bluuebunny/crossref_metadata_2025 huggingface dataset:
An Approach to Scale up of an Intermetallic Composite Material for Structural Applications
Authors: Anthony F. M.
Published: August 2009

Refractory nonmetallic materials are attractive for high-temperature structural applications, but in most instances the most promising materials have been produced only on a laboratory scale. This paper describes one such material and the efforts to scale up the processing procedures to an extent where practical structural components can be produced. The point of view is that of the designer rather than that of the materials engineer. The material is a multiphase body formed from zirconium diboride (ZrB2), molybdenum disilicide (MoSi2), and boron carbide (B4C) powders by means of cold pressing and sintering. The scale-up program, while following essentially standard procedures, was established to give more direct attention to user requirements than is normally the case with material scale-up activities. Early consideration of microstructural and chemical gradients, inspection requirements, and surface finish characteristics resulted from a close cooperation of the user and the material supplier. Throughout the scale-up effort, emphasis is being placed on maintaining similarity of the material as produced for test bars and for components. In this way, the designer is provided with a maximum of confidence in the characteristics to be expected from the material used for structural hardware. Control of sintering conditions, configuration of green shapes to be sintered, and machining procedures were identified as items of major importance for maintaining similarity. Electron microprobe techniques, radiographic and ultrasonic inspection techniques, and metallographic examination at high magnification provided valuable information regarding the degree of similarity obtained.
Materials Needs for Energy Absorption in Space-Vehicle Landings
Authors: Warner R. W. , Marble D. R.
Published: August 2009

In the design of systems to absorb the landing impact energy of space vehicles, such as the system which will be used to protect the Lunar Excursion Module of the Apollo spacecraft in touching down on the moon, the specific energy absorption (energy absorbed divided by the weight of the material deformed) is not necessarily the primary factor. Other factors which must be considered include the compatibility of the deforming structure with its support, the packaging volume of the system, the control of penetration into the landing surface, and the desirability of the system with respect to tip-over stability and maximum permissible acceleration. These factors can lead to consideration of systems which do not employ energy absorbers of maximum efficiency. Materials improvements leading to better energy absorption in these systems could result in significant gains, particularly for the systems having relatively inefficient absorbers. In addition, it is recommended that materials be improved by decreasing their elastic bounce-back and increasing their resistance to the effects of the rocket exhaust and the space environment. Such materials improvements may play a major role in the selection of energy-absorbing systems.
Extrusion of Beryllium Structural Shapes
Authors: Siergiej J. M.
Published: August 2009

Despite the many attractive properties of beryllium, its use has been limited by a number of problems, such as its lack of three-dimensional ductility, the difficulty of fabricating complex shapes, and the high cost of the special processing techniques required. In recent years, however, considerable productive effort has been expended to enable the use of commercially available beryllium as a structural material. Because of the many design requirements for long lengths of uniform cross section, such as longerons, the extrusion process was naturally one of the fabrication methods which received considerable attention. For the purpose of this presentation, the term “extrusion” will be used to apply only to those extrusion techniques consistent with the requirements for generating long lengths. (Not included, for example, are low-reduction extrusions and back-extrusions of heavy-wall sections.)
Introduction
Authors: Juve A. E.
Published: August 2009

The devices discussed in these papers are designed to measure some cure-dependent property, while the cure is in process and at the curing temperature. The five devices to be discussed are recent developments and have created interest among those in the rubber industry comparable to the interest generated about ten years ago in analysts with the appearance of gas Chromatographic equipment. These devices will supplant the classical method of determining curing characteristics — to cure a series of slabs for increasing time intervals, determine their stress-strain properties, and from these data deduce cure rate and other information. Much more precise information is obtainable in a simple, fast test. However, they will not displace stress-strain testing for other purposes since, as Gehman and Ogilby state, the ultimate properties of tensile strength and elongation are of considerable value and importance in most service applications of rubber. They will be used as control testing devices for monitoring production batches, for development compounding work, for research studies in many aspects of rubber technology, and are being considered for control testing in the production of carbon blacks for the rubber industry, and the synthetic rubber industry. An ad hoc committee has been set up in Committee D-11 to develop standard procedures for extracting information from the traces obtained.
Plasticity and Cure Control and Cross-Linking Studies of Rubber Using the Wallace-Shawbury Curometer
Authors: Norman R. H. , Hickman J. A. , Payne A. R.
Published: August 2009

