Spent FCC Catalyst for Preparing Alkali-Activated Binders: An Opportunity for a High-Degree Valorization

Spent FCC catalyst is a waste from the petrochemical industry which has excellent pozzolanic properties, containing more than 90% silica and alumina. Its similarity to metakaolin creates interesting prospects for its use in the production of alkali-activated binders. In this study, the alkali activation of this residue, spent FCC catalyst, through mixtures with alkali hydroxide and silicate solutions (both sodium and potassium) has been carried out. The alkali cation had an important role in the nature of AA-FCC pastes: some differences in the mass loss in the thermogravimetric tests and in the X-ray mineral characterization were found. No significant differences in compressive strength were observed for mortars cured for 3 days in several conditions: room temperature and 65oC. Prepared AA-FCC mortars had a compressive strength of about 65-70 MPa. Microstructural studies showed that an amorphous, dense and compact microstructure was obtained, independent of the activating solution and curing condition.

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Grinding Kinetics of Slag and Effect of Final Particle Size on the Compressive Strength of Alkali Activated Materials

Minerals ◽

10.3390/min9110714 ◽

2019 ◽

Vol 9 (11) ◽

pp. 714 ◽

Cited By ~ 6

Author(s):

Evangelos Petrakis ◽

Vasiliki Karmali ◽

Georgios Bartzas ◽

Konstantinos Komnitsas

Keyword(s):

Particle Size ◽

Compressive Strength ◽

Particle Size Distribution ◽

Size Distribution ◽

Ageing Time ◽

Reduction Rate ◽

Curing Temperature ◽

Alkali Activation ◽

Final Particle ◽

Alkali Activated

This study aims to model grinding of a Polish ferronickel slag and evaluate the particle size distributions (PSDs) of the products obtained after different grinding times. Then, selected products were alkali activated in order to investigate the effect of particle size on the compressive strength of the produced alkali activated materials (AAMs). Other parameters affecting alkali activation, i.e., temperature, curing, and ageing time were also examined. Among the different mathematical models used to simulate the particle size distribution, Rosin–Rammler (RR) was found to be the most suitable. When piecewise regression analysis was applied to experimental data it was found that the particle size distribution of the slag products exhibits multifractal character. In addition, grinding of slag exhibits non-first-order behavior and the reduction rate of each size is time dependent. The grinding rate and consequently the grinding efficiency increases when the particle size increases, but drops sharply near zero after prolonged grinding periods. Regarding alkali activation, it is deduced that among the parameters studied, particle size (and the respective specific surface area) of the raw slag product and curing temperature have the most noticeable impact on the compressive strength of the produced AAMs.

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Experimental Study on Compound Binding Material of Alkali Activated Metakaolin and Ground Granulated Blast Furnace Slag

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.287-290.1275 ◽

2011 ◽

Vol 287-290 ◽

pp. 1275-1279

Author(s):

Yong Jia He ◽

Lin Nu Lu ◽

Shu Guang Hu

Keyword(s):

Compressive Strength ◽

Blast Furnace ◽

Blast Furnace Slag ◽

Hydration Product ◽

Alkali Activation ◽

Granulated Blast Furnace Slag ◽

Binding Material ◽

Measurement Results ◽

Furnace Slag ◽

Alkali Activated

Compound binding material was prepared by the alkali activation of metakaolin and ground granulated blast furnace slag. Hydration product components, microstructure and mechanical properties of the hardened paste were investigated by IR, XRD, SEM, MIP, and compressive strength measurement. Results indicated that hydration products included C-S-H and geopolymer, and both of them were amorphous although there were differences in their structure and morphology. When the dosage of slag was less than 50%, the compressive strength of hardened paste increased as the dosage increased, which was mainly because C-S-H produced by the reaction of GGBFS and alkali filled void in geopolymer phase, and part of unreacted slag particles acting as microaggregate to prevent from extension of microcrack in the hardened paste, so the porosity of hardened paste decreased and compressive strength increased.

