bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of IVa and Va Elements on Void Formation in Neutron-Irradiated 316 Stainless Steels
Authors: Ohnuki S , Yamashita S , Takahashi H , Kato T
Published: April 2008

In a previous electron irradiation study it was shown that additions of elements from the IVa and Va columns of the periodic table to 316L stainless steel could have a pronounced effect on its swelling resistance. The results suggested that vacancy binding was the main operative mechanism, increasing in strength with increasing size factor. In the current experiment these same alloys were irradiated with fast neutrons, but the influence of the size factor does not appear to be the only important mechanism. Whereas essentially precipitation was limited during electron irradiation, substantial precipitation occurred during neutron irradiation at lower displacement rates, overshadowing the effect of size factor on swelling. The addition of Hf and especially Zr, however, was particularly effective in suppressing swelling in both the electron and neutron cases, although the suppression mechanism in the neutron case appears to be a combination of both size effect and precipitation to alter the sink structure.
Stress-Modified Welding of Neutron Irradiated Steels
Authors: Wang C-A , Wikle HC , Grossbeck ML , Chin BA
Published: April 2008

Catastrophic centerline fractures in the fusion zone have been observed in neutron irradiated steels after welding using the conventional gas tungsten arc (GTA) welding process. Specimens of type 316 stainless steel, Prime Candidate Alloy (PCA) and Sandvik HT-9 were obtained from a capsule irradiated at 200°C in the Oak Ridge Research Reactor. Severe fusion zone cracking was observed in type 316 stainless steel (up to 75 appm He) and PCA alloy (up to 86 appm He) after GTA welding. No cracking was observed in HT-9 steel with up to 2.5 appm He concentrations. The application of a compressive stress during GTA welding eliminated fusion zone cracking in both 316SS and PCA. The results indicate that the stress-modified welding technique may be used to suppress and control helium-induced cracking during repair welding of irradiated materials.
Thick Plate Welding of Irradiated Stainless Steel
Authors: Asano K , Katsura R , Kawano S , Koshiishi M
Published: April 2008

Recent welding tests using either neutron irradiated or tritium charged material have shown that there was a good chance of success when there was no repeated heat cycle during welding, e.g., stringer bead welding, single pass laser welding, etc. However, the replacement/repair of the actual load carrying components often requires thick plate welding which can only be realized with multi-layer welding. In the present study, 20-mm-thick grooved plate of type 304 stainless steel was irradiated and then butt-welded by multi-layer welding. The weld heat input used was 1.0 and 2.0 MJ/m, which required 28 and 14 passes to fill up the groove. The samples were irradiated to 2.5×1021 ∼ 1.8×1023 n/m2 (E>1MeV), which resulted in 0.1∼1.6 appm of helium being produced. A conventional gas tungsten arc welding procedure was employed. The welded joints were subjected to the tensile test, side bend test, root bend test and cross-sectional metallography. The samples containing as much as 0.14 appm of helium passed all the tests; the mechanical properties fulfilled the standard requirement for the unirradiated base metal. At 0.6 appmHe and 1.0 MJ/m heat input, the welded joint showed sufficient strength, however, tiny intergranular cracking was observed in the HAZ where repetitive thermal cycles operated.
Cracks in TIG Welded, Neutron-Irradiated 304 Stainless Steel
Authors: Kohyama A , Hirose T , Suzuki T , Narui M , Katoh Y
Published: April 2008

In fission and fusion reactor applications, properties of welds and welded joints are key factors that limit component service conditions including their lifetime. Therefore, the availability of reliable repair welding techniques is strongly required in order to reduce the cost of electricity. One of the most difficult and unique characteristics, which repair welding has to overcome, is the radiation damaged microstructure including nuclear transformed gaseous atoms, such as helium from the (n, α) and hydrogen from the (n, p) reaction. There have been many attempts to investigate weldability of heavily neutron-damaged materials for establishing criteria for the repair welding process. The objective of this research is to clarify the mechanisms of weld cracking, especially for heat affected zone cracking in heavily neutron irradiated stainless steels.
Effect of Neutron Irradiation on Mechanical Properties of Cn-Alloy/SS316 Joints
Authors: Tsuchiya K , Nakamichi M , Kawamura H
Published: April 2008

The effects of neutron irradiation on tensile properties of the Cu alloys to type 316 stainless steel (SS316) joints fabricated by friction welding method were examined. Additionally, irradiation tests of Al2O3-dispersed copper alloy (Al-15), oxygen free copper (OF-Cu) and SS316 were conducted. The Al-15/SS316 and OF-Cu/SS316 joints were irradiated in the Japan Materials Xesting Reactor (JMTR), and tension tests and metallographical observation of these joints have been performed as the post irradiation examination (PIE). In the tension tests of Al-15/SS316 and OF-Cu/SS316 joints, all irradiated specimens fractured at the copper sides. In the tension tests at 293K, tensile strength of the Al-15/SS316 joints irradiated at 693K was equal to that of the base metal (Al-15) irradiated in the same condition. On the other hand, tensile strength of Al-15/SS316 joints was smaller than that of Al-15 in the tension tests at the same temperature as each irradiation temperature. In this study, useful data of the irradiated Al-15/SS316 and OF-Cu/SS316 joints fabricated by friction welding method were obtained to design fusion reactors.
An Investigation into the Origin and Nature of the Slope and x-axis Intercept of the Shear Punch-Tensile Yield Strength Correlation using Finite Element Analysis
Authors: Hankin GL , Toloczko MB , Johnson KI , Khaleel MA , Hamilton ML , Garner FA , Davies RW , Faulkner RG
Published: April 2008

