bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Temperature on the Flexibility Characteristics of Asphaltic Paving Mixtures
Authors: Monismith CL
Published: March 2009

In the design of asphaltic paving mixtures for heavy-duty highways one of the important mix properties, and perhaps the least understood, is flexibility, which in part embraces the behavior of paving mixtures under repeated flexure. In a previous paper (1)2 the author defined a number of factors which influence flexibility, grouped as: (1) properties of materials, (2) structural effects, (3) external conditions. At the Soil Mechanics and Bituminous Materials Laboratory at the University of California, a systematic investigation of these factors and their interrelationships is being conducted which may lead to a better understanding of flexibility.
A Test for Production of Plastic Fines in the Process of Degradation of Mineral Aggregates
Authors: Ekse M , Morris HC
Published: March 2009

Degradation of mineral aggregates, particularly in base courses under flexible paving mats, is a natural process that results from the kneading action of moving wheel loads. Over a period of time, heavy traffic will tend to produce not only a progressively finer aggregate grading than was initially placed in the base course but also an excess of fine material in the particle-size range of silt and bordering on that of clay. The results of such degradation of base-course aggregates are: (1) reduction of angularity and interlock of the courser particles and (2) some “lubrication” of the coarser particles by increasing amounts of fine material distributed through the aggregate under moist conditions. The net effect is to reduce the stability of the base course.
Temper Embrittlement Study of Ni-Cr-Mo-V Rotor Steels: Part II—Statistical Design and Analysis
Authors: Stewart BK
Published: March 2009

A program was planned to obtain quantitative information on the effects of residual impurity elements on the reversible temper embrittlement susceptibility of Ni-Cr-Mo-V rotor steels. The statistical design of the experiment and statistical analysis of the data are described. The basic design was a supplemented ½ fraction of a 2 factorial to study the effects of P, Mo, Sn, As, and Sb, including 2-factor interactions among these elements.
Recent Trends in Underwater Soil Sampling Methods
Authors: Tirey GB
Published: March 2009

The recent trend in underwater soil sampling has been toward submersible, remote or diver operated equipment set on the seabed. Rotary and vibratory drills of these types are described.
A Static Cone Penetrometer for Ocean Sediments
Authors: Hirst TJ , Richards AF , Inderbitzen AL
Published: March 2009

A static cone penetrometer for deep ocean exploration has been developed and successfully tested in soft sea floor sediments at an ocean depth in excess of 1200 m. The penetration resistance of a standard 60-deg cone is detected by appropriately insulated strain gages whose output may be monitored remotely from the sensing unit. Initial deployment of the device was aboard the submersible Deep Quest in the San Diego Trough off the coast of southern California. Resistances as low as 7 N (1.6 lb) were measured near the surface of the sediment, generally increasing with depth. At the maximum depth of penetration of 1.1 m (restricted by the limited negative buoyancy of the submersible), tip resistance reached 80 N (18 lb). By means of a conventional bearing capacity analysis, the cone resistance was converted to in situ strength and compared to vane shear measurements taken in the immediate vicinity of the penetration tests. Reasonable agreement between vane shear and penetration strengths were obtained for an assumed bearing capacity factor No = 9.
Control for Underwater Construction
Authors: Johnson SJ , Compton JR , Ling SC
Published: March 2009

Activities and interests in offshore construction are reviewed as a basis for assessing experience in such work and appropriate construction control measures. Primary emphasis is placed on foundation engineering and soil mechanics aspects and to related construction considerations. Rapid, continued growth in underwater construction seems assured for projects in water depths varying from shallow, near-shore conditions to those at the limits of the continental shelf, or about 600 ft. Construction activities, including dredging, fill placement, tremie concrete placement, and pile-supported structures, present special problems in underwater construction. Such problems and corresponding construction control measures are reviewed for a variety of underwater conditions.
A Study of the Strength Characteristics of Marine Sediments Utilizing a Submersible
Authors: Inderbitzen AL , Simpson F
Published: March 2009

One of the tasks of the Lockheed Missiles and Space Company's submersible Deep Quest has been to obtain detailed information on the strength characteristics of the sea floor. Continuing projects, carried out with a corer and a vane shear machine mounted on the submersible, are a comparison of in-place and laboratory vane shear strength values and an investigation of the lateral and vertical variability of in-place shear strength. The area being investigated for these projects is approximately 13 nautical miles southwest of San Diego, Calif., on the floor of the San Diego Trough at a depth of 4050 ft.

