Title:
SettingTime and Strength of Concrete Using the Impact-Echo Method
Author(s):
Stephen P. Pessiki and Nicolas J. Carino
Publication:
Materials Journal
Volume:
85
Issue:
5
Appears on pages(s):
389-399
Keywords:
age; compressive strength; concretes; impact-echo method; mortars (material); nondestructive tests; setting (hardening); Materials Research
DOI:
10.14359/2312
Date:
9/1/1988
Abstract:
Tests were performed to evaluate the feasibility of using the impact-echo method to determine setting time and to monitor strength development of concrete. In the impact-echo method, the test object is subjected to point impact and the surface displacement is monitored at a point adjacent to the impact. From the measured displacement waveform and the thickness of the object, the P-wave velocity is determined. Changes in the P-wave velocity with time reveal information about the development of mechanical properties as the concrete matures. Setting-time tests were made on concrete mixtures of two water-cement ratios both with and without set-controlling admixtures. A strong correlation was found between the time of initial setting of mortars sieved from the concrete, as determined by penetration resistance (ASTM C 403), and the time when the P-wave velocity began to increase. Two approaches for using the impact-echo method to define the setting time of concrete are presented. Tests were performed to examine the relationship between P-wave velocity, as determined by the impact-echo method, and the compressive strength of concrete. At early ages (up to about 3 days at standard temperature), the relationship was independent of curing temperature and water-cement ratio. It is concluded that the impact-echo method is a promising nondestructive technique for monitoring the development of mechanical properties in concrete from initial setting to ages of several days.