scholarly journals Effect of Particle Size of Periclase on the Periclase Hydration and Expansion of Low-Heat Portland Cement Pastes

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Man Yan ◽  
Min Deng ◽  
Chen Wang ◽  
Zhiyang Chen
Keyword(s):  
Particle Size ◽  
Portland Cement ◽  
Cement Paste ◽  
Raw Materials ◽  
Internal Standard ◽  
Internal Standard Method ◽  
Hydration Degree ◽  
Cement Pastes ◽  
Effect Of Particle Size ◽  
Curing Age

In this paper, low-heat Portland cement (LHC) clinkers were prepared by calcining raw materials at 1350°C for 2.0 hours, 1400°C for 1.0 hour, 1400°C for 1.5 hours, 1400°C for 2.0 hours, 1450°C for 1.0 hour, and 1450°C for 2.0 hours. The clinkers were ground with gypsum to produce LHC. The particle size of periclase was analysed by BSEM. Expansion of LHC pastes due to hydration of periclase was measured. The hydration degree of periclase in LHC pastes was quantitatively determined by XRD internal standard method and BSEM. The results showed that the particle size of periclase was larger when clinkers were calcined at higher temperatures or for longer time. Smaller periclase (2.60 μm) in LHC pastes tended to hydrate faster. As a result, expansion of LHC pastes develops relatively faster. Smaller particle of periclase in clinker tends to result in higher hydration degree of periclase in pastes cured at 20°C for 240 days, and there is a small amount of brucite appearing around periclase. The hydration rate of 4.00 μm periclase particle in cement paste cured at 80°C is obviously faster than that in paste cured at 20°C and 40°C. When cement paste was cured at 80°C for 7 days, the periclase was hydrated for 32.56%. The smaller size periclase (1–3 μm) had fully hydrated when the curing age was 240 days, and a large amount of brucite was produced around the larger periclase particle.

The Influence of Particle Size of Cement and Different Additives on the Properties of Portland Cement Pastes

2016 ◽  
Vol 851 ◽  
pp. 104-109 ◽  
Author(s):  
Pavel Šiler ◽  
Iva Kolářová ◽  
Tomáš Sehnal ◽  
Roman Snop ◽  
Tomáš Opravil ◽  
...  
Keyword(s):  
Particle Size ◽  
Fly Ash ◽  
Portland Cement ◽  
Raw Materials ◽  
Cement Pastes ◽  
Secondary Raw Materials ◽  
Granulated Blast Furnace Slag ◽  
Concrete Production ◽  
Effect Of Particle Size ◽  
Effective Use

The consumption of concrete as a building material is still increasing over the world. Concrete production is closely associated with CO2 and other greenhouse gases emissions. The reduction of these emissions can be achieved by a higher utilization of secondary raw materials in cement mixtures. Particle size is an important factor for more effective use of these materials. This work is focused on the calorimetric determination of the effect of particle size of cement, finely ground granulated blast furnace slag (GBFS), high-temperature fly ash (FA) and fluidized fly ash (FFA) on the Portland cement hydration. Effect of particle size on the hydration of pure cement pastes and pastes with the addition of secondary raw materials is monitored by isoperibolic calorimetry. Other part of this work is aimed on the mechanical properties of resulting materials. The flexural strength and compressive strength were observed after 1, 7 and 28 days of curing.

Effect of Particle Size on Expansive Behaviour of MgO-Based Expansive Agent in Cement Paste

2011 ◽  
Vol 194-196 ◽  
pp. 1143-1146 ◽  
Author(s):  
Zhi Bin Zhang ◽  
Ling Ling Xu ◽  
Ming Shu Tang
Keyword(s):  
Particle Size ◽  
Cement Paste ◽  
Linear Expansion ◽  
Hydration Process ◽  
Early Age ◽  
Hydration Degree ◽  
Expansive Agent ◽  
Effect Of Particle Size ◽  
Higher Temperature

In order to investigate the effect of particle size on expansive behavior of MgO-based expansive agent (MEA), linear expansion of paste containing MEA and hydration process of MEA in paste were measured. The results indicated the expansion of paste increased with the drop of particle size at early age, however, MEA with lager particle size expanded faster at late age. Finally, the expansion of paste increased with the rise of particle size. MEA with larger particle size was detrimental to the soundness of cementitious matarials. These two rules were more obvious to MEA burned at higher temperature. In addition, the hydration degree of MEA increased with the drop of particle size.