Because the projects are still incomplete, no definitive conclusions can be made. However, initial results indicate inconsistencies in the difference between in-place and laboratory vane shear strength values. Lateral variability between in-place vane shear strength measurements does not appear to be related to distance between test locations. Vertical variability in in-place vane shear strength values appears to decrease with depth into the sediment.
Instrumenting RUM for in situ Subsea Soil Surveys
Authors: Anderson VC , Clinton JR , Gibson DK , Kirsten OH
Published: March 2009

The RUM (Remote Underwater Manipulator), one of the laboratory research vehicles of the Marine Physical Laboratory, is a tracked vehicle capable of operating on the sea floor to depths of more than 6000 ft. An umbilical coaxial strain cable connects it with a surface support platform ORB (Oceanographic Research Buoy) and provides the power and data transmission required for unmanned remote sea floor operations. A brief description of this sea floor work system is presented, whose main emphasis concerns the instrumentation suit developed for in situ soil trafficability studies with RUM. RUM has been instrumented for remote operation of a 2-ft-long 3-in.-diameter corer, a vane shear meter, a cone penetrometer, an anchor-winch-tensiometer combination for the measurement of drawbar pull, and a short range, high resolution echosounding profiler for examination of track depression. All of these instruments are adapted for use by the manipulator arm mounted on RUM, and all telemeter their data back to ORB via the coaxial strain cable. Results of initial measurements with the system are discussed.
Fatigue Testing of Asphaltic Concrete Slabs
Authors: Jimenez RA
Published: March 2009

This report is concerned with the description of devices for making and testing 18-in. diameter asphaltic concrete specimens for flexural fatigue characteristics. Additionally, data are presented to show effects of mixture variables on fatigue life of asphaltic concrete.
Fatigue of Asphalt Concrete Mixtures—Summary of Existing Information
Authors: Epps JA , Monismith CL
Published: March 2009

In order that considerations for fatigue distress of the asphalt concrete may be incorporated into pavement design procedures, it is necessary that definitive information on the fatigue behavior of asphalt concrete mixtures be determined. Data are presented based on a review of the literature as well as our research, which illustrate the effects of a number of mixture variables on fatigue response and include an indication of the influence of: mixture stiffness, air void content, aggregate gradation, aggregate type, asphalt content, and asphalt type.

A literature review indicates the variation of air void content, aggregate gradation, and asphalt content to be expected on typical construction projects. This information together with the fatigue data presented previously allows the engineer to assess the relative importance of these mixture variables on predicting the performance of pavements. Asphalt content and test temperature appear to be more critical than the variation associated with aggregate gradation, asphalt hardness, and air void content.
Analysis of Fatigue of Paving Mixtures From the Fracture Mechanics Viewpoint
Authors: Majidzadeh K , Kauffmann EM , Saraf CL
Published: March 2009

The paper discusses application of fracture mechanics to the analysis of fatigue characteristics of paving mixtures. A method of determination of crack growth parameters for asphaltic beams resting on elastic foundation is presented. The finite element method of analysis is used for the determination of stress intensity factors for various crack sizes. The effect of material characteristics, foundation modulus, and mode of loading on the crack growth process of asphaltic mixtures, is discussed. The effect of asphalt content, mixture density, and asphalt penetration on the Paris crack growth law is shown. It is also shown that fracture mechanics principles can be used to predict fatigue life of pavement material.
Pavement Design Method to Consider Fatigue of Asphalt Concrete
Authors: Kasianchuk DA
Published: March 2009

A design subsystem is presented which provides a framework in which the fatigue of asphalt concrete might be explicitly considered in the design of asphalt pavements. The operations included in the subsystem are outlined and discussed. The procedure is exemplified, first in a hypothetical situation, and then by instances of the use of the procedure in actual cases. Comment is made on the necessity for further field verification.
Fatigue Behavior: Field Observations and Analytical Predictions
Authors: Terrel RL
Published: March 2009

This paper evaluates and discusses the development of fatigue cracking in several test pavements and inservice pavements. Attention is focused on the cause and development of fatigue failure in the field. Examples are shown for several types of asphalt pavements including those with aggregate, asphalt treated, or cement treated base. Failure is described in terms of crack initiation through several possible mechanisms and crack propagation to the ultimate stage of alligator cracks. Discussion is presented as to the implications of fatigue failure with respect to design life. Computations and analysis show that a thick asphalt pavement may not resist complete fatigue failure any better than a pavement of the same thickness which was built in “stages,” if the overlay is applied before cracking occurs.
Effect of Geometric Characteristics of Aggregates on the Fatigue Response of Bituminous Paving Mixtures
Authors: Huang EY , Grisham DA
Published: March 2009

This paper presents the results of a laboratory study concerning the effects of the geometric characteristics of aggregates on the fatigue response of bituminous paving mixtures with both asphalt content and percentage of air voids constant. Three coarse aggregates and two fine aggregates, representing both natural and crushed materials were used. The geometric characteristics of these materials were determined by the particle index test for positive, quantitative identification.