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The Potential of Ladle Slag and Electric Arc Furnace Slag use in Synthesizing Alkali Activated Materials; the Influence of Curing on Mechanical Properties

Materials ◽

10.3390/ma12071173 ◽

2019 ◽

Vol 12 (7) ◽

pp. 1173 ◽

Cited By ~ 10

Author(s):

Češnovar ◽

Traven ◽

Horvat ◽

Ducman

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Room Temperature ◽

Electric Arc Furnace ◽

Electric Arc ◽

Alkali Activation ◽

Arc Furnace ◽

Curing Time ◽

Promising Alternative ◽

Alkali Activated

Alkali activation is studied as a potential technology to produce a group of high performance building materials from industrial residues such as metallurgical slag. Namely, slags containing aluminate and silicate form a useful solid material when activated by an alkaline solution. The alkali-activated (AA) slag-based materials are promising alternative products for civil engineering sector and industrial purposes. In the present study the locally available electric arc furnace steel slag (Slag A) and the ladle furnace basic slag (Slag R) from different metallurgical industries in Slovenia were selected for alkali activation because of promising amorphous Al/Si rich content. Different mixtures of selected precursors were prepared in the Slag A/Slag R ratios 1/0, 3/1, 1/1, 1/3 and 0/1 and further activated with potassium silicate using an activator to slag ratio of 1:2 in order to select the optimal composition with respect to their mechanical properties. Bending strength of investigated samples ranged between 4 and 18 MPa, whereas compressive strength varied between 30 and 60 MPa. The optimal mixture (Slag A/Slag R = 1/1) was further used to study strength development under the influence of different curing temperatures at room temperature (R. T.), and in a heat-chamber at 50, 70 and 90 °C, and the effects of curing time for 1, 3, 7 and 28 days was furthermore studied. The influence of curing time at room temperature on the mechanical strength at an early age was found to be nearly linear. Further, it was shown that specimens cured at 70 °C for 3 days attained almost identical (bending/compressive) strength to those cured at room temperature for 28 days. Additionally, microstructure evaluation of input materials and samples cured under different conditions was performed by means of XRD, FTIR, SEM and mercury intrusion porosimetry (MIP).

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Alkali Activated Binders Based on Metakaolin

Environment Technology Resources Proceedings of the International Scientific and Practical Conference ◽

10.17770/etr2015vol1.204 ◽

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

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. 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. 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. 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.

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Factors Affecting Alkali Activation of Laterite Acid Leaching Residues

Environments ◽

10.3390/environments8010004 ◽

2021 ◽

Vol 8 (1) ◽

pp. 4

Author(s):

Konstantinos Komnitsas ◽

Georgios Bartzas ◽

Vasiliki Karmali ◽

Evangelos Petrakis

Keyword(s):

Compressive Strength ◽

Environmental Sustainability ◽

Structural Integrity ◽

Acid Leaching ◽

Sodium Silicate Solution ◽

Curing Temperature ◽

Alkali Activation ◽

Curing Time ◽

Synthesis Conditions ◽

Alkali Activated

In this experimental study, the alkali activation of acid leaching residues using a mixture of sodium hydroxide (NaOH) and alkaline sodium silicate solution (Na2SiO3) as activators is investigated. The residues were also calcined at 800 and 1000 °C for 2 h or mixed with metakaolin (MK) in order to increase their reactivity. The effect of several parameters, namely the H2O/Na2O and SiO2/Na2O ratios present in the activating solution, the pre–curing time (4–24 h), the curing temperature (40–80 °C), the curing time (24 or 48 h), and the ageing period (7–28 days) on the properties of the produced alkali activated materials (AAMs), including compressive strength, porosity, water absorption, and density, was explored. Analytical techniques, namely X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and elemental mapping analysis were used for the identification of the morphology and structure of the final products. The experimental results show that the laterite acid leaching residues cannot be alkali activated in an unaltered state, and the compressive strength of the produced AAMs barely reaches 1.4 MPa, while the mixing of the residues with 10 wt% metakaolin results in noticeably higher compressive strength (41 MPa). Moreover, the calcination of residues at 800 and 1000 °C has practically no beneficial effect on alkali activation. Alkali activated materials produced under the optimum synthesis conditions were subjected to high temperature firing for 2 h and immersed in distilled water or acidic solution (1 mol L−1 HCl) for 7 and 30 days in order to assess their structural integrity under different environmental conditions. This study explores the potential of alkali activation of laterite leaching residues amended with the addition of metakaolin for the production of AAMS that can be used as binders or in several construction applications in order to enable their valorization and also improve the environmental sustainability of the metallurgical sector.

