Relating chemical composition, structure, and rheology in alkali‐activated aluminosilicate gels

Alkali-activated materials based on fly ash are widely developed and also produced on the present. Some of fly ashes are not suitable for production of alkali-activated materials because of their inconvenient chemical composition. Alumina-silicates are the most important components that are needed to accomplish the successful reaction. The proper content of amorphous phase of alumina-silicates and its proportion as well should be provided for the final composition of alkali-activated materials. The influence of pure aluminum oxide powder as well as raw milled natural perlite on mechanical properties and durability of alkali-activated mortars was investigated. These minerals were used as partial replacement of fly ash coming from black coal combustion. In addition, the mortars were prepared by using different alkali activators.

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Volcanic Ash as a Sustainable Binder Material: An Extensive Review

Materials ◽

10.3390/ma14051302 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1302

Author(s):

Andrés Játiva ◽

Evelyn Ruales ◽

Miren Etxeberria

Keyword(s):

Chemical Composition ◽

Portland Cement ◽

Urban Areas ◽

Volcanic Ash ◽

Mechanical Performance ◽

Cement Clinker ◽

Alkali Activation ◽

Cement Production ◽

Sustainable Solutions ◽

Alkali Activated

The construction industry is affected by the constant growth in the populations of urban areas. The demand for cement production has an increasing environmental impact, and there are urgent demands for alternative sustainable solutions. Volcanic ash (VA) is an abundant low-cost material that, because of its chemical composition and amorphous atomic structure, has been considered as a suitable material to replace Portland cement clinker for use as a binder in cement production. In the last decade, there has been interest in using alkali-activated VA material as an alternative material to replace ordinary Portland cement. In this way, a valuable product may be derived from a currently under-utilized material. Additionally, alkali-activated VA-based materials may be suitable for building applications because of their good densification behaviour, mechanical properties and low porosity. This article describes the most relevant findings from researchers around the world on the role of the chemical composition and mineral contents of VA on reactivity during the alkali-activation reaction; the effect of synthesis factors, which include the concentration of the alkaline activator, the solution-to-binder ratio and the curing conditions, on the properties of alkali-activated VA-based materials; and the mechanical performance and durability properties of these materials.

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Influence of High-Calcium Ash Composition on the Composite Binders’ Properties

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.316.1019 ◽

2021 ◽

Vol 316 ◽

pp. 1019-1024

Author(s):

O. A. Ignatova ◽

A. A. Dyatchina

Keyword(s):

Mechanical Properties ◽

Chemical Composition ◽

Cement Stone ◽

Normal Density ◽

Fine Aggregate ◽

Equivalent Amount ◽

High Calcium ◽

Composition Structure ◽

Kinetics Of ◽

Positive Effect

The paper presents the studies’ results of chemical composition, structure, and physico-mechanical properties of high-calcium ashes from the Kansk-Achinsk coals (2017-2019 selection). It was found that ash has a complex poly-mineral composition and contains hydraulically active minerals and oxides of СаОfr, β-C2S, CA, C3A, C4AF, C2F, CaSO4. According to the content of CaOfr, MgO does not meet standards’ requirements. The uniformity of the volume change is maintained by the composition with 50% of cement. The structure and hardening kinetics of ash and ash-cement stone compositions, obtained from the test of normal density, were analyzed. It was established that the hardening of compositions with ash from the Kansk-Achinsk coals was largely influenced by ash minerals. An equivalent amount of cement in composite binders cannot be replaced. In order to obtain a positive effect, compositions with ash instead cement of no more than 30% and a part of fine aggregate, without exceeding the ratio of ash: cement = 1: 1, should be used.

