scholarly journals Properties of Inorganic Polymers Produced from Brick Waste and Metallurgical Slag

Minerals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 551 ◽  
Author(s):  
Soultana ◽  
Valouma ◽  
Bartzas ◽  
Komnitsas
Keyword(s):  
Compressive Strength ◽  
Ageing Time ◽  
Metallurgical Slag ◽  
Curing Temperature ◽  
Added Value ◽  
Size Analysis ◽  
Alkali Activation ◽  
Inorganic Polymers ◽  
Synthesis Conditions ◽  
Optimum Synthesis

This paper explores the alkali activation potential of brick wastes and metallurgical slags. Inorganic polymers (IPs) were produced using an alkaline medium consisting of sodium hydroxide and sodium silicate solutions and the optimum synthesis conditions were determined. In this context, the variable parameters, such as solid to liquid (S/L) ratio, curing temperature (60, 80 and 90 °C) and ageing time (7 and 28 days) on the compressive strength and the morphology of the produced IPs were investigated. Specimens produced under the optimum synthesis conditions were subjected to high temperature firing and immersed in distilled water and acidic solutions for various periods of time, in order to assess their durability and structural integrity. The results showed that the IPs produced using a mix ratio of 50 wt % metallurgical slag and 50 wt % brick wastes, cured at 90 °C and aged for 7 days obtained the highest compressive strength (48.9 MPa). X-ray fluorescence analysis (XRF), particle size analysis, Fourier transform infrared spectroscopy (FTIR), mineralogical analysis (XRD), mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM) and thermogravimetric (TG) analysis also confirmed the optimum microstructural characteristics and the chemical reactions that took place during synthesis. The overall results of this study indicate that the co-valorization of different waste streams, which are produced in large quantities and cause environmental problems if not properly managed, is a viable alternative for the production of binders or secondary construction materials with higher added value.

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 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 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.

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

2019 ◽  
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 slag and evaluate the particle size distributions 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 multi fractal 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.

Mechanical Characterization of Hybrid (Organic-Inorganic) Geopolymers

2013 ◽  
Vol 569-570 ◽  
pp. 119-125 ◽  
Author(s):  
Giuseppe Lamanna ◽  
Alessandro Soprano ◽  
Flavia Bollino ◽  
Michelina Catauro
Keyword(s):  
Compressive Strength ◽  
Polyethylene Glycol ◽  
Testing Machine ◽  
Experimental Tests ◽  
Alkali Activation ◽  
Inorganic Polymers ◽  
Direction Parallel ◽  
Water Curing ◽  
Compressive Tests

The mechanical properties of geopolymers can be obtained through different kinds of experimental tests: this paper is focused on the compressive strength (i.e. in a direction parallel to the loading axis) for the case of uniaxial compression. The compressive strength of such materials is traditionally characterized by the 28th-day value, but their strength is expected to increase in time at a continuously decreasing rate. The knowledge of the strength vs. time law is of importance when a structure is subjected to a certain type of loading at a later age. In this work inorganic polymers from activated metakaolin (alumina silicate inorganic polymers, obtained from alkali activation of powders containing SiO2+Al2O3 > 80%wt) are reported. In order to improve their compressive strength a percentage of polyethylene glycol has been added, thus obtaining a hybrid (organic-inorganic) geopolymer. Many factors can influence significantly the compressive strength of such materials e.g. w/c ration, aggregate content, water curing period, polyethylene/glycol ratio. Afterwards experimental compressive tests (performed in a Zwick-Roell® testing machine) have been carried out varying the polyethylene/glycol ratio and the main dimensions of the samples.

Inorganic polymers of ground waste concrete and industrial waste slags as a low-cost sorbent of heavy metals

2021 ◽  
Author(s):  
Aikaterini Vavouraki
Keyword(s):  
Heavy Metals ◽  
Aqueous Solutions ◽  
Environmental Remediation ◽  
Low Cost ◽  
Cementitious Materials ◽  
Added Value ◽  
Sustainable Construction ◽  
Alkali Activation ◽  
Inorganic Polymers ◽  
Waste Concrete