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Preliminary Studies on the use of Sugar Cane Bagasse Ash (SCBA) in the Manufacture of Alkali Activated Binders

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.600.689 ◽

2014 ◽

Vol 600 ◽

pp. 689-698 ◽

Cited By ~ 7

Author(s):

Vinicius N. Castaldelli ◽

Mauro M. Tashima ◽

José Luiz P. Melges ◽

Jorge L. Akasaki ◽

J.M. Monzó ◽

...

Keyword(s):

Sugar Cane ◽

Binary Systems ◽

Mechanical Performance ◽

Sugar Cane Bagasse ◽

Mineral Admixtures ◽

Alkali Activation ◽

Sugar Cane Bagasse Ash ◽

Alkali Activated Binders ◽

Mechanical Strengths ◽

Alkali Activated

Alkali activated binders require the addition of a mineral-rich amorphous silica and alumina. This paper proposes the use of a mineral residue from the burning of sugar cane bagasse. The alkali activated mixtures were prepared containing binary mixtures of sugar cane bagasse ash (SCBA) and other mineral admixtures: fly ash (FA) or blast furnace slag (BFS). As alkaline activators, mixtures of alkali (Na+ or K+) hydroxide and alkali (Na+ or K+) silicate were used. Alkali-activated pastes and mortars containing binary systems SCBA/FA or SCBA/BFS were prepared and cured at 65 oC. Microstructural properties of these alternative binders were assessed by means of TGA, SEM, XRD and pH measurements. Mechanical strength of mortars was performed after 3 and 7 days at 65 oC. Compressive mechanical strengths of these mortars were in the range 30-55 MPa, showing the good mechanical performance achieved by the alkali activation. Microstructural studies suggested the development of stable matrices and the formation of typical gel.

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The Compressive Strength and Microstructure of Alkali-Activated Binary Cements Developed by Combining Ceramic Sanitaryware with Fly Ash or Blast Furnace Slag

Minerals ◽

10.3390/min8080337 ◽

2018 ◽

Vol 8 (8) ◽

pp. 337 ◽

Cited By ~ 2

Author(s):

Juan Cosa ◽

Lourdes Soriano ◽

María Borrachero ◽

Lucía Reig ◽

Jordi Payá ◽

...

Keyword(s):

Compressive Strength ◽

Blast Furnace ◽

Fly Ash ◽

Blast Furnace Slag ◽

Calcium Content ◽

Partial Replacement ◽

Alkali Activation ◽

High Calcium ◽

Furnace Slag ◽

Alkali Activated

The properties of a binder developed by the alkali-activation of a single waste material can improve when it is blended with different industrial by-products. This research aimed to investigate the influence of blast furnace slag (BFS) and fly ash (FA) (0–50 wt %) on the microstructure and compressive strength of alkali-activated ceramic sanitaryware (CSW). 4 wt % Ca(OH)2 was added to the CSW/FA blended samples and, given the high calcium content of BFS, the influence of BFS was analyzed with and without adding Ca(OH)2. Mortars were used to assess the compressive strength of the blended cements, and their microstructure was investigated in pastes by X-ray diffraction, thermogravimetry, and field emission scanning electron microscopy. All the samples were cured at 20 °C for 28 and 90 days and at 65 °C for 7 days. The results show that the partial replacement of CSW with BFS or FA allowed CSW to be activated at 20 °C. The CSW/BFS systems exhibited better mechanical properties than the CSW/FA blended mortars, so that maximum strength values of 54.3 MPa and 29.4 MPa were obtained in the samples prepared with 50 wt % BFS and FA, respectively, cured at 20 °C for 90 days.

