Modeling crystallization pressure in sulfate‑attacked cementitious materials: influence of four typical pore geometries

Pore geometry governs crystallizationpressure-driven expansion cracking under sulfate attack. Idealizing pores as equivalent spheres underestimates stresses in non‑spherical pores and ignores anisotropy, failing to explain microcrack initiation beyond regions. A multi‑physical coupled model incorporating thermal field on ion transport, reactions, and crystallization pressure is developed. Four representative pore geometries are identified – spherical, cylindrical, elliptical cylindrical, and ellipsoidal – and the corresponding analytical expressions for ettringite crystallization pressure are derived. Pore geometry controls pressure magnitude and evolution. Spherical pores shows the highest pressure, decaying exponentially with attack depth. Cylindrical pores shows loewr pressure owing to the axial relaxation. Elliptical cylindrical pores weakens from positive to negative, producting tensile stress on pore walls and revealing the origin of stress reversal in anisotropic pores. Ellipsoidal pores follows a similar trend but decay gradually under 3D asymmetric confinement. Treating pores as spheres overestimates crystallization pressure and mispredicts damage extent and progression rate.