Recent studies have shown that for a variety of unirradiated and irradiated materials, a slope of ∼2 is obtained for a correlation between yield in a shear punch test and yield in a uniaxial tensile test. Application of the von Mises yield criterion would predict a slope of √3. A finite element model (FEM) of the shear punch test was developed to aid in understanding the experimentally obtained slope of ∼2. FEM simulations of the shear punch test were conducted using stress-strain data from uniaxial tensile tests on 316 stainless steel in four initial cold-work conditions. A correlation was developed between the FEM-evaluated effective shear yield strength and the experimentally-evaluated uniaxial yield strength. The slope from this correlation was found to be nearly the same as for the slope from the correlation between the experimentally-evaluated effective shear yield strength and the experimentally-evaluated uniaxial yield strength. The finite element model showed that stresses other than pure shear exist in a specimen during a shear punch test, and these other stresses may explain why the slope of the experimental yield strength correlation is different than √3.
Thermoelectric Power: A Nondestructive Method for Monitoring Irradiation Effects in Ferritic Steels
Authors: Miloudi S , Jumel S , Pareige P , Coste J-F , Van Duysen J-C
Published: April 2008

We try to develop nondestructive methods to monitor the effects of neutron irradiation in ferritic alloys. In this paper we report results obtained with a method based on thermoelectric power (TEP). This method is already used to monitor the thermal aging of duplex stainless steels.

It is shown that the measurement of the thermoelectric power allows the monitoring of the effects of i) electron irradiations on Fe-Cu model alloys, and ii) neutron irradiations on industrial pressure vessel steels. The recovery of these irradiation effects during thermal annealing can also be followed with the proposed method.

On the basis of the results obtained on Fe-Cu alloys, we propose a law to determine the limit of copper solubility in α iron at temperatures below 600°C.
Design of a Dedicated Electron Beam Facility for Material Treatment
Authors: Mittendorfer J
Published: April 2008

Electron beam has been applied as source of ionizing radiation in a wide field of applications. Sterilization, decontamination, treatment of materials for cross-linking, curing, and polymerization have been carried at an industrial scale.

Interest in material treatment with accelerated electrons increased significantly over the last years. Especially industrial strength electron accelerators with energies up to 10 MeV make it possible to process with increased penetration depth, and offer new opportunities in electron curing of polymer matrix composites (PMC) and cross-linking.

10 MeV accelerators are currently used mostly in contract facilities such as sterilization of medical devices and material treatment. Therefore these facilities are not optimized for material processing tasks and thus less efficient and versatile.

In this paper requirements and design guidelines for a dedicated material processing facility are discussed.
Amorphization of Solids Irradiated by Fast Neutrons
Authors: Parkhomenko VD , Dubinin SF , Teploukhov SG , Goshchitskii BN
Published: April 2008

The diffraction patterns of amorphous solids produced by both a conventional technique and fast neutron irradiation were systematized. The diffraction patterns of the substances of these classes differ essentially. It was first ever shown that neutron radiation modified solids belong to the group of amrophous substances of a distortion type.
Neutron Irradiation Induced High Temperature Embrittlement of Pure Copper and High Strength Copper Alloys
Authors: Fabritsiev SA , Pokrovsky AS , Zinkle SJ , Edwards DJ
Published: April 2008

The effect of helium production during neutron irradiation on the high temperature tensile properties of copper and dispersion strengthened (DS) copper alloys was investigated in neutron-irradiated specimens containing different levels of boron. Sheet tensile specimens were irradiated at temperatures of 90°C, 150°C and 300°C to doses of 0.2–1 dpa. Considerable embrittlement (<3% total elongation at 400°C) was detectable in pure copper at He concentrations above 80 appm. The DS copper alloys tested under the same conditions showed higher resistance to helium embrittlement. Samples of DS copper alloy saturated to 60 appm helium on cyclotron also demonstrated high resistance to helium embrittlement. The present results indicate that under fusion energy conditions, where a high helium accumulation rate of ∼10 appm/dpa is expected, helium embrittlement may limit the maximum temperature of copper alloys for structural applications to ⩽ 400°C.
Effect of Neutron Irradiation on Tensile and Fracture Toughness Properties of Copper Alloys and Their Joints with Stainless Steel
Authors: Tähtinen SJ , Pyykkönen MT , Singh BN , Toft P
Published: April 2008