The Wallace-Shawbury curometer now has an improved paddle and platen system, which permits the determination of the stiffness (plasticity) of the unvulcanized rubber in addition to the scorch and cure times. The instrument is suited to routine operation and fundamental investigations. The stiffness of the unvulcanized rubber at the curing temperature is proportional to the square of Mooney viscosity measured at the same temperature, and the scorch time is similar to the time required for a one-point rise in Mooney viscosity at the same temperature. The curometer cure times of natural and synthetic rubber compounds compare satisfactorily with those obtained from conventional tension and hardness tests. The curometer may also be used for the measurement of homogeneity. The ratio of the instantaneous degree of cross-linking to the final value can be calculated from the curometer trace, and the relationship between cross-linking and time, for compounds of natural, neoprene, butyl, and SBR rubbers, is frequently that expected from a first-order reaction.
Cepar Measurements of Curing Constants
Authors: Conant F. S. , Claxton W. E.
Published: August 2009

A new, single-station apparatus is described which features kymograph recording, in situ sample preparation, and simple data interpretation. From the record of progressive modulus change during cure, all of the important curing constants are easily calculated. These include induction time, time to any required fractional cure, curing rate constant, and activation energies for both incipient and principal curing reactions. From these activation energies the appropriate temperature coefficients of vulcanization are easily obtainable if desired. The meaning and use of each of these indexes are described along with illustrative applications to technological problems associated with vulcanization. The examples include: (1) A method for direct calculation of fractional cure within a thick block of rubber under varying time-mold temperature conditions which is applicable to compounding studies on high temperature curing, (2) The rheological changes taking place during the induction period which are applicable to factory stock control, and (3) Tests on the cured cepar buttons (tensile, modulus, elongation, resilience, compression modulus, hardness, and specific gravity) which extend the range of usefulness of the apparatus.
Uses of an Oscillating Disk Rheometer for Determining the Rheological Properties of Elastomers During Vulcanization
Authors: Wise R. W. , Decker G. E.
Published: August 2009

The Monsanto oscillating disk rheometer is shown to be an instrument which quickly and precisely determines the dynamic properties, curing, and processing characteristics of elastomers during the entire curing cycle. Measurements with the rheometer are shown to correlate with measurements made by the more conventional methods. For example, interpretation of the rheometer chart of modulus versus cure time gives results which correlate well with Mooney scorch, Mooney viscosity, and tensile moduli of individual press cures. In addition, dynamic moduli measurements with the rheometer are shown to agree with heat buildup and dynamic moduli measurements made on a conventional dynamic moduli tester. Other uses and the design of the rheometer are briefly described.
The Viscurometer—A Study of Variables Associated with its Use
Authors: Veith A. G.
Published: August 2009

The Viscurometer is an apparatus that measures the cross-link induced change in shear stress of a rubber stock as a function of time at elevated cure temperatures. As such, it can be used to predict optimum cure, scorch time, mixed compound viscosity, and fully cured compound modulus. For this purpose a knowledge of the effect of such compounding variables as carbon black content, processing oil content, ultimate cross-link density, and temperature of test on the performance of the device is required. This paper describes an investigation of the influence of these variables. We will study this multivariable problem by the application of the systematic methods of statistical experimental design. The data of this program are analyzed by the methods appropriate to such designed experiments and the results are displayed in convenient, graphical form. A single material system is studied: SBR, HAF black, naphthenic oil, CBS accelerator, and sulfur.
Introduction
Authors: Glaser P. E.
Published: August 2009

The growth of the cryogenic industry over the past ten years and the accumulated experience in liquefaction, transportation, and storage have resulted in wide applications of cryogenic fluids. Fluids that formerly belonged to the realm of laboratory curiosities such as liquefied methane, oxygen, nitrogen, hydrogen, and helium have become commonplace, not only in the laboratory, but also in large-scale industrial operations. As the uses of these fluids have become widespread, their transportation to the point of use and their storage for extended periods have demanded improved insulation techniques. The doublewall, vacuum-insulated dewar flask which was the most widely used method for storing small quantities of cryogenic fluids has been supplanted by vessels in which thousands of gallons can be stored ready for use in the various industrial applications or as fuel for space missions. The thermal insulations which are required to meet the needs of the cryogenic industry fall into two major categories: (1) insulations which are gas filled and (2) insulations in which the gas has been evacuated to achieve a desired low pressure. The continuing advances being made in the thermal effectiveness of these insulations, particularly of the evacuated type, have brought about the need for an apparatus which not only can operate at cryogenic temperatures, but in addition has the required sensitivity to measure thermal conductivities several orders of magnitude lower than those of insulation materials encountered in industrial practice. Such an apparatus must be capable not only of measuring conventional homogeneous thermal insulations, but also permit the measurement of properties of materials of very high anisotropy as exemplified by multilayer insulations. To carry out meaningful measurements, the effects of variables which control the performance of the insulation such as density, type, and pressure of gas within the insulation, applied compressive loads and radiation interchange with apparatus surfaces have to be closely controlled. A thermal-conductivity measuring apparatus has to be useful in evaluating the thermal performance of different insulation materials and material combinations, as improvements of insulations take place, and to assist in the continuing development of new thermal insulations. To meet these demands, different laboratories either modified existing apparatus or developed new apparatus to carry out measurements. Intercomparison of results obtained by the different laboratories was hampered by the lack of well-characterized standard test material and by the variations in the type of test apparatus used. The continuing expansion of the cryogenic industry is predicated on the availability of thermal insulations with predictable performance characteristics. The standardization of test methods for measuring conductivity will be an important factor in achieving this objective.
A Flat-Plate Thermal-Conductivity Apparatus for Measuring Low-Conductivity Materials at Cryogenic Temperatures
Authors: Haskins J. F.
Published: August 2009

