NONDESTRUCTIVE DETERMINATION OF THE DYNAMIC MODULUS OF CONCRETE DISKS

The nondestructive determination of the dynamic modulus of concrete us ing circular disks has many potential applications. Circular disks, sa wn 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 structural 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 tes ting, is valuable. Existing methods of determining the dynamic modulus of concrete based on fundamental frequency measurements do not includ e methods for concrete disks. An investigation was conducted to determ ine the feasibility of nondestructively measuring the elastic modulus of relatively thin, circular concrete disks cut from a standard 100 nm x 200 nm (4 in. x 8 in.) test cylinder, using fundamental frequency t echniques. This study indicated that the dynamic modulus of the concre te specimens can be quickly, easily and accurately determined using re adily available, off-the-shelf technology.