Dispersion strengthened (CuAl25) and precipitation hardened (CuCrZr) copper alloys are being considered as candidate materials for the first wall and divertor components of ITER. In the present work, the tensile and fracture resistance properties of CuAl25 and CuCrZr alloys and their joints with 316LN stainless steel have been studied in the unirradiated and neutron irradiated conditions. The joints were produced by hot isostatic pressing (HIP) at 960°C for 3 hours at a pressure of 120 MPa. Test specimens of the base materials CuAl25 and CuCrZr alloys and of the joints (CuCrZr / 316LN and CuAl25 / 316LN) were irradiated with fission neutrons in the DR-3 reactor at Risø in the temperature range from 50°C to 350°C to a displacement dose level of about 0.3 dpa (NRT). Tensile specimens of these alloys were tested at temperatures in the range of 50°C to 350°C. Fracture resistance curves were determined using three point bend tests on specimens of the base materials and of the joints. Tensile and fracture toughness results, together with the metallography of the joints will be presented. Implications of these results and the deformation mechanisms will be briefly discussed.
Salt Spray Performance Evaluation: Proposed Image-Analysis-Based Test Method
Authors: Warburton YJ , Gibbon DL
Published: April 2008

ASTM Test Method for Evaluation of Painted or Coated Specimens Subjected to Corrosive Environments (D 1654-92) is the current industry standard. This standard assigns a number, from 0 to 10, to reflect the width of the paint delaminated as measured from a scribe line to the creepage front. At times when the width along the scribe is not uniform, it is difficult to apply this standard. The difficulty lies in the fact that the standard is attempting to describe a two-dimensional pattern with a linear parameter. A two-dimensional parameter should be more suitable, and delaminated area seemed to be an obvious choice. Image analysis is a powerful tool to aid in the evaluation of the proposed parameter. The results using percentage area correlate well and linearly with D 1654 ratings. Effects of scribe length, paint color, reproducibility, and operator-to-operator variance are also discussed.
Comparative Study of Standard Weathering Test Methods Using Image Analysis
Authors: Lee F , Pourdeyhimi B , Martin J
Published: April 2008

Human visual evaluation and photometric gloss and color measurements are the common techniques used for determining the surface deterioration in weathering and durability studies. However, the human visual inspection technique is a subjective and qualitative method and therefore lacks objectiveness as a standard method. The photometric techniques provide quantitative measurements but do not fully incorporate all aspects of surface morphology. Therefore, instrumental inspection techniques that integrate photometric response as well as surface morphology would be beneficial. In this report, the feasibility of an image analysis system as an objective and quantitative surface measurement technique is demonstrated. For the study, three different commercially available plastics were exposed to various weathering conditions conforming to five different industry standard test methods. The materials were periodically evaluated using the image analysis system, and the results were compared. In addition, conventional photometric evaluation results were compared to this new technique. Analysis of the data provided some insight into comparing the four different accelerated weathering tests.
On the Use of Ion Scattering Spectroscopy to Predict the Outdoor Durability of Polymeric Films
Authors: Adkins RR
Published: April 2008

Ion scattering spectroscopy (ISS) has been found to have potential as a fast method of predicting the outdoor durability of polymeric films. Three sets of samples were studied by ISS. The samples had been artificially weathered for 500 hours. The ISS measurements looked at the hydrogen/carbon (H/C) and the oxygen/carbon (O/C) ratios as a function of depth. There was no apparent correlation of the ratios of the weathered samples to known outdoor performance. However, when the H/C and O/C ratios of the file samples were divided by those of the artificially weathered samples as a function of depth, there was a correlation. The proportions of the H/C ratios were found to correspond directly to the known outdoor weathering results for two of the three sets of samples. The proportions of the O/C ratios were found to correspond to known outdoor weathering in the third set and also to one of the two sets in which there was correlation with the H/C ratios.
Stress Analysis and Accelerated Test Design for Interior Light Environments
Authors: Ketola WD , Fischer RM , Thomas LJ
Published: April 2008

A procedure for development of a simple, small-scale laboratory accelerated test based on the same light source used in the actual indoor application is described. This simple laboratory accelerated test can be used to evaluate durability of paints, coatings, or colorants used in art or graphic displays exposed to the interior lighting source. The steps used to develop the test include characterization of the light and thermal stresses for actual use conditions and applying the results to design an accelerated test. Examples for developing tests based on two different interior light sources are shown. Procedures for characterizing spectral power distribution, for calculating an irradiance acceleration factor, and for determining the uniformity of light and thermal stresses of the accelerated test are described. Results from measurements made using these procedures are used to establish the conditions for a practical small-scale laboratory accelerated test.
Lightfastness of Artists' Pencils: Natural & Accelerated Exposure Results
Authors: Brennan PJ , Everett ET
Published: April 2008