<p>Inorganic polymers (IPs) are alkali activated aluminosilicate materials. Research on the synthesis of alternative cementitious materials such as IPs receives substantial attention not only for their physico-chemical properties that they acquire but for being cost-effective components of the future toolkit of sustainable construction materials (<strong>Provis, 2018; Vavouraki, 2020</strong>). In addition to potential uses of alkali activation materials for the disposal of industrial solid wastes and by-products, there is a great scientific interest in deploying IPs for environmental remediation purposes (<strong>Rasaki et al., 2019</strong>). In particular IPs can possess application value in pollution treatment of immobilization of toxic (and/ or nuclear) wastes, both inorganics and organics (<strong>Ji & Pei, 2019</strong>). Green sustainable aluminosilicate-based adsorbents may facilitate the elimination of toxic metal and organic pollutants from water and/ or wastewater (<strong>Tan et al., 2020</strong>). IPs are considered low-cost sorbents not only for successful recycling of waste materials but also considering added-value materials for the removal of heavy metals from aqueous solutions. However limited number of studies examines waste-slag-based IPs for the removal capacity of heavy metals.</p><p>The aim of this study is to synthesize IPs from ground waste concrete and industrial slags and investigate their uptake capacity for heavy metals from aqueous solutions. The calcite-bearing and industrial-slags IPs as sorbent materials were examined for the uptake of solely Cu(II), Zn(II) and, Pb(II) and also or along with competitive aqueous solutions. Kinetics and equilibrium experiments were performed and analytical techniques involving XRF, XRD, FTIR, SEM/ EDS and XPS were used for the characterization and morphology analysis of the produced IPs.</p><p><strong>References: </strong>Ji & Pei, 2019. J. Environ. Manage. 231, 256–267; Provis, 2018. Cem. Concr. Res. 114, 40–48; Rasaki et al., 2019. J. Clean. Prod. 213, 42–58; Tan et al., 2020. Environ. Technol. Innov. 18, 100684; Vavouraki, 2020. J. Sustain. Metall. 6, 383–399.</p>

A Taguchi Approach for the Synthesis Optimization of Metakaolin Based Geopolymers

2014 ◽  
Vol 92 ◽  
pp. 44-49 ◽  
Author(s):  
Alexandros Tsitouras ◽  
Sotirios Tsivilis ◽  
Glykeria Kakali
Keyword(s):  
Compressive Strength ◽  
Synergetic Effect ◽  
Initial Mixture ◽  
Molar Ratio ◽  
Strength Development ◽  
Inorganic Polymers ◽  
Curing Conditions ◽  
Synthesis Conditions ◽  
Control Factors ◽  
Synthesis Parameters

There are several factors that affect geopolymerization, including the type and ratios of the starting materials as well as the curing conditions of the initial mixture. The effect of the synthesis parameters on the formation of inorganic polymers are usually examined by “changing one factor at a time”. In this study Taguchi experimental designing model was applied in order to study the synergetic effect of selected synthesis parameters on the compressive strength development of metakaolin based geopolymers. The experimental design involved the variation of three control factors in five levels. The selected factors and the corresponding level range were: i) the alkali to aluminum molar ratio in the starting mixture (0.5-1.5), ii) the kind of alkali ion (Na and/or K) and iii) the molar ratio of Si to alkali oxide in the activation solution (0-2.0). The compressive strength of geopolymers was measured and the final products were also examined by means of XRD, FTIR and SEM. As it is concluded, the optimal synthesis conditions for metakaolin geopolymers are R/Al=0.75, Na/(Na+K)=0.50 and [Si]/R2O=1.50, while the factor having the highest impact on the development of compressive strength is the [Si]/R2O ratio.

Variasi Penambahan Sika Cim Dan Fiber Kawat Pada Beton Mutu Fc’ 30 Mpa

2018 ◽  
Vol 9 (2) ◽  
pp. 67-73
Author(s):  
M Zainul Arifin
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Curing Temperature ◽  
Test Results ◽  
Concrete Compressive Strength ◽  
Normal Concrete ◽  
Astm Method ◽  
Additive Type ◽  
Composition Variation ◽  
Compressive Strength Of Concrete

