Use of a Moisture Sensor for Monitoring the Effect of Mixing Procedure on Uniformity of Concrete Mixtures

Abstract

The present research is to explore a new approach to monitoring uniformity of concrete mixtures. A given concrete mix was subjected to three different mixing procedures. A moisture sensor was installed inside a pan mixer to monitor moisture content of the concrete mixtures during mixing. The concrete mixtures were considered as uniformly mixed when stable moisture content was detected by the moisture sensor. The concrete workability and strength were then evaluated, and the concrete's microstructure (pore distributions and aggregate-paste interface) was examined. The preliminary results indicated that the moisture sensor provided reliable test results describing moisture distribution in concrete mixtures. The sensor readings well captured the subtle changes, such as the loading sequence of concrete materials, in the concrete mixing process. The material loading sequence, mixing time, and aggregate moisture condition had significant influences on the concrete workability, air void system, and strength. These research results provide researchers and engineers with insight into the control of concrete mixing quality and the optimization of mixing procedures in the lab and field.