Colored pencils are the medium of choice for many artists, however, there is currently no standard methodology to help artists choose between pencils with good, bad, or indifferent lightfastness. A research project to correlate the performance of artists' pencils was initiated by the ASTM D01.51.14 Colored Pencil Task Group. Three artist pencil manufacturers participated in the study. Replicate pencil specimens were exposed in Florida and Arizona benchmark locations under glass and in three different models of Xenon Arc lightfastness test apparatus. Two of the models were small, less expensive “tabletop” units, while the third xenon-arc was a full-size, free-standing tester. The resulting data was analyzed using both rank order and ASTM D4303 lightfastness categories. There was excellent rank order correlation between natural and accelerated exposures.
The Durability of Modern Sculptures Constructed of Glass
Authors: Adams PB , Ben Tré H
Published: April 2008

A large water fountain sculpture has been installed in a city park. The fountain incorporates glass castings whose resistance to environmental effects is not well understood. A study of the glass properties and accelerated environmental tests predict that the sculpture will remain relatively unchanged for 20 years or more.
Comparison of the Dimensional Stability of Kel-F 81 and Neoflon CTFE M400H Polychlorotrifluoroethylenes Used in Valve Seat Applications
Authors: Waller JM , Newton BE , Beeson HD , Haas JP
Published: April 2008

The dimensional stability of polychlorotrifluoroethylene (PCTFE) valve seats used in gas cylinder regulator applications was evaluated by thermomechanical analysis (TMA). Testing focused on two commercial grades of PCTFE, Kel-F® 81 and Neoflon® CTFE M400H, and on actual PCTFE valve seats obtained from different manufacturers. The effects of resin grade, percent crystallinity, and process history on TMA deflection were evaluated. TMA results frequently showed low-temperature dimensional instability between 40 and 70 °C. The corresponding permanent height change resulting from brief cyclic heating of as-received material to 150 °C ranged from to +3.9 to -8.5 percent. Complementary differential scanning calorimetry data indicated the origin of the dimensional instability to be anomalous relaxation at or close to the glass transition. The data are discussed in the context of several proposed valve seat failure mechanisms: contaminant promotion, flow resonance, and flow friction. The combined data show significant property variations within the PCTFE resin family. Such property variations could have important implications for the use of PCTFE in valve seat applications.
Promoted Ignition-Combustion Behavior of Engineering Alloys at Elevated Temperatures and Pressures in Oxygen Gas Mixtures
Authors: Zawierucha R , Million JF
Published: April 2008

Promoted ignition, and more recently, promoted combustion are terms which have been used to describe a situation where a substance with low oxygen compatibility ignites and promotes the combustion of a more combustion resistant material. The literature in recent years has been enriched by studies of this phenomenon as it relates to carbon steel, stainless steels and significant alloys in the nickel, cobalt and copper families.

However, the bulk of past literature has involved experiments conducted at ambient temperatures and elevated pressures. Published elevated temperature promoted ignition-combustion data and studies are scarce. Yet, applications involving the use of oxygen-enriched atmospheres at elevated temperatures are increasing.

In this paper, a unique experimental apparatus, which has been used to conduct flammability tests of engineering alloys at elevated temperatures and pressures in heated flowing oxygen, is described. Issues pertinent to elevated temperature flammability tests in heated oxygen are discussed. Promoted ignition-combustion data for carbon steel, stainless steel and nickel alloys in various heated pressurized oxygen gas mixtures at temperatures up to 895°C are presented and discussed.
Ignition of Aluminum by Impact in LOX — Influence of Contaminants
Authors: Barthélémy H , Roy D , Mazloumian N
Published: April 2008

Impact tests in LOX according to ASTM D 2512 were conducted on thin aluminum films (7 to 20 μm) together with glass fibers films used for the super insulation of vacuum insulated cryogenic vessels. Influence of the film thickness, type of material and number of layers were investigated. Practical information is given concerning the requirements for such insulation.

Impact tests in LOX according to ASTM D 2512 were also conducted on thick aluminum foils (0.2 mm) used for heat exchangers of air separation units (ASU). Test samples were usually three layers of corrugated foil contaminated by various hydrocarbons but mainly by hexadecane. The standard striker pin as per ASTM D 5212 and also a modified striker pin were used. The influence of HC contaminants (type and quantity) on the Al foils, but also of impurities in the LOX (N2O, Ar, N2), was investigated. The results of these tests can be used to understand the risk of ignition of some aluminum exchangers or structures used in ASU.
Promoted Ignition-Combustion Tests of Brazed Aluminum Heat Exchanger Samples in Gaseous and Liquid-Oxygen Environments
Authors: Zawierucha R , Million JF
Published: April 2008

Most air separation plants employ compressors to increase oxygen pressure for customer usage. An alternative approach is to extract liquid oxygen from the separation column, which is pumped to higher pressure and then boiled in a heat exchanger to directly provide an elevated pressure gaseous oxygen product. Brazed aluminum heat exchangers (BAHX) are normally utilized as the product oxygen vaporizers.

