Title:
Assessment of Approaches for Determining Time-Zero of Concrete
Author(s):
Liang Li
Publication:
Materials Journal
Volume:
121
Issue:
3
Appears on pages(s):
43-52
Keywords:
autogenous strain; early ages; high-performance concrete; setting times; temperature rate; time-zero; ultrasonic pulse velocity (UPV)
DOI:
10.14359/51740565
Date:
5/1/2024
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 a waterbinder
ratio (w/b) of 0.25 are experimentally assessed. It is found
that the ultrasonic testing and temperature rate methods are 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.