Structural performance of sustainable glass fiber – fly ash engineered cementitious composite slabs under moving wheel loads: An integrated experimental and finite element study

Engineered Cementitious Composites (ECC) represent a promising alternative to conventional rigid pavement concrete, offering superior crack-bridging performance. However, the structural-scale performance of sustainable ECC pavement slabs remains underexplored. This study investigates the development of a sustainable, cost-effective (ECC) utilizing Glass Fibers (GF) and Fly Ash (FA) for heavy-duty pavement applications. An experimental program evaluated nine ECC mixes with varying GF content (1%, 2%, 3%) and FA replacement levels (10%, 20%, 30%). Mechanical characterization through compressive strength, indirect tensile strength, flexural strength, deflection capacity, crack width, and elastic modulus testing revealed that FA 30% with GF 3% (S9) improved indirect tensile strength by 140%, while FA 10% with GF 3% (S3) enhanced flexural strength by 75%. Mix S6 (FA 20%, GF 3%), was selected as the optimal balanced mix due to its superior ductility, controlled micro-cracking, and higher cement replacement ratio. Following experimental validation of the numerical model, a parametric 3D ANSYS FEM study was conducted on 3x3m pavement slabs subjected to pseudo-static moving edge loads (40 kN and 80 kN) across varying thicknesses (50–150 mm). The numerical results reveal a systematic non-monotonic relationship between slab thickness and bottom tensile stress, governed by the radius of relative stiffness and consistent with Westergaard's edge loading theory. Substituting conventional concrete with mix S6 at a constant 50 mm slab thickness achieves equivalent structural performance to doubling the conventional slab thickness to 100 mm. These findings provide an integrated material-to-structure design framework for sustainable ECC rigid pavements under heavy vehicular loading.