scholarly journals Mine Clay Washing Residues as a Source for Alkali-Activated Binders

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 83
Author(s):  
Caterina Sgarlata ◽  
Alessandra Formia ◽  
Cristina Siligardi ◽  
Francesco Ferrari ◽  
Cristina Leonelli
Keyword(s):  
Ionic Conductivity ◽  
Chemical Stability ◽  
High Performance ◽  
Industrial Process ◽  
Strong Impact ◽  
Integrity Test ◽  
Homogeneous Microstructure ◽  
Calcined Clay ◽  
Alkali Activated Binders ◽  
Alkali Activated

The aim of this paper is to promote the use of mine clay washing residues for the preparation of alkali activated materials (AAMs). In particular, the influence of the calcination temperature of the clayey by-product on the geopolymerization process was investigated in terms of chemical stability and durability in water. The halloysitic clay, a mining by-product, has been used after calcination and mixed with an alkaline solution to form alkali activated binders. Attention was focused on the influence of the clay’s calcination treatment (450–500–600 °C) on the geopolymers’ microstructure of samples, remaining in the lower limit indicated by the literature for kaolinite or illite calcination. The mixtures of clay and alkali activators (NaOH 8M and Na-silicate) were cured at room temperature for 28 days. The influence of solid to liquid ratio in the mix formulation was also tested in terms of chemical stability measuring the pH and the ionic conductivity of the eluate after 24-h immersion time in water. The results reported values of ionic conductivity higher for samples made with untreated clay or with low temperature of calcination (≥756 mS/m) compared with values of samples made with calcined clay (292 mS/m). This result suggests that without a proper calcination of the as-received clay it was not possible to obtain 25 °C-consolidated AAMs with good chemical stability and dense microstructure. The measures of integrity test, pH, and ionic conductivity in water confirmed that the best sample is made with calcined clay at 600 °C, being similar (53% higher ionic conductivity of the eluate) or equal (integrity test and pH) to values recorded for the metakaolin-based geopolymer considered the reference material. These results were reflected in term of reticulation and morphology of samples through the analysis with scanning electron microscope (SEM) and X-ray diffraction (XRD), which show a dense and homogeneous microstructure predominantly amorphous with minor amounts of quartz, halloysite, and illite crystalline phases. Special attention was dedicated to this by-product to promote its use, given that kaolinite (and metakaolin), as primary mineral product, has a strong impact on the environment. The results obtained led us to consider this halloysite clay very interesting as an aluminosilicate precursor, and extensively deepening its properties and reactivity for the alkaline activation. In fact, the heart of this work is to study the possibility of reusing this by-product of an industrial process to obtain more sustainable high-performance binders.

Alkali-activated binders based on incinerator bottom ash combined with limestone-calcined clay or fly ash

2022 ◽  
Vol 320 ◽  
pp. 126306
Author(s):  
Jun Liu ◽  
Zhen Liang ◽  
Hesong Jin ◽  
Gediminas Kastiukas ◽  
Luping Tang ◽  
...  
Keyword(s):  
Fly Ash ◽  
Bottom Ash ◽  
Calcined Clay ◽  
Alkali Activated Binders ◽  
Alkali Activated

scholarly journals The Effect of Fibrous Reinforcement on the Polycondensation Degree of Slag-Based Alkali Activated Composites

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2664
Author(s):  
Isabella Lancellotti ◽  
Federica Piccolo ◽  
Hoang Nguyen ◽  
Mohammad Mastali ◽  
Mohammad Alzeer ◽  
...  
Keyword(s):  
Ionic Conductivity ◽  
Cellulose Fiber ◽  
Point Of View ◽  
Alkaline Media ◽  
Low Carbon ◽  
Integrity Test ◽  
Chemical Measurements ◽  
The Matrix ◽  
Alkaline Conditions ◽  
Alkali Activated

Alternative cementitious binders, based on industrial side streams, characterized by a low carbon footprint, are profitably proposed to partially replace Portland cement. Among these alternatives, alkali-activated materials have attracted attention as a promising cementitious binder. In this paper, the chemical stability of the matrix, in fiber-reinforced slag-based alkali-activated composites, was studied, in order to assess any possible effect of the presence of the reinforcement on the chemistry of polycondensation. For this purpose, organic fiber, cellulose, and an inorganic fiber, basalt, were chosen, showing a different behavior in the alkaline media that was used to activate the slag fine powders. The novelty of the paper is the study of consolidation by means of chemical measurements, more than from the mechanical point of view. The evaluation of the chemical behavior of the starting slag in NaOH, indeed, was preparatory to the understanding of the consolidation degree in the alkali-activated composites. The reactivity of alkali-activated composites was studied in water (integrity test, normed leaching test, pH and ionic conductivity), and acids (leaching in acetic acid and HCl attack). The presence of fibers does not favor nor hinder the geopolymerization process, even if an increase in the ionic conductivity in samples containing fibers leads to the hypothesis that samples with fibers are less consolidated, or that fiber dissolution contributes to the conductivity values. The amorphous fraction was enriched in silicon after HCl attack, but the structure was not completely dissolved, and the presence of an amorphous phase is confirmed (C–S–H gel). Basalt fibers partly dissolved in the alkaline environment, leading to the formation of a C–N–A–S–H gel surrounding the fibers. In contrast, cellulose fiber remained stable in both acidic and alkaline conditions.