The aggregate materials were combined to form three different gradations, and mixed with 6 percent (by weight) of an 85–100 penetration grade asphalt cement. The fatigue response of the various mixtures was determined by subjecting beam specimens to reversed bending at 3 constant stress amplitudes. The test program was designed according to the scheme of a factorial experiment and the data were analyzed in terms of the variances of the factors involved.

The results of the investigation show that the fatigue life of the mixtures increased with the value of the particle index of the fine aggregate. The effect of the fine aggregate was the same for all levels of the applied stress, within chance variation as measured by experimental error. The fatigue behavior of the mixtures tested was not significantly affected by the geometric characteristics of the coarse aggregate, nor was it affected by the gradation of the aggregates in these mixtures.
The J Integral as a Fracture Criterion
Authors: Begley JA , Landes JD
Published: March 2009

The path independent J integral, as formulated by Rice, can be viewed as a parameter which is an average measure of the crack tip elastic-plastic field. This together with the fact that J can be evaluated experimentally, makes a critical J value an attractive elastic-plastic fracture criterion. The JIc fracture criterion refers to crack initiation under plane strain conditions from essentially elastic to fully plastic behavior.

Experiments supporting the validity of a JIc fracture criterion are presented in this paper. Values of the J integral were determined experimentally for two steel alloys, one of low and the other of intermediate strength. A review is given of the analytic support for the JIc fracture criterion. The range of applicability of the JIc concept, its limitations, and its advantages are also discussed.
J Integral Estimation Procedures
Authors: Bucci RJ , Paris PC , Landes JD , Rice JR
Published: March 2009

By making use of plastically adjusted linear elastic fracture mechanics analysis and plastic limit load solutions, a method is developed for reasonable approximation of Rice's path independent J integral which is applicable for test specimens or other configurations which exhibit considerable plasticity prior to fracture. Employing this, J is expressed as a function of load point displacement. Estimations of the J versus displacement relationships developed compared quite well to those previously established experimentally at Westinghouse Research Laboratories for Ni-Cr-Mo-V and A533B steels. For these comparisons, the test specimen configurations considered were three point bend, center notch, and compact tension test specimen configurations, all of which exhibit significantly different plastic limit load slip line flow fields. Thus, the method developed for approximating J is thought to be widely applicable.
Fracture Toughness of Duplex Structures: Part I — Tough Fibers in a Brittle Matrix
Authors: Antolovich SD , Shete PM , Chanani GR
Published: March 2009

Tough maraging steel fibers were embedded in a relatively brittle maraging steel matrix by a special diffusion bonding and heat treating technique. Three indices of fracture toughness were computed. KIc as recommended by the ASTM, Komax, the fracture toughness based on the maximum load and initial crack length and Kimax, the fracture toughness based on the maximum load and instantaneous crack length. While KIc for the fibrous composite was no higher than KIc for the matrix material, both Komax and Kimax were significantly higher for the composite. Since fracture of the fibrous composites occurred in a stable manner (fast fracture was not observed) the load displacement records were converted into crack growth resistance curves. The R curves exhibited a serration at GIc, but continued to increase significantly above GIc and multiple serrations, apparently as a result of the fibers, were present. An approximate calculation shows that the increase in crack growth resistance cannot be attributed solely to plastic deformation of the fibers. Scanning electron microscopy revealed local decohesion between the fibers and the matrix and the character of the R curve was attributed to local crack front pinning by blunting or reduction in constraint. As a model of delamination in a fibrous structure, holes were drilled perpendicular to the parting plane in 7075-T6 aluminum specimens. The load versus displacement and R curves were similar to those observed in the fibrous composites. In addition, pinning of the fatigue crack was observed in the vicinity of the holes.
Relationship between Material Fracture Toughness using Fracture Mechanics and Transition Temperature Tests
Authors: Sailors RH , Corten HT
Published: March 2009

Although the effect of flaws in stressed bodies can be quantitatively characterized by methods of linear elastic fracture mechanics (LEFM), it is sometimes necessary to assess the fracture susceptibility using only conventional transition temperature tests. In order to gain the advantages and best features of each approach, a correlation between the two methods of fracture assessment is needed. The existing correlations between LEFM results and transition temperature test results are reviewed in light of new data on A533B steel. A complete series of test results obtained by the HSST Program (ORNL) for both LEFM and transition temperature tests in both unirradiated and irradiated conditions permit fracture toughness, KIc and KId, to be correlated with charpy V-notch energy, nil-ductility transition temperature, DT transition temperature, and low temperature cleavage stress. By following fundamentals of LEFM, whenever possible, a consistent pattern of fracture behavior is demonstrated for a class of pressure vessel steels similar to A533B.
Removal of Radiotagged Fatty Soil From A Glass Surface
Authors: Harris JC , Anderson RM
Published: March 2009

Comparative detergency values for removal of radiotagged tristearin from glass are given for several surfactant materials, illustrating the applicability of the radiotracer procedure to routine laboratory detergency evaluation.
Calcium-45-Tagged Clay as Detergency Test Soil
Authors: Hensley JW , Inks CG
Published: March 2009

Lack of progress in reaching any general agreement on standard laboratory tests for laundry detergency performance may be related to the general use of carbon blacks as standard soils and limitations on measurement methods. Availability of radioisotopes and sensitive methods of measurement facilitate investigations with other soil materials more similar to those encountered in practice.

