scholarly journals Leaching of alkali-activated tungsten mining waste materials by electrical conductivity and DRX

2019 ◽  
Vol 274 ◽  
pp. 02002
Author(s):  
Ana Fernandes ◽  
Manuel Magrinho ◽  
João Castro-Gomes
Keyword(s):  
Electrical Conductivity ◽  
Portland Cement ◽  
Research Work ◽  
High Energy ◽  
Mining Waste ◽  
Ftir Analysis ◽  
Compression Tests ◽  
Chemical Leaching ◽  
Alkali Activated Binders ◽  
Alkali Activated

The production of Portland cement leads to high energy and natural resource consumption, as well as relevant emission of CO2 into the atmosphere. Thus, this research work intends to contribute to the study of Portland cement alternative alkali activated binders, which utilization can contribute to counteract to this status. Different samples of alkaline activated binders using different combinations of tungsten mining waste from Panasqueira Mines, milled glass and metakaolin were made. Compression tests were performed at 3, 7, 14 and 28 days of curing. For evaluating reactivity chemical leaching was measured. For such, conductivity tests were carried out simultaneously with pH measurement, SEM-BSE and ATR-FTIR analysis. Electrical conductivity tests enabled to preliminary identify the chemical leaching for different precursors. Additionally, by SEM-BSE it was possible to observed reacted and nonreacted particles, and the reactivity extend was confirmed by ATR-FTIR.

Alkali Activated Binders Based on Metakaolin

2015 ◽  
Vol 1 ◽  
pp. 200
Author(s):  
Laura Sele ◽  
Diana Bajare ◽  
Girts Bumanis ◽  
Laura Dembovska
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Water Absorption ◽  
Raw Materials ◽  
Sodium Silicate Solution ◽  
Total Porosity ◽  
Lead Silicate ◽  
Cement Production ◽  
Alkali Activated Binders ◽  
Alkali Activated

<p>According to research conducted in last 25 years, alkali activated binders have been considered as one of the most progressive alternative binders, which can effectively replace Portland cement. Production of alkali activated binders differs from the Portland cement production and is associated with lower CO2 emissions. The use of recycled industrial by-products and wastes is also possible, what corresponds to the future guidelines and principles of sustainable binder production in the world.<br />The aim of this study was to create innovative alkali activated binders by using secondary raw materials, which will be different from the ones described in the scientific literature – alkali activated binders with porous structure. Raw materials used for the binders were metakaolin containing waste, waste from aluminium scrap recycling factory and recycled lead-silicate glass; solid contents were activated with modified sodium silicate solution with an addition of sodium hydroxide.<br />The physical properties of alkali activated binders, such as density, water absorption, open and total porosity, were determined and flexural and compressive strength of hardened alkali-activated binders were tested at the age of 28 days. Durability was examined by sulphate resistance test, which was performed according to SIA 262/1, appendix D: applicability and relevance for use in practice. 40x40x160 mm prismatic specimens were used for expansion measurement and determination of compressive strength. <br />The open porosity of obtained materials was up to 45%, density from 380 to 1720 kg/m3, compressive strength up to 29,8 MPa, water absorption 6 – 114 wt.%. After analysing the results from the sulphate test it was concluded that glass additive reduced the alkali activated binder resistance to sulphate attack.</p>

Possibilities of Reusing Sugar Cane Straw Ash in the Production of Alternative Binders

2015 ◽  
Vol 668 ◽  
pp. 304-311 ◽  
Author(s):  
João Cláudio Bassan de Moraes ◽  
Daniela Cintra de Araújo Queiroz ◽  
Jorge L. Akasaki ◽  
José Luiz Pinheiro Melges ◽  
M.V. Borrachero ◽  
...  
Keyword(s):  
Portland Cement ◽  
Sugar Cane ◽  
Room Temperature ◽  
Raw Material ◽  
Supplementary Cementitious Material ◽  
Cement Mortars ◽  
Naoh Solution ◽  
Alkali Activated Binders ◽  
Alkali Activated ◽  
Straw Ash

Sugar cane production is increasing in Brazil due the demand in manufacturing sugar and alcohol. During production process, several wastes are generated, such as sugar cane straw. After a burning process of this waste material, sugar cane straw ash (SCSA) is obtained, and may be used in the production of alternative binders. The aim of this paper is to assess the possibility of reuse SCSA as supplementary cementitious material in blended Portland cement mortars and as raw material in the production of alkali-activated binders. Blended Portland cement mortars were prepared using 0%, 20% and 30% of SCSA in replacement of Portland cement. For alkali-activated mortars, the activating solution is based on sodium hydroxide (NaOH) solution and different Slag/SCSA proportions in mass were assessed: 100/0, 75/25 and 50/50. Mechanical strength of mortars cured at room temperature was tested for 7 and 28 curing days. The results confirm that enhanced mechanical properties can be obtained for both alternative binders using SCSA on its composition.