The increased use of BAHXs to produce pressurized oxygen as an alternative to the use of oxygen compressors led to a series of experimental programs pertinent to the safe use of BAHXs for boiling oxygen at elevated pressures. One of these programs, involving flammability experiments with 3 kg to 13 kg miniature BAHX samples, was presented in an earlier ASTM publication, STP 1319. This is a companion to that study and the experimental work actually preceded the work reported in STP 1319.

In this experimental program, over 60 separate tests were conducted on 200 g – 400 g BAHX block samples in gaseous and liquid oxygen. Oxygen purities ranged from 86.90% to 99.96%. Test pressures ranged from atmospheric to 7858 kPa. Nichrome-hydrocarbon and several different reactive metal promoters were utilized. The purity of the liquid oxygen was found to affect the pressure threshold above which a violent energy release (VER) occurred. Data cited from the program form a part of the technical basis for a Compressed Gas Association pamphlet entitled: “Safe Use of BAHXs for Producing Pressurized Oxygen”.
Determination of Hydrocarbon Adsorption on Solid CO2 and N2O in LOX at Ambient Pressure
Authors: Lassmann E , Meilinger M
Published: April 2008

The enrichment of hydrocarbons represents a serious hazard for Air Separation Units (ASU), as several incidents have shown in the past. Regarding the potential hazard due to acetylene accumulation in Revex-plants, literature exists reporting a considerable acetylene amount adsorbed on solid CO2. Thus a potential risk was estimated due to hydrocarbon adsorption on solids in the liquid oxygen (LOX) bath of ASUs. Therefore, Linde Process Engineering and Contracting Division was interested in checking the literature results.

With two model hydrocarbons, acetylene and propane, adsorption tests on solid CO2 and N2O in LOX at ambient pressure were performed. The loading was determined by evaporation of the liquid (“indirect determination” method) or the solid CO2/N2O (“direct determination” method) in a pressure vessel. The loading was consistent with the ratio concentration hydrocarbon/concentration CO2 or N2O and is expressed in Vppm (Volume parts per million).

Propane exhibited a very small loading on CO2 as well as on N2O. In comparison with the alkane the alkine, acetylene, adsorbed much better on CO2 and N2O. Amounts of up to 700 Vppm acetylene on solid CO2 were found at 89.7 K. The loading depended on the way the solid was generated, but was not affected by the concentration of acetylene in the investigated range. However, the accumulation of acetylene by adsorption should not attain a dangerous amount in the LOX of ASUs.
Metals Flammability: Review and Model Analysis
Authors: Wilson DB , Stoltzfus JM
Published: April 2008

With its founding in 1975, ASTM Committee G-4 embarked on the process of defining the concept of the flammability of metallic materials in oxygen-enriched atmospheres. While joined in this process by the National Aeronautics and Space Administration, the National Fire Protection Association, and the Compressed Gas Association, there is yet no explicit definition. However, it is clear that the postignition concept of flammability equates to combustion propagation, synonymous with steady-state burning under specified conditions. In this paper, four models are developed under specified environmental conditions that characterize flammability. Three incorporate the system-independent properties of heat of combustion, burn ratio, thermal conductivity, and flame temperature; four involve the system-dependent properties of promoted combustion, threshold pressure, oxygen index, and burn rate. A model solution, therefore, provides a measure of flammability.
Use of Resilient Modulus Test Results in Flexible Pavement Design
Authors: Nazarian S , Abdallah I , Meshkani A , Ke L
Published: April 2008

The state of practice in designing pavements in the United States is primarily based on empirical or simple mechanistic-empirical procedures. Even though a number of state and federal highway agencies perform resilient modulus tests, only few incorporate the results in the pavement design in a rational manner. A concentrated national effort is on the way to develop and implement mechanistic pavement design in all states. In this paper, recommendations are made in terms of the use of the resilient modulus as a function of the analysis algorithm selected and material models utilized. These recommendations are also influenced by the sensitivity of the critical pavement responses to the material models for typical flexible pavements. The inaccuracies in laboratory and field testing as well as the accuracy of the algorithms should be carefully considered to adopt a balance and reasonable design procedure.
Implementation of Startup Procedures in the Laboratory
Authors: Groeger JL , Bro A , Rada G , Lopez A
Published: April 2008

As part of the Federal Highway Administration's (FHWA) Long-Term avement Performance Program (LTPP) Materials Characterization effort, a quality control/quality assurance (QC/QA) procedure was developed to verify the proficiency of laboratory equipment and personnel in performing resilient modulus testing. This effort is documented in report FHWA RD-96-176, “Resilient Modulus of Unbound Materials (LTPP Protocol P46) Laboratory Startup and Quality Control Procedure” (Alavi, et al. 1997). Since issuance of that report, a great deal of experience has been gathered in using the procedure. This present paper provides an outline of the procedure, the rationale behind the procedure, and documents recent changes that have been developed by the authors. The paper also discusses issues to look for when implementing the startup procedure. Finally, a brief list of issues that have been found by using the procedure is presented.
Resilient Modulus of Soils and Soil-Cement Mixtures
Authors: Trindade TP , Carvalho CAB , Silva CHC , de Lima DC , Barbosa PSA
Published: April 2008