scholarly journals Alkali-Activated Binders Using Bottom Ash from Waste-to-Energy Plants and Aluminium Recycling Waste

2021 ◽  
Vol 11 (9) ◽  
pp. 3840 ◽  
Author(s):  
Alex Maldonado-Alameda ◽  
Jofre Mañosa ◽  
Jessica Giro-Paloma ◽  
Joan Formosa ◽  
Josep Maria Chimenos
Keyword(s):  
Bottom Ash ◽  
Physicochemical Characterization ◽  
Waste To Energy ◽  
Promising Alternative ◽  
Leaching Potential ◽  
Aluminium Recycling ◽  
Alkaline Activator ◽  
Alkali Activated Binders ◽  
Energy Plants ◽  
Alkali Activated

Alkali-activated binders (AABs) stand out as a promising alternative to replace ordinary Portland cement (OPC) due to the possibility of using by-products and wastes in their manufacturing. This paper assessed the potential of weathered bottom ash (WBA) from waste-to-energy plants and PAVAL® (PV), a secondary aluminium recycling process by-product, as precursors of AABs. WBA and PV were mixed at weight ratios of 98/2, 95/5, and 90/10. A mixture of waterglass (WG) and NaOH at different concentrations (4 and 6 M) was used as the alkaline activator solution. The effects of increasing NaOH concentration and PV content were evaluated. Alkali-activated WBA/PV (AA-WBA/PV) binders were obtained. Selective chemical extractions and physicochemical characterization revealed the formation of C-S-H, C-A-S-H, and (N,C)-A-S-H gels. Increasing the NaOH concentration and PV content increased porosity and reduced compressive strength (25.63 to 12.07 MPa). The leaching potential of As and Sb from AA-WBA/PV exceeded the threshold for acceptance in landfills for non-hazardous waste.

scholarly journals Dual-Cation Electrolytes Crosslinked with MXene for High-Performance Electrochromic Devices

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 874
Author(s):  
Soyoung Bae ◽  
Youngno Kim ◽  
Jeong Min Kim ◽  
Jung Hyun Kim
Keyword(s):  
Ionic Conductivity ◽  
Response Time ◽  
Indium Tin Oxide ◽  
High Performance ◽  
Fast Response ◽  
High Ionic Conductivity ◽  
Electrochromic Device ◽  
Fast Response Time ◽  
Coloration Efficiency ◽  
Conduction Pathway

MXene, a 2D material, is used as a filler to manufacture polymer electrolytes with high ionic conductivity because of its unique sheet shape, large specific surface area and high aspect ratio. Because MXene has numerous -OH groups on its surface, it can cause dehydration and condensation reactions with poly(4-styrenesulfonic acid) (PSSA) and consequently create pathways for the conduction of cations. The movement of Grotthuss-type hydrogen ions along the cation-conduction pathway is promoted and a high ionic conductivity can be obtained. In addition, when electrolytes composed of a conventional acid or metal salt alone is applied to an electrochromic device (ECD), it does not bring out fast response time, high coloration efficiency and transmittance contrast simultaneously. Therefore, dual-cation electrolytes are designed for high-performance ECDs. Bis(trifluoromethylsulfonyl)amine lithium salt (LiTFSI) was used as a source of lithium ions and PSSA crosslinked with MXene was used as a source of protons. Dual-Cation electrolytes crosslinked with MXene was applied to an indium tin oxide-free, all-solution-processable ECD. The effect of applying the electrolyte to the device was verified in terms of response time, coloration efficiency and transmittance contrast. The ECD with a size of 5 × 5 cm2 showed a high transmittance contrast of 66.7%, fast response time (8 s/15 s) and high coloration efficiency of 340.6 cm2/C.

scholarly journals A Critical Review for an Accurate Electrochemical Stability Window Measurement of Solid Polymer and Composite Electrolytes

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3840
Author(s):  
Adrien Méry ◽  
Steeve Rousselot ◽  
David Lepage ◽  
Mickaël Dollé
Keyword(s):  
Ionic Conductivity ◽  
Energy Density ◽  
High Performance ◽  
Mechanical Stability ◽  
Electrochemical Stability ◽  
Solid Polymer Electrolytes ◽  
Solid Polymer ◽  
Composite Electrolytes ◽  
Battery System ◽  
Electrochemical Stability Window

