ASTM C42/C42M-11

    Historical Standard: Método Normalizado de Ensayo de Obtención y Ensayo de Núcleos Perforados y Vigas Aserradas de Concreto


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    Significance and Use

    This test method provides standardized procedures for obtaining and testing specimens to determine the compressive, splitting tensile, and flexural strength of in-place concrete.

    Generally, test specimens are obtained when doubt exists about the in-place concrete quality due either to low strength test results during construction or signs of distress in the structure. Another use of this method is to provide strength information on older structures.

    Concrete strength is affected by the location of the concrete in a structural element, with the concrete at the bottom tending to be stronger than the concrete at the top. Core strength is also affected by core orientation relative to the horizontal plane of the concrete as placed, with strength tending to be lower when measured parallel to the horizontal plane. These factors shall be considered in planning the locations for obtaining concrete samples and in comparing strength test results.

    The strength of concrete measured by tests of cores is affected by the amount and distribution of moisture in the specimen at the time of test. There is no standard procedure to condition a specimen that will ensure that, at the time of test, it will be in the identical moisture condition as concrete in the structure. The moisture conditioning procedures in this test method are intended to provide reproducible moisture conditions that minimize within-laboratory and between-laboratory variations and to reduce the effects of moisture introduced during specimen preparation.

    There is no universal relationship between the compressive strength of a core and the corresponding compressive strength of standard-cured molded cylinders. The relationship is affected by many factors such as the strength level of the concrete, the in-place temperature and moisture history, and the strength gain characteristics of the concrete. Historically, it has been assumed that core strengths are generally 85 % of the corresponding standard-cured cylinder strengths, but this is not applicable to all situations. The acceptance criteria for core strength are to be established by the specifier of the tests. ACI 318 provides core strength acceptance criteria for new construction.

    The apparent compressive strength of concrete as measured by a core is affected by the length-diameter ratio (L/D) of the core as tested and this must be considered in preparing core specimens and evaluating test results.

    1. Alcance

    1.1 Este método de ensayo trata sobre la obtención, preparación y ensayo de núcleos perforados a partir deconcreto para determinaciones de longitud o resistencia a la compresión o resistencia a la tracción indirecta.

    NOTA 1—El Apéndice X1 proporciona recomendaciones para la obtención y ensayo de vigas aserradas para determinar su desempeño a flexión.

    1.2 Los valores se indican en unidades SI o en unidades pulgada-libra para ser considerados separadamente como los estándares. Los valores indicados en cada sistema pueden no ser exactamente equivalentes; por ello, cada sistema debe ser utilizado independientemente del otro. La combinación de valores de los dos sistemas puede resultar en la no conformidad con la norma.

    1.3 El texto de esta norma cita notas y notas al pie de página que proveen material explicativo. Estas notas y notas al pie de página (excluyendo aquellas en tablas y figuras) no deben ser consideradas como requisitos de la norma.

    1.4 Esta norma no pretende dirigir todas las inquietudes sobre seguridad, si las hay, asociadas con su utilización. Es responsabilidad del usuario de esta norma establecer prácticas apropiadas de seguridad y salud y determinar la aplicabilidad de las limitaciones reguladoras antes de su uso.

    2. Documentos Citados

    C1231/C1231M Practice for Use of Unbonded Caps in Determination of Compressive Strength of Hardened Cylindrical Concrete Specimens

    C1542/C1542M Test Method for Measuring Length of Concrete Cores

    C1604/C1604M Test Method for Obtaining and Testing Drilled Cores of Shotcrete

    C174/C174M Test Method for Measuring Thickness of Concrete Elements Using Drilled Concrete Cores

    C39/C39M Test Method for Compressive Strength of Cylindrical Concrete Specimens

    C496/C496M Test Method for Splitting Tensile Strength of Cylindrical Concrete Specimens

    C617/C617M Practice for Capping Cylindrical Concrete Specimens

    C642 Test Method for Density, Absorption, and Voids in Hardened Concrete

    C670 Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials

    C78/C78M Test Method for Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading)

    C823/C823M Practice for Examination and Sampling of Hardened Concrete in Constructions