Effect of drying on the structure of sol-gel synthesized calcium silicate hydrate gels

Abstract

This article investigates the effect of lyophilization, air drying, and vacuum drying on the structural changes of synthetized calcium-silicate-hydrate (C–S–H) gel. X-ray photoelectron Spectroscopy (XPS) and Fourier-Transform infrared (FT-IR) spectroscopy were employed to analyze the structural changes induced by each drying method. Our findings reveal that lyophilization most significantly affects the C–S–H gel structure, leading to its substantial decomposition, particularly affecting samples prepared under acidic and alkaline conditions. In contrast, air drying and vacuum drying proved to be gentler alternatives, effectively preserving the inherent C–S–H gel structure. Among the methods tested, vacuum drying emerged as the most suitable technique for preparing C–S–H gel samples, primarily due to its superior control over drying conditions. These results underscore the critical importance of selecting an appropriate drying method for accurate and reproducible characterization of synthetized C-S-H gel, providing valuable insights to C–S–H gel formation mechanism.