Knowledge of the resilient modulus (MR) of the sub-grade soils and materials that compose the layers of road pavements is mandatory for an efficient analysis of their structural behavior as a whole. However, laboratory determination of MR requires employment of relatively sophisticated loading systems and data acquisition, besides demanding considerable testing time. Therefore, it is desirable to look for standard test methods that can be used to estimate this engineering parameter. This paper presents geotechnical engineering parameters of two soils and their soil-cement mixtures, and provides empirical correlations between CBR, unconfined compression strength determined at 1% of axial strain, Young's tangent modulus, and measured values of MR of these soils and mixtures.
A Simple Method for Determining Modulus of Base and Subgrade Materials
Authors: Nazarian S , Yuan D , Williams RR
Published: April 2008

The resilient modulus test is commonly used to determine the modulus of base or subgrade materials as well as to establish their nonlinear behavior. Since the resilient modulus test is time consuming, the number of tests performed for a given project is limited. For day-to-day operation of highway agencies, a more rapid test method is needed. The stress wave (or seismic) method is being considered in Texas for this purpose. Seismic methods of testing can rapidly and nondestructively provide fundamentally correct moduli at known states of stress. Unlike the resilient modulus test, comparative field testing methods are available for seismic methods that can provide similar results under similar conditions. This paper describes the seismic test procedure and its relationship to the resilient modulus test results. Also discussed are the repeatability and reproducibility of the results as a function of operator experience, type of soil, and preparation method.
Resilient Modulus Test — Triaxial Cell Interaction
Authors: Boudreau RL , Wang J
Published: April 2008

During developmental work by the Strategic Highway Research Program (SHRP, 1987–1992) and the Federal Highway Administration (FHWA, 1993-present), it was recommended that knowledge and assessment of triaxial equipment and sample interaction be correctly applied to both test command and data reduction routines for the accurate measurement of resilient modulus properties of unbound materials using external instrumentation configuration. This concern is briefly addressed in the American Association of State Highway and Transportation Officials (AASHTO) test method T307-99, under paragraph 8.3.2.1. The paragraph refers only to calculations necessary to correct for the proper magnitudes of seating load based on known properties of the triaxial cell. The method does not contain information describing the methods and calculations needed to consider these parameters in the data reduction portion of the test. Further, the test method does not address other influences unique to a triaxial testing cell, namely frictional forces resulting from poorly manufactured or improperly designed seals, alignment issues and compliance.

This paper addresses the sensitivities of the results due to appropriate and inappropriate interpretation of the correction factors necessary, as well as influences of seal drag forces. The sensitivities have been calculated for two specific triaxial cells. Note that each triaxial cell and instrumentation configuration possesses unique values needed for the correction. Generally, the larger the triaxial cell (larger rod diameter, larger mass of rod), the greater the influences of the uplift and static weight components of load.

Users must be knowledgeable about their test equipment and the ability of the software to correctly apply proper loads and properly assess these loads for the correct calculation of resilient modulus. Further, physical tolerances must be developed for triaxial cells with respect to seal drag, alignment and compliance. These issues are extremely important when comparing results between laboratories, as the errors associated with miscalculation, misinterpretation or incorrect measurement of loads can result in variations outside the precision of the test itself.
Comparison of Laboratory Resilient Modulus with Back-Calculated Elastic Moduli from Large-Scale Model Experiments and FWD Tests on Granular Materials
Authors: Tanyu BF , Kim WH , Edil TB , Benson CH
Published: April 2008

A comparison is made between resilient moduli obtained from (i) a conventional small-scale resilient modulus test, (ii) a large-scale model experiment (LSME), and (iii) a falling weight deflectometer (FWD) in the field. The LSME is a large prototype-scale test simulating a pavement section. The FWD tests were conducted on a highway test section. All tests were conducted on a typical base course material and two granular industrial by-products used as subbase. Relationships between elastic modulus and bulk stress were derived from the LSME data by modeling the set-up as a nonlinear elastic layered system using the computer program KENLAYER. Elastic moduli were back-calculated from the FWD data using the program MODULUS. Reasonable correspondence between the elastic moduli measured at different scales was obtained when empirical corrections were made for strain amplitude using a backbone curve for granular materials and by matching stress levels. However, even when corrections are applied, the low-strain (or maximum) elastic modulus for the industrial byproducts inferred from the laboratory resilient modulus test tends to be lower (by a factor of 1.5 to 4) than the operative elastic modulus inferred from the LSME and the FWD tests. In addition, the minimum bulk stress provided by the laboratory resilient modulus test can be higher than the bulk stress existing in the field. In such cases, the elastic modulus at the field bulk stress can be estimated by extrapolation using a power function.
Resilient Modulus Testing of Unbound Materials: LTPP's Learning Experience
Authors: Rada GR , Groeger JL , Schmalzer PN , Lopez A
Published: April 2008

