A Review of Instrumentation Technology for the Minnesota Road Research Project

This report presents a literature review of instrumentation practices for the measurement of stresses, strains, and deflections in pavement structures. Various types of instruments that are commonly employed in pavement instrumentation projects are discussed, as well as the factors that influence their performance. In a series of laboratory experiments, the performance of three different types of embedment strain gages, two LVDTs, and one soil stress cell are investigated. These experiments are designed to evaluate the accuracy and durability of commercially available transducers. For strain gages, the selection of an appropriate transducer must balance compliance and measurement sensitivity. All of the strain gages tested in concrete gave reasonable results. It was found that hermetically sealed LVDTs should be sufficient enough for robust installations. Experiments with soil stress cells embedded in sand indicate the variability that may be expected in the field due to installation procedures, and emphasize the need for in-soil calibrations. A set of recommendations are provided with respect to the sensor procurement and installation specifications for Mn/ROAD.