bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Ultrasonic Fatigue Testing Techniques to the Evaluation of the Corrosion-Fatigue Strength of Materials
Authors: Roth LD , Willertz LE
Published: December 2008

A corrosion fatigue testing system has been developed for examining the corrosion-fatigue strength of engineering materials in the very high cycle regime (109 to 1010 cycles) typical of many design lifetimes. Central to this resonant fatigue testing system is a high efficiency, large displacement, piezoelectric transducer which operates at a frequency of 20 kHz, thus enabling the accumulation of large numbers of cycles in a reasonable amount of time. A description of apparatus, environmental controls, and testing method is presented. Experimental 20 kHz and low frequency corrosion fatigue results for a number of engineering materials, including a 12% chromium stainless steel, show similar reductions in fatigue limit at a specified number of cycles, despite the difference in frequency. This result holds for a variety of aqueous environments with and without electrochemical controls imposed during testing. The data illustrate the capabilities of the ultrasonic corrosion-fatigue technique and are analyzed to assess its advantages and limitations.
Corrosion Fatigue of 7000 Series Aluminum Alloys
Authors: Henry Holroyd NJ , Hardie D
Published: December 2008

Results of fatigue testing of 7017-T651 aluminum alloy in seawater at frequencies from 0.1 to 70 Hz have been assessed in relation to the stress corrosion behavior of this material. In particular, the applicability of a simple superposition model is examined. Detailed fractographic examination indicates a dependence of fracture mode upon both crack growth rate and frequency that is consistent with a dependence upon the rate of diffusion of hydrogen in the material. Despite this, it seems that some other process provides the rate-determining step in the cracking. Various possibilities are considered.
New Solvent Extraction Process for Zirconium and Hafnium
Authors: Takahashi M , Miyazaki H , Katoh Y
Published: December 2008

The authors' company developed a new solvent extraction process for zirconium and hafnium separation, and started production of zirconium sponge by this new process in September 1979.

The process utilizes selective extraction of zirconium oxysulfate using high-molecular alkyl amine, and has the following advantages:

1. This extraction system has a separation factor as high as 10 to 20 for zirconium and hafnium in the range of suitable acid concentration.

2. In the scrubbing section, removal of all the hafnium that coexists with zirconium in the organic solvent can be effectively accomplished by using scrubbing solution containing hafnium-free zirconium sulfate. Consequently, hafnium in the zirconium sponge obtained is reduced to less than 50 ppm.

3. The extractant undergoes no chemical changes but is very stable for a long period. In particular, its solubility in water is small, about 20 ppm maximum, posing no environmental pollution problems such as are often caused by other process raffinates.

At the present time, the zirconium and hafnium separation operation is very stable, and zirconium sponge made by this process can be applied satisfactorily to nuclear reactors.
Electron-Beam Remelting of Zircaloys
Authors: Mitchell A , Brown R
Published: December 2008

We have constructed and operated an electron-beam (EB) melting furnace using a 15-kW von Ardenne electron gun. The evaporation of tin from metling Zircaloys and the dissolution of nitride inclusions in melting Zircaloys have been studied.

We conclude that Zircaloys can be melted successfully in a 500-mm ingot diameter EB furnace at melting rates between 200 and 500 kg/h without special composition precautions with respect to tin. This configuration will also dissolve zirconium nitride precipitates successfully.
In-Reactor Creep of Zr-2.5Nb
Authors: Causey AR , Holt RA , MacEwen SR
Published: December 2008

The anisotropy of irradiation creep of Zr-2.5Nb alloy tubes at 570 K has been investigated using creep of helical springs and stress relaxation of twisted rods and bent beams. These tests measure creep rate directly since strains associated with irradiation growth are absent. Creep rates from these tests and from results on creep of pressurized tubes reported in the literature can be correlated through consideration of the crystallographic texture, slip systems, and dislocation density of the Zr-2.5Nb tubing. A creep model based on glide of 1∕3〈11¯20〉 type dislocations on prismatic planes in combination with secondary glide of 1∕3〈11¯22〉 dislocations on {10¯11} pyramidal planes provides a consistent correlation. The creep rate is only slightly dependent on dislocation density as measured by X-ray diffraction.
Influence of Metallurgical Condition on the In-Reactor Dimensional Changes of Zircaloy Fuel Rods
Authors: Garde AM , Smerd PG , Garzarolli F , Manzel R
Published: December 2008

Microstructure strongly affects the in-reactor creep and growth behavior of Zircaloy. The observed influence of microstructure on the in-reactor creep behavior can be opposite to that found ex-reactor. Fully annealed Zircaloy exhibits less in-reactor growth strains than stress-relief-annealed Zircaloy.

Two approaches to estimate the effect of microstructural variation on the in-reactor creep and growth behavior are discussed. These evaluations are based on diametral and axial strain data, for exposures of up to 8 × 1021 neutrons/cm2 (E > 0.82 MeV), obtained from tests conducted in the Obrigheim reactor (Germany) and in Calvert Cliffs I (United States). In the former tests the Zircaloy-4 cladding was manufactured by several vendors using different combinations of degree of cold work and final heat treatment while in the latter tests cladding of one type was used. All irradiated cladding had similar crystallographic textures.

