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    ASTM C702-98(2003)

    Historical Standard: Práctica normativa para Reducir las muestras de agregados a tamaño de prueba

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    Significance and Use

    Specifications for aggregates require sampling portions of the material for testing. Other factors being equal, larger samples will tend to be more representative of the total supply. This practice provides procedures for reducing the large sample obtained in the field or produced in the laboratory to a convenient size for conducting a number of tests to describe the material and measure its quality in a manner that the smaller test sample portion is most likely to be a representation of the larger sample, and thus of the total supply. Failure to carefully follow the procedures in this practice could result in providing a nonrepresentative sample to be used in subsequent testing. The individual test methods provide for minimum amount of material to be tested.

    Under certain circumstances, reduction in size of the large sample prior to testing is not recommended. Substantial differences between the selected test samples sometimes cannot be avoided, as for example, in the case of an aggregate having relatively few large size particles in the sample. The laws of chance dictate that these few particles may be unequally distributed among the reduced size test samples. Similarly, if the test sample is being examined for certain contaminants occurring as a few discrete fragments in only small percentages, caution should be used in interpreting results from the reduced size test sample. Chance inclusion or exclusion of only one or two particles in the selected test sample may importantly influence interpretation of the characteristics of the original sample. In these cases, the entire original sample should be tested.

    1. Alcance

    1.1 La presente práctica cubre tres métodos para la reducción de muestras grandes de agregado al tamaño adecuado para ensayo utilizando técnicas que tienen la intención de minimizar las variaciones en las características medidas entre las muestras de ensayo seleccionadas de esta manera, y la muestra grande.

    1.2 Los valores en unidades SI deberán ser considerados como la norma.

    1.3 La presente norma no pretende cubrir todas las cuestiones de seguridad, en su caso, asociadas con su uso. Es responsabilidad del usuario de la presente norma establecer prácticas sanitarias y de seguridad apropiadas y determinar la aplicabilidad de las limitaciones normativas antes de su uso.

    2. Documentos Citados

    C125 Terminology Relating to Concrete and Concrete Aggregates

    C128 Test Method for Density, Relative Density (Specific Gravity), and Absorption of Fine Aggregate

    D75 Practice for Sampling Aggregates