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BIOFILM MATRIX – CHEMICAL COMPOSITION, STRUCTURE, FUNCTIONS

Microbiology&Biotechnology ◽

10.18524/2307-4663.2016.4(36).86349 ◽

2016 ◽

Vol 0 (4(36)) ◽

pp. 6-27

Author(s):

М. Б. Галкін ◽

В. О. Іваниця ◽

Б. М. Галкін ◽

Т. О. Філіпова

Keyword(s):

Chemical Composition ◽

Structure Functions ◽

Composition Structure ◽

Biofilm Matrix

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Production and investigation of powders for additive synthesis from a new beta-solidifying TiAl-based alloy

Journal of Physics Conference Series ◽

10.1088/1742-6596/2144/1/012004 ◽

2021 ◽

Vol 2144 (1) ◽

pp. 012004

Author(s):

P V Panin ◽

I A Bogachev ◽

E A Lukina

Keyword(s):

Phase Composition ◽

Chemical Composition ◽

Equilibrium Phase ◽

Fold Increase ◽

Induction Melting ◽

Technological Properties ◽

Powder Flowability ◽

Powder Particles ◽

Additive Synthesis ◽

Composition Structure

Abstract Chemical composition, structure, and technological properties have been investigated for metal powder compositions (MPCs) of a new six-component TiAl-based alloy with Gd microadditions: Ti-31.0Al-2.5V-2.5Nb-2.5Cr-0.4Gd, wt.% (Ti-44.5Al-2V-1Nb-2Cr-0.1Gd, at.%). Three MPCs fractions (10–63, 40–100, 80–120 μm) were produced by electrode induction melting and inert gas atomization technique and targeted for the additive synthesis of parts. It is shown that the chemical composition of the MPCs for the main elements corresponds to that of the electrode. In contrast, a 1.5-fold increase of the oxygen content in the MPCs was observed, which is being the result of natural oxidation of powder particles upon air environment due to developed specific surface. It has been determined that the phase composition of the MPCs (γ+α(α2)+β) differs from the equilibrium phase composition of the electrode (γ+α2)+β0/B2) and corresponds to a rapidly quenched metastable state, which indicates high solidification rates in the atomization process, exceeding critical cooling rates of the alloy. The technological properties, specifically the powder flowability, were found to be improved for 40–100 and 80–120 μm fractions, making them applicable for additive synthesis of parts from the studied alloy by selective electron-beam melting method

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Modeling the influence of chemical composition on compressive strength behavior of alkali-activated phosphorus slag cement using statistical design

Canadian Journal of Civil Engineering ◽

10.1139/cjce-2018-0132 ◽

2018 ◽

Vol 45 (12) ◽

pp. 1073-1083 ◽

Cited By ~ 3

Author(s):

Hamideh Mehdizadeh ◽

Ebrahim Najafi Kani

Keyword(s):

Compressive Strength ◽

Chemical Composition ◽

Statistical Design ◽

Molar Ratio ◽

Statistical Experimental Design ◽

Molar Ratios ◽

Strength Behavior ◽

Optimum Chemical Composition ◽

Optimum Chemical ◽

Alkali Activated

In this study, a statistical experimental design based on response surface methodology (RSM) has been applied to predict and optimize the compressive strength of alkali-activated phosphorus slag in different ages (3, 7, and 28 days). For this purpose, the binder samples were prepared with different molar ratios of SiO2/Na2O (S/N), Na2O/Al2O3(Na/Al), and H2O/Al2O3(H/Al) as alkali activator. Results showed that S/N molar ratio plays its role in early ages of curing and Na/Al molar ratio, and showed its significant effect on 7 and 28 days of compressive strength. H/Al molar ratio had the most significant effect on compressive strength compared to the other parameters. The derived RSM models were statistically adequate and could be used to predict the compressive strength. The optimum chemical composition of activator to obtain the highest compressive strength was achieved as 0.39, 1.34, and 30 for S/N, Na/Al, and H/Al molar ratios, respectively, with compressive strength of 30, 65, and 100 MPa at 3, 7, and 28 days of curing.

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Correction: Materials space of solid-state electrolytes: unraveling chemical composition–structure–ionic conductivity relationships in garnet-type metal oxides using cheminformatics virtual screening approaches

Physical Chemistry Chemical Physics ◽

10.1039/d0cp90141e ◽

2020 ◽

Vol 22 (26) ◽

pp. 15058-15058

Author(s):

Natalia Kireeva ◽

Vladislav S. Pervov

Keyword(s):

Chemical Composition ◽

Solid State ◽

Ionic Conductivity ◽

Virtual Screening ◽

Metal Oxides ◽

Chem Phys ◽

Solid State Electrolytes ◽

Composition Structure ◽

Screening Approaches ◽

Phys Chem Chem Phys

Correction for ‘Materials space of solid-state electrolytes: unraveling chemical composition–structure–ionic conductivity relationships in garnet-type metal oxides using cheminformatics virtual screening approaches’ by Natalia Kireeva et al., Phys. Chem. Chem. Phys., 2017, 19, 20904–20918, DOI: 10.1039/c7cp00518k.