The metallurgical condition of Zircaloy tubing is controlled in part by the degree of cold work prior to the final annealing treatment and by the annealing conditions. In one approach, the net effect of annealing time and temperature is empirically defined in terms of a “normalized annealing time.” A nonlinear relationship was obtained between the “normalized annealing time” and the in-reactor diametral and axial strains.

The other approach involves using the high-temperature yield strength as an effective reflection of the microstructure. The high-temperature yield strength of Zircaloy is routinely included in the Zircaloy tubing manufacturer's certifications and can be easily measured. There is a semilogarithmic relationship between the in-reactor diametral strain and the hot (673 K) yield strength of Zircaloy. The model is also useful in estimating the diametral strain variation within a lot if the within-lot yield strength variability is known. A similar correlation was obtained between the axial strain and the unirradiated yield strength. Although based on data from fuel rods of one design, the correlations are expected to be qualitatively applicable to fuel rods of different designs. Relationships between these empirical correlations and creep and growth mechanisms are discussed.
Irradiation Growth of Annealed Zircaloy-2
Authors: Williams J , Darby EC , Minty DCC
Published: December 2008

The irradiation growth behavior of annealed polycrystalline Zircaloy-2 has been investigated in the DIDO reactor at Harwell at fluences up to 1 × 1025 neutrons (n)m−2 (E > 1 MeV) and in the temperature range 513 to 673 K. Growth strain data for two batches of rolled, annealed Zircaloy plate did not obey the G ∝ (1 − 3f) texture relationship with transverse direction specimens (f = 0.25 and f = 0.35) exhibiting negative growth following an initial positive transient. The effect of irradiation temperature on growth was not marked over the range studied except that, at 673 K, growth strains appeared to saturate at low fluences. Apart from this, longitudinal and transverse growth strains decreased slightly with increasing temperature above 573 K. Specimens of large grained, β-annealed Zircaloy with a completely random structure showed virtually no sensitivity of growth to either fluence or temperature under the conditions studied. The apparently anomalous growth behavior of the transverse annealed plate materials cannot be explained by the influence of density changes during growth. It is proposed that the deviation from the expected growth-texture relationship is due to the effects of intergranular stresses which occur as a result of, and in opposition to, irradiation growth in polycrystalline materials.
Irradiation Growth of Zircaloy (LWBR Development Program)
Authors: Willard HJ
Published: December 2008

Irradiation growth of recrystallized annealed (RXA) Zircaloy is divided into four stages and a model is presented to account for each stage. Stage I is a short-time, low-strain transient caused by the accumulation of point defects, small interstitial loops, and vacancy clusters. Stage II is a quasi-steady-state region of relatively low strain rate during which the loops grow and intrinsic dislocations climb. Stage III is a transient during which the strain rate increases due to the production and motion of irradiation-induced dislocation lines. Stage IV is a high-strain-rate, steady-state region during which nonrecoverable strain is caused predominantly by glide of the irradiation-induced dislocations.

The proposed model is based on two new mechanisms: (1) direct production of an interstitial dislocation loop accompanied by a vacancy cluster in the primary damage event, and (2) production of dislocations due to the activation of Frank-Read sources by internal stresses caused by interaction of the loops with themselves and with intrinsic (cold work) dislocations. Nonconservative, recoverable strain is due to climb of all dislocations, whereas conservative, nonrecoverable strain is caused by glide of irradiation-induced and intrinsic dislocations under the action of the internal stress. The conservative strain follows a (1–3f) texture dependence.

The model provides a reasonable representation of growth behavior of longitudinally oriented RXA Zircaloy, the effect of texture and cold work on growth, and the temperature dependence of growth. Equations used to represent the model were solved in their transient forms at each time step of irradiation histories which permitted variations in flux and temperature. Calculations revealed that a nonlinear flux dependence can exist in growth behavior under various conditions of temperature and material structure and that this dependence can change as the irradiation history accumulates. Thus, the current practice of using fluence as the independent variable in data analysis and model development is questionable. The results of using the model to examine recent data obtained in the Experimental Breeder Reactor II at high temperatures and fast fluxes suggest that growth under these conditions is strongly sensitive to variations in flux and rather weakly dependent upon temperature.
Characterization of ZrO2 Films Formed In-Reactor and Ex-Reactor to Study the Factors Contributing to the In-Reactor Waterside Corrosion of Zircaloy
Authors: Stehle H , Garzarolli F , Garde AM , Smerd PG
Published: December 2008

An examination has been conducted of irradiated oxides which were formed during the waterside corrosion of Zircaloy-clad fuel rods operating in several pressurized-water reactors (PWR's), in order to understand the corrosion behavior. The structural integrity of the oxide layer was found to be excellent. The thermal conductivity remained high for oxides up to 70 μm thick.

