Quantitative Analysis of Portland Cement Clinker with Rietveld Refinement: Implications of the Amorphous Matter

Six ordinary Portland cement (OPC) clinkers and one white cement clinker were analyzed with the Rietveld method, using ZnO internal standard (IC), to determine the presence of amorphous matter (AM). All clinkers contain abundant AM and have lower silicate phase contents when compared with the same clinkers analyzed without IC, whereas the abundances of the aluminate and ferrate phases were not affected by AM. The white cement clinker had the highest AM content. Determination of AM is important for complete characterization of the OPC clinker and might contribute to a better understanding of the mechanical properties of the clinker.

Topological Weaire–Thorpe models of amorphous matter

Amorphous solids remain outside of the classification and systematic discovery of new topological materials, partially due to the lack of realistic models that are analytically tractable. Here we introduce the topological Weaire–Thorpe class of models, which are defined on amorphous lattices with fixed coordination number, a realistic feature of covalently bonded amorphous solids. Their short-range properties allow us to analytically predict spectral gaps. Their symmetry under permutation of orbitals allows us to analytically compute topological phase diagrams, which determine quantized observables like circular dichroism, by introducing symmetry indicators in amorphous systems. These models and our procedures to define invariants are generalizable to higher coordination number and dimensions, opening a route toward a complete classification of amorphous topological states in real space using quasilocal properties.

Determination of amorphous matter in industrial minerals with X-ray diffraction using Rietveld refinement.

A great variety of fine grained industrial rocks, which are valued by the industry contain variable amounts of amorphous or poorly crystalline matter, which is not easily detectable by the conventional mineralogical analysis methods based on X-ray diffraction (XRD). The quantification of amorphous matter in industrial rocks is a major task because it provides a thorough characterization of the raw materials and assists to interpret their reactivity. Among the most reliable methods used for quantification of amorphous matter, are those which are based on Rietveld refinement. In this study we prepared 1:1 mixtures of synthetic or natural calcite and quartz with 5-80% glass flour and added corundum (α-Al2O3) internal standard and applied the Autoquan2.80 © software based on the BGMN computer code to quantify the amorphous matter content. The mixtures with synthetic minerals yielded results with minimum absolute error due to the similar particle size of the minerals, the internal standard and the glass. By contrast, the mixtures with natural minerals displayed greater relative error due to the particle size difference between the minerals on the one hand and the internal standard and the glass on the other, due to the microabsorption effect. Moreover, preferred orientation was important in the case of natural calcite, due to perfect cleavage plane. Mixtures containing up to 25% amorphous matter did not display the characteristic hump at 20-30 °2θ, suggesting that the lack of the hump is not a safe criterion for the recognition of amorphous matter.

Alkali-Aggregate Reaction: A study of the influence of the petrographic characteristics of volcanic rocks

When the rock involved in the alkali-aggregate reaction (AAR) is volcanic, the matter present in the interstices of the grains, called mesostasis is considered responsible for the expansions. Mesostasis is a residue which consists of mineral phases rich in silica and alkalis (K and Na) and in optical microscopy looks like amorphous matter. By means of scanning electron microscopy (SEM) and with the aid of energy dispersive spectroscopy (EDS), the presence of well-crystallized mineral phases in mesostasis can be observed. The objective of this study was to evaluate the amount, the chemical composition and the degree of crystallinity of mesostasis on the reactive potentiality of volcanic rocks.