Resilient modulus is a key data element for characterizing unbound pavement materials within the LTPP program. Although the test has been around for nearly three decades, its implementation within the program has been a challenge. A suitable test protocol was not available when the program began in 1987. It was incorrectly assumed in the early years that equipment manufactured for the test would work as intended. It was also incorrectly assumed that properly operating equipment and knowledgeable personnel imply good data. This paper has been prepared to share LTPP's experience over the past 14 years in achieving repeatable, high-quality resilient modulus data. Specific issues addressed in the paper include the test protocol, laboratory startup and quality control procedures, quality control and quality assurance processes, and comprehensive guidelines contained in an easy-to-use, interactive CD-ROM.
Resilient Modulus — Pavement Subgrade Design Value
Authors: Boudreau RL
Published: April 2008

Much resilient modulus research work has been completed recently, mostly as part of the Long Term Pavement Performance (LTPP) study. This work has led towards the adoption of the resilient modulus test procedure, T307-99, in the current release of the American Association of State Highway and Transportation Officials (AASHTO) Tests. Neither the test procedure nor the current design guideline addresses how to approach selecting a design resilient modulus value from the fifteen stress-dependent numbers generated by the laboratory test.

Cohesive and non-cohesive subgrade soils are generally nonlinear inelastic materials, thus their stiffness is dependent on the stress condition subjected to. Recognizing this, the project-specific case study discussed in this paper examines the stress-dependency of soils encountered through laboratory determination of resilient modulus.

This paper uses a recognized constitutive model and layered elastic methodology approach (iterative solution) to objectively interpret results from a laboratory test program and apply the results for input into the 1993 AASHTO Design Guide for Pavement Structures (or DarWIN).

Through the use of the stress-dependent constitutive model: Mr = K1(Sc)K2 (S3)K5 and simple 85th percentile statistics, the process created uses the predicted subgrade modulus values at an assumed stress state. The 85th percentile value is selected as input into the 1993 AASHTO structural number (SN) requirement. A conventional pavement system (layer type and thickness) is then developed using typical mechanistic properties of asphalt concrete and aggregate base, which satisfy the SN. The layered elastic model ELSYM5 is then used to approximate vertical and horizontal stresses at the top of the subgrade layer. These stresses are compared to those assumed values used in the initial iteration. Adjustments are made and iterations continue until the values used to predict subgrade modulus reasonably match the calculated stresses in the pavement system.

The final iterated value for resilient modulus is the design resilient modulus. It is recommended that this design value be used to calculate pavement thickness requirements for all pavement types under consideration for the project.
Characterization of Resilient Modulus of Coarse-Grained Materials Using the Intrusion Technology
Authors: Titi HH , Mohammad LN , Herath A
Published: April 2008

The objective of this study was to investigate the applicability of the cone penetration test to determine the resilient modulus of coarse-grained materials. Field and laboratory investigations were conducted at the sites of two pavement projects in Louisiana. Field tests consisted of continuous intrusion miniature cone penetration tests and soil sampling. Laboratory tests included the repeated load triaxial test and other tests for materials characterization. The test results were used to develop a correlation for predicting the resilient modulus of coarse-grained materials using the cone penetration test parameters and basic soil properties. Another laboratory investigation was conducted to investigate the effect of moisture content and unit weight on the cone penetration test parameters and resilient modulus. Test results were used to validate the model developed for predicting the resilient modulus. The resilient modulus values predicted were consistent with those obtained using the repeated load triaxial test.
It's What's on the Inside that Counts - The Chemistry of Floor Polishes
Authors: Owens JM
Published: April 2008

The chemicals that are typically blended to produce a commercial floor polish are listed and discussed with an emphasis on the properties that each brings to the final formulation and polish film. The distribution and function of the components is followed through polish application and film formation.
Portable Slip Testers
Authors: Lewis PF
Published: April 2008

The world has seen a vast number of portable floor slip-resistance testers over the years. But what do they actually measure? How do they work? Which testers can be used interchangeably? And which work as effectively as the United States-recognized James Machine? This paper addresses all of these issues and discusses latest trends in floor safety.
Regulatory Issues Affecting Floor Polish
Authors: Gindling MA
Published: April 2008

This paper includes three sections. The first, “Crosslinked Floor Finishes (Zinc Metal),” reviews a position paper written by the Polishes and Floor Maintenance Division of CSPA (CSMA). Allowable zinc discharge amounts are regulated by the EPA through local POTW's (sewer districts), and are based on the receiving stream's natural zinc content. The second, “Maintenance Procedures For Flooring Containing Asbestos,” reviews a study done by the Polishes and Floor Maintenance Division of CSPA (CSMA) and the U.S. EPA. Review recommended procedures, resulting from the study, for stripping, buffing and high speed-burnishing asbestos containing floors. The third, “Americans With Disabilities Act, Accessibility Guidelines, Section. A4.5 Ground And Floor Surfaces Appendix B Slip Resistance Requirements,” reviews work done by the Polishes and Floor Maintenance Division of CSPA (CSMA) and the U.S. Architectural and Transportation Barriers Compliance Board.
Quality Control Guidelines for Factory Applied Structural Silicone Glazing
Authors: Carbary LD , Gustafson J
Published: April 2008

Factory applied structural silicone application has become the preferred method of structural silicone glazing and panel attachment within the curtainwall industry. This preference is due to the fact that the factory environment can be environmentally controlled, quality control practices are easier implemented, and supervision is readily available compared to the field environment. This paper describes the proper methods for quality control learned by the authors over the past 15 years and a description of the benefits.

