and volume resistivity than individually carbon black filled HDPE and EPDM due to “double percolation” effect. Carbon fibers were also added to the polymer-carbon black mixtures to enhance the conductivity and mechanical properties. The electrical conductivity of composites with different ratios of carbon black (CB) content to carbon fiber (CF) content was studied. The CB content is the main factor to determine the resistivity of the composites filled with CB and CF. Mechanical properties, including tensile strength, elongation at break, and impact strength of the conductive composites were evaluated. The results showed that incorporation of CB and CF in the composites will enhance tensile strength, but decrease elongation at break and impact strength of the composites. In mechanical properties, CF content has a greater effect than CB content. From the comparison of the resistivity and mechanical properties of the composites filled with CB and CF with that of the composites filled with CB only, it is concluded that using CF as a substitute for part of the CB in CB-filled composites can enhance electrical and mechanical properties.

Reference materials provide the foundation for assessment of analytical chemistry methods, accurate quantification of occupational and environmental exposures, and conduct of in vitro and in vivo toxicology studies for health effects research. Although the National Institute of Standards and Technology (NIST) supplies industry, academia, government, and other users with over 1300 reference materials of the highest quality and metrological value, the number of beryllium reference materials is limited. Currently available beryllium reference materials include standard spectroscopy solutions of beryllium and copper-beryllium alloy in the form of blocks, chips, and rods. Beryllium is present as a trace element in some standard soil-sludge, coal fly ash, and urine reference materials. Beryllium on filter media was available at one time, but is not currently available. A number of opportunities exist for identification and development of needed beryllium reference materials for beryllium-containing ores, beryllium oxide, beryllium metal, beryllium metal-matrix materials, beryllium-containing alloys, and beryllium in biological samples. These opportunities will require multidisciplinary and multi-organizational collaboration. Needed actions include consensus on the relevant chemical and physical forms of beryllium; market analyses of demand for the materials; identification of candidate industrial or laboratory-produced samples of the materials; selection of samples that meet criteria for uniformity, physical form, measured quantities, and continued availability; development of production protocols for collection and preparation of the materials, including adequate provisions for occupational health and environmental protection; incorporation of these materials into a supply, distribution, and cost-recovery infrastructure; and continued feedback and information sharing to ensure that the reference materials are meeting user needs or are modified as necessary. Lessons from other major initiatives for reference materials of lead, silica, and similar materials provide guidance on how to optimize and implement an enhanced program for beryllium reference materials.

ASTM G 175 is a standard test method for evaluating the ignition sensitivity and fault tolerance of oxygen regulators used for medical and emergency applications. To show the ASTM G 175 test method was repeatable at different laboratories, a series of interlaboratory tests were performed on medical oxygen regulators in late 2002. These tests were performed on six regulator designs at three laboratories. Three of the regulator models employed a compressed gas association (CGA) 870-style connection and the other three regulator models used a CGA 540-style connection. Five of the regulators were commercially available and the other one was a CGA 870-style regulator that was intentionally designed to tail the test. The results of the round robin tests are presented and discussed.

Measurements of quench distortion and internal residual stresses in quenched cylinders have been performed for many years. Distortion and stress distribution patterns have been identified in the typical steels and cooling conditions. Pioneers of the heat treatment simulation compared their simulated results with experimental data obtained and reported in the 1970s and 1980s. However, these early researchers did not fully explain the mechanism of distortion and residual stress generation based on their simulated results. Although there were several reports on distribution changes of stress, similar reports relating to strains were rarely reported. In this research, water quenched steel cylinders were simulated and an origin of distortion and residual stress generations was explained using the simulated stress and strain distribution changes.

A recent survey by the Association of Modified Asphalt Producers showed that a majority of states now use some form of PG+ specifications, meaning that they have added tests or requirements to the Performance Graded (PG) binder specification. The situation for the Superpave mix design system is analogous. States have added requirements, changed various parameters, and implemented or declined to implement revisions to the AASHTO specifications. In 2004 and 2005, the National Asphalt Pavement Association and Federal Highway Administration sponsored a series of regional workshops across the country to assess the current state of the practice with Superpave and hot mix asphalt in general. Four workshops were held in conjunction with the regional asphalt user producer group meetings. At these workshops, industry and agency personnel shared their experiences with Superpave. One key objective of the workshops was to determine what changes had been made to the mix design system and the rationale for those changes. This paper summarizes the changes that have been made to the system across the country, giving a snapshot of the current state of the practice.