scholarly journals Rheology, Mechanical Properties and Porosity of Ternary Alkali-Activated Binders Based on Mining Mud Waste with Waste Glass and Metakaolin

CivilEng ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 236-253
Author(s):  
Abdelhakim Benhamouda ◽  
João Castro-Gomes ◽  
Luiz Pereira-de-Oliveira
Keyword(s):  
Mechanical Properties ◽  
Portland Cement ◽  
Yield Stress ◽  
Relative Yield ◽  
Rheological Behaviour ◽  
Waste Glass ◽  
Plastic Viscosity ◽  
Rheological Parameters ◽  
Alkali Activated Binders ◽  
Alkali Activated

Alkali-activated materials have the potential to replace Portland cement in certain applications. To better understand these binders’ properties, it is relevant to study their rheological behaviour at early ages, like in the case of Portland cement paste. There are already many studies on the rheological behaviour of these materials in the available literature, using fly ash, metakaolin, and ground granulated blast furnace slag as precursors. However, this study discusses the rheological behaviour, mechanical properties, and porosity of ternary alkali-activated binders based on mining mud waste, waste glass, and metakaolin. The precursor consisted of a volume mix of 70% of tungsten mining waste mud, 15% glass waste, and 15% of metakaolin. The activator was a combination of sodium hydroxide and sodium silicate solution. Five activator/precursor (A/P) ratios (0.37, 0.38, 0.39, 0.40, and 0.4) were studied. The result showed that the activator/precursor ratio affects the rheology of paste and their rheological behaviour fit the Bingham model. The relative yield stress (g) and plastic viscosity (h) increased inversely with the A/P ratio, while the workability increased proportionally. Furthermore, some empirical models are proposed to describe the characteristic of yield stress: plastic viscosity and spread diameter versus the A/P ratio and time with a correlation between the rheological parameters and the spread diameter. The increase in A/P ratio has also followed a decrease in compressive strength in all tested samples for all the ages. As expected, an increase of the porosity accompanied the increase of the A/P ratio.

Energy Absorption Characteristics of a Thin-Walled Tube Filled With Carbon Nano Polyurethane Foam and Application in Car Bumper

2014 ◽  
Author(s):  
D. Tankara ◽  
R. Moradi ◽  
Y. Y. Tay ◽  
H. M. Lankarani
Keyword(s):  
Energy Absorption ◽  
Research Work ◽  
High Energy ◽  
Primary Objective ◽  
Absorption Capacity ◽  
Collapse Mechanism ◽  
Compression Tests ◽  
Thin Walled Tube ◽  
Thin Walled ◽  
Absorption Characteristics

Over the past few decades, much research work has been conducted on the development of advance crashworthy structures to increase the energy absorption of mechanical systems. Thin-walled tubes are primarily used as structural reinforcements and as energy absorbing components. The high-energy absorption characteristics of cellular foams have attracted great attention to further enhance this superior capability. In particular, nanotechnology has been utilized in the development of advanced cellular materials for the automotive and aerospace industry. The primary objective of this study is to conduct a parametric study using experimental and finite element methods to examine and quantify the performances of thin-walled tube when filled with carbon nano particulates. To accomplish this study, compression tests are carried out to obtain the load-deflection curves of the nano-foams when subjected to different weight percentages of carbon nano fibers. Next, the specific energy absorbed and the collapse mechanism of nano foam filled thin-walled tubes are analyzed and compared with the empty ones. Finally, an illustrative study on the use of nano foams for vehicular applications is presented by using a vehicle bumper numerical model. The carbon nano foam is installed into the cavity of the bumper model and a full-frontal crash simulation is performed. Overall, this study has shown that the energy absorption capacity of thin-walled structures can be significantly enhanced with the use of carbon nano foams.

scholarly journals Effects of EAF-Slag on alkali-activation of tungsten mining waste: mechanical properties

2019 ◽  
Vol 274 ◽  
pp. 01003 ◽  
Author(s):  
Naim Sedira ◽  
João Castro-Gomes
Keyword(s):  
Mechanical Properties ◽  
Sodium Silicate ◽  
Mining Waste ◽  
Alkali Activation ◽  
X Ray Diffraction ◽  
Eaf Slag ◽  
Electric Arc Furnace Slag ◽  
Solid Liquid ◽  
Alkali Activated Binders ◽  
Alkali Activated