Scanning electron microscope (SEM) examinations revealed that the bulk of the oxide had a spherical, granular microstructure providing for interconnected porosity, mainly at the triple points. With the exception of the steam autoclaved specimens, a thin inner layer was detected close to the metal substrate; this inner layer had a microstructure which was difficult to resolve with the SEM. The in-reactor corrosion enhancement was greater for oxides which had a more pronounced granular appearance at the metal-oxide interface.

Post-irradiation corrosion testing in autoclaves indicated a pronounced memory effect only for those specimens which previously had a high in-reactor enhancement.

The analyses of potential impurities in the oxide gave no indication of a significant enrichment of any chemical species from the primary coolant water.

The modest in-reactor corrosion enhancement observed in the PWR environment may be partly due to irradiation accelerated recrystallization of the oxide, especially at the inner layer, and partly due to changes in the corrosive medium present in the porous outer section of the oxide.
Improved Characterization of Aqueous Corrosion Kinetics of Zircaloy-4
Authors: Peters HR
Published: December 2008

In the analysis of the post-transition corrosion regime of Zircaloys in a water environment it has typically been assumed that the cycles occurring after the first cycle (pretransition) could be approximated by a constant rate. Recently, a long-term testing of Zircaloy-4 has shown this assumption to be nonconservative. Post-transition rates are seen to increase with increasing weight gain or time until a steady-state post-transition rate is achieved. The corrosion of Zircaloy-4 in a water environment is, therefore, now seen to have a transitory regime in addition to the pretransition and steady-state post-transition regimes. The mathematical description of this transitory regime is shown to fit the following: corrosion rate, R = A · ΔW + B, which results in a general equation for weight gain during the transitory regime of ΔW = (B/A) · (eAt - 1). This formulation provides a more accurate description of long-term Zircaloy-4 corrosion for use in engineering design than assuming post-transition kinetics based on a linear fit to the cyclic regime following the first cycle.
Modeling of Zircaloy Stress-Corrosion Cracking: Texture Effects and Dry Storage Spent Fuel Behavior
Authors: Tasooji A , Einziger RE , Miller AK
Published: December 2008

A phenomenological model has been developed for predicting iodine-induced stress-corrosion crack (SCC) initiation and growth in Zircaloy cladding. This model is capable of predicting various observed behaviors related to SCC.

A recently developed submodel for predicting the effect of texture on SCC has been incorporated into the original stress-corrosion crack initiation and growth (SCCIG) model. It utilizes basal pole figure data. This allows predictions of a number of observed phenomena on the effect of texture on SCC. In the process the model helps to explain why texture has different apparent effects on Zircaloy SCC depending on the test conditions.

The SCCIG model can also be used for predicting cladding SCC behavior under dry storage conditions. In this study the model has been used to predict the cladding SCC limiting temperature (SLT) for several specific fuel rod conditions.
Cracking Zirconium Alloys in Hydrogen
Authors: Coleman CE , Cox B
Published: December 2008

We have loaded precracked double-cantilever-beam specimens of coldworked Zircaloy-2 and Zr-2.5Nb to a constant displacement in a hydrogen atmosphere at 290 to 420 K and measured the characteristics of crack propagation using optical and acoustic emission techniques. With cold-worked Zr-2.5Nb at 293 K the Stage II crack velocity, V, was almost independent of stress-intensity factor, KI, at about 3 × 10−6 m/s, between about 70 and 20 MPa√m. As KI decreased with crack extension to below 20 MPa√m, V diminished and approached zero at ≈14 MPa√m. The crack surfaces were covered with a layer of hydride up to 300 μm thick in places. The main fractographic features were cleavage typical of hydride cracking. At 350 K, the Stage II crack velocity was 2 × 10−5 m/s, and the critical value of KI remained at ≈14 MPa√m. At 420 K, only limited crack propagation at high KI-values has been observed. In the pressure range 100 to 10 kPa at 293 K, the V versus KI curves were indistinguishable but at 1 kPa cracking was difficult to initiate, once started V (in Stage II) was 1.5 × 10−6 m/s and KIH was 22 MPa√m. This apparent effect of hydrogen pressure may result from traces of contaminants, since deliberate small additions of oxygen to a 10-kPa hydrogen atmosphere stopped the cracking. Additions of helium up to 10 kPa had no effect on cracking. The implications of the results are that zirconium alloys exposed to gaseous hydrogen at room temperature will crack only if the hydrogen is very low in oxidizing impurities. If zirconium alloys are used to store tritium, then helium from transmutation will not impede tritium absorption.
Deformation and Failure of Zircaloy Fuel Sheaths Under LOCA Conditions
Authors: Sagat S , Sills HE , Walsworth JA
Published: December 2008

A unified, microstructural creep law which simulates the transient creep deformation of Zircaloy at temperatures above 750 K has been used to follow the interaction of diffusional and dislocation creep with changes in material microstructure (grain size, recrystallization, phase fraction and anisotropy) under loss-of-coolant accident (LOCA) conditions. Comparison of a membrane sheath model using this creep law with a large number of tube tests (>700) in an inert environment has demonstrated good predictive capability.

