Ultrasonic Testing for Quality Control of Ultra-high Performance Concrete

摘要

Ultra-high performance concrete (UHPC) is proposed as an innovative new material for the construction of highway bridge superstructures. UHPC mix designs typically include no aggregates larger than sand, and include steel fibers 0.2 mm in diameter and 13 mm in length. These steel fibers and special mix design increase the strength and toughness of the UHPC significantly relative to more traditional concretes. However, low water to cement ratios typically used result in difficult casting and curing conditions and as a result there is a need to evaluate strength and stiffness parameter of as-cast members. This research reports on the development of ultrasonic methods for monitoring the elastic properties of UHPC under a series of curing scenarios. Ultrasonic velocity measurements are used to estimate the bulk elastic modulus, shear modulus and Poisson’s ratio of UHPC and results are compared with traditional, destructive methods. Changes in ultrasonic velocities during curing and relationships to early-age strength of the materials are discussed. The application of ultrasonic testing for the evaluation of early-age material properties and for nondestructive, in-situ materials characterization are explored. The potential for the development of practical quality control techniques for the future implementation of UHPC is also discussed.