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Rheological measurements are often performed using a rotational rheometer. In this type of rheometer, the tested fluid is sheared between two surfaces, one of which is rotating [1]. Usually, an angular velocity is imposed on the fluid (through the rotating surface) and this angular velocity determines the shear rate the fluid is subjected to.^The response of the material is monitored by the measurement of the resultant torque on the shaft of the rheometer; this torque can then be converted to shear stress.^In order to calibrate a rheometer, a standard oil of known viscosity should be tested in the rheometer to verify that the instrument is operating correctly.^However, these standard oils are expensive; which makes it impractical for use in calibrating with the rheometer with a large capacity as needed for concrete.^Additional, these standard oils that are not suspensions (i.e.^they do not have solid particles suspended in the media), and thus using them may not capture some issues that may occur in a suspension rheology. Therefore, a relatively inexpensive, reference material is needed that incorporates aggregates for concrete rheometers. As concrete and mortar are non-Newtonian, the reference material should also be non-Newtonian.^This report follows the development and serves as re-certification of a Standard Reference Material (SRM) for cement paste [2].^A multiscale approach will be utilized to develop SRMs for mortar and concrete in the future.^The SRM 2492 will be the matrix fluid for a mortar SRM that will in turn become the matrix fluid for a concrete SRM.^The report SP 260-174 Rev.2012 [2] describes how this SRM 2492, a Bingham Paste Mixture for Rheological Measurements was developed and provides all the details on the various ingredients.^After an inter-laboratory study under the sponsorship of the American Concrete Institute (ACI) committee 238, Workability of Fresh Concrete, it was found that the instructions provided to prepare the SRM were inadequate to obtain reproducible data in all laboratories. Thus after establishing a better preparation method, new instructions were drafted and it was found that the certified values were no longer valid.^Thus, it was necessary to redo a series of testing to obtain a new certified value.^This report provides all measurements obtained, the calculation of the new rheological characteristics and the statistical analyses.

Standard reference materials.

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This report presents a correlated height and width measurement model for particle size analysis of spherical particles by atomic force microscopy (AFM). It is complementary to more familiar methods based on a single value of the particle height or on a line average obtained from a close-packed particle array. Significant influence quantities affecting the determination of average particle size and its uncertainty are considered for the important case of polystyrene latex (PSL) reference materials. Particlesubstrate deformation, resulting from adhesive contact between particle and substrate during sample preparation, is estimated as a function of particle size. Post-processing of AFM datasets is explored as a means of eliminating bias due to non-steady state measurement conditions. These biases arise from variable particle-tip interaction caused by drift of instrumental parameters from their optimal settings during long acquisition times and inevitable wear of the AFM probe. Changes of the initial probe shape are established using a Si/SiO2 multilayer tip characterizer and are updated periodically during the analysis of sequential data sets for combinations of several particles sizes and different probes. Finally, the capability of this procedure to serve as a statistical error-correction scheme in AFM particle-size metrology is assessed.

Atomic force microscopy. --- Polystyrene. --- Standard reference materials.

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JAPANESE LANGUAGE. --- Japanese language --- Japonés --- REFERENCE MATERIALS. --- Reverse indexes. --- Glosarios, vocabularios, etc. --- Shinmura, Izuru,

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Materials --- Standards --- Standard Reference Materials Program (National Institute of Standards and Technology (U.S.))

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Materials --- Materials --- Standards --- Standards. --- Standard Reference Materials Program (National Institute of Standards and Technology (U.S.)) --- Standard Reference Materials Program (National Institute of Standards and Technology (U.S.)) --- United States.