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.

Experimental Study on Mechanical Properties and Micro-Mechanism of All-Solid-Waste Alkali Activated Binders Solidified Marine Soft Soil

2021 ◽  
Vol 1036 ◽  
pp. 327-336
Author(s):  
Ya Lei Wu ◽  
Jun Jie Yang ◽  
Si Chen Li ◽  
Man Wang
Keyword(s):  
Mechanical Properties ◽  
Solid Waste ◽  
Coal Fly Ash ◽  
Soft Soil ◽  
Deformation Modulus ◽  
Alkali Activation ◽  
Activation Process ◽  
Pozzolanic Materials ◽  
Alkali Activated Binders ◽  
Alkali Activated

Utilizing granulated blast furnace slag (GBFS), coal fly ash (FA), and furfural residue incineration ash (FRIA) as pozzolanic materials, then activated with calcium carbide residue (CCR) respectively to prepare all-solid-waste alkali activated binders (ASW binders). The laboratory tests were performed to research the effects of pozzolanic materials with different reactivity on the macro- and micro- characteristics of solidified marine soft soil. Results show that the mechanical properties and alkali-activation process of ASW binders solidified soil was determined mainly by the reactivity of pozzolanic materials, the higher reactivity of the pozzolanic materials in ASW binders couldn’t change the main hydration products, however, it would accelerate the hydrate reaction. The degree of hydrate reaction increased, the microstructure became denser with the increase of the reactivity of the pozzolanic materials in ASW binders solidified soil, on the macro- side, the strength and deformation modulus of the solidified soil increased, meanwhile, the brittleness of the solidified soil will be more obvious during the deformation resistance process. ASW binders (CCR:GBFS=1:1) solidified soil could reach the strength of cemented soil under the same conditions.

scholarly journals Alkali-Activated Binders Based on Tungsten Mining Waste and Electric-Arc-Furnace Slag: Compressive Strength and Microstructure Properties

CivilEng ◽  
2020 ◽  
Vol 1 (2) ◽  
pp. 154-180
Author(s):  
Naim Sedira ◽  
João Castro-Gomes
Keyword(s):  
Compressive Strength ◽  
Electric Arc ◽  
Mining Waste ◽  
Arc Furnace ◽  
Reaction Products ◽  
X Ray ◽  
Eaf Slag ◽  
Electric Arc Furnace Slag ◽  
Furnace Slag ◽  
Alkali Activated

The valorization and reusing of mining waste has been widely studied in recent years. Research has demonstrated that there is great potential for reusing mining waste for construction applications. This work experimentally investigated the strength development, pore structure, and microstructure of a binary alkali-activated binder. This is based on tungsten mining waste mud (TMWM) and electric-arc-furnace slag (EAF-Slag) using different proportions of TMWM (10, 20, 30, 40, and 50 vt.%). The precursors were activated using sodium silicate (Na2SiO3) and potassium hydroxide (KOH 8M) as alkaline activator solution with solid:liquid weight ratio = 3. Pastes were used to assess the compressive strength of the blended binder and their microstructure. The reaction products were characterized by X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), and Fourier transform infra-red (FT-IR) spectroscopy, while the porosity and the pores size properties were examined by mercury intrusion porosimetry (MIP). The results show that the partial replacement of TMWM with EAF-Slag exhibited better mechanical properties than the 100TM-AAB. A maximum strength value of 20.1 MPa was obtained in the binary-AAB sample prepared with 50 vt.% TMWM and EAF-Slag. The pastes that contained a higher dosage of EAF-Slag became more compact with lower porosity and finer pore-size distribution. In addition, the results obtained by SEM-EDS confirmed the formation of different types of reaction products in the 100TM-AAB, 100FS-AAB, and the binary-AABs mixtures such as N-A-S-H, C-A-S-H and (N, C)-A-S-H gels frameworks in the system as the major elements detected are Si, Al, Ca, and Na.

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.

scholarly journals Microstructure Features of Ternary Alkali-activated Binder Based on Tungsten Mining Waste, Slag and Metakaolin

2020 ◽  
Author(s):  
Naim Sedira ◽  
João Castro-Gomes
Keyword(s):  
Sodium Silicate ◽  
Room Temperature ◽  
Mining Waste ◽  
Dense Matrix ◽  
Microstructural Properties ◽  
Reaction Products ◽  
Granulated Blast Furnace Slag ◽  
Alkaline Activator ◽  
Furnace Slag ◽  
Alkali Activated

This study determines the effect of ground granulated blast furnace slag (GGBFS) and metakaolin (MK) on the microstructural properties of the tungsten mining waste-based alkali-activated binder (TMWM). During this investigation, TMWM was partially replaced with 10 wt.% GGBFS and 10 wt.% MK to improve the microstructure of the binder. In order to understand the effect of the substitutions on the microstructure, two pastes were produced to make a comparative study between the sample contain 100% TMWM and the ternary precursors. Both precursors were activated using a combination of alkaline activator solutions (sodium silicate and sodium hydroxide) with the ratio of 1:3 (66.6 wt.% sodium silicate combined with 33.33 wt.% of NaOH 8M). The alkali-activated mixes were cured in oven at temperature of 60 °C in the first day and at room temperature for the next 27 days. The reaction products N-A-S-H gel and (N,M)-A-S-H gel resulted from the alkaline activation reaction process. In addition, a formation of natrite (Na2CO3) with needles shape occurred as a reaction product of the fluorescence phenomena. However, a dense matrix resulted from the alkline activation of the ternary precursors containg different gels such as N-A-S-H, C-A-S-H and (N,M)-C-A-S-H gel, these results were obtained through SEM-EDS analyses, as well FTIR tests. Keywords: Mining Waste, Alkali-activated, Microstructure, Slag, Metakaolin

scholarly journals Mechanical Properties of Alkali Activated Material Based on Red Clay and Silica Gel Precursor

