Utilizing Crushed Limestone as a Sustainable Alternative in Shotcrete Applications

Area of Science:

• Civil Engineering
• Geotechnical Engineering
• Materials Science

Background:

• Mining operations generate significant crushed limestone (CL) waste, posing disposal challenges.
• Natural sand consumption in construction is high, necessitating sustainable material alternatives.
• Rockbursts and spalling failures are critical risks in deep tunnel excavation, requiring robust support systems like shotcrete.

Purpose of the Study:

• To investigate the feasibility of using crushed limestone (CL) as a sustainable aggregate in shotcrete for deep tunnel support.
• To evaluate the mechanical properties and crack initiation behavior of shotcrete mixes incorporating varying proportions of CL.
• To assess the potential of CL to replace natural sand in shotcrete applications, contributing to waste valorization and resource conservation.

Main Methods:

• Preparation of shotcrete samples with different percentages of crushed limestone (CL) replacing natural sand.
• Conducting comprehensive strength characterization tests on the prepared samples.
• Utilizing stress-strain-based models to determine crack initiation stress and evaluate spalling strength.

Main Results:

• Shotcrete mixes containing crushed limestone (CL) exhibited increased crack initiation stress compared to conventional mixes.
• The crack initiation stress, indicative of in situ spalling strength, showed a positive correlation with increasing CL content.
• The study confirmed the viability of CL as a functional aggregate in shotcrete formulations.

Conclusions:

• Crushed limestone (CL) demonstrates significant potential as a sustainable substitute for natural sand in shotcrete used for deep tunnel support.
• Utilizing CL in shotcrete can mitigate mining waste issues and reduce reliance on natural sand resources.
• The findings support the integration of recycled CL into construction materials, enhancing both environmental sustainability and structural performance in underground excavations.