bluuebunny/crossref_metadata_2025 huggingface dataset:
Microgravity and Normal Gravity Combustion of Metals and Alloys in High Pressure Oxygen
Authors: Steinberg TA , Wilson DB , Benz FJ
Published: March 2009

The NASA White Sands Test Facility has completed an extensive test program aimed at evaluating the burning characteristics of metals and alloys in microgravity environments. The metals and alloys burned in 100% oxygen include rods of 2219 aluminum, 316 stainless steel, copper, nickel 200, Monel K-500, zinc, magnesium, tungsten, iron, and titanium. Sheets and meshes of 316 stainless steel were also tested to study configuration effects. All metals and alloys tested supported combustion in the absence of gravity which indicates surface tension induced circulation is sufficient to ensure fuel/oxidizer mixing. The microgravity combustion of 316 stainless steel volatilized the chromium or chromium oxide, a result that does not occur in similar normal gravity tests. In microgravity the melting surface no longer remains horizontal but becomes slanted and the molten ball obtains a spherical shape and is often observed to precess around the rod. As in normal gravity, during the microgravity burning of the rods, the regression rate of the melting surface increases with either increasing oxygen pressure or decreasing rod diameter. In microgravity, however, the regression rate of the melting surface is significantly faster than in similar normal gravity tests. Metals and alloys considered nonflammable in normal gravity up to oxygen pressures of 68.9 MPa burned at significantly lower pressures in microgravity and configurations not considered flammable in normal gravity readily burned under similar microgravity conditions. These observations are consistent with the conclusion, due to retention of the molten material during microgravity burning, that the temperature in the molten ball in microgravity is greater than in normal gravity.
A Hazards Analysis Method for Oxygen Systems Including Several Case Studies
Authors: Daniel JA , Christianson RC , Stoltzfus JM , Rucker MA
Published: March 2009

Oxygen systems and components have hazards associated with the ignitability and flammability of the constituent materials. The NASA Johnson Space Center White Sands Test Facility developed a method for analyzing the hazards of oxygen systems and components. Using this method, material flammability and the risks associated with various ignition modes were addressed. In addition, secondary hazards, such as those caused by seal leakage and the formation of oxygen-enriched environments exterior to pressure-retaining components were addressed. This hazards analysis method is presented as a systematic investigation tool and as a means of training individuals on the nature and level of severity of oxygen-enriched combustion. Three case studies drawn from work performed at the NASA Johnson Space Center White Sands Test Facility are presented. These case studies were conducted on a space flight component, an aircraft flight system, and a facility installation.
The Measurement of the Friction Coefficient and Hear of Metals in High-Pressure Oxygen
Authors: Homa JM , Stoltzfus JM
Published: March 2009

The frictional forces generated during rubbing contact of metals greatly influence the ignitability of the bulk material when exposed to high-pressure oxygen environments. Previous works have ranked the ignition susceptibility of metals by frictional heating tests and by promoted combustion tests. Variations in the rankings by these two methods have been explained by differences in the friction coefficient and the resulting differences in frictional heat generation. A material with a higher coefficient of friction will produce more heat and will therefore achieve its ignition temperature at a lower PV product, where P is the normal load divided by the rubbing area and V is the relative linear velocity between the samples. A ranking of frictional ignition data taking into account the friction coefficient was shown to agree quite well with promoted combustion rankings. To further investigate the effects of the friction coefficient on ignition, a series of pin-on-disk friction tests were performed on five selected metals. These tests measured the friction and wear of each metal during the pre-ignition phase, while exposed to high-pressure oxygen. Wear characteristics appeared dramatically different for the pin-on-disk tests compared to the hollow cylinder configuration of the frictional heating test for some materials. Among the metals tested, three types of wear were observed: a severe adhesive wear resulting in high frictional forces; a mild wear characterized by a glazed oxide coating and low friction coefficients; and an adhesive-delamination wear combined with the release of many burning wear particles. The wear configuration was found to be extremely important when assessing the frictional heating properties that lead to ignition in oxygen-enriched atmospheres.
Relationship Among Statistical Distributions, Accelerated Testing and Future Environments
Authors: Staehle RW
Published: March 2009

The relationships among future environments, accelerated testing and statistical distributions are discussed. A stepwise procedure for predicting performance is described which starts first with defining environments. Next steps include definition of modes and submodes of corrosion, the definition of materials, and superposition of environmental and mode definitions. Incorporating the dependencies of environmental variables in distribution parameters is discussed.
Corrosion Prediction from Accelerated Tests in the Chemical Process Industries
Authors: Silverman DC
Published: March 2009

Increasing pressures to move products and processes quickly out of the laboratory coupled with decreased resources for making materials evaluations have forced greater reliance on accelerated tests for making lifetime predictions. This paper discusses how combining both electrochemical and non-electrochemical tests can enable successful lifetime predictions to be made when testing must be limited. Examples are used to show that appropriate use of these tools when combined with experience which may be captured in an artificial neural network, enables the corrosion practitioner to overcome the dilemma of having to make important materials decisions from insufficient data.
Application of Service Examinations to Transuranic Waste Container Integrity at the Hanford Site
Authors: Duncan DR , Burbank DA , Anderson BC , Demiter JA
Published: March 2009

