Characterization of fatigue damage accumulation and prediction of modulus deterioration for cement stabilized base.

Cement stabilized materials (CSM) are widely used in the pavement base and subbase of highway structures which are susceptible to fatigue cracking and modulus deterioration under traffic loads. The residual modulus is a key indicator for the performance of CSM, and is an important factor for the rehabilitation design of the pavement with cement stabilized base. This study focuses on the damage accumulation and modulus decay of CSM. Firstly, the strength and fatigue performance of the CSM were tested. Then, fatigue transfer functions and their reliability models for the different types of CSM were established. Eight fatigue transfer equations with different reliability of the base CSM (6% cement) and subbase CSM (4% cement) were developed. It is found damage accumulation of CSM shows typical three phases: initial change in phase I (10%−15% of fatigue life), stable decay in phase II (60%−80% of fatigue life), and rapid damage in phase III (10%−25% of fatigue life). The range of parameters for the three phases of CSM fatigue damage is presented. Finally, three prediction models for modulus decay are established, including the incremental-recursive deterioration model, three-phase deterioration model, and the MEPDG's CSB fatigue model. These findings can be used for predicting the residual performance of the CSM base, which are useful for enhancing the rationality of pavement maintenance and rehabilitation (M&R) and ensuring the durability and reliability of highway structures. [ABSTRACT FROM AUTHOR]