Quantitative X-Ray Diffraction Analysis of Anhydrous and Hydrated Portland Cement – Part 1: Manual Methods

2015 ◽  
Vol 1087 ◽  
pp. 493-497 ◽  
Author(s):  
Duong D. Nguyen ◽  
Liam Devlin ◽  
Pramod Koshy ◽  
Charles C. Sorrell
Keyword(s):  
Portland Cement ◽  
Building Materials ◽  
Internal Standard ◽  
Mineralogical Composition ◽  
Xrd Analysis ◽  
Internal Standard Method ◽  
X Ray Diffraction ◽  
Accurate Analysis ◽  
Cement Pastes ◽  
X Ray

Portland cement is one of most important construction and building materials and its properties depend strongly on the mineralogical composition. Consequently, accurate analysis of the mineralogical composition of anhydrous Portland cement is crucial for both product quality control and optimisation of performance following initial hydration. In the latter sense, analysis of the mineralogical composition of hydrated Portland cement paste is critical to understand (1) the mechanism and kinetics of hydration of unmodified pastes and those modified with additives and (2) the resultant properties of cement pastes, mortars, and concretes. Such analyses typically are undertaken by quantitative X-ray diffraction (XRD).The present work reviews current practices in quantitative XRD analysis of anhydrous and hydrated Portland cement. To this end, Part 1 of this two-part work briefly mentions the point-counting method and the Bogue calculation method. The more commonly applied internal standard method and reference intensity ratio (RIR) method are discussed in more detail.

Interaction Between Naphthalene Sulfonate and Silica Fume in Portland Cement Pastes

1987 ◽  
Vol 114 ◽  
Author(s):  
Sidney Diamond ◽  
Leslie J. Struble
Keyword(s):  
Portland Cement ◽  
Silica Fume ◽  
Cement Paste ◽  
Uv Spectrophotometry ◽  
Residual Concentration ◽  
Cement Pastes ◽  
High Ph ◽  
Substantial Concentration ◽  
Low Dosage

ABSTRACTPortland cement pastes were mixed with predissolved naphthalene sulfonate superplasticizer at normal water:cement ratios. Solutions were separated from the fresh pastes at intervals and the residual concentration of the superplasticizer determined by UV spectrophotometry. At low dosage levels essentially all of the superplasticizer was found to be removed from solution within a few minutes; at high dosage levels a substantial concentration was maintained in solution at least to approximately the time of set. In pastes in which silica fume replaced 10% by weight of the cement, it was found that the incorporation of silica fume significantly increased the uptake of superplasticizer. In separate trials it was found that the silica fume by itself adsorbed little superplasticizer, even from high pH solution simulating that of cement paste.

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

2020 ◽  
Vol 56 (1) ◽  
pp. 1
Author(s):  
George Christidis ◽  
Katerina Paipoutlidi ◽  
Ioannis Marantos ◽  
Vasileios Perdikatsis
Keyword(s):  
Particle Size ◽  
Rietveld Refinement ◽  
Raw Materials ◽  
Internal Standard ◽  
Absolute Error ◽  
Matter Content ◽  
Size Difference ◽  
X Ray Diffraction ◽  
X Ray ◽  
Amorphous Matter

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.

Mathematical modeling of cement paste microstructure by mosaic pattern. Part II. Application

1997 ◽  
Vol 12 (7) ◽  
pp. 1741-1746 ◽  
Author(s):  
Paul D. Tennis ◽  
Yunping Xi ◽  
Hamlin M. Jennings
Keyword(s):  
Mathematical Modeling ◽  
Spatial Distribution ◽  
Portland Cement ◽  
Cement Paste ◽  
Pattern Analysis ◽  
Mosaic Pattern ◽  
Cement Pastes ◽  
Multiphase Materials ◽  
Spatial Features ◽  
Complex Shapes

A model based on mosaic pattern analysis is shown to have the potential to describe the complex shapes and spatial distribution of phases in the microstructures of multiphase materials. Several characteristics of both micrographs of portland cement pastes and images generated using the few parameters of the model are determined and, for the most part, agreement is good. The advantage is that spatial features of the microstructures can be captured by a few parameters.

scholarly journals Preparation of Portland Cement with Gold Ore Tailings

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Qiang Wang ◽  
Geng Yao ◽  
Xiangnan Zhu ◽  
Junxiang Wang ◽  
Peng Wu ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Portland Cement ◽  
Raw Materials ◽  
Setting Time ◽  
Hydration Product ◽  
Difficult Problem ◽  
Initial Setting Time ◽  
Gold Ore ◽  
Curing Age