Transuranic waste containers in retrievable storage trenches at the Hanford Site and their storage environment are described. The containers are of various types, predominantly steel 0.21-m3 (55-gal) drums and boxes of many different sizes and materials. The storage environment is direct soil burial and aboveground storage under plastic tarps with earth on top of the tarps. Available data from several transuranic waste storage sites are summarized and degradation rates are projected for containers in storage at the Hanford Site.
High Level Nuclear Waste Management in U.S.A.
Authors: Verink ED
Published: March 2009

Designing a system for the safe disposal of spent fuel and high-level defense waste will require being able to predict repository performance over time spans exceeding the total known time of human existence on this planet.

Historically, primary reliance has been placed on natural (geological) barriers to prevent or retard release of radionuclides to the accessible environment. These have included crystalline rock (Sweden, Finland, Switzerland and Canada), salt domes (Germany), clay (Belgium), and tuff (U.S.A.). In all countries except the United States, the potential disposal environments are saturated with moisture. By contrast, the site at Yucca Mountain, Nevada, currently being characterized by the United States, is located in an arid climate, and the zone proposed for the repository is an unsaturated zone well above the water table. As a result, one can say that the site under evaluation in the U.S.A. is unique. It provides special opportunities and challenges with respect to radioactive waste disposal.

Recently, there has been some “erosion,” of confidence in international circles about the ability of geological barriers to provide the degree of containment originally assumed. This has led to an increased interest in a number of countries in the development of engineered barriers of various kinds that work in concert with the natural barriers. Designs under consideration cover a wide range of concepts, for example, special materials for more robust waste containers; new concepts for the emplacement of waste containers--such as room or drift emplacement; chemical control of the container environment; use of thermal energy as a design parameter, and growing interest in a more “systems oriented approach” to the storage, transportation and emplacement of spent fuel and high-level waste through the use of multi-purpose containers.

Because of increased interest in multi-purpose containers and because they may allow us to improve our ability to predict radionuclide containment over long periods of time, corrosion behavior of the various materials remains a major consideration. As experiments to predict and measure corrosion behavior are designed, we must also develop statistical methods to evaluate the data collected during these experiments.
Approaches to Life Prediction for High-Level Nuclear Waste Containers in the Tuff Repository
Authors: Beavers JA , Thompson NG , Durr CL
Published: March 2009

An assessment was performed of approaches to life prediction for high-level nuclear waste containers. It was concluded that the commonly used remaining life assessment techniques are inadequate for the prediction of performance of the waste canisters primarily because of the reliance on empirical damage accumulation laws. The best hope for prediction of performance of the repository relies on utilizing mechanistic models based on first principles. It was further concluded that prediction of performance of the waste containers should rely primarily on propagation phenomenon, because of the uncertainties in proving that initiation will not occur.

The above philosophy imposes significant restrictions on the selection of container materials, and selection of the repository site. The materials selection for the waste canister should focus on corrosion allowance materials because the general corrosion rate can be bounded and the rates of pitting corrosion are expected to be much lower than for corrosion resistant materials. Corrosion resistant materials should be avoided because the probability of pit initiation is high for the range of possible environments and the rates of pitting corrosion are expected to be high, as a result of hydrolysis reactions. In order to reduce possible rates of localized corrosion, an anoxic repository should be selected. Because of the uncertainties in the predictive capability of the mechanistic models, corrosion monitoring, and a multiple barrier design for the waste package should be used.
Crack Growth Behavior of Candidate Waste Container Materials in Simulated Underground Water
Authors: Park JY , Shack WJ , Diercks DR
Published: March 2009

Fracture-mechanics crack growth tests were conducted on 25.4-mm-thick compact tension specimens of Types 304L and 316L stainless steel and Incoloy 825 at 93°C and 1 atmosphere of pressure in simulated J-13 well water, which is representative of the groundwater at the Yucca Mountain site in Nevada that is proposed for a high-level nuclear waste repository. Crack growth rates were measured under various load conditions: load ratios of 0.2–1.0, frequencies of 2 × 10@4-1 Hz, rise times of 1–5000 s, and peak stress intensities of 25–40 MPa˙m1/2. The measured crack growth rates are bounded by the predicted rates from the current ASME Section XI correlation for fatigue crack growth rates of austenitic stainless steel in air. Environmentally accelerated crack growth was not evident in any of the three materials under the test conditions investigated.
Correlation of Autoclave Testing of Zircaloy-4 to In-Reactor Corrosion Performance
Authors: Parkins RA , Shann S-H
Published: March 2009

