A comprehensive nitrogen adsorption measurement on the pore structure of calcium-silicate-hydrate subjected to cryogenic attack

Abstract

This study carried out a comprehensive nitrogen adsorption evaluation on the cryogenic attack impacts on the micropores and mesopores of calcium-silicate-hydrate (C-S-H). Pore volume and pore size distribution were analyzed by using Barrett-Joyner-Halenda (BJH), non-local density function theory (NLDFT), Dubinin-Radushkevich (DR), and Horvath-Kawazoe (H-K) methods. Surface fractal dimensions were analyzed by Frenkel-Halsey-Hill (FHH) model. The tortuosity factors were estimated using the corrugated pore structure model (CPSM) simulation. Results show that the cryogenic attack may chemically transform C-S-H surface, leading to a higher attraction to the adsorbates. The mesopores of C-S-H with a high Ca/Si ratio were better preserved. Furthermore, the ultramicropores and small supermicropores are more sensitive to the cryogenic attack than those larger micropores. In addition, it is found that the cryogenic attack has a significant influence in increasing the complexity and irregularity of the C-S-H mesopore structure. The CPSM simulation results provide additional evidence for the microcrack formation.