Title: Assessment of Approaches for Determining the Time-Zero Of Concrete

Author(s): Liang Li

Publication: Materials Journal

Volume:

Issue:

Appears on pages(s):

Keywords: autogenous strain, early ages; high-performance concrete; temperature rate, setting times; time-zero; ultrasonic pulse velocity

DOI: 10.14359/51740565

Date: 2/8/2024

Abstract:
Time-zero is of considerable significance for determining both deformational and mechanical properties of high-performance concrete from very early ages. In this paper, four methods for determining the time-zero are investigated comparably, including stress evolution measurement, autogenous strain method, ultrasonic testing, and temperature rate method. A critical review of the theoretical basis behind each method is presented, with emphasis on the applicability and limitations of each method. Based on a case study, the practical capabilities of all four methods for determining the time-zero of high-performance concrete with w/b of 0.25 are experimentally assessed. It is found that the ultrasonic testing and the temperature rate method are noted to be better suited due to their simplicity and availability compared to the other two methods. Besides, the temperature of cement-based composites at very early ages can affect the determined values of time-zero, which needs further research.