Sodium Silicate Concentration Research Articles

Effect of silica fume on the mechanical property and hydration characteristic of alkali-activated municipal solid waste incinerator (MSWI) fly ash

The incorporation of silica fume provides the solution to solve the low silica content of municipal solid waste incinerator fly ash, which hinders its utilisation in manufacturing alkali-activated solid waste incinerator fly ash. This paper reported the effect of silica fume and sodium silicate nature on the hardened properties, including compressive strength, hydration product and microstructure of alkali-activated municipal solid waste incinerator fly ash. In addition to characterising the property of municipal fly ash, the effect of silica fume in compressive strength of alkali-activated municipal solid waste incinerator fly ash under different sodium silicate dosage and modulus was investigated and its hydration products were determined by XRD and SEM. The results demonstrated that adding silica fume significantly improved the compressive strength by promoting the formation of C–S–H hydration product. Moreover, a higher sodium silicate content and modulus resulted in a higher compressive strength. The concentration of leachable heavy metals from harden specimen with 10% SF specimen was significantly reduced to the value which is much lower than the recommendation from Chinese standards.

WITHDRAWN: Mechanical characterization of alkali activated GGBS based geopolymer concrete

The mix of Geopolymer concrete (GPC) requires alkali solutions(AS) like Sodium hydroxide(SH), sodium silicate(SS). Manage the AS, by taking into reflection of unlike molarities of SH (NaOH) resembling 9 M, 14 M, and 19 M and unlike concentrations of SS (Na2SiO3) similar to 20%, 35%, and 50%. The alkali-solution of NaOH & Na2SiO3 kept separately for 1 h before to the combination of GPC. The result shows the mechanical properties(MP) such as compressive strength(CS), young modulus(E) and density of GPC. The specimens were toughened following 28 days of ambient curing(AC). The trial result shown that mix proportion of 1:2:4 mixes produces CS and E values.

Crystalline and amorphous PEO based ceramic coatings on AA6061: Nanoindentation and corrosion studies

Present study reports the detailed nanomechanical and corrosion behaviours of crystalline and amorphous plasma electrolytic oxidation (PEO) coatings developed on Aluminium alloy-6061. The concentration of sodium silicate in the electrolyte is tailored to achieve crystalline and amorphous natures of the PEO coatings. X-ray diffraction (XRD), scanning electron microscopy (SEM) and nanoprofilometry techniques are utilized to investigate microstructural and morphological properties of the PEO coatings. XRD studies confirmed that crystalline ceramic phases are obtained at lower silicate concentration while amorphous nature occurred for comparatively higher concentration of silicate in the electrolyte. Nanoindentation technique is utilized to study the mechanical properties such as hardness (H) and Young's modulus (E) of the PEO coatings. The scatter of the data is treated with well-established Weibull statistical method. Finally, in depth corrosion behaviour of the coatings are investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. Amorphous coatings exhibited superior mechanical properties compared to the crystalline coatings. This is possibly linked with the presence of aluminosilicate phases and difference in silicon content in the coatings. However, as expected crystalline PEO coatings offer better corrosion resistance than the amorphous coatings and this behaviour is explained in terms of porosity contents of the coatings.

WITHDRAWN: Assessment of young’s modulus of alkali activated ground granulated blast-furnace slag based geopolymer concrete with different mix proportions

To Prepare the Eco-friendly concrete we require alkali solutions like Sodium hydroxide and sodium silicate. Organize the alkali solutions, by taking into consideration of dissimilar molarities of Sodium hydroxide (NaOH) resembling 9 M, 14 M, and 19 M and dissimilar concentrations of sodium silicate (Na 2 SiO 3 ) resembling 20%, 35%, and 50%. Get ready the alkali-solution of NaOH & Na 2 SiO 3 alone 1 h earlier to the combination of Geopolymer Concrete. The result shows the mechanical properties such as compressive strength, young are modulus and density of Geopolymer Concrete. The specimens be hardened after 28 days of ambient curing. The investigational result shown that mix proportion of 1:1:2 mix produces compressive strength and Young’s Modulus values.

