scholarly journals Marble Waste Valorization through Alkali Activation

Minerals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 46
Author(s):  
Konstantinos Komnitsas ◽  
Athanasia Soultana ◽  
Georgios Bartzas
Keyword(s):  
Structural Integrity ◽  
Raw Materials ◽  
Curing Temperature ◽  
Alkali Activation ◽  
Environmental Footprint ◽  
X Ray Diffraction ◽  
Molar Ratios ◽  
Alkali Activated ◽  
Activating Solution ◽  
Marble Waste

In the present study, the valorization potential of marble waste in the presence of metakaolin via alkali activation was explored. The activating solution used consisted of NaOH and sodium silicate solutions. The effects of marble waste to metakaolin ratio, particle size of raw materials, curing temperature, and Na2O/SiO2 and H2O/Na2O molar ratios present in the activating solution on the main properties and the morphology of the produced alkali-activated materials (AAMs) was evaluated. The durability and structural integrity of the AAMs after firing at temperatures between 200 and 600 °C, immersion in deionized water and 1 mol/L NaCl solution for different time periods and subjection to freeze–thaw cycles were also investigated. Characterization techniques including Fourier transform infrared spectroscopy, X-ray diffraction, mercury intrusion porosimetry and scanning electron microscopy were used in order to study the structure of the produced AAMs. Τhe highest compressive strength (~36 MPa) was achieved by the AAMs prepared with marble waste to metakaolin mass ratio of 0.3 after curing at 40 °C. The results indicated that the utilization of marble waste in the presence of metakaolin enables the production of AAMs with good physical (porosity, density and water absorption) and mechanical properties, thus contributing to the valorization of this waste type and the reduction of the environmental footprint of the marble industry.

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 Factors Affecting Alkali Activation of Laterite Acid Leaching Residues

Environments ◽  
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.

EFFECT OF CURING TEMPERATURE ON THE PROPERTIES OF 100% CLAY-BASED GEOPOLYMER CONCRETE

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Muhammad Mukhlesur Rahman ◽  
David w. Law ◽  
Indubhushan Patnaikuni
Keyword(s):  
Structural Integrity ◽  
Curing Temperature ◽  
Superior Performance ◽  
Clay Material ◽  
Geopolymer Concrete ◽  
X Ray Diffraction ◽  
X Ray ◽  
Binder Material ◽  
Alkali Activated Binders ◽  
Alkali Activated

Substantial researches have already been carried out on alkali-activated binders for the production of geopolymer concrete but studies on clay-based geopolymer concrete is still insufficient. The aim of this paper is to identify the effect of curing temperature on the properties of 100% clay-based geopolymer concrete. Clay pre-treated at 80°C and 120°C for 24 hours were selected as the source binder material. Four Activator Modulus (AM); 1.0, 1.25, 1.5 and 1.75 for each of two Sodium Oxide (Na2O) dosages of 10% and 15% were selected as the activator material for this investigation. X-ray diffraction (XRF) was applied to characterize the clay material. Specimens were cured at 80°C and 120°C for 24 hours. Specimens were tested under compression at seven, 14, 28 and 40 days. Specimens cured at 80°C took a longer duration (>28 days) to achieve structural integrity while the specimens cured at 120°C achieved structural integrity within seven days. Compressive strength of specimens prepared with AM of 1.0 for both of the Na2O dosage of 10% and 15% exhibited superior performance to other AMs investigated.

scholarly journals Study of an alkali-activated binder based on tungsten mining mud and brick powder waste

2018 ◽  
Vol 163 ◽  
pp. 06002 ◽  
Author(s):  
Naim Sedira ◽  
João Castro-Gomes
Keyword(s):  
Compressive Strength ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Raw Materials ◽  
Weight Ratio ◽  
Alkali Activation ◽  
X Ray Diffraction ◽  
Brick Powder ◽  
Alkali Activated

Blends of Tungsten mining waste mud (TMWM) and brick waste powder (BP) with different dosages were used as precursors for the study of a new binder obtained by alkali-activation. The synthesis was obtained at 60ºC curing during the first 24 hours and at 20°C during the remaining period. A combination of sodium hydroxide (SH) and sodium silicate (SS) solutions was used with SS/SH weight ratio equal 1.5. The solid precursors/liquid activators weight ratio equal to 4. And the modules SiO2/Na2O increase with the increasing of BP dosages 5.21 and 5.59 for dosages 10% and 50%, respectively. Mineralogical characterisation of raw materials was carried out by X–ray diffraction (XRD). The effect of the dosage of BP on the compressive strength and pore size distribution of the new binder was investigated from 24 hours up to 28 days. The pore size distribution was obtained mercury intrusion porosimetry (MIP). The increase in the dosages of BP, between 10 to 50%, was followed by an increase in compressive strength, from 25 to 59 MPa, for all the tested ages. The binder matrix become more dense and compact with the gradually increase of BP dosages, as found out by MIP.