A guarded-hot-plate technique has been developed for making thermal-conductivity measurements at low temperature. The apparatus has been used to measure materials with conductivities in the range 0.01 < K < 10 Btu in./hr ft2 deg F. A thin electrical heater is placed between two panels of the test material. The heater system consists of two parts: a center heater surrounded by a guard heater. The heaters are fed by separate power supplies, making it possible to cancel out lateral heat flow. A cryogenic fluid provides a heat sink and fixes the outside panel wall temperature. Thermocouples measure the thermal balance between heaters and the gradient across the specimen. The electrical power establishes the inner wall temperature and determines the heat which flows through the guarded area. The advantages of this method are: (1) A fixed outside wall temperature is established by using the boiling and freezing points of various liquids. (2) The thin flexible heater helps reduce lateral heat flow and allows the center and guard heaters to conform to slight variations in the panels. Factors considered in the error analysis are: effective heater area, measurement of power to heater, thermocouples, panel thickness, contact resistance, panel bowing, and gas environment. Certain improvements in both apparatus and technique have been made by careful analysis of the data generated during several hundred measurements.
A Double-Guarded Cold-Plate Thermal-Conductivity Apparatus
Authors: Black I. A. , Glaser P. E. , Perkins P.
Published: August 2009

The capabilities of the apparatus for measuring the thermal conductivity of multilayer insulations, powders, fibers, and foams are pointed out, and the details of the construction are summarized. The vacuum system and instrumentation are briefly described. Special attention is devoted to a method of controlling the pressure of the gas above the boiling cryogenic liquid and to an automatic method of measuring small boil-off rates. Calibration of the apparatus, reproducibility of test results, and the effects of guarding of the exposed edges of the specimen are discussed.
A Cryogenic Heat-Flow-Meter Apparatus
Authors: Kinzer G. R. , Pelanne C. M.
Published: August 2009

A cryogenic thermal-conductivity heat-flow-meter apparatus (cryogenic heat meter), a modification of the apparatus described in a previous ASTM publication, is described. This apparatus enables a rapid determination of thermal conductivity of felt, powder, and block materials to be made at cryogenic temperatures and at atmospheric pressure. The apparatus is particularly suitable for screening a large number of specimens, for obtaining product development information, and for quality control testing. The correlation among results obtained with the cryogenic heat meter and the Wilkes calorimeter and a National Bureau of Standards' cryogenic calorimeter is excellent. Correlation of cryogenic heat-meter results with those obtained at higher temperatures on a heat-flow-meter apparatus and a guarded-hot-plate apparatus is good. A range of temperatures can be applied to the test specimen. Therefore, use conditions can be simulated, if desired.
Fatigue Crack Propagation in Structures with Simulated Rivet Forces
Authors: Figge I. E. , Newman J. C.
Published: August 2009

Analytical and experimental studies were conducted on rates of fatigue crack propagation in sheet specimens containing either symmetric or nonsymmetric cracks subjected to uniform external loadings, simple concentrated loadings, or combinations of both. The concentrated loads simulated the rivet forces in an actual structure and were applied by a special hydraulic fixture which is described. An experimentally determined relation between the stress state near the tip of the crack and the fatigue crack propagation rate for a given material was employed to predict the crack growth for specimens subjected to simple loading conditions with good agreement. Superposition of stress-intensity factors for simple loading was used sucessfully to predict crack growth for specimens subjected to complex loadings.
Low Cycle Fatigue Crack Propagation Resistance of Materials for Large Welded Structures
Authors: Crooker T. W. , Lange E. A.
Published: August 2009

The development and application of modern, higher strength materials for large welded structures, combined with the realization that flaw-free fabrication cannot be ensured, have created a need for methods to evaluate the low cycle fatigue crack propagation resistance of structural metals. In this paper a test method is discussed which has been applied to a broad spectrum of structural metals, both ferrous and nonferrous, including yield strengths from 30 to 200 ksi. The results apply to structural lives ranging from 100 to 100,000 cycles. Data are presented in terms of an empirical power-law relationship between fatigue crack growth rate and total (elastic plus plastic) strain range. Comparisons are made among the low cycle fatigue crack propagation characteristics of competitive materials, and a first-order translation of crack growth rates to an index of structural fatigue life is developed. The influences of aqueous environments and mean strain are described.
The Influence of Metallurgical Structure on the Mechanisms of Fatigue Crack Propagation
Authors: Laird Campbell
Published: August 2009

