A Simple Method on Transformer Principle for Early Age Hydration Monitoring and Setting Time Determination of Concrete Materials

Abstract

This paper deals with the development of a low-cost measurement system based on transformer principle with a lossy capacitive load for setting time determination of freshly mixed cement paste. The initial setting time is an important parameter to ensure transporting, placing, and compacting of material to be utilized for the civil structure. Determination of the final setting time helps in removal of a framework after appropriate strength gaining. The proposed method employs a test cell of Vicat instrument with two parallel metal plates. The cement paste behaves as a lossy dielectric kept in the test cell. To determine the setting times, the sample cell was connected to the secondary terminals of a transformer and the primary current was measured at a regular interval of time. The measured primary current was utilized to monitor the possible early age hydration and to determine the initial and final setting time of the different mixture of the cement samples. Results are compared with the results of the conventional Vicat apparatus and are found to be effective for setting time determination. This proposed technique gives privilege for online hydration monitoring of the cement paste and can alternately be used in place of Vicat apparatus.