Multi-walled carbon nanotube dispersion methodologies in alkaline media and their influence on mechanical reinforcement of alkali-activated nanocomposites

The focus of present research is the establishment of a practical procedure for effective incorporation of multi-walled carbon nanotubes (MWCNTs) into alkali-activated materials (AAMs) with the aim of mechanical reinforcement. Investigated composite in this work was an alkali-activated matrix composed of fly ash (FA) and ground-granulated blast furnace-slag (GGBS) as solid aluminium-calcium-silicate precursors along with highly concentrated sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) as liquid alkaline activators. Na2SiO3, NaOH, and a combination of them were used for dispersion of MWCNTs. An anionic surfactant, naphthalene sulfonate (NS), and ultrasonication were applied to assist in the preparation of nanofluids. Optical microscopy, integral light transmission (ILT), and Fourier-transform infrared spectroscopy (FTIR) were performed to assess the colloidal behaviour of MWCNTs in the nanofluids. The possible dispersion mechanisms were furthermore hypothesised for each alkaline medium. Based on the outcomes, MWCNTs had the best dispersion performance in the Na2SiO3 based nanofluids. The relevant nanocomposites accordingly, in comparison to the other preparation methodologies in this research, indicated the highest improvements in flexural (65%) and compressive (30%) strengths as a consequence of 0.050 wt% MWCNT incorporation. Scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) further clarified the reinforcement functionality and microstructure refinement of the MWCNTs dispersed in the Na2SiO3 based nanofluids. Altogether, this paper represents a broad insight concerning a better understanding of MWCNTs’ interactions in alkaline activators, i.e. dispersion media, and AAMs, i.e. host matrices, to obtain the highest possible mechanical and microstructural performance of reinforced nanocomposites.

WITHDRAWN: Stiffness determination of alkali activated ground granulated blast furnace slag based geo-polymer concrete

The mix of Geopolymer concrete (GPC) requires alkali solutions (AS) like Sodium hydroxide (SH), sodium silicate (SS). Manage the AS, by taking into reflection of unlike molarities of SH (NaOH) resembling 9 M, 14 M, and 19 M and unlike concentrations of SS (Na2SiO3) similar to 20%, 35%, and 50%. The alkali-solution of NaOH & Na2SiO3 kept separately for 1 h before to the combination of GPC. The result shows the mechanical properties (MP) such as compressive strength (CS), young modulus (E) and density of GPC. The specimens were toughened following 28 days of ambient curing (AC). The trial result shown that mix proportion of 1:1.5:3 mixes produces CS and E values.

Electrically conductive composite material based on silicon carbide

The article presents the results of the study aimed at establishing the main process parameters of the preparation of an electrically conductive composite material containing silicon carbide, graphite, aluminous cement and sodium silicate. This composite material can be used as a heating element in heat accumulators for the operating temperature range of 600–10000C. The effects of the amount of sodium silicate within the range of 12–18 wt.% and the compacting pressure within the range of 40-70 N / mm2 on the changes in the properties of the samples after drying were investigated. It was established that the mechanical strength of the samples of 34.2 N mm–2 and 33.4 N mm–2 can be achieved at the compacting pressure of 60 N mm–2 and 50 N mm–2 and the sodium silicate content of 14 wt.% and 16 wt.%, respectively. It was shown that a porous microstructure of the composite is formed in the course of samples annealing at the temperatures of 600–10000C due to physicochemical processes of transformations of sodium silicate and its interaction with aluminous cement; this porous microstructure is characterized by open porosity in the range of 23.14–25.11% and mechanical strength in the range of 33.2–32.0 N mm–2. The fabricated composite material after its annealing at 10000C shows a low electrical resistivity of 0.06710–2–0.01410–2 Ohmm at the electric current of 28–94 A and the voltage of 19.2–13.2 V.

Effect of Sodium Silicate Concentration on Morphology of Ceramic Coatings Produced on Commercially Pure Aluminum Using Plasma Electrolytic Oxidation

Microstructure of ceramic coatings formed on commercially pure aluminum by plasma electrolytic oxidation using different amounts of sodium silicate was studied. Analysis of chemical composition and microhardness measurements of the coatings were carried out to characterize the morphology of the coatings. The addition of sodium silicate (1–3 g/L) increased the thickness about 8 orders of magnitude and promotes the growth of the coatings. Chemical analysis of the coatings showed that with increasing sodium silicate concentration in the electrolyte from 1 to 3 g/L, the amount of manganese in the coatings was reduced ∼12%. The contribution of aluminum and silicon changed with a reciprocal relationship. When the concentration of Na2SiO3 changed from 1 to 2 g/L, the aluminium content was reduced about 26% and silicon increased about 80%. When the concentration of Na2SiO3 changed from 2 to 3 g/L, the aluminium content increased about 38% and the concentration of silicon reduced about 60%. The microhardness of the coatings was increased about 2 orders of magnitude by increasing the concentration of sodium silicate from 1 to 3 g/L.