Studies of fatigue fractures have indicated that crack propagation takes place by two stages. The first stage propagates at 45 deg with respect to the stress axis, while the second does so at 90 deg. The evidence for crack growth is reviewed, and it is concluded that the Stage II mode occurs by plastic blunting of the crack tip during the tensile part of a fatigue cycle followed by resharpening of the crack in the compression part. The mechanism of Stage I growth occurs on too small a scale to be studied directly but is deduced to be essentially the same as Stage II. The softness of fatigue slip bands with respect to the bulk of the material, however, provides an easy path for crack propagation in Stage I and thus causes propagation at about 45 deg to the stress axis. On the other hand, in Stage II, the larger stress concentration associated with the longer crack dominates the structure at the crack tip and orients the path of crack propagation at 90 deg to the stress axis. The morphological details of fracture surfaces are considered in the light of these mechanisms. The role of microstructure in influencing the mechanisms is treated from two aspects. First, it is shown that the various kinds of hardened structures merely act to control the degree of deformation at a crack tip in relaxation, and thus the kinetics of crack propagation. Otherwise, microstructures hardened to extremes by cold-working or by precipitation can be the exception to the generalization, acting in conjunction with other testing variables to change the mode of propagation so as to introduce cleavage or quasi-cleavage fracture to the crack propagation process.
Microstructures at the Tips of Growing Fatigue Cracks in Aluminum Alloys
Authors: Grosskreutz J. C. , Shaw G. G.
Published: August 2009

The technique of transmission electron microscopy has been used for direct observation of the microstructures at fatigue crack tips in 1100-O, 2024-T4, and 7075-T6 aluminum alloys. The dislocation morphology and density, and the metallurgical structures which are formed in the plastic zone were studied. In 1100-O, the dislocations are distributed in a subgrain structure, while in 2024-T4 they are distributed uniformly throughout the grain, and many dislocation loops are found. In 7075-T6, dislocations are tightly packed and show little sign of motion or interaction. No correlation was found between the dislocation structure just beneath the fracture surface and the regularly spaced crack growth striations found on the surface. Dislocation densities 6 μ from the crack range from about 1010 lines/cm2 in 1100-O to about 1011 lines/cm2 in 7075-T6. No localized reversion or overaging was observed to occur in the plastic zones of these alloys. The possibility of a general change in metallurgical structure is discussed, and it is concluded that reversion of very small Guinier-Preston zones or a limited, general overaging would not have been detected by our techniques.
Investigation of Cyclic Crack Growth Transitional Behavior
Authors: Wilhem D. P.
Published: August 2009

Observations of tensile to shear transition behavior of fatigue crack fronts have been recorded numerous times during tension-tension cycling of sheet materials. Based on recent crack growth data, correlation of shear lip development and associated crack tip stress intensities has been obtained for a variety of aluminum, steel, and titanium alloys. Assumption of a crack growth transition zone region allows for direct application to deviations in crack growth rate versus stress-intensity relationships at low crack tip intensities. A stress-controlled specimen of 7075-T6 aluminum sheet was fatigue cycled from tensile to shear and back to tensile within the transition zone; crack front behavior was microscopically observed. Macroscopic and microscopic correlations were established with discontinuities in stress intensity versus crack growth semilog relationships. The beginning of shear lip development in 2024-T3 aluminum appears to be independent of thickness and dependent only on the stress-intensity factor at transition.
Fatigue-Crack Propagation in Some Ultrahigh-Strength Steels
Authors: Wei R. P. , Talda P. M. , Li Che-Yu
Published: August 2009

Fatigue-crack propagation studies were carried out on some ultrahigh-strength steels in controlled environments using the fracture-mechanics approach. The steels investigated include a medium-carbon low-alloy ultrahigh-strength steel tempered to two strength and toughness levels, a 250-grade 18Ni maraging steel, and a 300-grade 18Ni steel. The results indicate that, in the inert environment, the rates of fatigue-crack propagation in these steels are about the same and show no obvious correlation with other mechanical properties of the steels. The sensitivity of the rates of fatigue-crack propagation to the presence of moisture in the test environment shows rough correlation with plane-strain fracture toughness for steels of similar composition. The role of water vapor in promoting fatigue-crack propagation is considered. The results are also discussed in terms of existing theories and metallographic observations.
Fatigue Crack Propagation Under Program and Random Loads
Authors: McMillan J. C. , Pelloux R. M. N.
Published: August 2009

