Deformation characteristics and prediction of unbound volcanic ash pavement based on the mechanistic-empirical design guide

The objective of this study is to determine the deformation characteristics and prediction methods of volcanic ash in pavement ME design. For this purpose, the chemical composition, physical properties and mechanical properties of volcanic ash have been investigated. The results show that volcanic ash is an unbound fine-grained material with a maximum particle size of<2 mm, dominated by quartz, feldspar, magnetite, hematite. In this paper, repeated load triaxial (RLT) tests are conducted on 100 volcanic ash cylindrical specimens. Shakedown theory has been applied to evaluate the plastic deformation characteristics of volcanic ash, and a new criterion has been proposed to determine the shakedown boundaries of volcanic ash. The mechanistic-empirical design guide (MEPDG) model is used to determine the permanent deformation properties of the volcanic ash based on the measured permanent strain curves. Prediction models for permanent deformation properties are proposed, which consider water content, confining pressure and dynamic loads. To verify the accuracy of the prediction models proposed in this study, 10 sets of validation tests are conducted on volcanic ash specimens. The results show that the prediction models have good prediction accuracy for specimens in Rang A and Rang B under the new criterion, and poor prediction for specimens in Rang C state. However, it is important to avoid using materials in the Rang C state. Therefore, the prediction models proposed in this study can be applied to the prediction of deformation for volcanic ash pavement materials.

Automated summary

The objective of this study is to determine the deformation characteristics and prediction methods of volcanic ash in pavement ME design. The chemical composition, physical properties and mechanical properties of volcanic ash have been investigated. The study proposes new prediction models for permanent deformation properties of volcanic ash based on water content, confining pressure and dynamic loads. Validation tests show good prediction accuracy for certain states. The results suggest that the prediction models proposed in this study can be applied to the prediction of deformation for volcanic ash pavement materials.