This model has been extended to cover other aspects affecting deformation and failure of CANDU (CANada Deuterium Uranium) fuel sheaths such as: nonuniform structure distribution resulting from temperature profiles along the sheath length, oxidation of the fuel sheaths, cracking of the oxidized layers and localized straining, large strain failure, and failure by beryllium-assisted cracking.
Comparison of JIc Test Methods Recommended by ASTM and JSME
Authors: Kobayashi H , Nakamura H , Nakazawa H
Published: December 2008

The elastic-plastic fracture toughness JIc test method recommended by the Japan Society of Mechanical Engineers (JSME) Standard Method of Test for Elastic-Plastic Fracture Toughness JIc S001-1981 is outlined. Its applicability and utility compared with the ASTM Test for JIc, a Measure of Fracture Toughness (E 813) are discussed in this paper. It appears that JSME Standard S 001-1981 offers a superior approach to ASTM JIc determination in some aspects.
A Sensitivity Study of the Unloading Compliance Single-Specimen J-Test Technique
Authors: Futato RJ , Aadland JD , Van Der Sluys WA , Lowe AL
Published: December 2008

A sensitivity analysis of the unloading compliance single-specimen J-test technique was performed to determine the effect of errors in test parameters on calculated ductile fracture toughness JIc values and the shape of the J-R curve. Systematic errors in measured specimen dimensions, material properties, and load and displacement transducer calibration were considered. In addition, the effect of extensometer nonlinearity on the test results was modeled. The results of the study indicate that the shape of the J-R curve and the calculated JIc value are relatively insensitive to errors in parameters in the magnitudes allowed by the ASTM Test Method for JIc, a Measure of Fracture Toughness E 813 and the Tentative Procedure for Determining the Plane Strain J1-R curve. However, the JIc calculation appears to be quite sensitive to the location and spacing of J-Δa data points along the J-R curve. Means for desensitizing the JIc calculation to the manner in which the test is run are discussed.
Experimental Observations of Ductile Crack Growth in Type 304 Stainless Steel
Authors: de Vries MI , Schaap B
Published: December 2008

J-integral fracture toughness tests were performed at room temperature on small compact tension (1/2TCT) specimens of stainless steel Type 304 (Unified Numbering System [UNS] S30400). The ductile crack growth resistance curve was measured with the multi-specimen heat tinting method and automatically recorded using the potential drop (PD) technique and an optical system. The first parts of the curves were different for each method, however, for larger Δa values the curves were nearly the same. Profile measurements of the stretch zone showed blunting to be best represented by the formula J = 3.5σfΔa. There was no distinct separation between the blunting and stable crack growth phenomena. A continuous process of alternating crack-tip stretching and ductile crack extension was observed from the very beginning up to final crack extension (about 3 mm). Ductile initiation (formation of first dimples) was measured at about 300 kJ · m−2 (Ji) and “onset of stable crack growth” was measured at about 750 kJ · m−2 (JQ).
Elastic-Plastic Fracture Toughness Tests with Single-Edge Notched Bend Specimens
Authors: Anderson TL , McHenry HI , Dawes MG
Published: December 2008

Fracture toughness tests have been performed on five geometries of single-edge notched bend (SENB) specimens machined from a 25.4-mm (1.0-in.) thick plate of ABS Grade EH36 steel, a normalized carbon-manganese steel. Critical values of the J integral and the crack-tip opening displacement (CTOD) were measured as a function of temperature. Test temperatures, which ranged from −196 to 25°C, covered the entire ductile-to-brittle transition range. On the upper shelf, critical values of J and CTOD at the onset of stable crack growth were insensitive to specimen geometry. However, in the ductile-to-brittle transition region, where fracture occurred by unstable cleavage, fracture toughness decreased with increasing specimen thickness and crack length. This effect of geometry on fracture toughness in the transition region is attributed to changes in cracktip region constraint with geometry.

Various aspects of the SENB fracture toughness test have been examined. Experimental results indicate that both J and CTOD can be accurately measured with a single clip gage. Work hardening caused the ratio of J to CTOD to increase with strain. The m factor, which relates J to CTOD and flow stress, was directly proportional to the notch constraint factor. The η factor, which is a dimensionless constant used to relate the J integral to energy absorbed by the specimen, was independent of crack length for SENB specimens of ABS EH36 steel with a/W ranging from 0.19 to 0.75. The rotational factor rp was not a strong function of temperature or specimen geometry in the material studied.
Determining Crack Extension Using a Displacement Based Key-Curve Method
Authors: Andrews WR
Published: December 2008

A method for determining crack-growth resistance curves previously proposed by the author is derived from fundamental relationships. Data are presented that further demonstrate the application of the method to materials having a wide range of properties. It is concluded that the use of this method results in obtaining fracture properties not previously measured directly.
The Unloading Compliance Method for Crack Length Measurement Using Compact Tension and Precracked Charpy Specimens
Authors: Neale BK , Priest RH
Published: December 2008