The influence of maximum stress, stress range, and sequence of load application on the rate and mechanism of fatigue crack propagation in 2024-T3 aluminum alloy was studied by means of electron fractography. Variable-amplitude loading programs were designed to provide tests under the following conditions: (1) constant maximum stress with three different levels of stress range, (2) constant stress range with three and four levels of maximum stress, (3) pseudo-random load application achieved by random distribution of the load spectra defined in Items 1 and 2, and (4) uniform maximum stress with peak overloads and underloads. The macroscopic growth rates were determined on center-notched crack growth panels, and the fracture surfaces were examined by electron fractography. The analysis of the influence of program loads on the rate and mechanism of fatigue crack growth was accomplished by: 1. Comparing plots of crack length versus measured rates of crack propagation for the different programs. The measured rates were also compared with rates calculated by a computer program. 2. Relating the count and spacing of the fatigue striations observed on the fracture surfaces with the applied load program.
Introduction
Authors: Bramer Henry C.
Published: August 2009

Federal Water Pollution Control legislation enacted in 1965 requires that the States establish water quality criteria and provide for implementation of quality controls based upon such criteria. These criteria should be based upon sound scientific fact if the public interest is to be served by this legislative directive. ASTM Committee D-19 on Industrial Water believes that this National Meeting has been a worthwhile contribution of the professional community to the task faced by the States in complying with the Water Quality Act of 1965. It has been the purpose of this Meeting to evaluate the present state of scientific knowledge of quality requirements for water to be used in agriculture, for municipal and industrial supplies, and for recreation.
Municipal Water from Eastern Rivers
Authors: Flentje M. E.
Published: August 2009

In the eastern United States, 47 per cent of the population derive their water supply from surface sources (reservoirs and rivers) Generally, the supplies are taken from river tributaries rather than from the more polluted main stems. The paper suggests, in meeting the growing need for water it may become necessary to use more polluted sources through the utilization of the full capabilities of modern water purification plants. Examples are cited where good operation and relatively simple plant additions have increased plant capability for handling high coliform bacteria loadings, algae in high concentrations, tastes and odors, and organic matter removal. Suggested criteria limits for such plants are given.
Quantitative Assessment of Irrigation Water Quality
Authors: Bernstein Leon
Published: August 2009

New formulas are proposed for quantitatively assessing irrigation water quality. Except for extremely unsuitable waters, irrigation water quality can be assessed only in the context of the conditions under which the water is to be used. These conditions include the infiltration rate of the soil (I), the evapotranspiration rate (E), the irrigation frequency and duration (tc and ti, respectively) the net downward drainage rate below the root zone (O) and the maximum permissible salinity and chloride concentration for the crop to be grown (ECd and Cld, respectively). When drainage is non-limiting, the potential leaching fraction (LF) is given by: LF = 1 − (Etc/Iti) and when drainage is limiting by: LF = O/(E + O). The maximum permissible EC and Cl concentration of irrigation waters (ECi and Cli, respectively) are calculated from: ECi = LF × ECd and Cli = LF × Cld. Potential leaching fraction calculations will also be useful for estimating CaCO3 precipitation, and the degree to which specific toxic materials will be concentrated as water is evapotranspired.
Water for Supplemental Irrigation
Authors: Lunin Jesse
Published: August 2009

There is no single set of water quality criteria for supplemental irrigation water because of the interactive effects of the many variables involved. These include the chemical and physical characteristics of the soil, the physiological characteristics of the plant, and climatological conditions. Detrimental effects of poor water quality on plant growth result from salinity, presence of toxic elements, and indirect effects on soil properties. Problems vary depending on whether brackish water (contaminated by sea water) is used, or effluents from industrial plants. Criteria will differ depending upon whether irrigation is used for crop production or land disposal of effluents.
Water Use for Aquatic Life
Authors: Wurtz C. B.
Published: August 2009

Aquatic life in general is quite tolerant of deteriorated water. Aquatic organisms vary in their responses to environmental alteration from extreme sensitivity to equally extreme tolerance. Compared to the quality of water required for domestic and industrial use, the aquatic life of the nation is not very demanding. To protect all water-use interests pollution must be defined, criteria for natural waters developed, and standards for specific discharges fixed. It is probable that no single, equitable set of criteria for aquatic life can be established over a geographic area larger than the basin of a first- or second-order tributary of our major rivers. Water quality change brings about a concomitant biological change, but extreme conditions must exist and be persistent before aquatic life is eliminated. Environmental control is essential if optimal conditions for aquatic life are to be developed and maintained. Waste disposal, properly controlled, need not conflict with the use of water for aquatic life.
Measurement of Water Quality with the Pacific Oyster Embryo Bioassay
Authors: Woelke C. E.
Published: August 2009