As the service environment for core materials for Pressurized Water Reactors (PWRs) becomes more severe due to increases in water temperature, changes in water chemistry, longer cycle lengths and higher burnups; the corrosion performance of Zircaloy-4 which is used for fuel cladding and structural components becomes more important. The standard three day, 400°C steam autoclave test which has been used to evaluate the uniform corrosion resistance of Zircaloy-4 is no longer sufficient. Some cladding which has given acceptable results in this test has not exhibited satisfactory in-reactor corrosion performance. A series of cladding types for which in-reactor corrosion measurements are available has been subjected to extended autoclave testing in steam at 400 and 415°C. A better correlation to the in-reactor performance is obtained if the 400 °C test is extended to at least 100 days or if the test temperature is raised to 415°C. At 415°C, a test duration of three days is best for evaluating Zircaloy-4 since extended time does not improve the correlation.
Corrosion Life Prediction of Oil and Gas Production Processing Equipment
Authors: Kolts J , Buck E
Published: March 2009

A large number of tools are used in corrosion life prediction of new oil and gas facilities during engineering of these projects. The corrosion prediction tools are generally based on laboratory tests and are occasionally verified by field performance. These tools are described in this paper.
A New Index for the Crevice Corrosion Resistance of Materials
Authors: Xu Y , Pickering HW
Published: March 2009

Recent studies have revealed the crucial role played by the macro corrosion cell (potential coupling between the inside and outside of a cavity) in crevice and pitting corrosion. It was found that acidification and the existence of chloride ions in the local cell are not the sole and necessary conditions for localized corrosion to occur, and that their accelerating effects on crevice corrosion and pit growth can be explained within the framework of the macro cell (the IR voltage mechanism). Upon analysis of the results of the experiments, quantitative modeling, and the literature, a new characteristic parameter - the critical distance into the crevice, dc - has been suggested for indexing the crevice corrosion resistance of a material under specified conditions. The advantages of using dc as the index of the crevice corrosion resistance are: (1) it may be obtained through experiment and may also be estimated through computational approaches; (2) it has a distinct and straightforward physical meaning; (3) it may be employed in engineering design and (4) it is a single parameter which can reflect the integrated influence of several factors known to affect the crevice corrosion resistance of a material from past practical experience and research work. Preliminary work has shown good agreement between the measured and the computed values of dc. The experimental technique and the principle of the mathematical approach to obtain dc are described.
Application of a Multipotential Test Method for Rapid Screening of Austenitic Stainless Steels in Process Environments
Authors: Aaltonen PA , Pohjanne PK , Tähtinen SJ , Hänninen HE
Published: March 2009

The advantage of using MultiPotential Test, MPT, method together with, for example, double U-bend specimens is that in a single exposure a wide variety of corrosion phenomena can be screened in any environment. The MPT method has been applied in several tests both in simulated environments and in real process conditions. The measurement of threshold potential for stress-corrosion cracking of cold deformed and sensitized stainless steels in simulated boiling water reactor environment (BWR) is an example of successful applications of the MPT method. The MPT method applies a current source combined with potentiostat and resistors to polarize different specimens to desired potentials. The electrochemical potential range, which can be obtained, depends on the electrical instrumentation and also on the conductivity of the electrolyte.
Spot-Welded Specimen Maintained Above the Crevice-Repassivation Potential to Evaluate Stress Corrosion Cracking Susceptibility of Stainless Steels in NaCl Solutions
Authors: Tsujikawa S , Shinohara T , Lichang W
Published: March 2009

A test is proposed to evaluate the susceptibility of austenitic stainless steels to SCC, particularly in low-concentration chloride solutions. A spot-welded specimen with both a crevice and residual stresses was immersed in the NaCl solutions, and kept potentiostatically for 72 hours at a potential slightly above the crevice repassivation potential with no additional applied stress. This method was also adopted in the development of an improved SCC resistant type 304 steel. The SCC critical temperature was measured for a group of 52 highly purified steels in which the P, Cu, Mo and Al contents were systematically varied. A 14Cr-16Ni-0.013P-2CU-1A1-(0.3̃1) Mo steel was found to have a high critical temperature of HOC, which is markedly higher than that of the conventional type 304 steel (50C) and therefore, it is a good candidate for industrial applications.
Constant Extension Rate Testing and Predictions of In-Service Behavior: The Effect of Specimen Dimensions
Authors: Louthan MR , Porr WC
Published: March 2009

Constant extension rate test measurements of a material's susceptibility to environmental degradation may depend on the dimensions of the test specimen. Long, slender samples will appear to be more susceptible to degradation than will short, thick samples of the same material. This sample size effect is due to the importance of the tearing modulus on the onset of unstable fracture. Therefore, if constant extension rate tests are used to qualify materials for in-service applications, the effect of specimen size on test results should be evaluated.
Applications of Electrochemical Potentiokinetic Reactivation Test to On-Site Measurements on Stainless Steels
Authors: Verneau M , Charles J , Dupoiron F
Published: March 2009

The aim of the paper is to present some applications of the Electrochemical Potentiokinetic Reactivation (EPR) technique to the characterization of the corrosion resistance of stainless steels apparatus.

In particular, the use of the technique to the detection of chromium depletions on insufficiently pickled austenitic steels is explained. The application of the method to determine the degree of sensitization of duplex stainless steels by intermetallic phase precipitations is also discussed.

