Chloride penetration of shotcrete with crushed waste glass aggregates

Shotcrete is a type of concrete sprayed onto surfaces using a nozzle, making it ideal for applications with irregularly shaped substrates such as rock support in deep mines and retaining walls. Unlike conventional concrete, however, shotcrete requires a mix design with enhanced pumpability which is typically achieved by increasing sand content. On the other hand, the surge in construction projects has led to sand depletion due to excessive natural sand extraction, resulting in environmental damage, habitat loss, and beach erosion. To mitigate the sand depletion issues, alternative synthetic aggregates made from crushed waste glass (CWG) have been explored in recent years as substitutes for natural sand in shotcrete production. Evaluating CWG's feasibility in shotcrete involves assessing its performance to ensure it meets standard requirements, particularly its longterm durability. One critical durability factor is shotcrete’s resistance to chloride penetration. Chloride ions, commonly originating from seawater or contaminated groundwater, can infiltrate shotcrete, corrode embedded rebar, and compromise structural integrity, ultimately reducing its lifespan. This study tested shotcrete mixes with varying percentages of CWG for chloride penetration resistance using the Rapid Chloride Penetration Test (RCPT) and the bulk resistivity method. Results demonstrated that incorporating CWG in shotcrete significantly improved durability, showcasing its potential as a sustainable alternative in shotcrete production.