Evaluation of Drilled Shafts with Self-Consolidating Concrete

Drilled shafts with self-consolidating concrete were prepared and tested with cross-hole sonic logging (CSL). Self-consolidating concrete, which has high workability, was placed in the drilled shafts of bridges on Route 28 over Broad Run in Bristow in Prince William County, Virginia. During placement, properties of the fresh concrete were tested, and specimens were prepared to determine the hardened properties. The integrity of the bridge shafts within the reinforcing cage was determined with the use of CSL. Another sonic method, sonic echo-impulse response, was used to evaluate several test shafts. The use of acoustoultrasonic measurements to determine the cover depth outside the reinforcing cage was evaluated during laboratory testing. The results indicated that self-consolidating concrete was highly desirable for drilled shafts; it flowed easily and filled the hole; the removal of the temporary casing was facilitated by this highly workable material. CSL is a satisfactory nondestructive method to determine the integrity of shafts. Sonic echo impulse response also showed promise as a method to complement CSL for determining the integrity of a shaft. Acoustoultrasonic testing was promising in the laboratory but needs further development for implementation in the field.