The unloading compliance method has been used to measure crack lengths during the fracture toughness testing of an A508 Class II (Unified Numbering System [UNS] K12766) steel. It is shown that accurate crack length predictions (within ±4%) can be achieved by accounting for the extraneous compliance inherent in the testing fixture. Both precracked Charpy and 25-mm compact tension specimens have been tested over the temperature range − 150 to 300°C. From a comparison of the data, an assessment of the capability of precracked Charpy specimens to measure the fracture toughness of pressurized water reactor (PWR) steels is made.
Composition of Hardened Masonry Mortar: A Critical Review of Test Methods and Calculations
Authors: Isberner AW
Published: December 2008

Masonry mortar samples removed from masonry evidencing distress may be petrographically and chemically analyzed for composition. The success in reconstructing the original mortar composition depends upon the method of analysis, the availability of the parent materials or proper assumptions regarding their composition, and considerations during calculation. This report highlights various considerations for any analysis of mortar composition.
Thermal Shock and Maximum Temperature Investigation of a Single Unit Clay Brick Masonry Chimney
Authors: Huizer A , Ward MA
Published: December 2008

A double-wall clay chimney flue liner, which has been shown to pass the requirements for “zero clearance” applications at hearth temperatures of approximately 700°C (1292°F), was subjected to an additional series of tests presently only prescribed for metal chimneys. Although the National Building Code of Canada at this point in time does not require clay flue liners to pass the test requirements set for metal chimneys, the authors considered it to be a distinct possibility that in the near future there will be some pressure to have clay liners attain the same standards that the metal ones presently are required to meet. Therefore, the unit under investigation was subjected to the most severe conditions that might be experienced by clay flue liners such as thermal shock, creosote burnout, and extremely high flue gas temperatures. Test results showed that at present the unit would not pass the new standards set for metal chimneys, and that it will be necessary to reevaluate its geometry as well as the properties of the clays used in its manufacture.
Subsurface Pollution Containment Using a Composite System Vertical Cutoff Barrier
Authors: Druback GW , Arlotta SV
Published: December 2008

A new concept for constructing a vertical impermeable barrier to prevent the migration of polluted groundwater or leachate from a contaminated site or waste disposal area is presented. The composite system is a hybrid cutoff wall constructed with high density polyethylene (HDPE) and sand backfill and is installed using the slurry trench construction method. When installed, a very low permeability, composite, vertical barrier is established with unique engineering properties, including improved chemical resistance, leak detection, and groundwater migration control.

A full-scale construction test project of the system was performed at an existing sanitary landfill in New Jersey in the fall of 1982 to demonstrate the overall fabrication and construction procedures. The test project was conducted in three phases: (1) the excavation of a trench filled with the bentonite slurry mixture through the landfill waste; (2) the cutting and seaming of HDPE material to form an envelope; and (3) the placement of the envelope and subsequent backfilling with sand and water. The success of the operation under often difficult conditions proved that the theory and construction concept of the composite system barrier can be utilized to construct a cutoff wall. Useful information for future applications at contaminated sites was gained.
Laboratory Testing of Cement-Bentonite Mix for Proposed Plastic Diaphragm Wall for Complexe LaGrande Reservoir Caniapiscau, James Bay, Canada
Authors: Gill SA , Christopher BR
Published: December 2008

A comprehensive laboratory investigation was carried out to determine a suitable mix of cement-bentonite for a slurry trench cutoff wall for Caniapiscau Reservoir project in James Bay, Canada in 1980. Specifications required the mix to have a permeability of less than 0.01 μm/s and to be able to sustain a plastic deformation of 10% without fissuring as measured at 90 days in a triaxial compression test with a lateral pressure of 196 kPa. Laboratory samples were prepared with different mixes of cement, bentonite, sand, and water and kept in a curing chamber of 100% humidity. Permeability determination and triaxial compression tests were performed after curing periods ranging from 10 to 120 days. Over 84 specimens were tested. The compression tests included unconfined tests, unconsolidated-undrained tests at a constant rate of strain, unconsolidated-drained tests with varying strain rates and at a controlled rate of stress, and a consolidated-drained test. Permeability tests were performed before and, in some cases, after loading. The specimens were examined for fissures and cracks after a strain of 10%. It was concluded that a mixture of 6% (by weight) Ultra Gel 180 bentonite and 160 kg of cement in each cubic metre of the mixture would meet the required specifications. Recommendations for standardized test procedures are made.
The Permeability of Clay to Acidic and Caustic Permeants
Authors: Lentz RW , Horst WD , Uppot JO
Published: December 2008

Results of a laboratory study of the effects of acidic and caustic permeants upon the permeability of various fine-grained soils are reported. Triaxial falling head permeability tests were performed on specimens of kaolinite, kaolinite-bentonite mixture, and magnesium montmorillonite. Permeants used were hydrochloric acid with pH values of 1, 3, and 5 and water and sodium hydroxide with pH values of 9, 11, and 13. In no case for any of the clays or permeant pH did the permeability increase during the passage of six pore volumes of permeant, which indicates that no significant dissolution of clay minerals occurred. The only permeant that caused significant change in permeability was sodium hydroxide at a pH of 13, which caused a reduction in permeability of the magnesium montmorillonite by a factor of 13. This was found to be due to precipitation of magnesium hydroxide in the pores. Results are compared with findings reported by other researchers.

