Fatigue Behavior of Supersulfated Cement-Stabilized Crushed Stone for Highway Pavement Bases Considering Micro-Expansion-Induced Self-Stress

Cement-stabilized crushed stone is widely used in semi-rigid pavement bases, but fatigue cracking can reduce pavement durability. Supersulfated cement-stabilized crushed stone is a promising low-carbon alternative, yet its fatigue behavior under the micro-expansion induced by ettringite (AFt)-seeded hydration has rarely been clarified. This study investigated the fatigue performance of AFt-seeded SSC-stabilized crushed stone with explicit consideration of the resulting self-stress, through paste expansion tests, splitting fatigue experiments, and a coupled finite element–discrete element analysis. The seeded paste developed a stable free expansion of approximately 400 με, which was converted to an equivalent expansion of 18.5 με and an estimated compressive self-stress of 0.283 MPa at the crushed-stone scale. The material reached a 90-day indirect tensile strength of 1.45 MPa, approximately 57.6% higher than that of the OPC-stabilized reference. Under comparable normalized stress levels of 0.45 and 0.49, the SSC-stabilized crushed stone achieved 17,441 fatigue cycles, exceeding the reference by 28%, with slower stiffness degradation and lower permanent deformation accumulation. Numerical simulation further showed that the self-stress delayed bond breakage and crack penetration, with simulated base fatigue failure at approximately 5.3 × 105 cycles. These findings clarify the role of micro-expansion-induced self-stress in fatigue resistance. They also indicate its potential for durable, low-carbon pavement bases.