This research was conducted to determine the value of the highest compressive strength from the ratio of normal concrete to normal concrete plus additive types of Sika Cim with a composition variation of 0.25%, 0.50%, 0.75%, 1.00%, 1.25%, 1 , 50% and 1.75% of the weight of cement besides that in this study also aims to find the highest tensile strength from the ratio of normal concrete to normal concrete in the mixture of sika cim composition at the highest compressive strength above and after that added fiber wire with a size diameter of 1 mm in length 100 mm with a ratio of 1% of material weight. The concrete mix plan was calculated using the ASTM method, the matrial composition of the normal concrete mixture as follows, 314 kg / m3 cement, 789 kg / m3 sand, 1125 kg / m3 gravel and 189 liters / m3 of water at 10 cm slump, then normal concrete added variations of the composition of sika cim 0.25%, 0.50%, 0.75%, 1.00%, 1.25%, 1.5%, 1.75% by weight of cement and fiber, the tests carried out were compressive strength of concrete and tensile strength of concrete, normal maintenance is soaked in fresh water for 28 days at 30oC. From the test results it was found that the normal concrete compressive strength at the age of 28 days was fc1 30 Mpa, the variation in the addition of the sika cim additive type mineral was achieved in composition 0.75% of the cement weight of fc1 40.2 Mpa 30C. Besides that the tensile strength test results were 28 days old with the addition of 1% fiber wire mineral to the weight of the material at a curing temperature of 30oC of 7.5%.

scholarly journals Compressive Strength Gain Behavior and Prediction of Cement-Stabilized Macadam at Low Temperature Curing

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Yongli Xu ◽  
Guang Yang ◽  
Hongyuan Zhao
Keyword(s):  
Compressive Strength ◽  
Low Temperature ◽  
Curing Temperature ◽  
Strength Development ◽  
Construction Process ◽  
Strength Gain ◽  
Estimation Model ◽  
Maturity Method ◽  
Temperature Ranges ◽  
Natural Temperature

For cement-based materials, the curing temperature determines the strength gain rate and the value of compressive strength. In this paper, the 5% cement-stabilized macadam mixture is used. Three indoor controlled temperature curing and one outdoor natural curing scenarios are designed and implemented to study the strength development scenario law of compressive strength, and they are standard temperature curing (20°C), constant low temperature curing (10°C), day interaction temperature curing (varying from 6°C to 16°C), and one outdoor natural temperature curing (in which the air temperature ranges from 4°C to 20°C). Finally, based on the maturity method, the maturity-strength estimation model is obtained by using and analyzing the data collected from the indoor tests. The model is proved with high accuracy based on the validated results obtained from the data of outdoor tests. This research provides technical support for the construction of cement-stabilized macadam in regions with low temperature, which is beneficial in the construction process and quality control.

scholarly journals Effect of Calcium Nitrate on the Properties of Portland–Limestone Cement-Based Concrete Cured at Low Temperature

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1611
Author(s):  
Gintautas Skripkiūnas ◽  
Asta Kičaitė ◽  
Harald Justnes ◽  
Ina Pundienė
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Setting Time ◽  
Calcium Nitrate ◽  
Curing Temperature ◽  
Hardened Concrete ◽  
Cement Pastes ◽  
Initial Setting Time ◽  
Initial Setting ◽  
Early Strength

The effect of calcium nitrate (CN) dosages from 0 to 3% (of cement mass) on the properties of fresh cement paste rheology and hardening processes and on the strength of hardened concrete with two types of limestone-blended composite cements (CEM II A-LL 42.5 R and 42.5 N) at different initial (two-day) curing temperatures (−10 °C to +20 °C) is presented. The rheology results showed that a CN dosage up to 1.5% works as a plasticizing admixture, while higher amounts demonstrate the effect of increasing viscosity. At higher CN content, the viscosity growth in normal early strength (N type) cement pastes is much slower than in high early strength (R type) cement pastes. For both cement-type pastes, shortening the initial and final setting times is more effective when using 3% at +5 °C and 0 °C. At these temperatures, the use of 3% CN reduces the initial setting time for high early strength paste by 7.4 and 5.4 times and for normal early strength cement paste by 3.5 and 3.4 times when compared to a CN-free cement paste. The most efficient use of CN is achieved at −5 °C for compressive strength enlargement; a 1% CN dosage ensures the compressive strength of samples at a −5 °C initial curing temperature, with high early strength cement exceeding 3.5 MPa but being less than the required 3.5 MPa in samples with normal early strength cement.

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