Some investigations have been carried out with a test soil consisting of calcium-45-tagged clay dispersed in lubricating oil and applied to cotton swatches. This soil has been employed in a miniature laboratory wash apparatus to evaluate soil removal and redeposition properties of detergents. Data are given on precision of the test method and effects on evaluations of certain test variables. Employing various detergent compositions as well as commercial laundry products, comparisons have been made between evaluations with the oily tagged clay and a conventional carbon black soil. Pronounced contradictions were found in relative evaluations with the two methods, particularly with regard to the effect of alkalies as builders, the effectiveness of unbuilt nonionic surfactant, and the action of NaCMC in promoting whiteness retention of a built anionic surfactant. Evaluations with the tagged clay soil appear to be in better general accord with practical observations than those with carbon black soil.
Measurement of Moisture and Density in Soils by the Nuclear Method
Authors: Kuranz JL
Published: March 2009

A nuclear method for the measurement of moisture and wet density in soils is described in this paper. The method can be used for either absolute or relative determinations.
Tracer Techniques for Thickness of Very Thin Vacuum-Evaporated Metal Films
Authors: Preuss LE
Published: March 2009

The vacuum evaporation process has attained importance in the field of optical coatings, sensitization methods, printed circuitry, and similar applications. Some problems exist in the determination of condensed metal film thickness, evaporant spatial dispersion, condensand profiles, and composition. A number of assay methods, such as the microbalance system, light absorption, beta scatter, and others, may be used for measurement of condensed films which vary in thickness from less than the mono-layer to over several hundred Ångstroms. Conventional methods are not sufficiently sensitive for exceedingly thin films, but the direct tracer scheme with the tagged radioactive metal charge exhibits an experimental reach sufficient to assay even the most tenuous sensitization layers.

Determinations of dispersion patterns, condensand surface concentration, condensand profile and uniformity, binary evaporant assay, trace contaminations, and alloying may be made by the tracer scheme. Techniques and the advantages and disadvantages of the method are discussed.

This paper will be concerned exclusively with the determination of surface concentrations of the more tenuous thin films-those metal layers which fall about, or below, 100 Å in thickness. Although the technique is also applicable to films of thicknesses greater than 100 Å, the thicker condensates are accurately measurable by sundry well-established systems (1,2).2 Discussion of the direct tracer scheme will be here limited principally to those films below the 100-Å region and, in particular, to its application to the condensand at the mono-layer and even below. It is in this range that the direct tracer technique may have some useful application which will supplement and compete efficiently with the various other methods for assay of thin layers.

The method will be described principally in connection with metallic layers condensed from the evaporant produced by the vacuum distillation of certain metal charges, although the direct system is not inapplicable to other tagged layers. It is safe to predict that as the direct system of test is pursued, the distilland condensate assay will become a minor application of this test mechanism.

The incorporation of the tagged element into a film to determine surface concentration is not a unique idea (3). This, in essence, could be done each time a dry planchet is assayed. Nevertheless, the method has a distinct applicability to the vacuum distillation phenomena and to the very thin condensands associated with the evaporation of metal charge.
Permeability Tests for Organic Sheet Materials
Authors: Pobereskin M
Published: March 2009

The permeability of sheet materials to gases and vapors is a property that is the basis for many of their modern applications. Plastic films and plastic-coated papers, for example, are used extensively in packaging of perishable foods because of their relative imperviousness to air and moisture. The permeability of plastic and rubber sheet materials to air and other gases affects also their use in balloons. By the same token, permeability of rubber to air is a factor in its use in tire tubes. Other applications of interest are related to the permeability of rubber and other elastomers to volatile liquids and the transmission of water vapor through protective coatings. In the latter case, the protective coatings may serve to maintain the electrical properties of wires, cables, and appliances, or to retard corrosion in the substrate material.
Early History of Fire Endurance Testing in The United States
Authors: Shoub H
Published: March 2009

Testing of building structures for their endurance in fire, necessitated by the rise of skeleton-type construction, was started in the last years of the nineteenth century. But before this, there was an effort to provide fire resistant buildings by the use of noncombustible materials such as masonry walls, and iron columns, girders, and beams. A particular problem, and the basis of many early tests, was the design of floors. The need for a fire-resistive covering for the protection of the iron—and later steel—columns also became apparent. To inpede the horizontal spread of fires, resistive partition constructions were developed. In addition to presenting a review of some of the early tests for fire endurance of these structures and a few concurrent tests of building materials, the paper describes the establishment of ASTM standards for such tests, under the cognizance of what is at present Committee E-5.
A Treatise on Theoretical Fire Endurance Rating
Authors: Harmathy TZ
Published: March 2009