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Composition, Structure and Mechanical Properties of Industrially Sputtered Ta–B–C Coatings

Coatings ◽

10.3390/coatings10090853 ◽

2020 ◽

Vol 10 (9) ◽

pp. 853

Author(s):

Michael Kroker ◽

Pavel Souček ◽

Pavol Matej ◽

Lukáš Zábranský ◽

Zsolt Czigány ◽

...

Keyword(s):

Mechanical Properties ◽

Chemical Composition ◽

Protective Coatings ◽

Multilayered Structure ◽

Number Density ◽

Substrate Rotation ◽

Industrial Batch ◽

Axis Rotation ◽

Composition Structure ◽

Sputter Deposited

Ta–B–C coatings were non-reactively sputter-deposited in an industrial batch coater from a single segmented rotating cylindrical cathode employing a combinatorial approach. The chemical composition, morphology, microstructure, mechanical properties, and fracture resistance of the coatings were investigated. Their mechanical properties were linked to their microstructure and phase composition. Coatings placed stationary in front of the racetrack of the target and those performing a 1-axis rotation around the substrate carousel are compared. Utilization of the substrate rotation has no significant effect on the chemical composition of the coatings deposited at the same position compared to the cathode. Whereas the morphology of coatings with corresponding chemical composition is similar for stationary as well as rotating samples, the rotating coatings exhibit a distinct multilayered structure with a repetition period in the range of nanometers despite utilizing a non-reactive process and a single sputter source. All the coatings are either amorphous, nanocomposite or nanocrystalline depending on their chemical composition. The presence of TaC, TaB, and/or TaB2 phases is identified. The crystallite size is typically less than 5 nm. The highest hardness of the coatings is associated with the presence of larger grains in a nanocomposite structure or formation of polycrystalline coatings. The number, density, and length of cracks observed after high-load indentation is on par with current optimized commercially available protective coatings.

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Zeolite Adsorption of Chloride from a Synthetic Alkali-Activated Cement Pore Solution

Materials ◽

10.3390/ma12122019 ◽

2019 ◽

Vol 12 (12) ◽

pp. 2019 ◽

Cited By ~ 1

Author(s):

Jorge Osio-Norgaard ◽

Wil V. Srubar

Keyword(s):

Chemical Composition ◽

Pore Solution ◽

X Ray Diffraction ◽

X Ray ◽

Elemental Chlorine ◽

Cage Size ◽

Synthetic Zeolites ◽

Diffraction Patterns ◽

Alkali Activated ◽

Alkali Activated Cement

This work presents experimental evidence that confirms the potential for two specific zeolites, namely chabazite and faujasite (with a cage size ~2–13 Å), to adsorb small amounts of chloride from a synthetic alkali-activated cement (AAC) pore solution. Four synthetic zeolites were first exposed to a chlorinated AAC pore solution, two faujasite zeolites (i.e., FAU, X-13), chabazite (i.e., SSZ-13), and sodium-stabilized mordenite (i.e., Na-Mordenite). The mineralogy and chemical composition were subsequently investigated via X-ray diffraction (XRD) and both energy- and wavelength-dispersive X-ray spectroscopy (WDS), respectively. Upon exposure to a chlorinated AAC pore solution, FAU and SSZ-13 displayed changes to their diffraction patterns (i.e., peak shifting and broadening), characteristic of ion entrapment within zeolitic aluminosilicate frameworks. Elemental mapping with WDS confirmed the presence of small amounts of elemental chlorine. Results indicate that the chloride-bearing capacity of zeolites is likely dependent on both microstructural features (e.g., cage sizes) and chemical composition.

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