English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The present study regards the incorporation of sulfur in dicalcium silicate (Ca2SiO4), a crystalline phase that represents 20 to 40 wt. % of the common Portland cement clinker. In the cement industry this compound is known as C2S (2CaO.SiO2) or belite. It has five polymorphs, and the monoclinic high temperature β-C2S has the highest reactivity with water. The synthesis of the C2S samples was made with high purity reactants with addition of sulfur as CaSO4.2H2O, mixed according to the stoichiometric proportion 2Ca:(1-x)Si:xS, in which x corresponds to the cationic proportion of sulfur, with the values 0; 0.05; 0.3; 0.6; 0.1 and 0.2. The composition of the samples, as well as the cell parameters of the C2S polymorphs, was determined with the Rietveld method using X-ray diffraction data. Determination of micro-deformation and crystallite average size was made by peak profile function refinement, after calibration of the instrument with a cerium oxide standard. Micro-deformation values show a positive correlation with the sulfur content in the C2S structure. The reactivity of C2S with water was measured by the differential scanning calorimetry (DSC) of the heat of hydration. The results reveal a higher reactivity and consequently higher rate of portlandite formation after hydration, in samples with increasing sulfur contents. The presence of sulfur in the C2S structure stabilizes the high temperature polymorph βC2S. The highest SO3 incorporation in C2S, replacing SiO2, is 5 mol%, according to mass balance calculations with chemical composition obtained by X-ray fluorescence. The presence of sulfur caused a progressive variation in the cell parameters: up to 0.1% (Å) in the crystallographic axis (a, b, c) and 0.4% in the β angle. This variation suggests a substitutional solid solution between Si and S in the C2S structure.

Incorporação de enxofre no silicato dicálcico do clínquer de cimento Portland: influência na estabilidade de polimorfos e na reatividade hidráulica