Since the 1950s, when first the Army and then NASA developed mechanical impact testing of materials, researchers have continued efforts to gain a better understanding of the chemical, mechanical, and thermodynamic nature of the phenomenon. The impact mechanism is a proven ignition mechanism, which must be considered and understood in the design of an oxygen system. The use of test data from this test method has been questioned because of the lack of a clear method of application of the data and variability found between tests, material batches, and facilities. This effort explores a large database, which has accumulated over a number of years, and its overall nature. Moreover, testing was performed to determine the statistical nature of the test procedure to help establish sample size guidelines for material characterization. The current practice of reporting reaction frequency data at dropped energy rather than energy the sample receives does not offer a way to compare data between facilities.

Over the last decade, the restrained ring test has trequently been used to assess the cracking susceptibility of a concrete mixture when it is restrained from shrinking treely. Despite the trequent use of the ring test, limited analysis has been performed to understand how the specimen geometry influences the results of the test. This paper discusses the influence of specimen geometry on the results of the ring test considering three conditions: (1) uniform shrinkage of the concrete ring, (2) shrinkage caused by drying from the top and bottom surfaces of the concrete ring, and (3) shrinkage caused by drying from the outer circumference of the concrete ring. The role of moisture gradients, thickness of the concrete and the restraining (i.e., steel) rings, and the stiffness of concrete are considered in a series of numerical simulations. Results from these simulations can enable better selection of test specimen geometries and interpretation of the results from the ring test. Analytical expressions are provided to use for determining the geometry of the ring specimen that better simulates specific field conditions while providing the most useful information from the test.

This paper describes the negative influence of high residual aluminum which is used as a deoxidant in the steel and raises the newest control requirement for high carbon steel on residual aluminum. By means of thermodynamic calculation and production practices, the total oxygen (Σ[O]) in the steel can be 10 ppm through carbon-oxygen reaction under the conditions of high vacuum, proper top slag composition, and argon stirring during ladle refining/vacuum degassing (LF/VD) processes of high carbon chromium bearing steel. Meanwhile, the size of D-type inclusion in the steel is obviously reduced. Thus, the purity of the bearing steel is improved. Since the consumption of aluminum used for deoxidation is reduced, the unit cost of bearing steel is obviously reduced.

This experimental study was conducted to investigate the effects of the alkali-silica reactivity (ASR) on the mechanical properties of concrete, and in particular the strength and the modulus of elasticity under direct tension. Two highly reactive aggregates, a coarse (Quebec City limestone) and a fine (Texas sand) were used. The results suggest that the effects of ASR on the mechanical properties of concrete may vary with the reactive aggregate involved. At least, they depend on the particle size and/or the degree of reactivity of this aggregate. The direct tensile strength was the mechanical property of concrete, the most affected and the most-rapidly affected by ASR. At 0.1 % expansion, for instance, concrete cylinders cast with the Quebec City limestone showed moderate losses of 16 % in compressive strength and in splitting strength (Brazilian test), but as high as 48 % in direct tensile strength. The modulus of elasticity presented similar values in compression and in direct tension, and its reduction also gives a very good idea of the progress of the damage due to ASR. At 0.1 % expansion, for instance, concrete cylinders containing the Quebec City limestone showed a loss in modulus of 19 % in direct tension and 23 % in compression.

The focus of this research was to gain an increased understanding of how microstructure influences pit growth, pit-to-crack transition, and critical crack propagation to fracture. Two thicknesses of 7075-T6 aluminum alloy were etched and subjected to corrosion fatigue in a 3.5% sodium chloride environment. 7075-T6 aluminum alloy is of particular interest to the aging aircraft community, as this alloy has been used extensively on wing and fuselage structures for both military and commercial aircraft in the past. Testing was interrupted at various intervals to obtain information on pit generation, growth, and potential cracking. Results indicated that microstructure has a significant influence on pit-to-crack transition and fatigue crack propagation. Short cracks (

