STUDIES ON ULTRA SONIC, REBOUND AND COMBINED METHODS USING FULL SCALE MODEL STRUCTURES : Estimation of strength of concrete in structures by non-destructive testing

Abstract

Full scale model structures with several mixes of concrete were used to study estimation of strength of concrete in structures by non-destructive testing. Estimation equations by rebound number method, pulse velocity method and combined method of reboud number and velocity were propsed. Furthermore, supplement of parameters by the water cement ratio of concrete to equations decreased in estimation error. Ranges of dispersion of estimations, represented by two times of the standard deviation were apprpximately as follows : 80 kgf/cm^2 for rebound number method, 120 kgf/cm^2 for pulse velocity method, 74 kgf/cm^2 for combined method and 53 kgf/cm^2 for combined method with water cement ratio as an additional parameter.