The effect of fluorapatite in limestones on the mineral compositions of Portland cement clinkers

In cement-based materials, alkalis mainly exist in the form of different alkali sulfates. In this study, the impacts of different alkali sulfates on the shrinkage, hydration, pore structure, fractal dimension and microstructure of low-heat Portland cement (LHPC), medium-heat Portland cement (MHPC) and ordinary Portland cement (OPC) are investigated. The results indicate that alkali sulfates magnify the autogenous shrinkage and drying shrinkage of cement-based materials with different mineral compositions, which are mainly related to different pore structures and hydration processes. LHPC has the lowest shrinkage. Otherwise, the effect of alkali sulfates on the autogenous shrinkage is more profound than that of drying shrinkage. Compared with the pore size distribution, the fractal dimension can better characterize the shrinkage properties of cement-based materials. It is noted that the contribution of K2SO4 (K alkali) to the promotion effect of shrinkage on cement-based materials is more significant than that of Na2SO4 (Na alkali), which cannot be ignored. The microstructure investigation of different cement-based materials by means of nuclear magnetic resonance (NMR), mercury intrusion porosimetry (MIP) and scanning electron microscope (SEM) shows that this effect may be related to the different pore structures, crystal forms and morphologies of hydration products of cement-based materials.

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Alteration of Bentonite Reacted with Cementitious Materials for 5 and 10 Years in the Mont Terri Rock Laboratory (CI Experiment)

Minerals ◽

10.3390/min11030251 ◽

2021 ◽

Vol 11 (3) ◽

pp. 251

Author(s):

Shingo Yokoyama ◽

Misato Shimbashi ◽

Daisuke Minato ◽

Yasutaka Watanabe ◽

Andreas Jenni ◽

...

Keyword(s):

Portland Cement ◽

Ordinary Portland Cement ◽

Current Knowledge ◽

Cementitious Materials ◽

Opalinus Clay ◽

Secondary Products ◽

Rock Laboratory ◽

Mineral Compositions ◽

Mont Terri ◽

Mont Terri Rock Laboratory

The cement–clay interaction (CI) experiment was carried out at the Mont Terri rock laboratory to complement the current knowledge on the influence that cementitious materials have on Opalinus Clay (OPA) and bentonite (MX). Drill cores including the interface of OPA, concrete (LAC = low-alkali binder, and OPC = ordinary Portland cement), and MX, which interacted for 4.9 and 10 years, were successfully retrieved after drilling, and detailed analyses were performed to evaluate potential mineralogical changes. The saturated compacted bentonites in core samples were divided into ten slices, profiling bentonite in the direction towards the interface, to evaluate the extent and spatial variation of the mineralogical alteration of bentonite. Regarding the mineral compositions of bentonite, cristobalite was dissolved within a range of 10 mm from the interface in both LAC-MX and OPC-MX, while calcite precipitated near the interface for OPC-MX. In LAC-MX and OPC-MX, secondary products containing Mg (e.g., M-S-H) also precipitated within 20 mm of the interface. These alterations of bentonite developed during the first 4.9 years, with very limited progress observed for the subsequent 5 years. Detectable changes in the mineralogical nature of montmorillonite (i.e., the formation of illite or beidellite, increase in layer charge) did not occur during the 10 years of interaction.

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INFLUENCE OF THE SCOPE ADDITION ON THE STRUCTURE FORMATION OF THE CEMENT STONE BY THE METHOD OF QUANTITATIVE X-RAY PHASE ANALYSIS

The Russian Automobile and Highway Industry Journal ◽

10.26518/2071-7296-2019-4-504-518 ◽

2019 ◽

Vol 16 (4) ◽

pp. 504-518

Author(s):

I. L. Chulkova ◽

I. A. Selivanov ◽

V. D. Galdina

Keyword(s):

Portland Cement ◽

Structure Formation ◽

Phase Analysis ◽

Mineral Composition ◽

Large Scale ◽

Building Materials ◽

Cement Matrix ◽

Cement Stone ◽

X Ray ◽

Mineral Compositions

Introduction. The processes of structure formation of cement compositions and the development of effective technologies of building materials is an urgent task for building material science. The use of large-scale man-made product of pulp and paper enterprises – osprey as a fibrous filler in organic and mineral compositions is the successful decision of the problem. The paper analyzes the ways of using osprey in the building materials’ production. The aim of the research is to study the osprey influence on the processes of structure formation of cement stone by quantitative x-ray phase analysis.Materials and methods. The organic and mineral compositions were obtained on the basis of portland cement and osprey. The authors studied the compositions’ phase of osprey, portland cement and the processes of cement stone structure formation in organ and mineral compositions by quantitative x-ray phase analysis.Results. The authors determined the compositions’ phase of mineral impurities of osprey, cellulose, cement, cement stone, organic and mineral compositions and two compositions containing 25 and 75% by weight.Discussion and conclusions. The osprey application as a filler in the organic and mineral composition causes inhibition of processes of cement hydration. The presence of osprey in the hardening organic and mineral composition leads to a change in the composition and structure of the cement stone in comparison with the phase composition of the cement stone without additives. The result of these changes is a significant increase in the amount of calcite, waterite and a significant decrease in the amount of portland. The authors establish that the effective joint work of the reinforcing component of the osprey with the cement matrix is possible with a limited amount of osprey in organic and mineral compositions.

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Distribution of sulfate between phases in Portland cement clinkers

Cement and Concrete Research ◽

10.1016/s0008-8846(98)00241-5 ◽

1999 ◽

Vol 29 (8) ◽

pp. 1173-1179 ◽

Cited By ~ 40

Author(s):

H.F.W. Taylor

Keyword(s):

Portland Cement ◽

Cement Clinkers

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Rietveld full-profile quantification of Portland cement clinker: The importance of including a full crystallography of the major phase polymorphs

Powder Diffraction ◽

10.1017/s0885715600010769 ◽

2000 ◽

Vol 15 (1) ◽

pp. 7-18 ◽

Cited By ~ 29

Author(s):

J. C. Taylor ◽

I. Hinczak ◽

C. E. Matulis

Keyword(s):

Portland Cement ◽

Rietveld Method ◽

Cement Clinker ◽

Point Counting ◽

Xrf Analysis ◽

Portland Cement Clinker ◽

Full Profile ◽

Polymorphic Forms ◽

Cement Clinkers ◽

Xrd Method

Crystalline phases present in the three NIST SRM Standard Portland cement clinkers 8486, 8487, and 8488 have been quantified from XRD powder patterns, (CoKα radiation), using the full-profile Rietveld method. Included in the Rietveld refinement are rhombohedral (R), monoclinic (M), and triclinic (T) crystal polymorphic forms of C3S, as well as crystal polymorphs of C2S and C3A. It is necessary to specify the phase crystallography including polymorphs, because of the extreme superposition of alite and belite XRD lines in the clinker patterns. Unsatisfactory results occur when only one or two of the C3S polymorphs are used in the Rietveld quantification; best results occur when all three polymorphs for C3S are included. The latter are called RMT-type refinements. The Rietveld full-profile XRD method is as precise as the microscope point-counting (MPC) method, but much less labor-intensive. The Rietveld method can quantify the C3S phase polymorphs, as well as total C3S. Rietveld and MPC methods give the same phase weight percentages for the three NIST standard clinkers. Calculated oxide weight percentages obtained from Rietveld phase weight percentages agree well with oxide percentages determined by XRF analysis. Bogue mineral weight percentages do not agree with Rietveld or MPC data, while transformation of the Bogue mineral percentages to oxides does not compare well with XRF analysis.

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