Effect of Capping Materials and Procedures on the Measured Compressive Strength of High-Strength Concrete

    Volume 16, Issue 2 (December 1994)

    ISSN: 0149-6123

    CODEN: CCAOAD

    Page Count: 8


    Lobo, CL
    Staff engineer, laboratory manager, and executive vice president, National Ready Mix Concrete Association-National Aggregates Association (NRMCA-NAA), Silver Spring, MD

    Mullings, GM
    Staff engineer, laboratory manager, and executive vice president, National Ready Mix Concrete Association-National Aggregates Association (NRMCA-NAA), Silver Spring, MD

    Gaynor, RD
    Staff engineer, laboratory manager, and executive vice president, National Ready Mix Concrete Association-National Aggregates Association (NRMCA-NAA), Silver Spring, MD

    Abstract

    The effect of end conditions and testing procedures on the measured strength of 100- by 200-mm (4- by 8-in.) concrete cylinders were evaluated. Concretes representing three strength levels: 50, 75, and 120 MPa (7000, 11 000, and 17 000 psi) were prepared. Cylinder end conditions included grinding and capping with two types of sulfur mortar and cement paste. Effect of thickness of capping material was also evaluated.

    Cement paste caps produced, on average, 1% higher strengths than ground ends, regardless of concrete strength level and cap thickness. Cylinders capped with sulfur mortar 2 h prior to testing produced 2 to 7% lower strengths than the ground condition. Capping cylinders with sulfur mortar seven days prior to testing produced strengths equivalent to the ground condition, except with thick caps of sulfur mortar on the 120 MPa (17 000 psi) concrete, in which case lower strengths were observed. No significant difference between sulfur mortars was evident, even though one was advertised for use with high-strength concrete.


    Paper ID: CCA10296J

    DOI: 10.1520/CCA10296J

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    Author
    Title Effect of Capping Materials and Procedures on the Measured Compressive Strength of High-Strength Concrete
    Symposium , 0000-00-00
    Committee C09