Six sealant samples that had been weathered outdoors for 6.8 years in Japan were evaluated using an Optical Imaging/Image Analysis System, Atlas VIEEW™. The specimens were first visually evaluated with aesthetic ratings assigned. These ratings were then used as the reference for the optical image analysis. Image analysis was carried out on sealant images taken under optimized diffuse illumination at a constant illuminance. Two sets of images were captured per specimen, first the weathered surface for deterioration evaluation, and second the unweathered surface as a control (reference) image. Four distinct surface defects are quantifiable in the samples. These are cracking (crazing), visual color change, spatial uniformity of deterioration (due to dirt pick-up and uneven color change, or both), and overall surface texture. Chalking and dirt pick up, as rated visually prior to this evaluation, could not be accurately assessed with the digital imaging technique. The analysis shows that surface cracking and crazing generally can be well characterized using the automated VIEEW™ system. Judging color changes visually is problematic, since cracking and crazing interferes with color judgment. Further investigations are needed to develop an automated surface characterization method for sealants.

Fracture toughness (KJ (cleavage)) measurements made within the ductile-to-brittle transition region for ferritic pressure vessel steels are not always described by the shape of the Master Curve currently given in ASTM Standard E 1921. The objective of this paper is to show how the shape of the transition toughness curve may be related to the shape of the material's resistance to crack extension curve (KJR) once the crack tip starts to blunt and ductile crack extension precedes cleavage failure. Using an empirical relationship between the mean ductile crack extension (Δa) prior to the onset of cleavage failure and temperature (Δa=λ exp(ϕT)), then the relationship between KJ and T may simply be given by KJ=KA+α[λ exp(ϕT)]β, where KA, α, and β are simply the coefficients to an offset power law to KJ versus Δa data given by KJR=KA+α(Δa)β. For specimens of different sizes, a reference temperature TK may be defined for a given reference level of Δa or equivalent KJ. Unique curves may be defined for materials with differing crack extension resistance curves through plots of KJ versus (T−TΔa(ref)) or (T−TK(ref)). The generalized form of the transition curve may be given by KJ=KA+α{Δa(ref) exp[ϕ(T−TΔa(ref))]}β or KJ=KA+(K(ref)−KA){exp[ϕ(T−TK(ref))]}β. Experimentally, ϕ has been estimated as approximately 0.08 for nuclear pressure vessel materials such as A533B/A508. Using a specific situation wherein the value of K A = 30 MPa √ m , K ( ref ) = 100 MPa √ m , and β=0.25 then, for a B=25-mm specimen, within experimental scatter this provides an almost exact match to the Master Curve given by KJ=30+70 exp[0.019(T−TK100)]. The predictions of transition curve shape using the material's resistance to crack extension curve are believed to be complementary to the Master Curve method, and may describe the shape of the transition curve when there is ductile crack extension prior to cleavage failure. Further work is recommended to investigate the relationship between the predicted ductile-to-brittle transition curve and the Master Curve for probabilities of cleavage failure post-initiation.

Although residual stress in welded structures and components has long been known to have an effect on their fatigue performance, access to reliable, spatially accurate residual stress field data has been limited. Recent advances in neutron and synchrotron X-ray diffraction allow a far more detailed picture of weld residual stress fields to be obtained that permits the development and use of predictive models that can be used for accurate design against fatigue in aircraft structures. This paper describes a fully integrated study of the three- dimensional residual stress distribution accompanying state-of-the-art fusion welds in 2024-T4 aluminum alloy, and how it is affected by subsequent machining and service loading. A particular feature of this work has been the development of techniques allowing the nondestructive evaluation of the residual stress field in the full range of specimens used to provide the design data required for welded aircraft structures and the integration of this information into all aspects of damage tolerant design.

The space flight community has been investigating lightweight composite materials for use in propellant tanks for both liquid and gaseous oxygen for space flight vehicles. The use of these materials presents some risks pertaining to ignition and burning hazards in the presence of oxygen. Through hazard analysis process, some ignition mechanisms have been identified as being potentially credible. One of the ignition mechanisms was reciprocal friction; however, test data do not exist that could be used to clear or fail these types of materials as "oxygen compatible" for the reciprocal friction ignition mechanism. Therefore, testing was performed at White Sands Test Facility (WSTF) to provide data to evaluate this ignition mechanism. This paper presents the test system, approach, data results, and findings of the reciprocal friction testing performed on composite sample materials being considered for propellant tanks.

