Influence of mechanical and chemical activation on the hydraulic properties of gamma dicalcium silicate

• Published in: Cement and concrete research 2014-01, Vol.55, p.59-68
• Main Authors: Kriskova, Lubica, Pontikes, Yiannis, Zhang, Fei, Cizer, Özlem, Jones, Peter Tom, Van Balen, Koenraad, Blanpain, Bart
• Format: Article
• Language: English
• Subjects: Activated; Activation; Activation energy; Aggregates and other concrete constituents; Applied sciences; Buildings. Public works; Cement concrete constituents; Cements; Characterisation (B); Dicalcium silicate; Exact sciences and technology; Fluid dynamics; Fluid flow; Gamma dicalcium silicate (D); Hydration; Hydration (A); Hydraulics; Materials; Properties of anhydrous and hydrated cement, test methods; Stainless steel slag; Strength of materials (elasticity, plasticity, buckling, etc.); Structural analysis. Stresses
• ISSN: 0008-8846; 1873-3948
• DOI: 10.1016/j.cemconres.2013.10.004

The aim of this work is to clarify the effect of various activation methods on the hydraulic properties of γ-C2S, one of the main phases in stainless steel slags. Synthetic C2S, sintered at 1450°C for 20h, consisted of 88wt.% γ-C2S and 12wt.% β-C2S. Two activation paths were followed: mechanical activation, by means of high energy milling, and chemical activation, by means of NaOH and Na2CO3 addition. Results indicated that both mechanically and chemically activated γ-C2S hydrated at ambient temperature. XRD analysis showed that the amount of amorphous phase increased during hydration, whereas TGA/DTG data revealed weight loss in the decomposition region of C–S–H. Analyses by FTIR and SEM also support that C–S–H is one of the main hydration products. Mortars prepared with mechanically and chemically activated γ-C2S developed mechanical strength, reaching the values of 9.1MPa and 10.3MPa at 90days, respectively.