Process Modeling and Automation of Concrete Cylinder Testing

Abstract

Concrete is used more than any other man-made material to make dams, parking lots, building structures, roads, pavements, and more. Even a small crack in concrete can lead to failure of a structure. As a result, concrete is tested for quality assurance with respect to many characteristics, and most importantly for its strength. When doing so, a compressive axial load is typically applied to molded concrete cylinders within a prescribed range until failure occurs. The load at which this occurs is then divided by the cross-sectional area of the cylinder to calculate the compressive strength of the specimen. Within a concrete testing facility, the logistics of undertaking this process for hundreds and perhaps thousands of cylinders can become quite complex since typically a set of six cylinders is tested at 7 and 28 days for every 50 cubic yards of concrete produced. This thesis describes the process of cylinder testing at the Concrete Testing Facility at Advance Testing Company, Inc., New York. Critical and repetitive activities are identified and an alternative process model is suggested with the use of RFID (Radio Frequency Identification Tags) and automation devices. The use of RFID reduces the risk of missing cylinders and improves the checking process at the laboratory, which is found to be the most critical activity. To eliminate tedious and repetitive activity of measuring cylinders, development of a prototype device is proposed using a 68hc12 microcontroller and ultrasonic sensors to measure the diameter, an approach which also eliminates human error. A Java-based simulation program compares both current and proposed process models for time differences. Results show a reduction of total time for ii overall cylinder testing by more than half. With the proposed process model, the capacity of the testing facility can be increased by a factor of four with no increase in manual labor.