The Swedish bearing steel industry dates back a century. Already in the early days, Swedish bearing steels were characterized by an exceptionally high quality due to the availability of pure iron ores that made it possible to produce bearing steels by the acid open-hearth processes. Development of the ladle furnace process using inductive stirring made it possible to use the much more flexible and cost effective electric arc melting process. The strive to produce ever better steel products has been strong, driven by increasing demands on final product performance. Developments in steel processing technology, process know-how, and understanding of the complex relationships governing steel cleanliness are worth noting. Methods used have undergone vast improvements in recent times and the development continues. The same situation is valid for the quality assurance methods employed in the manufacturing of steel products.

As computer models are increasingly being integrated into modern agricultural operations, the comparison of field-collected data to the model prediction improves the confidence that aerial applicators, researchers, and regulators have in the model. The field-collected data were compared to the AGDISP model predictions for the tests conducted in soybeans and cotton and over a concrete runway on two different days. The meteorological effects on spray movement were then explored by analyzing individual replications in the spray trials. The effect of varying the surface roughness coefficient over the range of values for bare ground (i.e., runways) in the AGDISP model on downwind spray movement was determined. The final analyses presented showed the dramatic decrease in downwind spray movement as a result of increasing canopy height as predicted by the AGDISP model. The AGDISP model predicted 1–6 times higher levels of spray materials than that measured by field samplers. The model predictions were 1–3 times greater than the field collected data in the runway studies and 2–6 times greater in the canopy studies. Surface roughness coefficients over bare ground had minimal impacts as predicted by the AGDISP model. When the actual weather conditions of one of the treatments in this study were input into the AGDISP model, a 1.5 m/s increase in wind speed resulted in a 100% increase in the spray flux at 50 m from the application site. When crop height inputs into the AGDISP model were changed from 0.3 m to 1.3 m, the spray flux decreased by 20-fold, demonstrating the dramatic filtering effect that a canopy can have on a spray cloud and will serve as a stimulus for future studies designed to fully characterize the effect of crop canopy on spray movement.

Implant debris remains the major factor limiting the longevity of total joint replacements. Whether soluble implant debris of Zr and Nb containing implant alloys constitute a greater risk than other implant metals remains unknown. We evaluated the relative effects of soluble forms of Zr+4 and Nb+5 (0.001–10.0 mM) relative to Cr+3, Mo+5, Al+3, Co+2, Ni+2, Fe+3, Cu+2, Mn+2, Mg+2, Na+2, and V+3 chloride solutions on human peri-implant cells (i.e., osteoblast-like MG-63 cells, fibroblasts, and lymphocytes). Metals were ranked using a 50% decrease in proliferation and viability to determine toxic concentrations. Lymphocytes, fibroblasts, and osteoblasts were, generally, similarly affected by metals where the most toxic metals, Co, Ni, Nb, and V required 1.0 mM challenge to produce toxicity. Overall, Co and V were the most toxic metals tested, thus Zr and Nb containing implant alloys would not likely be more toxic than traditional implant alloys. Below concentrations of 0.1 mM, neither Zr nor Nb reduced osteoblast, lymphocyte, or fibroblast proliferation. Zr was generally an order of magnitude less toxic than Nb to lymphocytes, fibroblasts, and osteoblasts. Our results indicated that soluble Zr and Nb resulting from implant degradation likely act in a metal- and concentration-specific manner capable of producing adverse local and remote tissue responses to the same degree as metals from traditional implant alloys, e.g., Ti-6Al-4V (ASTM F 138) and Co-Cr-Mo alloys (ASTM F 75).

A light-water nuclear power reactor core configuration is described, which does not require any isotopic enrichments (e.g., D2O or U-235) without the use of graphite. This reactor design utilizes plates of natural uranium (NU) metal and Beryllium. The coolant is natural water, which flows between two plates of NU and is required to add additional moderator to attain criticality. Only square reactor shapes of uniform plate thickness are evaluated. Commercial viability is not demonstrated but the proposed design does warrant further study. The configuration shows potential to meet GEN IV sustainability and GNEP closed fuel cycle goals. Aspects covered include neutronics, criticality, costs and nonproliferation.