It is concluded that because of the wide variety of reactions possible between clays and permeant, future reports of permeability changes should give as much detail as possible about the chemistry and mineralogy of the soil studied. The equipment used and testing technique also have significant effects on reported test results and should be described in detail. Also, it is suggested that research is needed into possible reactions which could be induced within the soil pores to create favorable changes in permeability.
The Effect of Organic Fluids on Hydraulic Conductivity of Compacted Kaolinite
Authors: Acar YB , Hamidon A , Field SD , Scott L
Published: December 2008

The effects of four organic fluids on hydraulic conductivity of compacted kaolinite are presented. Permeation fluids were 0.1 and 100% solutions of nitrobenzene, acetone, phenol, and benzene, which represent a wide range of dielectric constants. Full saturation hydraulic conductivities were obtained in flexible wall permeameters under continuous back pressure, at hydraulic gradients of less than 100 and effective stresses of 69 kPa (10 psi). Reference hydraulic conductivity values were determined with 0.01 N calcium sulfate (CaSO4) solution.

The effect of the testing scheme was evaluated by measuring the hydraulic conductivity of acetone in both a flexible wall permeameter at variable effective stresses and in a rigid wall permeameter. Dramatic hydraulic conductivity increases were observed in rigid wall permeameters. The results indicate that increases in the hydraulic conductivity measured in rigid wall permeameters can only be explained by side leakages due to shrinkage of the specimen.

All tests with chemicals at low concentrations resulted in slight decreases of hydraulic conductivity. Hydraulic conductivity with pure solutions slightly increased with acetone and phenol and significantly decreased with benzene and nitrobenzene. Diffusion through the cell membrane was found to be a considerable source of error in assessing the full strength of organic fluids. The direction of variations in the liquid limit and the free swell of kaolinite with organic fluids was observed to be inversely related to changes in absolute values of hydraulic conductivity at low effective stresses. These results together with fabric studies indicated that changes in hydraulic conductivity with organic fluids can be explained by the variations in the surface forces of interaction on clay particles affecting the flow characteristics.
Interactions Between Acidic Solutions and Clay Liners: Permeability and Neutralization
Authors: Peterson SR , Gee GW
Published: December 2008

Liner failure, defined as an increase in liner permeability, was not found to be a problem when acidic uranium mill tailings solutions percolated through clay liner materials for periods extending up to three years. Liner materials taken from mill sites in Wyoming decreased in permeability with time in the laboratory columns when permeated with tailings solution. One clay liner decreased in permeability from one half to over two orders of magnitude, depending on the given clay sample and contacting solution. These decreases in permeability were attributed to pore plugging resulting from the precipitation of minerals and solids and to soil particle dispersion.

The clay liner material from Morton Ranch, Wyoming, exhibited a residual buffering capacity that was able to maintain column effluent pH values at higher levels than the influent pH values for extended time (in excess of 30 pore volumes). A likely cause for the elevated pH is the redissolution of iron and aluminum hydrous oxides. Redissolution of iron and aluminum hydrous oxides consumes hydrogen ions.
Field Permeability Test for Clay Liners
Authors: Day SR , Daniel DE
Published: December 2008

A method of measuring the hydraulic conductivity of compacted clay liners in the field using single-ring infiltrometers has been developed. It is assumed that the ring has a diameter that is no less than the thickness of the clay liner and that the clay liner is underlain by a freely draining material with negligible suction. Finite element analyses were performed to develop correction factors that account for horizontal seepage for cases in which the ring infiltrometer is partially embedded into the liner. The correction factors were developed for a range in diameter of the ring and for ratios of horizontal to vertical hydraulic conductivity of 1, 10, and 100. Laboratory experiments were conducted to verify the results of finite-element analyses, but the laboratory results showed considerable scatter and were successful only in demonstrating that the finite-element results show the proper trends. Finally, the test method was tried in the field on a full-sized clay liner in which the actual hydraulic conductivity of the entire liner could be calculated from the known rate of leakage. The hydraulic conductivity measured in the infiltration test agreed almost perfectly with the computed overall hydraulic conductivity of the entire liner. It is concluded that the single-ring infiltration test can be used to measure the hydraulic conductivity of clay liners, although it is difficult to measure hydraulic conductivities that are substantially lower than 1 × 10−7 cm/s. In addition, the field tests may take several weeks to complete.
Soil-Cement Liners
Authors: Adaska WS
Published: December 2008

For over 30 years soil-cement has been effectively used to line lakes, reservoirs, ditches, and irrigation ponds. More recently, wastewater treatment lagoons, sludge drying and ash settling ponds, and coal storage areas have been lined with soil-cement. In addition to its low permeability, soil-cement also provides a reliable method of slope protection.

Numerous laboratory permeability tests have been performed on various soil-cement mixtures. One study included the addition of lime and fly ash to the mixture. Research has been also conducted on shrinkage cracking in soil-cement and its effect on total seepage.

