STP1356

    Unbonded Capping for Concrete Masonry Units

    Published: Jan 1999


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    Abstract

    Due to the manufacturing process, the bearing surfaces of concrete masonry units are often somewhat rough and uneven. Therefore, concrete masonry units must be capped when tested in compression according to ASTM C 140-96, Standard Test Methods of Sampling and Testing Concrete Masonry Units. Capping of concrete masonry units is time consuming and expensive. Several studies of compression tests on concrete cylinders indicate that the use of elastic pads in rigid retaining caps give similar compressive strength results to approved capping methods. An unbonded capping system for concrete masonry units similar to that described in ASTM C 1231-93, Standard Practice for Use of Unbonded Caps in Determination of Compressive Strength of Hardened Concrete Cylinders, was developed. The average compressive strength results obtained when using the unbonded capping system ranged from 92–94% of the average compressive strength results obtained when using ASTM C 140-96 approved methods. Further, use of the unbonded capping system was found to increase productivity and substantially reduce testing cost.

    Keywords:

    concrete masonry units, compressive strength, loadbearing, unbonded cap, neoprene


    Author Information:

    Crouch, LK
    Associate Professor of Civil Engineering, Tennessee Technological University, Cookeville, TN

    Knight, ML
    Graduate teaching assistant, Tennessee Technological University,

    Henderson, RC
    Assistant Professor of Civil Engineering, Tennessee Technological University, Cookeville, TN

    Sneed, WA
    President, WASCO, Nashville, Tennessee


    Paper ID: STP14201S

    Committee/Subcommittee: C15.03

    DOI: 10.1520/STP14201S


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