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

Minerals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 714 ◽  
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.

scholarly journals Alkali Activation of Oil Shale Ash Based Ceramics

2012 ◽  
Vol 9 (3) ◽  
pp. 1373-1388 ◽  
Author(s):  
A. Hamadi ◽  
K. Nabih
Keyword(s):  
Oil Shale ◽  
Experimental Approach ◽  
Acid Leaching ◽  
Alkali Activation ◽  
X Ray Diffraction ◽  
Oil Shale Ash ◽  
X Ray ◽  
Eds Analysis ◽  
Shale Ash ◽  
Activating Solution

Timahdit oil shale was subjected to firing transformation via ceramics processing followed by alkali activation to synthesis a materials combining the mechanical properties of ceramics and Zeolites. The mineralogical transformations during firing oil shale have been studied. The main crystalline phases found in oil shale ash (OSA) were wollastonite, gehlenite and augite. Modified oil shale ash (MOSA) was obtained with HNO3acid-leaching in the aim to diminish Ca content. Our experimental approach required a NaOH alkaline activating solution with different concentrations (0.5; 1; 2; 4; 6 and 8M). In our study, X-ray diffraction (XDR), Fourier transform infrared (FTIR) and SEM/EDS analysis were used to evaluate the effect of alkali activation on the structural arrangement of the starting materials (OSA and MOSA) in our study. The quantity and the type of the produced zeolites depended critically on the starting materials and on the NaOH concentration.

scholarly journals Assessment of Alkali Activation Potential of a Polish Ferronickel Slag

2019 ◽  
Vol 11 (7) ◽  
pp. 1863 ◽  
Author(s):  
Konstantinos Komnitsas ◽  
Georgios Bartzas ◽  
Vasiliki Karmali ◽  
Evangelos Petrakis ◽  
Witold Kurylak ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Structural Integrity ◽  
Analytical Techniques ◽  
Curing Temperature ◽  
Alkali Activation ◽  
Inorganic Polymers ◽  
X Ray ◽  
Synthesis Conditions ◽  
Activation Potential ◽  
Ferronickel Slag

In this study, the alkali activation potential of a Polish ferronickel slag (PS), for the production of inorganic polymers (IPs), is investigated. The effect of the main synthesis parameters, i.e., strength of the activating solution, consisting of NaOH and Na2SiO3 solutions and affecting (SiO2 + Al2O3)/Na2O and other important molar ratios in the reactive paste, pre-curing period, curing temperature and time and ageing period was investigated. The structural integrity of the produced specimens was tested after their (i) immersion in distilled water and acidic solutions for a period of 7–30 days, and (ii) firing at temperatures between 200 °C and 1000 °C. Several analytical techniques including X-ray diffraction, X-ray fluorescence, Fourier transform infrared spectroscopy, Differential scanning analysis-Thermogravimetry and Scanning Electron Microscopy were used for the characterization of the produced IPs. Results show that under the optimum synthesis conditions the IPs obtain compressive strength that exceeds 65 MPa. An innovative aspect of this study is that after heating at 400 °C, the specimens acquire compressive strength of 115 MPa and this indicates that they can be also used as fire resistant materials. This study highlights the potential of alkali activation for the valorization of a ferronickel slag and the production of IPs that can be used as binders or in several construction applications, thus improving the sustainability of the metallurgical sector.

scholarly journals XRD and TG-DTA Study of New Phosphate-Based Geopolymers with Coal Ash or Metakaolin as Aluminosilicate Source and Mine Tailings Addition

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 202
Author(s):  
Dumitru Doru Burduhos Nergis ◽  
Petrica Vizureanu ◽  
Andrei Victor Sandu ◽  
Diana Petronela Burduhos Nergis ◽  
Costica Bejinariu
Keyword(s):  
Mine Tailings ◽  
Room Temperature ◽  
Raw Materials ◽  
Coal Ash ◽  
Water Evaporation ◽  
Oxidation Reactions ◽  
X Ray Diffraction ◽  
Xrd Patterns ◽  
First Time ◽  
Alkali Activated