Then, the paper presents the possibility of use of the EPR test for on-site measurements, with a portable equipment.
New Electrochemical Method to Evaluate the Atmospheric Corrosion Resistance of Stainless Steels
Authors: Muto I , Sato E , Ito S
Published: March 2009

The quantitative evaluation of atmospheric corrosion resistance of stainless steels exposed to a marine environment was carried out by using a newly developed electrochemical method. This new method simulates field atmospheric conditions where most of stainless steels experience rust staining under a thin electrolyte layer. The incubation time to the breakdown of passive film under a thin electrolyte layer corresponds to the rating number of initial rust staining of the specimen exposed to the actual environment for 1 year, and depends on alloy compositions. Through the analysis of change in the rating number of the specimens exposed to the marine environment for 10 years, it was clarified that tendency of the change of rating number was directly related to exposure time, not to alloy compositions. The rating number of rust staining of stainless steels after several years can be predicted from the equation introduced through the results of both the accelerated test and the exposure test.
An Assessment of Fe-Cr-Mn Austenitic Alloys for Fusion Service Using Fast Reactor Irradiation
Authors: Garner FA , McCarthy JM
Published: March 2009

A series of model Fe-Cr-Mn alloys and various solute-modified high manganese alloys have been irradiated in the Fast Flux Test Facility in order to provide an early assessment of the consequences of substituting manganese for nickel in austenitic stainless steel. The purpose of this substitution is to reduce the level of long term radioactivation of this alloy, a candidate structural material for use in fusion energy devices.

Simple Fe-Mn and Fe-Cr-Mn alloys were found to exhibit much of the same behavior observed in Fe-Ni and Fe-Ni-Cr alloys. In particular, they tend to swell at ∼1%/dpa after an incubation period that is dependent on irradiation temperature, alloy composition and cold working. The phase stability, both in and out of reactor, is altered substantially by the substitution of manganese, however. It nonetheless appears that appropriate levels of solute modification can be used to improve both the swelling resistance and phase stability. An alloy with a base composition of Fe-20Mn-15Cr appears to offer the best promise for further research.
The Dependence of ☌-Phase Formation in Fe-Cr-Mn Alloys on Cold Work, Aging, and Alloy Composition
Authors: Okazaki Y , Mochizuki M , Miyahara K , Hosoi Y
Published: March 2009

High manganese and high chromium steels are attractive as low activation materials for fusion reactors. The microstructural stability of Cr-Mn steels during long term service at around 873 K, however, is not yet fully understood. This study is aimed toward the study of changes in microstructure and mechanical properties of Fe-(12 to 16%)Cr-(10 to 30%)Mn alloys during aging in the temperature range from 773 K to 973 K for up to 3.6 Ms(1000 hrs).

As a solution treated at 1373 K for 3.6 ks, a microstructure of α′ + ε + γ is observed in the 15%Mn alloy, ε + γ in 20 to 25%Mn alloys and γ in the 30%Mn alloy, σphase formation is not observed in Fe-12%Cr-Mn alloys except at 30%Mn after aging at 873 K for 3.6 Ms. However, straining by rolling (50%in reduction at room temperature) prior to aging accelerates cr-phase formation. All of the strained Fe-12%Cr-Mn alloys form σphase during aging. In the case of 16%Cr alloys, σphase formation occurs more easily. There are three kinds of mechanisms for σphase formation depending on the manganese content, and increase in manganese content accelerates σ-phase formation.

These results suggest that the effect of manganese on σ-phase formation is different from the result shown in the Fe-Cr-Mn alloy diagram published by Schafmeister and Ergang.
Optimization of Reduced Activation Ferritic Steels
Authors: Abe F , Noda T , Araki H , Okada M
Published: March 2009

In order to develop potential reduced-activation ferritic steels for fusion reactor structures, phase stability, toughness and creep rupture strength were investigated for Cr-W and Cr-V steels. Primary concern focused on 9% chromium steels because of their superior high temperature strength compared to low chromium steels. The Cr-W steels exhibited a similar precipitation behavior to carbides and intermetallic compound with conventional Cr-Mo steels while the Cr-V steels exhibited a quite different behavior. Creep rupture strength of 9Cr-2 steels increased but their toughness decreased with increasing the tungsten concentration. A martensitic 9Cr-lW steel showed an excellent toughness. On the other hand, both toughness and creep rupture strength of 9Cr-V steels were poor. The minor additions of vanadium, tantalum, and boron to the 9Cr-lW steel significantly increase creep rupture strength without the degradation of its excellent toughness.
Low Chromium Reduced-Activation Ferritic Steels
Authors: Klueh RL , Maziasz PJ
Published: March 2009

Steels are being developed for fusion reactor applications containing only elements that produce radioactive isotopes that decay to low levels in a reasonable time. These reduced-activation or fast induced-radioactivity decay ferritic steels are being developed to be analogous to the Cr-Mo steels presently in the fusion program, but with molybdenum replaced by tungsten. In this paper, steels with 2.25% chromium will be discussed. To determine the effect of tungsten and vanadium on these steels, heats were produced with 2% tungsten, with 0.25% vanadium, with 1% tungsten and 0.25% vanadium, and with 2% tungsten and 0.25% vanadium. Tempering and microstructural studies were made and tensile and impact tests were conducted. Preliminary results indicate developing a low chromium Cr-W steel without molybdenum or niobium should be possible. Such steels should have properties as good as or better than the three Cr‐Mo steels presently being considered as candidates for fusion reactor applications.
The Post-Irradiation Tensile Properties and Microstructure of Several Vanadium Alloys
Authors: Braski DN
Published: March 2009

