Search

Browse

• Communities
• Authors
• Year
• Titles
• Subjects

My Space

• Login

Ποσοτική ανάλυση κλίνκερ τσιμέντου Portland και προσδιορισμός άμορφου υλικού με τη μέθοδο Rietveld

Dimitriadi Maria

Full record

---

Summary

The presence of amorphous or poorly crystalline phases in Portland clinker and cements is usually overlooked when studying their phase composition. This is largely due to the difficulty in determining amorphous content by conventional Powder X-Ray Diffraction (XRD) methods. The quantification of amorphous matter in industrial rock is important for the thorough characterization of the raw materials and assist to interpret their reactivity.The Rietveld method allows a precise quantitative phase analysis of mortars and building materials, and it is considered among the most reliable methods used for quantification of amorphous matter. In this thesis, the results of quantitative analyses with the usage of the Rietveld refinement of a series of six grey and one white Portland cement clinkers are presented. The clinkers were supplied by TITAN Cement Co., corresponding to industrial products of different production days and different cement plants (Kamari, Patra and Thessaloniki). Zinc Oxide (ZnO) was used as the internal standard to determine the amorphous matter content. The particle size analysis and the cement composition of the clinker were determined by laser diffraction analysis and X-Ray fluorescence (XRF) spectroscopy, respectively.The grey clinkers consist mainly of trialcium silicate (C3S, 54.4-61.4%) and calcium aluminate ferrite (C4AF, 12.7-17.4%), along with dicalcium silicate (C2S, 3.2-7.6%) and tricalcium aluminate (C3A, 2.2-4.4%) being secondary crystalline phases. C4AF is not detectable by PXRD in the white clinker sample. This might be attributed to the significant low Fe content (0.19 wt%) in the studied sample, while the latter has lower amounts of C3S (50.5%) and C2S (14.6%) than its grey counterparts. Finally, most samples contain traces of lime (0-4.5%), periclase (0-2%) and portlandite (0.82-4.5%). The six grey clinkers samples have a relatively constant amorphous matter content (13.6-20.2%), suggesting relatively controlled composition of the blend and constant firing conditions. By contrast, the white clinker sample has a considerably higher amorphous content (27.6%).Without the application of the Rietveld method, there is not clear evidence for the presence of amorphous matter. The mean particle size of the grey clinkers varied between 10-16.5 μm, were that of the white clinker was 15.4 μm. The theoretical Bogue composition of grey clinkers in characterized by higher contents of the four main crystalline phases, because it does not take into consideration amorphous matter. The Bogue composition of the white clinker yielded higher C3S and C3A contents but lower C2S content than Rietveld. These results strongly suggest that the determination of amorphous matter is necessary for accurate analysis of cement clinkers, rendering the use of Rietveld analysis a valuable tool in this aspect.

Available Files

Services