Meaningful water quality standards or criteria must be expressed in terms of consumer needs. If these needs are based on chemical parameters, the criteria or standards should be based on chemical measurements. If consumer needs are based on biological factors, standards or criteria should be based on biological measurements. Methods have been developed in which Pacific oyster embryo bioassays measure water quality in terms of response by a type of animal (consumer) found in many of our bays and estuaries. The method has been successfully employed in the laboratory to measure relative toxicity of pulp and paper wastes. Both polluted and unpolluted water from bays and estuaries are routinely bioassayed with oyster embryos. Based on these bioassays, areas of acceptable and unacceptable water quality have been delineated relative to oysters. It is recommended that this method and similar bioassay techniques be adopted as part of the measurements employed in defining water quality standards and criteria.
Selected Bibliography on Permeability and Capillarity Testing of Rock and Soil Materials
Authors: Johnson A. I. , Richter R. C.
Published: August 2009

This bibliography was prepared as a result of a cooperative study by the U.S. Geological Survey and the California Department of Water Resources to facilitate additional study of the testing methods discussed during the ASTM “Symposium on Permeability and Capillarity Testing for Rocks and Soils.” References selected were representative of a number of disciplines—soil engineering, petroleum geology, hydrology, and soil physics, for example. for reader convenience, the references are listed alphabetically under the heading of permeability or capillarity, indicating the main subject of the reference. The bibliography should not be considered representative of all material that has been written on either of these two subjects. However, the authors have attempted to present a list sufficiently representative so readers can pursue the subjects of permeability and capillarity in greater detail.
Introduction
Authors: Barnett H. A. , Adams P. B.
Published: August 2009

Atomic absorption spectroscopy has grown with amazing speed from its place in the early 1960's as a novel analytical technique to its present status as a method widely applied to all kinds of practical analytical problems. Proliferation of equipment and methods has been more rapid than for any other analytical technique. Consequently, perspective on capabilities of instruments and methods has sometimes been distorted. It was therefore appropriate that a symposium be designed with the express purpose of presenting the advantages and disadvantages of atomic absorption spectroscopy so that this technique could be inspected with objectivity. The invited speakers were selected, and their topics were coordinated so as to provide a comprehensive coverage of all aspects of atomic absorption. A. Walsh, the founder of atomic absorption, was to present a discussion of the theoretical physical aspect of the technique that would lay a sound basis for understanding instrumentation and flame processes. T. C. Rains, a recognized authority in the field, was to discuss the theoretical chemical aspects of atomic absorption, an understanding of which is essential to the design of practical working analytical methods. C. L. Grant and L. L. Lewis, representing Committees E-2 and E-3, were to put atomic absorption in perspective relative to other techniques by comparing it with other instrumental and classical chemical techniques. With these invited papers as a background, the authors of contributed papers could then concentrate on presenting the essentials of their original work without an extensive review and introduction. It can be said that in large measure the objectives of the symposium were achieved. Certainly, those attending obtained a clear view of the present state of theoretical knowledge. If the merit of atomic absorption relative to other techniques was somewhat less clear, it is only because sufficient time has not elapsed for this judgement to be made with finality. But there is no doubt that the ground rules for making that judgement were clearly defined.
Physical Aspects of Atomic Absorption
Authors: Walsh A.
Published: August 2009

In atomic absorption methods of chemical analysis a portion of the sample for analysis is atomized in a flame, and the absorbance of light by this vapor is measured at a specific wavelength which is characteristic of the element to be determined. Peak absorbance measurements are obtained by using an atomic spectral lamp source which emits lines having a much smaller half width than the absorption line. Alternatives to the flame for atomization have been investigated, including the L'vov furnace, cathodic sputtering, propellant powders and lasers, but all are of more limited application than the flame. New methods of measuring atomic absorption employ flame fluorescence, resonance detection, and selective modulators. Measurement of the resonance radiation emitted from atomic vapors liberated from the sample by cathodic sputtering offers the possibility of analyzing metals and alloys without prior solution of the sample.
Chemical Aspects of Atomic Absorption
Authors: Rains T. C.
Published: August 2009

The phenomenal growth of atomic absorption spectrometry in the past twelve years can be attributed to many factors such as the high sensitivity of the method for a large number of elements, advances in overcoming interferences, saving of time required for analysis, and the rapid improvement of instrumentation. The major interferences in atomic absorption are of a chemical nature; however, physical interferences which are associated with the chemical matrix often are present. To overcome chemical interferences and to eliminate or minimize their influences from phosphate, aluminum, titanium, and any other elements producing nonvolatile compounds, releasing agents, or high-temperature flames are used. Also, the use of a separation and preconcentration technique often becomes necessary when determining elements at the subtrace level. A list of organic ligands and solvents used in solvent extraction for absorption is presented as a means of preconcentration and removal of chemical interferences.
A Comparison of Atomic Absorption with Other Spectrochemical Methods
Authors: Grant C. L.
Published: August 2009