For most building materials, the enthalpy-temperature relationship is not linear but contains steep sections at places where latent heat is absorbed as a result of desorption of moisture, dehydration, dissociation, or transformation. Partly associated with these physicochemical changes, and partly independent of them, the thermal conductivity also undergoes considerable variation. These are the main reasons why the usual assumptions are not valid when the heat flow through building elements during fire exposure is to be calculated. A numerical method is described which can be used successfully for solving one-dimensional transient heat flow problems of any complexity. The application of this method to the calculation of temperature history of building elements during fire exposure is illustrated through some examples. In cases where the building element is not subject to thermal disintegration or collapse the numerical heat flow analysis will yield the fire endurance of the building element. In other cases the heat flow analysis must be coupled with a numerical stress-deformation analysis.
Surface Flammability of Materials: A Survey of Test Methods and Comparison of Results
Authors: Wilson JA
Published: March 2009

The fire hazard or surface flammability of materials is a matter of major interest to many public and private agencies. Although not a newly discovered phenomenon, most efforts to evaluate this property of materials quantitatively have taken place only in the past 25 years. These efforts have been uncoordinated, a considerable number of methods developed having little relation to one another or to actual fire conditions.
Factors Affecting Bond Strength and Resistance to Moisture Penetration of Brick Masonry
Authors: Ritchie T , Davison JT
Published: March 2009

Small panels of brick masonry have been used to study the resistance to moisture penetration and the strength of bond of brickwork in relation to several factors. Results of tests are presented to show the influence of properties of bricks and mortars on leakage and bond strength. Information is presented on the effects of several other factors that are governed by the technique used by the bricklayer in constructing masonry. These factors include the consistency of the mortar when used, the time interval between spreading a mortar bed and laying a brick in it, and the extent to which a brick is tapped into the mortar. The effects of tooling ol mortar joints and varying the thickness of mortar joints are also considered.
Actions of Calcium Sulfate and Admixtures in Portland Cement Pastes
Authors: Hansen WC
Published: March 2009

This paper presents a mechanism to explain the ability of Ca(OH)2 and CaSO4 to prevent flash set in portland cement pastes and the ability of CaSO4 and other salts to accelerate the rates at which calcium silicates develop strengths. The mechanism is developed on the basis of solid state reactions in which ions from the liquid phase of a cement paste are chemisorbed by ions in the surfaces of the crystals of the cement minerals and then diffuse into the crystals to produce the reaction products responsible for the setting and hardening of the cement paste. The abilities of organic compounds to retard the rates of these reactions, cause dispersion of the particles, reduce water requirements, and act as grinding aids are explained in terms of adsorbton of molecules and negative ions.
Observations in Testing and Use of Water-Reducing Retarders
Authors: Tuthill LH , Adams RF , Hemme JM
Published: March 2009

Continuing work in both laboratory and field with water-reducing and set-retarding admixtures has resulted in further helpful knowledge concerning them and has added to confidence in their use on the job. Significant benefits are obtained with these admixtures in job concrete, particularly in warm weather. Through postponement of the vibration limit, cold joints are less a hazard.

Reduction in water requirement to a large extent offsets normal increases in water due to warm weather, and due to higher slumps whatever their cause. At two days and later ages, strength is increased when the dosage is not above normal. At various ages beyond the first few days, the higher strengths achieved are greater than can be ascribed to reduction in water-cement ratio. Fear of the sugar content of the admixtures is apparently unfounded; troublesome delay in hardening is more likely to be the result of gross overdosage from malfunction of a dispenser. Hence dispensing equipment must be completely reliable and its performance readily verified for each batch. Such equipment is described.

Performance of the admixtures usually varies with concrete temperature and somewhat with various cements. Expected performance should be verified in advance using job materials. Dosages and sometimes the admixture must be changed accordingly, based on such test results and job performance.

The paper discusses these matters with related test data. It also discusses practical aspects of specifications, delivery, and acceptance testing when these are appropriate.
Detection of Lignosulfonate Retarder in Cement Suspensions and Pastes
Authors: Swenson EG , Thorvaldson T
Published: March 2009

The problem of detecting the presence of the lignosullonate type of retarder or plasticizer in hardened cement paste is investigated by a spectrophotometric method based on ultraviolet absorbance measurements of aqueous extracts. The interaction of hydrating portland cement and lignosulfonate salt, whether in water suspension or in hardened paste, results in the disappearance of the characteristic 280 mμ maximum of the original lignosulfonate and the appearance of two new maxima at wavelengths of 245 and 350 mμ. This change is attributed to alkaline hydrolysis, with the formation of vanillin. The experimental results are discussed in relation to the qualitative and quantitative aspects of the method in detecting lignosulfonates in portland-cement products.
Introduction to Producers' Papers on Water-Reducing Admixtures and Set-Retarding Admixtures for Concrete
Authors: Prior ME , Adams AB
Published: March 2009

Water-reducing admixtures and set-retarding admixtures are defined and the functional difference between them explained. The products of the four producers are divided into four chemical classifications, (1) lignosulfonic acids and their salts; (2) modifications and derivatives of lignosulfonic acids and their salts; (3) hydroxylated carboxylic acids and their salts; (4) modifications and derivatives of hydroxylated carboxylic acids and their salts. The four papers of the producers' group are concerned only with products falling within this classification.

