Strength characterization of limestone lithofacies under different moisture states

This study characterized the mechanical behaviours of massive fractured (MLS), fossiliferous (FLS), and siliceous (SLS) limestone lithofacies under natural, dry, and saturated conditions. Uniaxial compressive strength (UCS), point load index (PLI), and indirect tensile strength (ITS) tests, along with petrographic, mineralogical, and geochemical analyses, were used to evaluate the impacts of the lithofacies composition and environmental conditions on rock strength. The results indicate that lithofacies composition, including mineralogy and texture, has a considerable effect on rock strength and durability. Under dry conditions, UCS values increased by up to ~ 200% in MLS and SLS relative to natural conditions, while saturation reduced UCS by 30-60% depending on lithofacies. Similar trends were observed in ITS, which decreased by up to 55% under saturation. The high silica content of SLS produced the most durable lithofacies, whereas the high porosity of FLS made it the most vulnerable to weakening from water exposure. MLS exhibited intermediate properties, as it loses strength considerably when existing fractures become saturated. Statistical analysis indicates that the CaO, SiO₂, and MgO contents strongly influenced the rock mechanical properties. The study reveals relationships between lithofacies geochemistry, microstructural attributes (fractures, porosity, fossil interfaces), and mechanical responses under different moisture states. These insights allow for predictions about carbonate rock mechanical performance, making them crucial for geological research, engineering projects, industrial applications, and infrastructure design.