The objective comparison of related spectroscopic methods of analysis is discussed. Capability factors considered are: (a) scope of application, (b) sample preparation requirements, (c) sensitivity and limit of detection, (d) precision, and (e) accuracy. Economic factors considered are: (f) instrument cost or availability or both, (g) operational costs, (h) operator training requirements, and (i) time available for analysis. Methods considered are atomic absorption, atomic fluorescence, flame emission, arc-spark emission (photographic and direct reading), X-ray emission, and spark source mass spectroscopy. The method capability comparison of factors (c) through (e) is based primarily on the characteristics of the analytical calibration curve. A method for comparing the economic factors also is suggested.
Determination of Calcium in High Interference Systems by Atomic-Absorption Flame Photometry
Authors: Ulrich W. F. , Ramírez-Muñoz J.
Published: August 2009

The behavior of calcium has been investigated in the interference systems: hydrochloric acid/calcium, sodium chloride/calcium, acetic acid/calcium, aluminum/calcium, and phosphate/calcium. Possible mechanisms are detailed and corrective procedures tested. In general, presence of a concomitant in high concentration depresses calcium signals at different calcium concentration levels. These depressions are observed both with total consumption burners and laminar flow burners. In cases of heavy interference, protectors and releasers have been studied. With ethylenediametetraacetic acid, protective action is effective when only moderate concentrations are involved but is somewhat less desirable at higher concentrations because of the increase in burner contamination by the organic material. The presence of lanthanum is very helpful in such cases, and this approach has become routine in some applications. Strontium has been used in a similar manner and provides satisfactory results in many analyses. However, strontium appears to be less effective than lanthanum and usually is required in higher concentrations to provide equivalent protection. The nitrous oxide-acetylene flame has proven particularly useful even for the more difficult systems such as aluminum/calcium and phosphate/calcium. Addition of an ionization inhibitor such as potassium has also been investigated in connection with the high-temperature flame tests.
Introduction
Authors: Lundgren Raymond , D'Appolonia Elio
Published: August 2009

In recognition of the importance of deep foundations in foundation engineering, it was considered appropriate to organize a symposium to bring to the practicing engineer the most recent advances in the state of the art in the design and evaluation of deep foundations. Emphasis was placed on the following four needs in deep foundation design and performance: (1) a more rational analysis of the behavior of piles under both static and dynamic loads, (2) the correlation of pile-load-test data with soil data obtained during subsurface investigation, (3) controlled, well-documented pile group tests, and (4) the measurement in the real structure of load deformation of pile groups and a comparison of predicted and observed behavior. The symposium was divided into three main sections entitled: “Load Transfer, Lateral Loads, and Group Action of Deep Foundations,” “Dynamic and Earthquake Forces on Deep Foundations,” and “Testing, Specifications, and Construction Control.” Papers in these various categories were solicited from a number of the leading engineers in the country, both in practice and in the academic field. Rather than toward the traditional basic concerns with driving formulas and load tests on single piles, the symposium presentations and discussions were directed primarily toward the more sophisticated aspects of deep-foundation engineering. It is the hope of the authors and sponsors of this symposium that these papers will advance the state of knowledge so that practicing engineers can make use of recent progress in theory and practice to design and construct deep foundations with optimum safety and economy.
Downdrag Measurements on 270-Ft Composite Piles
Authors: Bozozuk Michael , Labrecque André
Published: August 2009

The Quebec autoroute on the North Shore of the St. Lawrence River between Montreal and Quebec City traverses deep deposits of compressible marine clay. One of the overpass structures at Berthierville is supported on twelve 39-in. (1 m) diameter reinforced concrete piles, which pass through 270 ft (82 m) of soil and finally rest on shale bedrock. The site was preloaded for one year, during which time about 5 ft (1.5 m) of settlement occurred. Steel casings for the piles were then driven and filled with concrete which was reinforced. Each pile was designed to carry 2000 tons (1814 metric tons) of which 1200 tons (1090 metric tons) were allowed for negative skin friction loads. Deformation gages were installed at various levels in two of the piles to measure the axial compression as the negative skin friction accumulated. Contrary to expectations, hydration caused the piles to lengthen about 0.06 in. (1.5 mm) during the 6-week period following placement of the concrete. Five months later this reduced to about 0.04 in. (1.0 mm) as skin friction loads overcame the expansive forces of hydration. In this same period the subsoils consolidated by more than 0.5 ft (0.15 m). Near the ground surface the pore water pressures and settlements were the same adjacent to a pile and at a distance of 22 ft (6.7 m). In November 1966 a cut was made to permit construction of the foundations for the overpass, causing the piles to lengthen about ƈ in. (6 mm). In December, electroosmosis was applied to relieve the test piles of the accumulated skin friction loads imposed by the consolidating clay subsoil. Subsequent measurements showed that they immediately began to accumulate negative skin friction loads, and that in the following 10-month period they compressed more than Ɖ in. (13 mm). Vertical pile deformations were also measured when the overpass was constructed. From these observations the vertical modulus of deformation of the composite piles was calculated and compared with the values obtained from uniaxial compression tests on test cylinders in the laboratory. The paper presents measurements of settlement and pore water pressures in the soil at various depths under the fill, and of axial deformations in two of the piles. It provides a set of relatively rare field observations on which to base an approximate evaluation of the rate and magnitude of negative skin friction development under the described field conditions.
Load Tests on Long Bearing Piles
Authors: Darragh R. D. , Bell R. A.
Published: August 2009

