Silicate-Based and Alkali-Free Accelerators for Shotcrete Applications: Field Study

The chapter delves into the application of silicate-based and alkali-free accelerators in shotcrete, highlighting their crucial role in achieving favorable properties such as shorter final setting times and higher early-age compressive strength. It discusses the chemical composition and effects of these accelerators on the hydration process of Portland cement, focusing on the initial reaction, induction, and acceleration periods. The study introduces an innovative silicate-based accelerator that shows promise in mitigating the reduction in compressive strength observed with traditional silicate-based accelerators at later ages. Through field studies, the chapter presents a comparative analysis of different shotcrete mixtures, examining their compressive strength at various curing times up to 90 days. Additionally, it employs advanced techniques such as X-ray diffraction (XRD) and thermogravimetric analysis (TGA) to investigate the hydration products and microstructure of the accelerated mixes. The findings indicate that the innovative silicate accelerator exhibits competitive behavior compared to other accelerators, offering a potential solution to long-standing challenges in shotcrete applications. The chapter concludes by suggesting further investigation into factors such as pore size and distribution that may influence the compressive strength of the tested mixtures.