Investigation on the deformation behavior of open-graded unbound granular materials for permeable pavement.

• The deformation behavior of base materials for permeable pavement were explored. • Porosity, moisture and stress highly correlated with properties of base materials. • The unbound granular material with larger particle sizes has lower water sensitivity. • Unbound granular materials can provide good properties for permeable pavement. Permeable pavement has many advantages on environment and has been applied in various fields. However, the performance of the base layer of permeable pavement in the field of heavy loads has not attracted enough attention. This paper explorted the deformation behavior of open-graded unbound granular materials (UGMs) for base layers of permeable pavement under repeated triaxial loading. The deformation behavior explored in this study included both resilient deformation and permanent deformation. Firstly, the resilient modulus of different gradations with different ranges of particle size was studied. The results indicated that the open-graded UGMs had enough resilient modulus ranging from 110 to 371 MPa. The different gradations at various levels of stress under dry and wet conditions were studied to simulate different work conditions of base layer for permeable pavement. The results showed that porosity, particle size, stress level and moisture had great impact on permanent deformation. In addition, stress level represented by the shear stress/strength ratio (SSR) was introduced into the permanent deformation characterization, and the results suggested that the permanent deformation under the stress level of SSR value within 0.4 belonged to the plastic creep, which was acceptable permanent deformation in the pavement design. Therefore, this study concluded that, compared with traditional UGMs, open-graded UGMs may also meet the bearing capacity requirement for base materials under wet condition. [ABSTRACT FROM AUTHOR]