A brief explanation of the function and mechanism of the actions of such admixtures in portland-cement concrete is suggested and discussed as it applies to this series of papers

The final section of this paper points out the significance of the design and quality control exercised by the producers to insure the functional performance of these admixtures. Particular emphasis is placed on this portion of tin-paper because of its importance to the consumer.
Effect of Water-Reducing Admixtures and Set-Retarding Admixtures on the Properties of Plastic Concrete
Authors: Vollck CA
Published: March 2009

Commonly used water reducers and set retarders are divided into four basic categories. The effect of materials from each of these classes on water reduc-tion, set retardation, air entrainment, bleeding, workability and unit weight of plastic concrete is discussed.

Data are presented to show the effect of normal dosage and over-dosage of the admixtures at various temperatures. Influence of type and brand of cement, air entraining agents, and other admixtures on properties of plastic concrete is shown.

Application and dosage of the admixtures are given. Qualities of plastic concrete containing water reducers or set retarders that may be used to the advantage of the engineer who is seeking to solve a particular problem in the con-struction of a project are discussed.
Water-Reducing Admixtures and Set-Retarding Ad-Mixtures for Concrete: Uses; Specifications; Research Objectives
Authors: Mielenz RC
Published: March 2009

When properly selected and proportioned, water-reducing admixtures and set-retarding admixtures (1) permit control of certain properties of fresh or hardened concrete, (2) aid in producing concrete meeting requirements of specifications when plain air-entrained concrete will not meet these requirements, (3) decrease costs of concrete and of concreting operations, and (4) permit use of design and construction practices not otherwise feasible.

Water-reducing admixtures and set-retarding admixtures should be purchased under specifications which assure uniformity, development in concrete of satisfactory qualities for the intended use, and freedom from deleterious qualities which may adversely affect significant properties of the concrete.

Major producers of these admixtures are engaged actively in basic and developmental research to improve their performance and expand their application.
Summary
Authors: Foster B
Published: March 2009

This closing paper is a summary of the main points brought out in the symposium.
The Radiochemical Determination of Uranium Burnup
Authors: Sunderman DN
Published: March 2009

A uranium burnup analysis is one which determines the extent to which fissile material has been consumed during a period of residence in a flux of neutrons. Other fissile materials may be encountered but this paper will deal exclusively with uranium-235.
Reactor Monitoring by Calorimetry
Authors: Hall KL , Klaver RF , Carroll JG , Bolt RO
Published: March 2009

Experience with monitoring mixed radiation fields in nuclear reactors is described. Dose rates were measured by the radiation-produced heat in simple calorimeters constructed for this purpose. Principles of construction are reviewed for two types of instruments. Accuracies of about 10 per cent are estimated.

One type of calorimeter measured the total reactor radiation. This device embodied a graphite radiation absorber suspended within a hollow cylinder. Heat flowed radially to the wall of the cylinder. Four units of this type were operated in the Materials Testing Reactor.

The other type of instrument measured only the gamma portion of the reactor radiation. Neutron sensitivity was minimized by using lead as the absorber. Heat flowed axially along the lead rod to a heat sink. Three versions were built in evolving the final model which was used to determine gamma heat in the Brookhaven graphite reactor.
Dosimetry Nomenclature in the United States
Authors: Tschaeche AN
Published: March 2009

The purpose of this paper is to present briefly the history of dosimetry, to describe the work done in the field of dosimetric systems and nomenclature by five national and one international committee, to present the current nomenclature attendant to material dosimetry, and to point out some of the current problems in the field.

The terms discussed are: absorbed dose, dosimetry, carbon dose, cadmium ratio, exposure dose, and neutron energy ranges. A new definition is suggested for absorbed dose. The concept of reference dose is discussed and defined.

The national committees concerned with nuclear technology are: (1) Aircraft Nuclear Propulsion Advisory Committee for Nuclear Measurements and Standards, (2) the National Research Council's Subcommittee on High Level Dosimetry, (3) the ASTM Joint Subcommittee, of Committees D-9 and D-20, on Radiation Effects to Plastics and Electrical Insulating Materials, (4) the ASTM Task Groups on Dosimetry, of Committee E-10 on Radioisotopes and Radiation Effects, (5) the Nuclear Standards Board's Subcommittee on Nuclear Terms, and (6) the International Commission on Radiological Units and Measurements.