A large-scale field test to determine seepage through a stairstep constructed soil-cement facing was conducted by the Bureau of Reclamation at the Lubbock Regulating Reservoir in Texas. The study indicated the soil-cement to be quite impervious and that most of the seepage occurred through either shrinkage cracks or along the horizontal contact planes. It also showed an overall decrease in seepage with time.

The U.S. Environmental Protection Agency (EPA) has reported laboratory test results on the compatability of soil-cement to various hazardous and other industrial wastes. The tests concluded that exposure to acids such as from electroplating sludges and acidic steel-pickling wastes should be avoided; however, for toxic pesticide formations, oil refinery sludge, toxic pharmaceutical wastes, and rubber and plastic wastes, soil-cement should perform satisfactorily. For caustic petroleum sludges, compatability tests should be conducted on the specific combination of soil-cement and waste.

This paper will include basic information on soil-cement as a linear material and describe in detail the research work on permeability and compatability testing, which has been briefly mentioned. The design, construction, and performance of some unique soil-cement-lined projects will be also presented as well as information on a new composite soil-cement/synthetic membrane liner system that meets the latest U.S. EPA requirements for containing hazardous wastes.
Vehicle Operating Costs Related to Operating Mode, Road Design, and Pavement Condition
Authors: Zaniewski JP , Butler BC
Published: December 2008

From 1979 through 1982 the Federal Highway Administration contracted with the Texas Research and Development Foundation to update vehicle operating cost tables. In this research five components of vehicle operating cost were studied, including fuel consumption, maintenance and repair, oil consumption, tire consumption, and depreciation. The approach used in this research was to identify the consumption involved for each of these parameters and then to price these components to obtain vehicle operating costs. This approach allows future updating of the vehicle operating cost tables from simply knowing the changes in prices. This is highly desirable since component consumption changes much less frequently than the unit prices. The results of this research present a new set of table relating vehicle operating costs to the serviceability index of pavements and the geometric design features of the roads. The component consumption tables were established for constant speed and speed change cycle operations.
Analytical Determination of Normal Contact Stresses for Arbitrary Geometries with Application to the Tire/Pavement Interaction Mechanism
Authors: Clapp TG , Kelley CT , Eberhardt AC
Published: December 2008

A method for approximating the normal contact pressure distribution and the contact length associated with tire/pavement interaction has been developed using deformed tire geometry as a measured function of position. The mathematical development of the method is based on classic contact stress theory for contact between an elastic half plane and a rigid indenter. The unknown pressure distribution satisfies a linear integral equation and is approximated by an M-order polynomial with M + 1 unknown coefficients. The unknown coefficients are found by evaluation of both sides of the integral equation at M + 1 points, and the polynomial pressure distribution is plotted. The order, M, of the pressure distribution polynomial is sequentially increased until the pressure distribution stabilizes, completing the solution process. The contact length is approximated from sign changes in the pressure distribution caused by the geometric characteristics of the deformation curve for the tire not in contact with the pavement surface.

Polynomial approximations for the pressure distributions compare favorably with the analytical pressure distributions for arc-shaped and triangular indenters. The approximated contact lengths are within 10% of those measured experimentally. These results provide basic verification of the approximation method. The information available through this method is essential for the generation of realistic time-fluctuating force inputs into analytical vibration response models when predicting tire vibration response on various types of pavement surfaces.
Aquatic Macrophyton Sampling: An Overview
Authors: WM Dennis
Published: December 2008

Aquatic macrophytes constitute an integral part of aquatic ecosystems, contributing to primary productivity, providing habitat for various organisms, and modulating water quality. Recent attention on the characterization and understanding of aquatic macrophyte communities within North America has primarily been the result of water-use problems caused by excessive infestations of “weedy” aquatic plant species.

Aquatic macrophyte communities have been sampled using such devices as oyster tongs and rakes, drag chains, various fixed-size quadrats, and complex hydraulically controlled pontoon-mounted mechanical biomass samplers. More recently, subsurface sampling techniques have evolved using scuba, and remote sensing techniques have been developed using various platforms from balloons to fixed-wing aircraft to satellites.

Sampling protocol for aquatic macrophyte studies should be designed to answer the specific question(s) at issue, applicable to the physical characteristics of the system, and able to provide reproducible results that allow comparison with other studies. The level of sampling detail is dictated by the complexity of the questions under consideration. Typical questions include what species are present, where, and in what amount. More complex questions may involve the functioning of aquatic macrophytes in nutrient and heavy metal uptake and turnover, their utilization as indicator organisms, and their effects on ambient water quality conditions.
Development and Use of the Waterways Experiment Station's Hydraulically Operated Submersed Aquatic Plant Sampler
Authors: Sabol BM
Published: December 2008

