Calcium silicate structure and carbonation shrinkage of a tobermorite-based material

Decalcification resistance of alkali-activated slag

“…The mechanism of C-S-H(I) decomposition due to leaching (decalcification) is quite similar to the mechanism of decalcification of C-S-H(I) due to carbonation [11,54,58].…”

Investigating temperature effect on degradation of well cement in HPHT carbonic acid environment

“…1: Conditions for the formation of CSH polymorphs (Adopted from Taylor, 1964) At approximately 60-150 o C and C/S ratio of about 1, tobermorite (a C-S-H phase) is the stable phase with good binding properties, high compressive strength and low permeability. Temperatures within this range of tobermorite stability have been recommended as optimum curing temperatures to prevent strength retrogression during early curing stage (Saunders and Walker, 1954 (Hara et al, 1978;Nelson et al, 1981;Henmi and Kusachi, 1992;Merlino et al, 2001;Matsushita et al, 2004;Richardson, 2008;Churakov, 2009). Above 150 o C, a moderately permeable but strong calcium silicate hydrate phase, called xonotlite (C 6 S 6 H), is formed (Noik and Rivereau, 1999;Fabienne et al 2002;Brand et al, 2011).…”

“…Cement degradation due to phase transformation of CSH to its polymorphs (generally identified as C-S-H) is a phenomenon that occurs predominantly during cement curing at elevated temperature (Saunders and Walker, 1954;Taylor, 1964;Eilers et al, 1980;Nelson, 1981;Matsushita, 2004;Richardson, 2008;Zhang, 2013). This transformation, which is dictated by prevailing downhole temperature and bulk lime-to-silica ratio (i.e CaO/SiO 2 or C/S ratio) in the cement, can alter the physical and mechanical properties of the set slurry.…”

Carbonation Reaction of Calcium Silicate Hydrates by Hydrothermal Synthesis at 150°C in OPC-γ-Ca₂SiO₄-α-Quartz Systems

“…Aging deterioration causes shrinkage and contraction cracks within these materials (Matsushita et al 2004). Therefore, it is necessary that building materials with autoclaved calcium silicate hydrates and carbonation inhibition characteristics be synthesized.…”