The conclusions derived from the discussion of the current state of material dosimetry nomenclature are that confusion exists in the field but that the nature of the confusion is recognized and work is being done to remedy the situation by establishing generally accepted nomenclature and methods for material dosimetry.
Dosimetry in Europe and the USSR
Authors: Guill JH , Moteff J
Published: March 2009

When high-energy radiation is used to produce a change in matter—whether a physical change, as in the testing of materials for use in reactors, a chemical change, as in the polymerization of plastics, or a biological change, as in the treatment of cancer —the radiation must be measured and controlled (1). The measurement of radiation in situations such as these constitute the subject of radiation dosimetry.
Effects of Gamma Radiation on Some Electrical Properties of TFE-Fluorocarbon Plastics
Authors: Loy WE
Published: March 2009

The investigation reported herein included the measurements of several dielectric properties of TFE-fluorocarbon (Teflon) plastics before, during, and after gamma irradiation by a cobalt-60 source.

Postirradiation measurements of dielectric constant of 32- and 125-mil specimens, irradiated to a dose of 5.7 × 10 7 r, indicated no change from the preirradiation values. Dielectric strengths of 3-, 5-, and 11-mil specimens, irradiated to a dose of 5.7 × 10 7 r, did not change significantly from the preirradiation values.

Volume resistivity of specimens irradiated at dose rates ranging from 3 × 10- 2 r per hr to 1.85 × 10 5 r per hr decreased very rapidly during irradiation. After approximately 20 hr resistivity reached a constant value which was at least a factor of 10 3 below the preirradiation value. Results indicate that the resistivity during irradiation is an inverse function of dose rate and specimen thickness.

After the removal of -4- and 8-mil specimens from the irradiation field, resistivity increased steadily toward the preirradiation value. The postirradiation resistivity of 250-mil specimens increased exponentially for approximately 8 hr after which a gradual decrease was observed for several hundred hours. Post irradiation values of resistivity indicate a dependence on the dose to which a specimen was irradiated.
Atomistic Interpretation of Radiation Effects in Metals
Authors: Sosin A
Published: March 2009

The present status of atomistic interpretations of radiation damage in metals is reviewed. Detailed consideration is si given to radiation effects and associated lattice delect phenomena in copper, since copper has received the most extensive experimental and theoretical study. The various mechanisms of defect production are presented and models lor point delect recovery are considered. The case ol radiation hardening is then concluded to he principally due to more extended radiation-induced defects such as displacement spikes. Finally a particular radiation damage problem, fuel swelling, is discussed with emphasis on its lattice defect implications.
Radiation Effects in Steel
Authors: Porter LF
Published: March 2009

As early as 1942 it was recognized that high-energy neutrons would have the ability to disrupt the crystal lattice of metals through which they might pass and that this disruption might lead to serious changes in the mechanical and physical properties of structural materials used in the construction of nuclear reactors. Since that time studies of these “radiation effects” have been conducted by solid stale physicists and by reactor development engineers working at or in conjunction with the various atomic energy installations. This paper is a survey of the published literature on the effect of neutron radiation on the mechanical properties of steels.

On theoretical grounds and on the basis of fundamental experiments it is postulaled that clusters of radiation-produced vacancies or interstitials, by interacting with dislocations already present and additional dislocations produced during plastic deformation, are primarily responsible for the increased strength and decreased ductility of irradiated metals.

From a tabulation of the existing information on the effect of neutron radiation on the mechanical properties of carbon, alloy, and stainless steels, it appears that relationships between the changes in properties and neulron exposure can be defined. These relationships indicate that steels behave in general as a class of material and are affected by neutron radiation in a similar manner so that the effects of a given neutron exposure can usually be predicted within rallier general limits.

Normally, a large proportion of the radiation-produced crystal lattice defects responsible for the changes in mechanical properties in steels can be removed by heating in the range 550 to 900 F. Likewise, irradiation at temperatures above 500 F usually results in less damage than irradiation at lower temperatures, presumably because of concurrent thermal annealing of the damaged regions. Under certain conditions, radiation may accelerate phase transformation or aging phenomena, and changes in mechanical properties as a result of such secondary effects may not be removed by the annealing treatments at 550 to 900 F.

