Non-Destructive Determination of the Dynamic Modulus of Concrete Disks

Abstract

The nondestructive determination of the dynamic modulus of concrete using circular disks has many potential applications. Circular disks, sawn from cores or cylinders, are widely used in measuring the chloride ion permeability of concrete. The dynamic modulus of disks taken from cores used in assessing structured adequacy is useful. Similarly, the dynamic modulus of cover-crete, the concrete over the reinforcing steel, determined from cores too short to be used for conventional testing, is valuable. Existing methods of determining the dynamic modulus of concrete based on fundamental frequency measurements do not include methods for concrete disks. An investigation was conducted to determine the feasibility of nondestructively measuring the elastic modulus of relatively thin, circular concrete disks cut from a standard 100 mm-by-200 mm (4 in-by-8 in) test cylinder, using fundamental frequency techniques. This study indicated that the dynamic modulus of the concrete specimens can be quickly, easily, and accurately determined using readily available, off-the-shelf technology.