A novel method to understand and quantify silicate tetrahedron in C-S-H by Time of flight secondary ion mass spectrometry analysis

The performance of cementitious materials is highly determined by calcium silicate hydrate (C-S-H). In this work, time of flight secondary ion mass spectrometry (TOF-SIMS) characterized by its high resolution was proposed to quantitatively determine the silicate tetrahedron content of C-S-H in a specific micron area. A C-S-H database in which the silicate content in local hydrates is quantified by ion intensity, was established for TOF-SIMS analysis. Results indicate that 8 negative ions and 19 positive ion fragments can be detected among the decomposition of C-S-H. By selecting the characteristic ions representing different silicate structures from ion fragments, the functional relationship between the intensity of characteristic ions and the silicate contents in C-S-H can be established. The quantification equation was proposed to calculate Qⁿ structure contents for various alite hydrates. The silicate structures with defects allocated in the control and pre-pressed sample was constructed successfully based on the TOF-SIMS quantitative results.