The disposal of gold ore tailings (GTs) has been a very difficult problem for a long time. Thus, this study explored a new approach to the management of GTs by preparing Portland cement. Physical properties, reaction mechanisms, and hydration product types of cement prepared with GTs (C-GTs) and ordinary Portland cement (C-SS) were compared. X-ray diffraction (XRD), thermogravimetric (TG), and scanning electron microscope energy-dispersive spectroscopy (SEM-EDS) analysis techniques were used to study the mineralogical phases of the clinker and raw materials, hydration product types, and microtopography. The consistency, setting time, flexural strength and compressive strength values of the cement samples (C-GTs and C-SS), and burnability of the raw materials were also studied. The burnability analysis indicated that GTs provided a higher reactivity. The XRD results showed that the clinker phases of the C-GTs were C3S, C2S, C3A, and C4AF. The XRD, TG, and SEM-EDS results showed that the hydration products were flaky calcium hydroxide, rod-shaped ettringite, and granular C-S-H gels. Its compressive strength and flexural strength were, respectively, 30.4 MPa and 6.1 MPa at the curing age of 3 days and 59.1 MPa and 9.8 MPa at the curing age of 28 days, which were slightly higher than those of the C-SS. Furthermore, the results showed that the consistency, initial setting time, and final setting time for the two kinds of cement were similar, which further suggested that GTs could be used to prepare Portland cement.

Estimation and Measurement of Porosity Change in Cement Paste

2010 ◽  
Author(s):  
Eunyong Lee ◽  
Haeryong Jung ◽  
Ki-jung Kwon ◽  
Do-Gyeum Kim
Keyword(s):  
Ionic Strength ◽  
Portland Cement ◽  
Cement Paste ◽  
Thermodynamic Model ◽  
Ordinary Portland Cement ◽  
Type I ◽  
Hydration Products ◽  
Cement Pastes ◽  
Porosity Change ◽  
Dissolution Reaction

Laboratory-scale experiments were performed to understand the porosity change of cement pastes. The cement pastes were prepared using commercially available Type-I ordinary Portland cement (OPC). As the cement pastes were exposed in water, the porosity of the cement pastes sharply increased; however, the slow decrease of porosity was observed as the dissolution period was extended more than 50 days. As expected, the dissolution reaction was significantly influenced by w/c raito and the ionic strength of solution. A thermodynamic model was applied to simulate the porosity change of the cement pastes. It was highly influenced by the depth of the cement pastes. There was porosity increase on the surface of the cement pastes due to dissolution of hydration products, such as portlandite, ettringite, and CSH. However, the decrease of porosity was estimated inside the cement pastes due to the precipitation of cement minerals.

Effect of Gypsum on Hydration Degree and Structure of Hardened Paste of Alite-Strontium Calcium Sulphoaluminate Cement

2011 ◽  
Vol 306-307 ◽  
pp. 1024-1028
Author(s):  
Qiu Ying Li ◽  
Ling Chao Lu ◽  
Shou De Wang
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Cement Clinker ◽  
Hardened Cement ◽  
Hydration Degree ◽  
Synthesis Conditions ◽  
Sulphoaluminate Cement ◽  
Calcium Sulphoaluminate ◽  
Calcium Sulphoaluminate Cement ◽  
Curing Age

Synthesis conditions and performance of alite-strontium calcium sulphoaluminate cement have been studied by introducing strontium calcium sulphoaluminate into Portland cement clinker. The effects of gypsum on compressive strength, hydration degree and structure of hardened alite-strontium calcium sulphoaluminate cement paste were studied in this paper. Composition and structure of the hardened cement paste were analyzed by XRD and SEM. Results show that appropriate content of gypsum could contribute to the hydration of alite-strontium calcium sulphoaluminate cement. When gypsum content is 9%, the compressive strengths for 1d, 3d and 28d curing age are 30.7MPa, 59.5MPa and 105.5MPa, and the corresponding hydration degree are 40.4%, 57.5% and 85.8%, respectively. The hydration products of alite-strontium calcium sulphoaluminate cement are mainly ettringite (AFt), Ca(OH)2, C-S-H gel. Large amount of AFt formed at early curing age provides a sound basis for early compressive strength, and a lot of C-S-H gel generated at later curing age increases the density of the hardened paste.

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