Mineralogy of C-S-H belite hydrates incorporating Zn-Al-Ti layered double hydroxides

Abstract

Recently, the belitic cements with low alite content were the subject of several research works which aimed to replace the Ordinary Portland Clinker (OPC) for ecological reasons (reduction of CO2 emissions), so to understand the reactivity of this cement, the hydration study of the C2S “dicalcium silicate” phase is primordial research step. As well for a clean environment, the TiO2 photocatalyst has been extensively applied in the science of building materials because of its ability to degrade the cement surface pollutants. New photocatalyst based layered double hydroxides (LDH) associated with zinc, aluminium and TiO2 was introduced to increase the compatibility with mortars. The present work is subjected to investigate the effect of the layered double hydroxides on the hydration of C2S in following the evolution of hydration by X-ray diffraction at 2, 7, 28 and 90 days and analyzing the calcium/silicon ratio of different formed hydrates.

Mineralogy of C-S-H belite hydrates incorporating Zn-Al-Ti layered double hydroxides

“…Nevertheless, despite of the almost immediate forming of the first hydrates, the hydration may continue for many years to come [2]. When the cement is hydrated, the reactions during the gauging form the Calcium Silicate Hydrate C-S-H (notation in the cement industry C = CaO, S = SiO 2 , and H = H 2 O) by releasing Ca 2+ and OH ions [3], these two species combine and form Portlandite. Dicalcium silicate C 2 S gives the same products with low quantities and slow kinetics compared to C 3 S. In Portland cement the dicalcium silicate has three polymorphic forms α-C 2 S, β-C 2 S and γ-C 2 S (metastable) with a composition which varies between 20% and 25% in the clinker.…”