Deflection-based techniques are being widely used to evaluate the structural integrity and for estimating the elastic moduli of in-service pavements. These deflections can be non-destructively induced and measured using various commercially available devices. In recent years, the Falling Weight Deflectometer (FWD) has gained worldwide acceptance among most highway agencies due to its versatility and ease of use. However, as with any testing using subject-driven, instrumented devices, the major concerns of the end usefulness of the resulting data are accuracy and precision. Although a level of uncertainty is always inherent to any measurement process, it must also be appropriately quantified or assessed. Therefore, the Florida Department of Transportation initiated the present field study to assess the level of precision of FWD measurements on flexible pavements. Deflection data were acquired using three FWD units concurrently on four different asphalt pavement sections. The precision was then addressed in terms of testing repeatability and reproducibility. In addition, the effects of buffer designs on deflection measurements were also evaluated. This paper presents a description of the testing program, data collection efforts, and subsequent analyses and findings. Precision statements for repeatability and reproducibility of field measurements were developed and are summarized herein. A generally high level of repeatability and reproducibility of the deflection measurements is demonstrated.

In this paper, the applicability of a new mesh-insensitive structural stress method is examined for the evaluation of multiaxial fatigue behaviors in welded joints. The mesh-insensitive structural stress method proves to be effective in characterizing stress concentration effects in multi-axial fatigue of welded components. In seeking an effective structural stress based fatigue parameter, some well-known published test data were analyzed. These include those published by researchers, e.g., from the Electric Power Research Intitute (EPRI), the Fraunhofer-Institute for Structural Durability (LBF), the University of Illinois at Urbana-Champaign (UIUC), and the Welding Institute (TWI) under bending, torsion, and in-phase and out-of-phase loading combinations. An effective structural stress parameter has then been formulated in a form of a proposed modified Gough's ellipse for considering both in-phase and out-of-phase multiaxial loading conditions. The aforementioned multiaxial fatigue data from a total of five independent sources can be effectively correlated with a structural stress based parameter presented in this paper, without introducing any other material-related empirical parameters. The present method is rather simple to use for day-to-day finite element based fatigue evaluation of welded joints in actual structures subjected to multiaxial loading conditions.

The problem of a stationary crack in functionally graded materials (FGM), subjected to a combination of thermal and mechanical loading is considered. An asymptotic analysis coupled with Westergaard's stress function approach is used to characterize the stress field around the crack tip. Thermal and mechanical properties (e.g., elastic modulus, coefficient of thermal expansion, and thermal conductivity) are assumed to vary exponentially. The crack is assumed to be inclined to the direction of the property gradation. The thermal loading is taken to be a uniform heat flow in a direction inclined to the crack. The principal of superposition from linear elasticity is used to solve the problem, whereby the problem is divided into a number of subproblems. The first four terms in the expansion of the stress field are derived to explicitly bring out the influence of nonhomogeneity on the structure of the stress field. It is observed that the presence of heat flow produced no additional singularity and hence the classical inverse square root singularity still prevails around the crack tip. Using these stress field contours of constant maximum shear stress are generated and the effect of thermal loading on the crack-tip stress field is discussed.

New materials intended for use in critical U.S. Navy applications are evaluated by a Fracture Toughness Review Process (FTRP) for acceptability. In addition to developing data on the mechanical properties, fatigue life, and fracture toughness, the FTRP requires that a representative structural element test be performed to verify that the material can withstand plastic deformation at high loading rates in the presence of a detectable flaw. A Fastener Structural Element Test (FSET) has been developed to certify fastener materials such that the results of fracture mechanics testing on candidate alloys can be verified. The testing required the development of a suitable specimen that best represented a fastener, flaw seeding, and pre-cracking techniques, load and displacement measurement techniques suitable for high loading rates, and material performance acceptance criteria. The complete results of the testing on titanium alloy Ti-5AI-1Sn-1Zr-1V-0.8Mo (a.k.a. Ti-5111) and a Co-Ni-Cr-Mo-Al-Fe alloy will be presented along with the test methodology, data acquisition, and analysis details. The challenges encountered and areas that require further refinement will also be discussed.