Tensile specimens of V-15Cr-5Ti, Vanstar-7, V-3Ti-lSi, and V-20TJ were irradiated at 420°C in FFTF-MOTA to a damage level of 82 dpa. Helium was preimplanted to levels up to 480 appm in selected specimens using a modified tritium trick. Irradiation hardeningwas the dominant effect influencing the post irradiation tensile properties, and it markedly increased the yield strength and reduced the total elongation. The V-15Cr-5Ti alloy was very sensitive to helium embrittlement, but Vanstar-7 and V-3Ti-lSi were only slightly affected. Without helium, negligible swelling was found in V-15Cr-5Ti and Vanstar-7, and only small values of swelling (<1%) were measured in V-3Ti-lSi and V-20Ti. Preimplanted helium increased swelling in V-3Ti-lSi by increasing cavity nucleation.
A TEM Study of V and V-lat.%10B with Fast Neutron Irradiations
Authors: Kawanishi H , Ishino S
Published: March 2009

A boron doping technique was employed to determine the microstructural response to differences in the rate of helium generation in vanadium under fission and fusion irradiation environments. Helium is enriched in the regions around boride and somewhat in the matrix due to (n,α) reactions, when boron doped alloys are irradiated in a fission reactor. The approach is achieved by microscopy examination of the helium-rich regions adjacent to boride and those beyond the helium region, or by comparison of the microstructure in materials doped and undoped with boron. The specimens with the compositions of V, V-lat.%10B and V-0 6at.%10B-0.9at.%11B were prepared. The irradiations were performed at 673 K up to 0.75 × 1025 n/m2 (0.3 dpa) in the fast breeder experimental reactor JOYO. Helium generation by the transmutation of 10B(n,α)7Li was estimated in the present case to be mainly due to epithermal neutrons with the energy <100 eV. This paper describes the results of (TEM) observations following the irradiations. A high density of cavities were produced with smaller sizes near V3B2 precipitates, depending on the precipitate size and the distance from the precipitate surface. This was mainly attributed to the effects of lithium products around the precipitates, while helium products exhibited the tendency of reducing swelling slightly. The swelling in the matrix without the precipitates has been recognized to be lower in unalloyed vanadium than that in boron doped alloys, though the degree is rather small. It has been confirmed that helium reduces the number densities of cavities, accompanying the decrease of their sizes at the early stage of the irradiation (0.3 dpa) at 673 K. In addition, it was shown that the irradiation of vanadium induces the uniform precipitation of thin platelets with a lattice parameter of about 0.41 nm.
Defect Behavior and Microstructural Evolution in Vanadium-Base Alloys Under Irradiation in a High-Voltage Electron Microscope
Authors: Muroga T , Araki K , Yoshida N
Published: March 2009

The formation and growth of dislocation loops have been investigated under irradiation in the high-voltage electron microscope (HVEM) for the V-20Ti and V-3Ti-lSi alloys at temperatures ranging from 100°C to 350°C. In all cases, the loop number density increased, reaching saturation. The dependence of the saturated loop density on the temperature and the irradiation intensity showed that, in either alloy, the interstitials are deeply trapped by matrix impurities providing the loop nucleation sites at lower temperatures. In the case of the V-3Ti-lSi alloy, di-interstitials are expected to be the effective loop nuclei at higher temperatures. The temperature dependence of loop growth rate showed the effective vacancy migration energy of 1.36 eV and 1.22 eV for the V-20Ti and V-3Ti-lSi alloy, respectively. The present experiments showed some characteristic sample degradation (local bending, contamination) during in-HVEM annealing or irradiation suggesting a need for careful heat or environmental control.
Initial Rate of Absorption of Clay Brick Considering Both Bed Surfaces in the as Received Condition and After Outside Exposure
Authors: Bailey WG , Matthys JH , Edwards JE
Published: March 2009

The initial rate of absorption test (suction) on a clay brick unit is generally conducted in the laboratory according to ASTM c-67. This test attempts to represent the effect of the unit on pulling water out of the mortar during assemblage construction. In ASTM C-15 committee work, two questions that have been raised are: 1) Is the IRA of a unit the same for both bed surfaces that will be in contact with mortar? 2) When as received units are exposed to typical Texas heat, is the IRA significantly affected?