Load tests were performed on corrugated step-tapered piles with pipe extensions and pipe piles driven through 120 ft of slightly overconsolidated, medium-to-stiff, fissured clays 1 to 10 ft into dense fine sands and silty sands. Failure loads for the bearing piles of 10¾ to 12¾ in. tip diameter varied from 180 to 280 tons. Design dead loads up to 90 tons, which could be temporarily carried in friction in the upper compressible soils, were expected to be eventually transmitted to the sand stratum. The bearing capacity of the sand was evaluated by subtracting friction in the upper clays, as measured by piles stopped above the sand, from the total load carried by the bearing piles. The developed friction capacity was uncertain because of variations in soil strength between load test locations. However, the following conclusions are indicated by the test data and wave equation analyses of the driven piles: (1) the corrugated step-tapered piles developed frictional resistances in the clays equal to or greater than the minimum undrained shear strength determined by unconfined compression tests, (2) pipe piling frictional resistances were about two thirds of the corrugated pile values, and (3) the bearing capacity of the sand was overestimated 70 to 100 percent by wave equation analyses of the ultimate resistance of bearing piles driven to practical refusal and 150 to 400 percent by bearing capacity formulae using full overburden pressures and bearing capacity factors for laboratory-measured angle of internal friction of the sand.
Lateral Load Tests on Drilled Piers
Authors: Davisson M. T. , Salley J. R.
Published: August 2009

Lateral load tests were performed on four 4-ft-diameter drilled piers extending through water bearing granular overburden and terminating in shale bedrock. Depth of overburden varied from 10 to 43 ft. The tests involved piers with both bell and socket bases. Electric resistance strain gages were used to measure strains at the reinforcing steel, and furnished data from which bending moments were determined. It was concluded that: (1) drilled piers are capable of resisting lateral loads of large magnitude, (2) soil embedment is very effective in attenuating moments caused by lateral loads, (3) bell and socket bases effectively resist lateral loads for short drilled piers terminating in rock, (4) lateral load resistance of long drilled piers is not influenced by the base conditions, and (5) cyclic loading causes deflections to double and moments to increase 20 to 50 percent, approximately, compared to the values for the first cycle of load.
Design of Caissons on Granular-Cohesive Soils
Authors: Housel W. S.
Published: August 2009

This paper presents procedures developed for designing caissons bearing on highly consolidated soil mixtures having both granular and cohesive characteristics. The ultimate bearing capacity of these materials approaches that of rock, but testing and design procedures for soil are applicable. Several hundred static loading tests on bearing piles made over the past 20 years have demonstrated that highly consolidated soils will carry loads up to the crushing strength of the sand and gravel particles without displacement. Their ultimate bearing capacity ranges up to several hundred tons per square foot considerably in excess of nominal bearing capacity normally used on rock. These piles have been driven to practical refusal, all but eliminating consolidation settlement which is a controlling factor in caissons. Lacking the opportunity for preconsolidation of the bearing materials, caisson design consequently is limited to the preconsolidation or initial strength of the soil support well below the ultimate capacity available to driven bearing piles. Preliminary design incorporated in plans and specifications for bidding purposes is based on the results of borings and laboratory tests with standard field penetration used as the basic control. The final design is made in the field at the time of construction when bell diameters are adjusted to the field penetration taken at the bottom of the caisson. The field and laboratory testing is described briefly. A general expression for bearing capacity is developed in terms of internal stability and cohesion of soil mixtures. Design charts for rapid determination of bearing capacity in situ and for the selection of final bell sizes are explained.
Measurements of Pile Load Transfer
Authors: Hunter A. H. , Davisson M. T.
Published: August 2009

Load transfer data are presented for six piles embedded in sand. The data were adjusted to account for residual loads caused by driving in order to arrive at the true variation of skin friction with depth. Residual loads of 25 to 48 tons were observed for conventionally driven piles, whereas the load for a pile driven with a vibratory hammer did not exceed the weight of the driver. Friction during compression was found to exceed that during tension by 30 percent. An average lateral earth pressure coefficient of 1.1 was observed, with a value of 0.75 being observed for a jetted pile. The data indicate that conventional hammers may compact the soil below the pile tip and improve point bearing capacity. Skin friction adjacent to the pile tip was found to be significantly lower than for other parts of the pile.