This paper presents a probabilistic analysis for evaluating the creep crack growth rate (CCGR) of type 316LN stainless steel. The CCGR data was obtained from the creep crack growth tests, which are conducted under various applied loads at 600°C. The crack growth rate was characterized as a function of the C* fracture parameter. In order to logically obtain the B and q values in the CCGR equation of a=B(C*)q, three methods of the least square fitting method (LSFM), a mean value method (MVM), and a probabilistic distribution method (PDM) were adopted. Also, using the Monte Carlo simulation, a number of random variables was generated, and the CCGR lines were predicted probabilistically. The three methods did not show a large difference in the CCGR lines, but the PDM was most useful because the CCGR line can be evaluated with a probabilistic reliability. Both the B and q coefficients followed a lognormal distribution, even though the B ones were a little scattered for the points of the data. In the case of a standard deviation of 1 σ for the probability variables, P (B,q), the results of the MCS and the PDM for the distribution ranges of the CCGR lines were compared and discussed.

A study was conducted to determine whether the efficacy of pyrethroid insecticides, formulated with Biodac2 (an inert carrier granule derived from paper recycling waste) could be enhanced through the addition of surfactants. Thus, a series of formulations of permethrin on Biodac was prepared so that the effect of several nonionic surfactants on granule efficacy could be studied. To compare the efficacy of the formulations, the granules were tested on imported red fire ants, Solenopsis invicta, under laboratory conditions. Formulations with surfactant outperformed the control formulation (no surfactant) by a wide margin.

A simple method to detect crack initiation is presented. By polishing the surface of carbon steel structure properly and using the Luders bands and orange peel as indicators for damage, it is possible to predict crack initiation with the naked eye. The initiation of the Luders bands is the yellow light of the crack initiation, for instance, in the traffic signal, and orange peel is the red light. The relationship between the observed surface condition and the cyclic stress-strain characteristics is discussed.

A new approach to pozzolanic index is proposed. The proposed index (from 0 to 1) is based on the percentage of the pozzolan that reacts with lime. The index is logical in that it is a description of the level of reactivity of the pozzolan. The optimum pozzolan percentage for use with cement can be calculated using the index. An index can be estimated from pozzolanic reactions with lime or based on its contribution to the strength of concrete or mortar. A model for concrete strength incorporating the index is proposed that can be used to estimate concrete strength.

The use of residual stress measurements for the analysis of the performance of rolling bearings has become a common tool in the bearing industry. The effects of rolling contact fatigue on the development of residual stresses in the loaded zones of a bearing has been investigated in much detail. In this paper, the developments of the use of X-ray microdiffraction for residual stress measurements in bearings will be described. In microdiffraction, measurements are performed with very small irradiated spots. Advances in X-ray diffraction technology have made it possible to determine the residual stresses in loaded components in small areas with a high level of detail. The method and its consequences for bearing analysis is discussed in this paper. Using the method, much more information on the exact operation conditions of a bearing can be extracted from the components compared to conventional X-ray diffraction methods. Residual stress measurements using microdiffraction have been successfully applied in an application analysis case, where the measurements were used to show the residual stress development in the bearing surface during operation. In such a case, microdiffraction could also be used to investigate local bearing life limiting features, such as surface damages.

In this work, the results of mechanistic studies of surface crack initiation due to the coalescence of microcracks from casting defects are presented. Two approaches are considered; namely, a continuum damage (CD) one and another where a microvoid is explicitly introduced in the vicinity of a notch. In both cases, a rate-dependent crystallographic theory is relied upon to describe the visco-plastic behavior of the single crystal. The numerical studies are conducted on a notched compact tension (CT) specimen with and without a single casting defect, idealized as a cylindrical void close to the notch surface. CD predictions of the formation of surface cracks under constant far-field loading, linked to the nucleation and coalescence of microcracks from internal porosities, are obtained from a recently proposed mechanistic anisotropic void growth model. In the explicit-void modeling approach, the time to crack initiation under constant load has been predicted using a strain-based failure criterion. Finite element analysis of the CT specimen revealed that, due to the strong localization of inelastic strain at the void, a microcrack will initiate in the vicinity of the void rather than at the notch surface. The numerical results have also shown that the time to crack initiation depends strongly on the applied load level and the void location. These results and those obtained from the CD predictions are compared and discussed. The applicability of a failure assessment approach, based on the linear elastic stress intensity factor to predict the crack initiation time under creep loading, is also considered.