Strength characterization of limestone lithofacies under different moisture states

Area of Science:

• Geotechnical Engineering
• Materials Science
• Sedimentary Petrology

Background:

• Limestone lithofacies exhibit diverse mechanical behaviors influenced by composition and environmental factors.
• Understanding rock strength under varying moisture conditions is critical for infrastructure and geological stability.
• Previous research has not fully elucidated the combined effects of lithofacies type and moisture on carbonate rock mechanics.

Purpose of the Study:

• To characterize the mechanical properties of massive fractured limestone (MLS), fossiliferous limestone (FLS), and siliceous limestone (SLS) under natural, dry, and saturated conditions.
• To evaluate the influence of lithofacies composition, mineralogy, texture, and moisture on rock strength parameters.
• To establish relationships between limestone geochemistry, microstructural features, and mechanical responses.

Main Methods:

• Mechanical testing including Uniaxial Compressive Strength (UCS), Point Load Index (PLI), and Indirect Tensile Strength (ITS).
• Petrographic, mineralogical, and geochemical analyses to determine lithofacies composition and microstructural attributes.
• Comparative analysis of rock strength under three distinct moisture conditions (natural, dry, saturated).

Main Results:

• Dry conditions increased UCS by up to 200% in MLS and SLS compared to natural states.
• Saturation reduced UCS by 30-60% and ITS by up to 55%, with FLS being most vulnerable due to high porosity.
• Siliceous limestone (SLS) demonstrated the highest durability, while massive fractured limestone (MLS) showed intermediate strength loss upon fracture saturation.

Conclusions:

• Lithofacies composition, particularly CaO, SiO2, and MgO content, significantly governs carbonate rock mechanical properties.
• Moisture state is a critical factor influencing rock strength, with saturation generally leading to weakening.
• These findings provide essential data for predicting carbonate rock performance in geological and engineering applications.