Fatigue damage evolution rule of cement stabilized macadam used in pavement’s base course at different curing time

•Cement stabilized base course could occur severe damage if opens to construction vehicle too early.•Damage model established in this paper can well reflect cement stabilized macadam’s damage evolution and fatigue life.•Three weeks of curing under standard condition or IDT strength of 0.68 MPa can be adopted as timing to open construction. Cement stabilized macadam is widely used as base course materials in semi-rigid asphalt pavement. Yet, due to its following disadvantages, very slow development of strength and very long period of curing, up to 90 days, its construction often has to start next step of paving process at their early curing stage, such as 7 ∼ 10 days even earlier. This situation could cause base course is damaged severely when subjected to construction vehicle, even cracking. In order to determine an applicable timing to open construction traffic, or provide some quantitative basis to evaluate base course’s damage extent, this paper conducts a series of IDT fatigue testing for cement stabilized macadam specimens under different curing stage or loading level, loading frequency. A fatigue damage model is also established according to the test data to describe the materials’ damage evolution, and base course’s damage extent after opening to construction traffic at different curing stage are also calculated. Their results indicate, strength and fatigue life of cement stabilized macadam at their early curing stage are very susceptible to curing time, while the model established to reflect this susceptibility and characteristic of different curing stage’s damage evolution is competent, which can well reflect the effect of curing time, load level and loading frequency on specimen’s fatigue life and damage. In addition, damage calculation indicates approximately 3 weeks under standard curing condition or an IDT strength of 0.68 MPa from coring sample could be applicable to open construction traffic.