SBIR-STTR Award

The broad objective of this proposal is to develop an apparatus that is capable of measuring the in-situ density and moisture content of pavement bases, embankments, and other construction sites. The PI's propose an approach based on combined measurement techniques that include time domain reflectometry, P-wave propagation, and in-situ saturation process. Phase I includes evaluation of the proposed methodology and the most appropriate technology to measure such properties. The research team envisions that the proposed approach will yield robust and accurate assessment of field density and moisture content. The proposed research has wide range of applications. The field density and moisture content measurements are required as a quality control/ quality assurance criterion in highway construction, construction of earth dams, and other earthwork projects. This research will lead to the development of a new field density/moisture content apparatus/gauge that has a major impact on the civil and construction engineering areas. Providing accurate and robust measurements results combined with no regulatory/safety restrictions will result in reducing labor time to conduct the field measurements, which means huge savings for the army and the construction engineering industry.

The research team has completed Phase I of the project that served as a proof-of-concept to identify the most promising procedure/technology for a robust evaluation of field density and moisture content using a combined electromagnetic and elastic wave approach. Phase I results showed that the new approach has the potential to measure soils properties needed to evaluate the mass density and water content of soils. The proposed methodology differs from current measurement practices that use old techniques such as sand cone method and nuclear gauge to determine the field density and oven-dried soil samples to calculate the field water content. Such techniques involve time consuming processes, inaccuracies, and the handling of regulated materials (i.e., nuclear moisture-density apparatus). The army field units and the engineering market are in a desperate need for a modern, robust, and fast device to accurately measure the field density and in-situ water content of natural and compacted soils. These measurements are essential in many applications such as assessing site suitability for deploying heavy mobile equipment, vehicle-soil traction calculations, highway construction, earthwork projects, etc. Therefore, the development of such a device is expected to have wide applications and a major practical impact and cost cutting in the operations of engineering units of the Department of Defense and civil engineering construction projects. For Phase II, the research team proposes to build the first self-contained prototype for the rapid measurement of the in-situ density and water content. As part of this proposed activity, several parallel studies will be performed. These studies include evaluation of the sensors compatibilities, selection of the proper electronics, improvement of the inversion algorithm, development of the software program for the self-contained prototype, and a parametric field analysis to evaluate the developed device. Electronic equipment and sensors for the proposed device include a TDR system, miniature piezoelectric accelerometer, signal conditioning systems, and oscilloscope for data acquisition. The research team envisages that the developed device will be battery-powered and will have a total weight of about 122.6 N (26 lbs). The successful completion of the prototype and the future commercialization of the product will give the engineers in the military and in the construction community a fast, reliable, and safe alternative to measure two important soil parameters.

Keywords:
COMPACTED SOILS, FIELD DENSITY, MOISTURE CONTENT, NEW DEVICE, NON-DESTRUCTIVE TECHNIQUE