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Influence of Water Content on Mechanical Strength and Microstructure of Alkali-Activated Fly Ash/GGBFS Mortars Cured at Cold and Polar Regions

Materials ◽

10.3390/ma13010138 ◽

2019 ◽

Vol 13 (1) ◽

pp. 138 ◽

Cited By ~ 4

Author(s):

Xiaobin Wei ◽

Feng Ming ◽

Dongqing Li ◽

Lei Chen ◽

Yuhang Liu

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Water Content ◽

Negative Temperature ◽

Polar Regions ◽

Uniaxial Compression Strength ◽

Influence Of Water ◽

Strength And Durability ◽

Alkali Activated Binders ◽

Alkali Activated

Negative temperature curing is a very harmful factor for geopolymer mortar or concrete, which will decrease the strength and durability. The water in the geopolymer mixture may be frozen into ice, and the water content is a crucial factor. The purpose of this paper is to explore the influence of water content on the properties of alkali-activated binders mortar cured at −5 °C. Fly ash (FA) and ground granulated blast furnace slag (GGBFS) were used as binders. Three groups of experiments with different water content were carried out. The prepared samples were investigated through uniaxial compression strength test, Scanning electron microscopy (SEM), and X-ray diffraction (XRD) for the determination of their compressive strength, microstructural features, phase, and composition. The results indicated that, the compressive strength of samples basically maintained 25.78 MPa–27.10 MPa at an age of 28 days; for 90 days, the values reached 33.4 MPa–34.04 MPa. The results showed that lower water content is beneficial to improving the early strength of mortar at −5 °C curing condition, while it has little impact on long-term strength. These results may provide references for the design and construction of geopolymer concrete in cold regions.

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

MATEC Web of Conferences ◽

10.1051/matecconf/201927401003 ◽

2019 ◽

Vol 274 ◽

pp. 01003 ◽

Cited By ~ 1

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.

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Use of Ceramic Sanitaryware as an Alternative for the Development of New Sustainable Binders

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.668.172 ◽

2015 ◽

Vol 668 ◽

pp. 172-180 ◽

Cited By ~ 7

Author(s):

Lucía Reig ◽

M.V. Borrachero ◽

J.M. Monzó ◽

Holmer Savastano ◽

Mauro M. Tashima ◽

...

Keyword(s):

Compressive Strength ◽

Portland Cement ◽

Sanitary Ware ◽

Pozzolanic Activity ◽

Raw Material ◽

Alkali Activation ◽

X Ray ◽

Amorphous Phases ◽

Ceramic Sanitary Ware ◽

Alkali Activated

Large amounts of ceramic sanitary-ware waste are generated in both the production process and construction and demolition practices. This waste contains amorphous phases that may react with the Portlandite that originates during Portland cement hydration or with an alkali solution, leading to a low CO2-binding material. This study investigated the pozzolanic activity of ceramic sanitary-ware waste, together with its potential to form new binders by alkali activation. For this purpose, raw material was characterized by X-ray diffraction, X-ray fluorescence, particle size distribution, thermogravimetry (TGA) and scanning electron microscopy (SEM). Percentages of ceramic waste of 15 wt.% and 25 wt.%, to replace Portland cement, were used to assess the pozzolanic behavior of this material, and samples were cured at 20oC for different curing times. Alkali-activated samples, in which Ca (OH)2 was used as a source of calcium, and NaOH and sodium silicate solutions were utilized as activators, were cured for 7 days at 65oC. The microstructural evolution of the developed binders was assessed in pastes by SEM and TGA analyses, and mortars were used to evaluate the compressive strength behavior. While some strength gain was observed due to pozzolanic activity, compressive strength values within the 14-36 MPa range were obtained in the alkali-activated mortars in accordance with the activator concentration and the percentage of Ca (OH)2 addition.

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