It is important to recognize that the above generalizations are based on results which show considerable scatter and that there is information available which indicates that such factors as grain size, microstructure, composition, and steel cleanliness can influence the magnitude of the radiation effect.
Postirradiation Oxidation and Molecular Weight Changes in Polystyrene and Poly(Methyl Methacrylate)
Authors: Parkinson WW , Binder D
Published: March 2009

The presence of reactive species in solid polymers after irradiation has been demonstrated over the past several years by various experimental techniques. Several investigations have shown that irradiated polymers have the ability to initiate polymerization in common monomers. Wall and Brown (1) supplemented such findings on poly(methyl methacrylate) by measuring the depolymerization produced by heating irradiated specimens of this material.
Postirradiation Dielectric Properties of Silicones
Authors: Currin CG
Published: March 2009

Reliable electrical insulating materials are essential for the generation, transmission, and utilization of electrical energy. Considerable effort is devoted to the development of new insulating materials which will perform at the high temperatures and under the other extreme environmental conditions now encountered, including nuclear radiation.
Postirradiation Effects: Monomers and Polymers
Authors: Degering EF , Caldarella GJ , Mancini M
Published: March 2009

During August of 1955 while preparing some samples for an irradiation exhibit some post irradiation effects were observed. A 1:1 mixture of acrylonitrile and styrene and of methacrylic acid and styrene were placed in 6 by 12 in. 3-mil polyester film bags, the air bubbles removed, the bags heat sealed, and the contents irradiated to a slightly viscous consistency. The bags were then placed on a peg board in a room with northern exposure for a few weeks; following this exposure it was observed that the mixture had changed from a slightly viscous consistency to a firm, solid mass. Inasmuch as the dilfusion of the monomer through the plastic film had been previously determined to be very low, it was inferred that postirradiation effects had completed the polymerization.
Determination of Radioactive Materials in Water
Authors: Barker FB
Published: March 2009

The U. S. Geological Survey has adopted methods for measuring the concentrations of certain radioactive materials in water. The methods described are useful in hydrogeochemical studies and for determining the conformance of potable water with health standards.

Gross concentrations of alpha- and beta-emitting nuclides are determined by measuring with a suitable counter the activity of the residue left upon evaporation. Sensitivities of about 1 micromicrocurie per 100 mg of solids for the determination of alpha activity and of 1 to 5 micromicrocuries per 100 mg of solids for the determination of beta activity may be obtained. Radium is determined by either of two carrier-precipitation methods depending upon the accuracy desired or the necessity for measuring concentrations of individual radium isotopes. The sensitivities vary from 0.1 to 1.0 micromicrocurie per liter depending upon calcium concentration. Radiostrontium is determined by a multiple precipitation method having a sensitivity of about 1 micromicrocurie per liter. Uranium is determined to 0.1 ppb by a fluorometnc procedure.
Dry Pressing Ceramic Fuel Elements to Close Tolerances
Authors: Hartwig FJ
Published: March 2009

Methods are presented for improving tolerances on dry-pressed ceramic fuel pellets for nuclear reactors. The basic principles of close control and the equation relating green and fired densities to dimensions are explained. A prediction is made of fired diameter based on green diameter and density with corrections for differential diameter to length shrinkage, volatile material losses, and other factors, and is compared with experimental results. The agreement is good, and it is concluded that close tolerances are possible with care in measurements and fabrication.
Silicon Carbide Clad Graphite Matrix Fuel Elements
Authors: Taylor KM , McMurtry CH
Published: March 2009

A spherical graphite matrix element fueled with uranium dicarbide and clad with an impermeable layer of silicon carbide is described for use in pebble bed gas-cooled reactors. The following topics are discussed: fabrication techniques, cladding permeability tests, oxidation resistance, carbon density, crushing strength, impact resistance, fuel distribution, self-welding characteristics, and resistance to thermal cycling.
Graphite as a Fuel Matrix
Authors: Riley WC
Published: March 2009

Recent work on fabrication development, laboratory evaluation, and reactor evaluation of fueled graphite is reviewed.

Methods of preparing fueled graphites are discussed with respect to possible differences in reactor perlonnance and processing costs. Geometries and fuel loadings that have been achieved are mentioned. Data are given on variation in physical properties with fuel content.

The experimental evidence presented indicates that neutron plus fission fragment irradiation at temperatures of about 1300 F tends to cause the matrix structure to change from graphite to disordered carbon.

With respect to dimensional distortion, the individual effects of fission fragment and neutron irradiation at about 1300 F have been separated. Each appears to cause contraction. A relationship between dimensional distortion and the number ol fission fragments attenuated in the matrix is suggested.

Fission product release from a number of types of fueled graphites are reported. Results of both laboratory heat-treatment studies following low-temperature, low-exposure irradiation and high-temperature in-pile studies indicated that the release of fission gases was the order of at least 1 per cent of those calculated to be present.

Methods for improving fission product retention are discussed. The experimental evidence presented indicates that surlace coatings, impervious graphite, and impervious cladding for fuel particles have some potential.

Available data on chemical reactions between fuel compounds and the graphite matrix are discussed briefly.

Recommendations for future developmental work are included. Emphasis should be placed on improved fission product retention and studies of radiation effects at high exposures.