Title: Nonlinear Ultrasonic Method to Evaluate Residual Mechanical Properties of Thermally Damaged Concrete

Author(s): Hong Jae Yim, Sun-Jong Park, Jae Hong Kim, and Hyo-Gyoung Kwak

Publication: Materials Journal

Volume: 111

Issue: 4

Appears on pages(s): 399-410

Keywords: degradation; impact modulation; mechanical properties; temperature; thermal damage

DOI: 10.14359/51686596

Date: 7/1/2014

Abstract:
An experimental study has been carried out to evaluate the residual mechanical properties of thermally damaged concrete using a nonlinear ultrasonic method. A nonlinearity parameter was measured by the impact-modulation technique, which sensitively reflects the degree of thermal damage in concrete. Key mechanical properties, compressive strength, elastic modulus, and peak strain were obtained from compressive stress-strain curves of cylindrical concrete samples. The correlations between the nonlinearity parameters and the mechanical properties were investigated for various conditions: high-temperature exposure time of 1, 2, and 3 hours and four different mixture proportions. The authors thereupon developed regression equations that can predict the residual mechanical properties from the measurement of a nonlinearity parameter, which indicates the degree of thermal damage.