Suggested architectural submittals regarding quality control guidelines for the surface preparation, structural silicone application, adhesion verification, and unit deglazing are discussed. Reporting this data in a logical fashion is essential so that a review by consultants, inspectors and / or building officials can be done. Guidelines for submitting this data are included. Interpretation of the data is a key part of this paper because the responsible parties must have a clear set of data to review to ensure the building owner of a successful project.

Included in this paper is a unique test method utilizing a portable tensile testing device to quantify accurately the structural silicone strength to verify that the installed sealant meets the minimum requirements set forth by ASTM Standard Specification for Structural Silicone Sealants (C1184-00). This quick method of testing deglazed panels can provide accurate tensile strength of the installed silicone in 24–48 hours after deglazing without destroying the curtainwall panel assembly. Immediately after testing the installed structural silicone, the curtainwall panel can be reglazed. This unique method is beneficial because the alternative pressure testing of curtainwall units to the point where the structural silicone would reach the requirements set forth in ASTM C1184 would substantially overload and destroy the curtainwall panel assembly. Suggested specification requirements regarding the type and frequency of quality control tests are given. When these requirements are followed, a reduction in the risk of failure with structural silicone glazed projects is obtained. Guidelines that are presented are state of the art, in concert with ASTM Standard Guide for Structural Sealant Glazing (C1401-02) and will ensure long-term performance of structural silicone glazed curtainwalls.
Influence of Polyester Powder Coating Chemistry on Adhesion Durability of Silicone Sealants
Authors: de Buyl F
Published: April 2008

Powder coated aluminum is one of the major substrates that is enjoying continuous market growth in window and door glazing as well as in structural glazing applications. In 1998, a European Community directive classified triglycidyl isocyanurate (TGIC) as toxic. TGIC was used as the curing agent in the fabrication of polyester powder coatings on aluminum. This environmental decision has led polyester powder suppliers to adopt new chemical compositions and to develop alternatives to TGIC-based powder coatings. These modifications have brought changes in the bulk properties and in the surface properties of the coatings, which are of particular interest with regard to the adhesion properties of silicone sealants. In this study, various commercial and developmental polyester powder coated aluminum substrates from different manufacturers were evaluated. An attempt was made to relate the surface energy, chemical composition and morphology of polyester powder coatings to the adherence of various silicone sealants. Overall, it was difficult to find a straight correlation between the adhesive bonding performances of the sealant studied and the contact angle data acquired from the various powder coating surfaces. This indicates that changes in the surface free energy due to substitution of the resins components used to prepare the coating are not solely responsible for the changes in adhesive performance of sealants. However, XPS and SEM analysis have clearly shown that in some coatings a wax is present at the surface. The presence of these waxes has a detrimental effect on subsequent adhesive bonding capabilities of silicone sealants, independent of whether a TGIC-containing or TGIC-free powder system was used. On a particular series of coatings, tensile-adhesive joint and peel-adhesive testing has shown a reasonably good correlation with conclusions from surface analysis. In particular, the higher the Polar component of the total surface energy, the better the adherence of silicone sealants was on polyester powder coated aluminum. Cleaning the coating with white spirit was effective in increasing the polar component of the total surface energy of the coating, which enhanced adhesive bonding of the silicone sealant. The effect of the silicone sealant chemistry (tin versus titanium ester catalyst, for instance) was also analyzed.
Effects on Silicone Sealant Adhesion Buildup on Float Glass Substrates
Authors: Ma JT , Chen SS , Zhou W , Wang S
Published: April 2008

Silicone sealants are widely used in building construction. Regardless whether the sealant is used in structural sealant glazing or in non-structural applications (such as weather-sealing joints), good adhesion of the silicone sealant to the building substrate is a prerequisite for good performance and long service-life (durability). Although silicone sealants typically show excellent unprimed adhesion to most building substrates, poor results have been reported occasionally, especially when sufficient care is not taken in substrate preparation. However, very occasionally, poor adhesion is observed, despite proper cleaning and priming of the substrate. Based on several years of work experience gained from laboratory testing and results obtained on thousands of substrate samples used for job site qualifications as well as from field performance inspections, the authors summarize important factors, which affect silicone sealant adhesion. These factors include sealant formulation, surface characteristics of the substrate, the effectiveness of the cleaner in removing surface contamination, et cetera. The authors' intention with this paper is to discuss each of these effects separately and to provide the sealant manufacturer and end user with useful information on how to avoid adhesion problems.