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Certification of SRM 2493: Standard Reference Mortar for Rheological Measurements

出版	U.S. Department of Commerce, National Institute of Standards and Technology, 2017
URL	http://books.google.com.hk/books?id=ZS77swEACAAJ&hl=&source=gbs_api

註釋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 acts as the rotating surface [1]. Usually, the rotational velocity is imposed and the response of the material is monitored by the measurement of the torque. Typically, manufacturers of rheometers recommend using a standard oil of known viscosity to verify that the instrument is operating correctly. However, these oils are expensive, and they cannot be used for the large volumes employed in concrete rheometers. Furthermore, the oils do not contain aggregates and may not offer a valid representation of concrete since concrete is a suspension with solid particulates and display non-Newtonian behavior. Therefore, a relatively inexpensive, accurate standard reference material (SRM) for concrete rheometers is needed. The development of this new SRM is based on a multiphase approach: (1) the first phase established the SRM 2492 for cementitious paste mixtures [2], (2) the second phase developed and certified the mortar phase SRM 2493, and (3) the completion of an SRM 2497 for concrete mixtures will mark the third stage. This third stage is currently in progress. The purpose of this report is to describe the process used to certify SRM 2493, a Standard Reference Mortar for Rheological Measurements. The results of the rheological testing used to determine the rheological characteristics of SRM 2493 are discussed, along with the corresponding statistical analyses that was conducted to certify that the proposed models and reference values are valid.