Permanent deformation behavior of unbound granular base materials with varying moisture and fines content

Specifications for unbound granular base materials vary among transportation agencies based on the availability of materials, climatic conditions, and function. Specifications aim to provide durable materials that meet design requirements and achieve the target design life with cost effective materials. This paper investigates the effect of the percentage fines (particles passing sieve No. 200) and moisture content on the plastic behavior of unbound granular materials. Plastic response of six gradations representing two types of material, 100% crushed limestone and gravel, was evaluated at two levels of moisture content. The shakedown concept was used to classify the deformation behavior of the materials. Results showed that limestone with an optimum fines content of 4.5% and gravel with an optimum fines content of 9% had better resistance to plastic deformation than other fines contents.