Coal ash-based geopolymers with mine tailings addition activated with phosphate acid were synthesized for the first time at room temperature. In addition, three types of aluminosilicate sources were used as single raw materials or in a 1/1 wt. ratio to obtain five types of geopolymers activated with H3PO4. The thermal behaviour of the obtained geopolymers was studied between room temperature and 600 °C by Thermogravimetry-Differential Thermal Analysis (TG-DTA) and the phase composition after 28 days of curing at room temperature was analysed by X-ray diffraction (XRD). During heating, the acid-activated geopolymers exhibited similar behaviour to alkali-activated geopolymers. All of the samples showed endothermic peaks up to 300 °C due to water evaporation, while the samples with mine tailings showed two significant exothermic peaks above 400 °C due to oxidation reactions. The phase analysis confirmed the dissolution of the aluminosilicate sources in the presence of H3PO4 by significant changes in the XRD patterns of the raw materials and by the broadening of the peaks because of typically amorphous silicophosphate (Si–P), aluminophosphate (Al–P) or silico-alumino-phosphate (Si–Al–P) formation. The phases resulted from geopolymerisation are berlinite (AlPO4), brushite (CaHPO4∙2H2O), anhydrite (CaSO4) or ettringite as AFt and AFm phases.

scholarly journals Research on Eco-friendly Alkali Activated Concrete Incorporating Industrial Wastes

2019 ◽  
Vol 8 (9S2) ◽  
pp. 477-482
Keyword(s):  
Raw Materials ◽  
Sodium Hydroxide Solution ◽  
Industrial Wastes ◽  
Liquid Sodium ◽  
Alkali Activation ◽  
Waste Glass Powder ◽  
Fine Aggregates ◽  
Alkaline Activator ◽  
Alkali Activated Concrete ◽  
Alkali Activated

In the present scenario, the production of green and sustainable concrete has become a must to substitute the ordinary Portland cement (OPC) concrete. It is an eminent fact that the manufacture of OPC requires burning of its raw materials which lead to a huge amount of carbon dioxide liberation; thus it requires a large amount of energy dissipation. The concrete produced using alkali activation has become renowned methods to replace the conventional OPC, which gives an answer to find a way to produce environmentally friendly concrete. In the current study, the alkaline activator used to activate the binder was sodium hydroxide solution dispersed in liquid sodium silicate. The utilization of industrial dissipate materials such as GGBS, fly ash, and waste glass powder was used as the binding ingredients, and stone crusher dust was used as fine aggregates. The experimental investigation showed that a quality concrete can be easily produced using alkali activation of industrial wastes satisfying its strength requirements. The statistical models developed shown that there is a significant relationship between various cube and cylinder strengths. Thus alkali-activated concrete(AAC) can effectively reduce the environmental hazards associated with OPC concrete, which also provides an effective way of utilizing major industrial byproducts

scholarly journals Radiological and physico-chemical characterization of red mud as an Al-containing precursor in inorganic binders for the building industry

2021 ◽  
Vol 36 (2) ◽  
pp. 182-191
Author(s):  
Ljiljana Kljajevic ◽  
Miljana Mirkovic ◽  
Sabina Dolenec ◽  
Katarina Ster ◽  
Mustafa Hadzalic ◽  
...  
Keyword(s):  
Construction Industry ◽  
Natural Radioactivity ◽  
Red Mud ◽  
Building Materials ◽  
Raw Materials ◽  
Construction Materials ◽  
Polymerization Process ◽  
Alkali Activation ◽  
Silica Alumina ◽  
Alkali Activated

The potential re-use of red mud in the building and construction industry has been the subject of research of many scientists. The presented research is a contribution to the potential solution of this environmental issue through the synthesis of potential construction materials based on red mud. A promising way of recycling these secondary raw materials is the synthesis of alkali-activated binders or alkali activated materials. Alkali-activated materials or inorganic binders based on red mud are a new class of materials obtained by activation of inorganic precursors mainly constituted by silica, alumina and low content of calcium oxide. Since red mud contains radioactive elements like 226Ra and 232Th, this may be a problem for its further utilization. The content of naturally occurring radionuclides in manufactured material products with potential application in the building and construction industry is important from the standpoint of radiation protection. Gamma radiation of the primordial radionuclides, 40K and members of the uranium and thorium series, increases the external gamma dose rate. However, more and more precedence is being given to limiting the radiological dose originating from building materials on the population these days. The aim of this research was to investigate the possible influence of alkali activation-polymerization processes on the natural radioactivity of alkali activated materials synthesized by red mud (BOKSIT a. d. Milici, Zvornik, Bosnia and Herzegovina) and their structural properties. This research confirmed that during the polymerization process the natural radioactivity was reduced, and that the process of alkali activation of raw materials has an influence on natural radioactivity of synthesized materials.

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