The mechanical properties of alkali-activated binders based on blends of tungsten mining waste mud (TMWM) and electric arc furnace slag (EAF-S) were investigated. The synthesis of alkali-activated binders was conducted at 60°C for 24 h with different TMWM/EAF-Slag ratios (90:10, 80:20, 70:30, 60:40, and 50:50 vt.%). Using sodium hydroxide (SH) and sodium silicate (SS) solutions as alkaline activators with ratio solid/liquid 4 by unit of volume, and the sodium silicate to NaOH (SS:SH) ratio of 2:1. The X-ray Diffraction (XRD), mercury intrusion porosimetry (MIP) were determined. The different percentages of the precursors and the alkaline activators were optimised to produce paste samples. The compressive strength of samples with 10 vt.% EAF-Slag was close to 20.7 MPa after 90 curing days. The mechanical properties were further increased up to 30 MPa by increasing the percentage of EAF-Slag to 50 vt.%. This demonstrates a new potential for re-using waste material for various constructional applications.

scholarly journals Self-Sensing Properties of Green Alkali-Activated Binders with Carbon-Based Nanoinclusions

2020 ◽  
Vol 12 (23) ◽  
pp. 9916
Author(s):  
Antonella D’Alessandro ◽  
Denny Coffetti ◽  
Elena Crotti ◽  
Luigi Coppola ◽  
Andrea Meoni ◽  
...  
Keyword(s):  
Electrical Resistance ◽  
The Self ◽  
Compression Tests ◽  
Electromechanical Properties ◽  
Sensing Properties ◽  
The Matrix ◽  
Voltage Signal ◽  
Alkali Activated Binders ◽  
Alkali Activated ◽  
Carbon Based

This paper is aimed at investigating the self-sensing properties of Portland-free alkali-activated binders doped with carbon-based nanofillers. Four different inclusions (carbon nanotubes, carbon nanofibers, carbon black and graphene nanoplatelets) were added into the matrix in the same amount. The physical and electromechanical properties were analyzed. The self-sensing capabilities of the samples were tested by applying a square wave voltage signal and measuring the variation of electrical resistance during cyclical compression tests. The results showed that the presence of nano-inclusions enhanced the sensing behavior of the materials, especially regarding the linearity and the hysteresis performances. Such results appear promising for the application of such novel and innovative nano-modified composites in the field of monitoring structures and infrastructures.

scholarly journals Adhesion characterisation of Portland cement concrete and alkali-activated binders

2019 ◽  
Vol 31 (2) ◽  
pp. 69-79 ◽  
Author(s):  
Tanakorn Phoo-ngernkham ◽  
Sakonwan Hanjitsuwan ◽  
Long-yuan Li ◽  
Nattapong Damrongwiriyanupap ◽  
Prinya Chindaprasirt
Keyword(s):  
Portland Cement ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Alkali Activated Binders ◽  
Alkali Activated

scholarly journals Durability of alkali-activated binders: A clear advantage over Portland cement or an unproven issue?

2012 ◽  
Vol 30 ◽  
pp. 400-405 ◽  
Author(s):  
F. Pacheco-Torgal ◽  
Z. Abdollahnejad ◽  
A.F. Camões ◽  
M. Jamshidi ◽  
Y. Ding
Keyword(s):  
Portland Cement ◽  
Clear Advantage ◽  
Alkali Activated Binders ◽  
Alkali Activated

scholarly journals Multi-scale analysis on soil improved by alkali activated binders

2019 ◽  
Vol 92 ◽  
pp. 11003 ◽  
Author(s):  
Enza Vitale ◽  
Giacomo Russo ◽  
Dimitri Deneele
Keyword(s):  
Engineering Properties ◽  
Test Results ◽  
Compression Tests ◽  
X Ray Diffraction ◽  
Multi Scale ◽  
Time Test ◽  
Alkali Activated Binders ◽  
Alkali Activated ◽  
Initial Reactivity ◽  
Mineralogical Phases

In the present paper, the use of alkali activated binders to improve engineering properties of clayey soils is presented as an alternative to traditional binders such as lime or cement. An alkali-activated fly ash and its chemo-physical evolution has been monitored at increasing curing times by means of X-Ray Diffraction and Scanning Electron Microscopy. Alkali-activated binder has been mixed with soil for evaluating the improvement of its mechanical behaviour. One-dimensional compression tests on treated samples have been performed with particular reference to effects induced by binder content and curing time. Test results showed a high initial reactivity of the alkali activated systems promoting formation of new mineralogical phases responsible of the mechanical improvement of the treated soil.

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