Extended X‐ray Absorption Fine Structure Investigation of Calcium Silicate Hydrates

Abstract

29 Si MAS‐NMR, and Ca‐EXAFS experiments have been conducted on calcium silicate hydrates (C‐S‐Hs) with structure derived from wollastonite. Crystalline compounds (wollastonite, xonotlite, hillebrandite, foshagite, 1.1 nm and 1.4 nm tobermorites, and jennite) and C‐S‐H were synthesized and characterized. 29 Si NMR provides information on silicate chains and EXAFS on calcium environment. The refined EXAFS values are in agreement with XRD data, except for tobermorite. The calcium order in C‐S‐H (C/S molar ratio from 0.7 to 1.4) is similar to that of tobermorite but different from that of jennite. Structural models of C‐S‐H are discussed.