To address these questions a project was conducted at The University of Texas at Arlington. In addition data was requested and received from various U.S.A. brick manufacturerers. Analysis of this data provided answers to the above questions.
Recommended Test for Slip Resistance on Brick Surfaces
Authors: Trimble BE
Published: March 2009

This paper examines current slip resistance test procedures and recommends an appropriate test method for use on brick surfaces. The current ASTM standard for paving brick, ASTM C 902-89a, Standard Specification for Pedestrian and Light Traffic Paving Brick acknowledges the need for considering skid/slip resistance; yet there is not a recommended test procedure to use. Other countries have tests and values for slip resistance on brick surfaces, as well as this country for materials similar to brick. Various test methods that are available for measuring slip resistance are discussed including advantages/disadvantages of each test in regard to brick surfaces. This paper also recommends an action to implement the test into appropriate ASTM standards. This paper addresses slip resistance only.
Effects of Aggregate Gradation on Properties of Masonry Cement and Portland Cement-Lime Masonry Mortars
Authors: Buchanan CE , Call BM
Published: March 2009

Eight laboratories participated in a round robin to evaluate variations in aggregate gradation when tested using Masonry cement and Portland cement-lime masonry mortars. A control gradation was used which,was near the center of C144 gradation limits and five other gradations were used which tested the limits of C144. It appears from the data that the limits on C144 can be broadened without appreciably altering the safety built in for user protection. Although not part of the original test program, a study was made of the yield of the various mortars produced, and it was determined that the masonry cements had on average a 5.3% increase in volume over the Portland cement-lime mixes.
Performance of Mortars Produced Under the Proportion Specification of ASTM C-270-86a
Authors: Matthys JH
Published: March 2009

ASTM C-270-86a “Mortar For Unit Masonry” lists different types of mortars (i.e., M, S, N, O) that can be produced from a proportion or a property specification. This is the first ASTM C-270 standard that has allowed the use of masonry cements as the only cementitious material for all the mortar types under the proportion specification. The Construction Research Center at the University of Texas at Arlington has conducted a comparative performance study of Portland cement lime (Type S lime) mortars to ASTM equivalent masonry cement (MC) mortars to determine whether mortars produced by the proportion specification meet the performance specification requirements of ASTM C-270. Eleven mortars consisting of eight masonry cement mortars and three Portland cement lime mortars were evaluated.
IRA and the Flexural Bond Strength of Clay Brick Masonry
Authors: McGinley WM
Published: March 2009

During a recent experimental investigation at the North Carolina A&T State University, the flexural bond strength of a variety of clay bricks and two masonry cement mortars were evaluated. Twenty prisms, comprising ten different brick types and two mortar types, were tested with a bond wrench testing apparatus to determine the flexural bond strengths of each mortar joint of the seven course prisms. Although the investigation only tested a limited number of prisms, the results of these tests indicated that the initial rate of absorption (IRA) of the brick units can have a greater influence on the flexural bond strength of the masonry assembly than is generally accepted by the masonry industry.

The experimental program is described, its results presented and the apparent effects of brick IRA on flexural bond are discussed.
A Compilation of Flexural Bond Stresses for Solid and Hollow Non-reinforced Clay Masonry and Portland-Lime Mortars
Authors: Gabby BA
Published: March 2009

The purpose of this paper is to make a general comparison of compiled flexural tensile stress values which were determined by using one of three standard test methods. The material in this paper was gathered from seventeen reports which used one or two of the following test methods: ASTM E 72, ASTM E 518 and ASTM C 1072. All of the flexural tensile stress values collected are those normal to the bed joints for solid and hollow non-reinforced clay masonry and Portland cement-lime mortar. The reports used contain specimens which were air cured and broken at or around twenty-eight days.
Nondestructive Evaluation of Masonry: An Update
Authors: Noland JL , Kingsley GR , Atkinson RH
Published: March 2009

Nondestructive evaluation (NDE) of masonry has been, to date, essentially an adaptation of available methods which have been used for evaluation of concrete. There has been an increasing amount of study and application of these methods in recent years. Limitations on the efficiency and utility of these methods has been observed. Improved methods of NDE of masonry are needed. Recent NDE developments in the medical, aerospace and other fields should be studied for their application to masonry.
Compression Tests of Hollow Brick Units and Prisms
Authors: Brown RH , Borchelt JG
Published: March 2009

It is customary to relate the compressive strength of the masonry to that of its components: mortar and units. The correlation between solid unit compressive strength, mortar type and assemblage compressive strength is well documented, and is generally independent of unit coring. The relationships of prism components and prism dimensions to assembly compressive strength and modulus of elasticity for hollow brick are presented in this paper.

Hollow brick meeting the requirements of ASTM C 652 in four widths were selected. Portland cement-lime mortars, Type N, S, M by proportions, were used. Both face-shell and full mortar bedding were used to construct prisms with height to thickness ratios from 2 to 5. Mortar, brick and prisms were tested in compression. Deformations measured during prism testing permitted the determination of modulus of elasticity in compression.

