Effects of Moisture Variation on Resilient and Seismic Moduli of Unbound Fine-Grained Materials

Moisture variation in a pavement structure due to the environment has a large impact on the moduli of unbounded layers. The moisture variation can affect the performance of the pavement as documented in a number of laboratory and field studies. As such, it is desirable to account for this behavior in the design or evaluation of a pavement. In this study, the effects of moisture variation and compaction effort were investigated through a series of well-controlled laboratory tests on different fine-grained geomaterials. Different sources of fine-grained materials were selected to prepare the laboratory specimens for both resilient and seismic modulus tests. The existing modulus-moisture models were evaluated during the moisture conditioning cycles for the specimens prepared and compacted at different moisture levels. Furthermore, the normalized difference of moisture content at the time of compaction and optimum moisture content was used to explain the trends. A model is proposed to improve the prediction of changes in resilient modulus based upon moisture content. The proposed model showed reasonable agreement with the experimental data.