Performance of Shotcrete with Various Accelerators: Laboratory, Field, and Numerical Analyses for Geotechnical Applications
Abstract
The use of shotcrete in tunneling and underground structures is extensive due to its excellent adhesion, low rebound, and rapid development of strength. Accelerators are key additives in shotcrete, significantly influencing its performance. This research investigates the interaction between various accelerators and cement-based shotcrete mixtures through laboratory experiments and full-scale field spraying trials. The study examines the effects of different accelerator types (silicate-based and alkali-free) and dosages on the mechanical properties, hydration kinetics, and microstructure of shotcrete mixtures. Laboratory tests were conducted on cement pastes to assess flowability, compressive strength development, and hydration behavior using isothermal calorimetry. Full scale field trials involved spraying shotcrete panels and evaluating early-age and long-term compressive strength, as well as analyzing the microstructure through X-ray diffraction and thermogravimetric analysis. The research highlights the significant differences between laboratory-mixed samples and field-sprayed shotcrete, providing insights into the impact of the spraying process on accelerator reactivity, hydration kinetics, and overall shotcrete performance. The findings contribute to a better understanding of shotcrete behavior in real-world applications and offer guidance for optimizing shotcrete mix designs for various construction projects. Furthermore, finite element analyses are conducted to realistically simulate shotcrete behaviour in two important geotechnical applications. The structural performance of shotcrete as a tunnel lining material and for rock support in deep excavation of a manhole is numerically investigated and its important performance characteristics in these applications are identified.