Hollow unit masonry prisms fail by tensile splitting of the crosswebs, regardless of their aspect ratio. Prism compressive strength and modulus of elasticity are influenced least by fully bedded, stack bond prims. Compressive strengths of prisms made from hollow brick have similar relations to h/t and mortar strength as prisms of solid brick, but less dependence on unit strength.
A Discussion of the Abuse of Some Common Masonry Industry Practices
Authors: Crooks RW , Herget FA
Published: March 2009

Theory and practical experience have been combined to develop standard practices for the design and construction of exterior masonry walls. Such practices have been presented in the literature and have stood the test of time. Strict adherence to these practices is critical with todays thinner masonry walls where abuse often results in costly repair or replacement of the masonry. Examples of some of the more typical abuses the authors have observed and subsequent repairs in the areas of workmanship, moisture control and differential movement are presented.
Problems & Cures in Masonry
Authors: Tomassetti AA
Published: March 2009

Although masonry construction is one of the best types of building methods known to man for cost, durability, beauty, and maintenance, it is subjected to certain problems, on occasion, due to short-comings in design, workmanship, and misuse of materials.

Some of the subjects covered are vari-colored mortar joints, efflorescence, blush (caused by surface coatings), lime deposit (also called lime runs and lime spots), metal wall caps, expansion due to thermal and moisture changes, creep, cleaning, stains, and mortar dry-outs.

All of the problems mentioned here are supported by slides of examples taken from “real” buildings and are coordinated with the material contained in this paper.
Research of Physical Properties of Masonry Assemblages Using Regional Materials
Authors: Laska WA , Ostrander CW , Nelson RL , Munro CC
Published: March 2009

A masonry research program was conducted in the Metropolitan Chicago market to determine certain physical properties of wall assemblages incorporating ASTM C652 [1] brick and different sizes of ASTM C90 [2] concrete masonry units. The purpose of the program is to make design professionals aware of testing masonry assemblies and the realistic values that can be obtained by using locally available masonry materials. This is necessary many times due to a lack of confidence or the absence of knowledge on the part of some designers of the adherent strength that masonry material possess. This paper consists of the following sections: Brick and concrete masonry units ASTM C652 [1], ASTM C90 [2], C140 [3] Mortar ASTM C270 [4] Concrete masonry unit prisms ASTM E447 [5] Brick prisms ASTM C1072 [6]
Concrete Masonry Prism and Wall Flexural Bond Strength Using Conventional Masonry Mortars
Authors: Matthys JH
Published: March 2009

ASTM C270-86a “Mortar For Unit Masonry” lists different types of mortar (i.e., M, S, N, O) that can be produced from either a proportion or a property specification. This is the first ASTM standard that has allowed the use of masonry cements alone in production of all mortar types via the proportion specification. There has been concern by some members of the building community with regard to masonry assemblage performance of such mortars. The Construction Research Center at the University of Texas at Arlington has conducted an investigation of the flexural bond strength of stack bonded prisms using ASTM C 1072 Bond Wrench Technique and full scale 4' × 8' walls. This paper describes the results of prisms constructed using eight masonry cement mortars and three portland cement lime mortars. Prisms are evaluated at 28 days and six months age. Both laboratory curing and outside curing are examined. The wall tests evaluate two Type S mortars at 28 days.
Towards Developing a Flexural Strength Design Methodology for Concrete Masonry
Authors: Hamid AA , Assis GF , Harris HG
Published: March 2009

In order to develop an appropriate flexural strength design methodology for concrete masonry, information about the nonlinear stress distribution in the compression zone is needed. This paper presents experimental results from grouted concrete masonry prisms tested under eccentric compression loading in the out-of-plane direction which is part of Task 1.2 (a) of the U.S.-Japan Coordinated Program on Masonry Building Research. The stress parameters k1k3 and k2 are presented for 150 mm (6 in.) concrete masonry and are used to predict the ultimate moment capacity of full-scale reinforced masonry walls. Good agreement was obtained between the predicted and the experimental moment capacities. An equivalent rectangular stress block is presented. It is concluded that a design methodology similar to that for reinforced concrete is feasible for grouted concrete masonry.
The Threshold Concentration of Chloride in Concrete for the Initiation of Reinforcement Corrosion
Authors: Hansson CM , Sørensen B
Published: March 2009

The mechanism by which chlorides initiate corrosion is by locally breaking down the passive film which forms on steel in the highly alkaline concrete pore solution. However, the breakdown of passivity requires a certain concentration of chlorides. The aim of the project described in the paper has been to determine the influence of a number of factors on the critical concentration of Cl- necessary for initiation of corrosion of steel embedded in concrete. The variables investigated include hardening conditions, water/cement ratio, cement type, reinforcing steel surface condition, and salt type.

Mortar samples containing a steel rod have been cast, hardened, and subsequently exposed to a sodium chloride or calcium chloride solution. The corrosion current of the embedded steel has been monitored electrochemically and initially was of the order of 10-4 A/m2, corresponding to a corrosion rate of approximately 0.1 μm/year from the steel surface. After a period of time, the corrosion current increased by several orders of magnitude indicating that the chloride had penetrated to the steel surface and had initiated corrosion. The rate of this penetration, the chloride concentration in the mortar adjacent to the steel at the onset of corrosion, and the subsequent corrosion rate have all been measured to determine the influence of the preceding variables.
Corrosion Rate Determination on Repaired Reinforced Concrete Specimens
Authors: Wheat HG
Published: March 2009