All-solid-state lithium batteries (ASSLB) are very promising for the future development of next generation lithium battery systems due to their increased energy density and improved safety. ASSLB employing Solid Polymer Electrolytes (SPE) and Solid Composite Electrolytes (SCE) in particular have attracted significant attention. Among the several expected requirements for a battery system (high ionic conductivity, safety, mechanical stability), increasing the energy density and the cycle life relies on the electrochemical stability window of the SPE or SCE. Most published works target the importance of ionic conductivity (undoubtedly a crucial parameter) and often identify the Electrochemical Stability Window (ESW) of the electrolyte as a secondary parameter. In this review, we first present a summary of recent publications on SPE and SCE with a particular focus on the analysis of their electrochemical stability. The goal of the second part is to propose a review of optimized and improved electrochemical methods, leading to a better understanding and a better evaluation of the ESW of the SPE and the SCE which is, once again, a critical parameter for high stability and high performance ASSLB applications.

scholarly journals Effect of CaSO4 Incorporation on Pore Structure and Drying Shrinkage of Alkali-Activated Binders

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1673 ◽  
Author(s):  
Hyeongmin Son ◽  
Sol Moi Park ◽  
Joon Ho Seo ◽  
Haeng Ki Lee
Keyword(s):  
Fly Ash ◽  
Pore Structure ◽  
Drying Shrinkage ◽  
Phase Changes ◽  
X Ray Diffraction ◽  
Activated Slag ◽  
Capillary Tension ◽  
Alkali Activated Binders ◽  
Internal Pore Structure ◽  
Alkali Activated

This present study investigates the effects of CaSO4 incorporation on the pore structure and drying shrinkage of alkali-activated slag and fly ash. The slag and fly ash were activated at a 5:5 ratio by weighing with a sodium silicate. Thereafter, 0%, 5%, 10%, and 15% of CaSO4 were incorporated to investigate the changes in phase formation and internal pore structure. X-Ray Diffraction (XRD), thermogravimetry (TG)/derivative thermogravimetry (DTG), mercury intrusion porosimetry (MIP), nuclear magnetic resonance (NMR), and drying shrinkage tests were carried out to find the correlation between the pore structure and drying shrinkage of the specimens. The results showed that CaSO4 incorporation increased the formation of thenardite, and these phase changes affected the pore structure of the activated fly ash and slag. The increase in the CaSO4 content increased the pore distribution in the mesopore. As a result, the capillary tension and drying shrinkage decreased.

High-performance and thermostable wire supercapacitors using mesoporous activated graphene deposited on continuous multilayer graphene

2021 ◽  
Author(s):  
TaeGyeong Lim ◽  
Ba Trung Ho ◽  
Ji Won Suk
Keyword(s):  
Chemical Stability ◽  
High Performance ◽  
Multilayer Graphene ◽  
Cvd Graphene ◽  
Highly Porous ◽  
Thermal And Chemical Stability

Highly porous activated graphene coated on CVD-graphene/Cu wires enables high-performance wire supercapacitors with enhanced thermal and chemical stability.

Sintering behavior and ionic conductivity of Li1.5Al0.5Ti1.5(PO4)3 synthesized with different precursors

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Bambar Davaasuren ◽  
Qianli Ma ◽  
Alexandra von der Heiden ◽  
Frank Tietz
Keyword(s):  
Grain Size ◽  
Solid State ◽  
Ionic Conductivity ◽  
Solid State Reaction ◽  
Sintering Temperature ◽  
Sintering Behavior ◽  
Homogeneous Microstructure ◽  
Micro Cracks ◽  
Primary Particles ◽  
Total Ionic Conductivity

Abstract Li1.5Al0.5Ti1.5(PO4)3 (LATP) powders were prepared from different NO x -free precursors using an aqueous-based solution-assisted solid-state reaction (SA-SSR). The sintering behavior, phase formation, microstructure and ionic conductivity of the powders were explored as a function of sintering temperature. The powders showed a relatively narrow temperature windows in which shrinkage occurred. Relative densities of 95% were reached upon heating between 900 and 960 °C. Depending on the morphological features of the primary particles, either homogeneous and intact microstructures with fine grains of about <2 µm in size or a broad grain size distribution, micro-cracks and grain cleavages were obtained, indicating the instability of the microstructure. Consequently, the ceramics with a homogeneous microstructure possessed a maximum total ionic conductivity of 0.67 mS cm−1, whereas other ceramics reached only 0.58 mS cm−1 and 0.21 mS cm−1.

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