Evaluation of mortar setting time by using electrical resistivity measurements

Abstract

Cement hydration induces microstructural evolution in cement-based materials, causing setting and hardening. Various experimental techniques were proposed to evaluate the time of setting, which includes the Vicat needle test and ultrasound inspections. This study aims to measure electrical resistivity in order to monitor microstructural evolution. For this purpose, an optimized experimental setup is proposed by performing a series of pre-test analyses. A total of 51 mortar mixes are prepared to study the effects of various mix-proportions and the use of various chemical admixtures. As a result, two parameters that represent a change in electrical resistivity are identified: the rising time, which indicates the onset of an increase in electrical resistivity, and the increasing ratio over time. Both parameters are discussed with conventional test results obtained from the penetration resistance method. Their correlation allows us to estimate the setting time of mortar.