2021 ◽  
Vol 25 (1) ◽  
pp. 931-943
Author(s):  
Girts Bumanis ◽  
Danute Vaiciukyniene
Keyword(s):  
Silica Gel ◽  
Raw Materials ◽  
Raw Material ◽  
Alkali Activation ◽  
Production Plant ◽  
X Ray Diffraction ◽  
Red Clay ◽  
Significant Strength ◽  
Naoh Solution ◽  
Alkali Activated

Abstract The search for alternative alumosilicates source for production of alkali activated materials (AAM) is intensively researched. Wide spread of natural materials such as clays and waste materials are one of potential alternatives. In this research AAM was made from local waste brick made of red clay and calcined low-carbonate illite clay precursor and its properties evaluated. Waste silica gel containing amorphous silica from fertilizer production plant was proposed as additional raw material. 6 M and 7 M NaOH alkali activation solutions were used to obtain AAM. Raw materials were characterized by X-ray diffraction, laser particle size analyser, DTA/TG. Raw illite clay was calcined at a temperature of 700 to 800 °C. Waste brick was ground similar as raw clay and powder was obtained. Replacement of red clay with silica gel from 2–50 wt.% in mixture composition was evaluated. Results indicate that the most effective activator was 6 M NaOH solution and AAM with strength up to 13 MPa was obtained. Ground brick had the highest strength results and compressive strength of AAM reached 25 MPa. Silica gel in small quantities had little effect of AAM strength while significant strength reduction was observed with the increase silica gel content. The efflorescence was observed for samples with silica gel.

scholarly journals Pressure-Induced Geopolymerization in Alkali-Activated Fly Ash

2018 ◽  
Vol 10 (10) ◽  
pp. 3538 ◽  
Author(s):  
Sol Park ◽  
Hammad Khalid ◽  
Joon Seo ◽  
Hyun Yoon ◽  
Hyeong Son ◽  
...  
Keyword(s):  
Fly Ash ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Sodium Silicate Solution ◽  
Silicate Solution ◽  
Elevated Pressure ◽  
X Ray Diffraction ◽  
27Al Mas Nmr ◽  
Alkali Activated

The present study investigated geopolymerization in alkali-activated fly ash under elevated pressure conditions. The fly ash was activated using either sodium hydroxide or a combination of sodium silicate solution and sodium hydroxide, and was cured at 120 °C at a pressure of 0.22 MPa for the first 24 h. The pressure-induced evolution of the binder gel in the alkali-activated fly ash was investigated by employing synchrotron X-ray diffraction and solid-state 29Si and 27Al MAS NMR spectroscopy. The results showed that the reactivity of the raw fly ash and the growth of the zeolite crystals were significantly enhanced in the samples activated with sodium hydroxide. In contrast, the effects of the elevated pressure conditions were found to be less apparent in the samples activated with the sodium silicate solution. These results may have important implications for the binder design of geopolymers, since the crystallization of geopolymers relates highly to its long-term properties and functionality.

Effect of Sodium Silicate Properties in Alkali-Activation of Mexican Blast Furnace Slag

2016 ◽  
Vol 1813 ◽  
Author(s):  
O. F. Cortés-Salmerón ◽  
M. L. García-Chávez ◽  
T. A. García-Mejía
Keyword(s):  
Blast Furnace ◽  
Sodium Silicate ◽  
Blast Furnace Slag ◽  
Alkali Activation ◽  
X Ray Diffraction ◽  
Weight Percentage ◽  
Average Value ◽  
Accelerated Curing ◽  
Compressive Strength Test ◽  
Furnace Slag

ABSTRACTThe present work is a study on alkali activation of Mexican blast furnace slag, using sodium silicate. The aim is to produce an optimal specimen, homogeneous without carbonation, and with small fraction of crystalline phases, similar to CSH, which provide mechanical properties suitable to use in the construction industry. The samples were prepared using sodium silicate activator solutions with modulus (SiO2/Na2O) of 1.25, 1.5, and 1.75. The weight percentage of Na2O in the activator solutions was added at 4, 6 and 8% relative to the slag weight. The prepared samples were stored in sealed molds, at room temperature (20°C), during 7 days. The X-ray diffraction has revealed the presence of an amorphous phase, semi crystalline clinotobermorite phase and signals of calcium carbonate for the samples of 4 and 6 % of Na2O; in contrast with the 8% Na2O, where the latter signals almost disappeared. The specimen selected as optimal was prepared with an activator concentration of 8% of Na2O /Slag, and SiO2/Na2O of 1.25. A specimen under these optimal conditions was prepared with accelerated curing (40°C, humidity, 48 hours), and a compressive strength test was attained, with an average value of 52 MPa at 3 days.

scholarly journals An overview of the utilisation of Fe-rich residues in alkali-activated binders: Mechanical properties and state of iron

2021 ◽  
pp. 129900
Author(s):  
Vitalii Ponomar ◽  
Juho Yliniemi ◽  
Elijah Adesanya ◽  
Katja Ohenoja ◽  
Mirja Illikainen
Keyword(s):  
Mechanical Properties ◽  
Alkali Activated Binders ◽  
Alkali Activated
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