The repair and maintenance of reinforced concrete structures is becoming increasingly important as structures become older and the use of condition surveys becomes more extensive. Although guidelines exist for repair methods, little is known about the corrosion behavior once repairs are made. In this investigation, electrochemical tests typically used on reinforced concrete specimens were used on repaired specimens which were subjected to wet (3.5% sodium chloride (NaCl) solution) and dry cycling. Repaired specimens made with a water/cement ratio of 0.6 and patched with a common repair material showed rust staining, severe delamination, and cracking after a number of cycles while the typical (control) samples did not. Although both types of specimens had comparable corrosion potentials, linear polarization measurements showed that Rp was lower, and therefore corrosion rates in the repaired specimens were higher than in the control specimens.
Measuring the Rate of Corrosion of Steel in Concrete
Authors: Escalante E , Ito S
Published: March 2009

A study on the relationship of pH, chloride concentration, and oxygen concentration shows that a drying cycle, which locally concentrates chloride and oxygen, initiates the corrosion of steel in concrete. Once corrosion is initiated, the pH at the anodic areas decreases allowing corrosion to proceed more easily. Oxygen controls the rate of corrosion, but chloride affects the number of sites where corrosion initiates.

Using a small portable computer system that applied the technique of polarization resistance with current interruption for elimination of iR error, the voltage measurement error generated when current flows through a resistive media, the corrosion of steel in concrete was measured in the laboratory. The portable system was then used to perform preliminary rate of corrosion measurements on reinforcing steel in three bridge decks in Frederick County, Maryland.
Study of the Corrosion of Concrete Reinforcement by Electrochemical Impedance Measurement
Authors: Lemoine L , Wenger F , Galland J
Published: March 2009

Electrochemical impedance measurement is a convenient method to analyze the corrosion phenomena of steel in concrete. A data analysis method is used on the basis of an equivalent circuit correlated to the properties of concrete and electrochemical mechanisms. The different parts of the diagram versus frequency allow characterization of the concrete cover, the presence of a film at the surface of steel, the transfer resistance connected to the anodic reaction, and some other relaxation phenomena. Some agreement has been obtained with mass losses.

A mathematical model has been developed in order to analyze the results on large concrete beams with a small-size auxiliary electrode. Particular emphasis is given to the spatial location of an active area in order to demonstrate the feasibility of such a method either on large specimens or on real structures. For this application, the principle of an alternative method was developed. An auxiliary electrode is used with an electrical guard. At low frequencies (<10 Hz), the first experimentation gives encouraging results.
Potential Mapping and Corrosion of Steel in Concrete
Authors: Elsener B , Böhni H
Published: March 2009

The results of potential mapping surveys of bridge decks of the Swiss highways, using a new eight-wheel electrode measurement system, are reported here. A comparison of the state of corrosion of the rebars (obtained by visual inspection after removing the concrete cover), including the potential fields in addition to theoretical considerations, clearly demonstrates that an absolute potential value (that is, -350 mV copper sulfate electrode (CSE) as proposed in ASTM Test for Half-Cell Potentials of Uncoated Reinforcing Steel in Concrete (C 876-80) for the identification of active corrosion of steel in concrete does not exist. Combining the local potential gradient on the surface with information on the electrical resistivity of the concrete (measured with the four-point method or a-c impedance) allows determination of a rough estimate of the corrosion rate in a single macrocell. Impedance spectroscopy, well suited for studying corrosion mechanisms in the laboratory, was found to be too time consuming and difficult to interpret in field measurements. Instead, a very rapid new technique—using galvanostatic pulse measurements—was tested successfully on site. It gives clear, unambiguous results on the corrosion state of the rebars, when half-cell potential measurements are uncertain.
The Use of a Potential Wheel to Survey Reinforced Concrete Structures
Authors: Broomfield JP , Langford PE , Ewins AJ
Published: March 2009

The design, construction, and use of a Potential Wheel is discussed. Its application for determination of corrosion of steel in concrete is explained with brief case histories. Laboratory tests of reproducibility and temperature effects are presented.
Mechanisms of Corrosion of Steel in Concrete
Authors: Borgard B , Warren C , Somayaji S , Heidersbach R
Published: March 2009

The corrosion of metals in concrete is a multibillion dollar problem which affects the construction, transportation, and many other industries. While much has been written about the problem, and numerous reports have appeared which discuss how this corrosion can be controlled, little has appeared on the mechanism whereby this corrosion occurs.

It is well known that highway structures corrode, for the most part, due to the influence of deicing salts or marine environments. Relatively little has appeared about the equally severe corrosion problems which occur in buildings and other nonhighway structures. Most of these structures are not exposed to the salts present in highway structures, yet they still corrode.

This paper discusses how all forms of concrete and similar cementitious environments protect embedded metals. It discusses the three protection mechanisms—passive film formation, changes in the conductivity of the electrolyte, and mineral scales—that have been used to explain how corrosion in concrete occurs. It also presents evidence to explain how, and why, corrosion occurs in these structures, even in the absence of deicing salts, marine environments, or other salt sources. Examples are discussed including buildings, marine piers, foundations, and highway structures.