A quantitative submersed aquatic plant sampler that can rapidly collect plants from a known area at any depth was developed for the U.S. Army Engineer Aquatic Plant Control Research Program. The design and use of this hydraulically operated cylindrical sampler and an improved second generation square-shaped sampler are discussed. Quantitative data are presented that compare these samplers to each other and to other sampling techniques including mechanical harvesters. Substantial differences between plant biomass estimates obtained by different techniques suggest that there may be biases associated with the different techniques making direct comparisons misleading. A large-scale systematic comparison test is needed to evaluate the various quantitative sampling techniques.
Problems in the Use of Closed Chambers for Measuring Photosynthesis by a Lotic Macrophyte
Authors: Hill BH , Webster JR , Linkins AE
Published: December 2008

Photosynthesis by Podostemum ceratophyllum in closed production chambers became inhibited by oxygen accumulation and carbon depletion during field investigations. Carbon-14 uptake by this plant during 180-min experiments was initially rapid, then decreased abruptly. The photosynthetic response corresponded to increased oxygen concentration of the chamber water and increased excretion of labelled organic carbon from the plants. Photosynthesis was probably further inhibited by inorganic carbon depletion since this plant is unable to use HCO3− as a carbon source. Alkalinity and pH in the chambers decreased and increased, respectively, reflecting this depletion of available carbon dioxide. These data suggest that use of sealed chambers for aquatic macrophyte production studies may seriously underestimate actual production.
Comparison of Microbial Transformation Rate Coefficients of Xenobiotic Chemicals Between Field-Collected and Laboratory Microcosm Microbiota
Authors: Lewis DL , Kellogg RB , Holm HW
Published: December 2008

Two second-order transformation rate coefficients—kb, based on total plate counts, and kA, based on periphyton-colonized surface areas—were used to compare xenobiotic chemical transformation by laboratory-developed (microcosm) and by field-collected microbiota. Similarity of transformer to nontransformer community structure in blended aufwuchs was indicated by kb values, and similarity of transformation rates per unit of periphyton-colonized surface area was indicated by kA values. Xenobiotic chemicals used for the comparisons were methyl parathion (MP), diethyl phthalate (DEP), and 2,4-dichlorophenoxyacetic acid butoxyethyl ester (2,4-DBE). Even though rate coefficients of each of the chemicals were similar among microcosm- and field-collected microbial samples, not all of the field-collected samples showed MP or DEP transformation. The MP transformation was suppressed by aqueous extracts of field-collected, algae-dominated aufwuchs. Lack of DEP transformation appeared to have resulted from an absence of DEP-transforming bacteria in field-collected aufwuchs samples.
Calibration of Laboratory Bioassays with Results from Microcosms and Ponds
Authors: Giddings JM , Franco PJ
Published: December 2008

Effects of an organic contaminant (a synthetic coal-derived crude oil) were measured in outdoor ponds and indoor pond-derived microcosms and compared with results of laboratory bioassays. Ponds and microcosms were treated with the oil continuously for eight weeks. Concentrations of phenolic compounds (the major water-soluble constituents of the oil) spanned the range of acute and chronic toxicity concentrations determined in single-species bioassays. Effects were similar in microcosms and ponds, implying that microcosms are suitable models for field studies for some purposes. Significant changes in community metabolism and zooplankton populations occurred in microcosms and ponds exposed to less than 0.05 mg/L phenols, near the 28-day lowest observed effect concentration (LOEC) for Daphnia magna. Ponds and microcosms were seriously damaged at concentrations near acute bioassay mean lethal concentration (LC50) values. Indirect effects in the ecosystems occurred at all treatment levels, and included changes in water quality, replacement of sensitive taxa by more tolerant competitors, and changes in abundance of some species because of increases or decreases in their predators or grazers. The safe exposure level determined from the ecosystem experiments was accurately predicted by an application factor of 0.03 in conjunction with the most sensitive acute bioassay result (the D. magna 48-h LC50). Less conservative extrapolation methods overestimated the safe concentration of this material in these ecosystems.
Comparison of Laboratory and Field Assessment of Fluorene—Part II: Effects on the Ecological Structure and Function of Experimental Pond Ecosystems
Authors: Boyle TP , Finger SE , Paulson RL , Rabeni CF
Published: December 2008

Fourteen experimental ponds were dosed with the energy-related polynuclear aromatic hydrocarbon fluorene to effect nominal concentrations of 0.12, 0.5, 2.0, 5.0, and 10.0 mg/L. Measurement of emergent aquatic insects revealed no effects due to fluorene application. Zooplankton density was drastically reduced by treatments at 5.0 and 10.0 mg/L; however, it recovered in one to three weeks due to an increase in the number of rotifers that replaced the crustacean zooplankton killed by fluorene. Species richness of the zooplankton community was also reduced by the treatments at 5.0 and 10.0 mg/L. The survival and yield of both largemouth bass (Micropterus salmoides) and bluegills (Lepomis macrochirus) were reduced by the treatment at 0.12 mg/L, as were the production and survival of bluegill recruits. The mean increase in weight of adult and recruit bluegills was inversely related to the number surviving, indicating that fluorene toxicity induced a secondary response in the restructuring of the fish community. A comparison of algae and invertebrate laboratory toxicity test results with data from the pond studies revealed that these organisms were more sensitive to fluorene in the laboratory. However, the two species of fish in the ponds were more sensitive to fluorene than in routine laboratory tests.