Geopolymerization mechanism of binder-free mine tailings by sodium silicate

The geopolymerization of solid substances rich in calcium and aluminum including mine tailings by sodium silicate is mainly believed to be under the influence of alkali activation. However, mine tailings’ relative neutral condition can decrease sodium silicate's overall alkalinity to an unfavorable condition for alkaline reactivity. The decreased sodium silicate's alkalinity initiates the silica gel's precipitation leading to the overall mine tailings’ geopolymerization. This makes sodium silicate as an alternative binder similar to Portland cement in cemented paste backfill. Any changes in mine tailings’ chemical state can accelerate or decelerate geopolymerization bringing inadequate knowledge about strength development. Thus, mine tailings’ geopolymerization by sodium silicate was investigated at different pH values and compared with cementation by Portland cement. It was found that the elevation in sodium silicate content decreases the acidification influence of mine tailings and postpones the strength development. The setting time of geopolymerised and cemented mine tailings were comparable, but pre-acidification of sodium silicate considerably accelerated the geopolymerization process. This made sodium silicate more advantageous over Portland cement because of manageable curing behavior and strength development. The obtained experimental results were discussed through several mechanical, rheological, microstructural, mineralogical, and chemical tests and analyses.

Selective insulation of water flows in a well based on the use of production waste

A method for isolating water inflows into the well by blocking high permeability zones with a gel-forming composition based on sodium silicate, including biologically active additives has been developed. Whey is used as a biologically active supplement. As a result of isolation of the watering intervals by the gel-forming composition, low-permeability oil-saturated areas are involved in the development. The gelation process can be adjusted depending on the concentrations of sodium silicate and whey, as well as the temperature at a certain depth of the reservoir, necessary for isolation. In order to prevent a premature coagulation process when the formation is saturated with hard formation water, fresh or softened water is pumped in front of the gel-forming composition. This technology is used to reach the residual resistance factor to the value 3.88, an increase in oil production will be 18.5%.

Influence of Critical Parameters of Mix Proportions on Properties of MK-Based Geopolymer Concrete

Conventional Portland cement concrete has been extensively used in the past century due to its superior performance compared to other building materials. Recognizing the environmental impact of cement composites and global pressure toward implementation of sustainable construction materials, geopolymer concrete has been introduced as a potential alternative to conventional cement concrete. This study investigates the properties of metakaolin-based geopolymer concrete by employing various mix design parameters based on locally sourced materials. The test results reported herein comprised 16 mixes divided into three groups to understand the influence of various parameters on the workability and compressive strength of the concrete and hence optimizing the mix proportions. The outcome of this research provided insights into the curing conditions, curing age, sodium hydroxide molarity, sodium silicate content, molar ratios of the mix, and aggregate water absorption effect on the geopolymer concrete behavior. A model is proposed for deciding the water to solids ratio based on the total aggregate percentage for workable geopolymer mixes. In order to produce MK-based geopolymer concrete for structural applications, thresholds are proposed for the three molar ratios, namely sodium oxide to silicon oxide, sodium oxide to aluminum oxide, and water to sodium oxide ratios.

Adhesion and Corrosion Resistance of Micro-Arc Oxidation/Polyurethane Composite Coating on Aluminum Alloy Surface

The adhesion and bonding performance of waterborne polyurethane (PU) coating on aluminum alloy surface was improved in this study. To achieve this objective, the effects of different sodium silicate concentrations on the aluminum alloy micro-arc oxidation (MAO) layer and the adhesion strength and corrosion resistance of MAO-PU composite coating before and after modification by MAO treatment of the 7050 aluminum alloy were studied. The experimental results showed that the modification of the MAO membrane layer by a silane coupling agent could significantly improve the adhesion strength and corrosion resistance of the composite coating. Moreover, the maximum adhesion strength was obtained when the concentration of sodium silicate was 12 g L−1.

Production of bio-waste granules and their evaluation as adsorbent for removal of hexavalent chromium and methylene blue dye

In this research, compost was used as raw materials in the production of biomass adsorbent granules using drum granulation technique. Different concentrations of aqueous sodium silicate solution were used as the binding agents. Chromium and Methylene Blue solutions were selected as model adsorbates for heavy metals and dyes, respectively. The results obtained showed that the concentration of sodium silicate used had a positive influence on the mechanical strength of the granules, increasing the concentration would increase the compressive strength of the granules. The adsorbent granules had sufficient strength to survive wet conditions they were subjected during the adsorption study. However, increasing the concentration has a negative influence on the adsorption properties of the compost granules for both Chromium and Methylene Blue.

Geopolymerization of soil by sodium silicate as an approach to control wind erosion

Transportation of fugitive dust over long distances because of wind erosion is a severe environmental threat. Different approaches are experienced to control wind erosion, but durability and costs are the main drawbacks of existing techniques. This study hereby investigates sodium silicate usage as an alkaline additive to bind soil particles and control wind erosion. Sodium silicate is an environmentally safe material and the precipitated inorganic silica gel from which has the affinity with soil texture that makes the overall geopolymerization materials and method clean and environmentally friendly. The neutral condition of natural soils can reduce the alkalinity of sodium silicate’s alkalinity upon contact to the silica gel formation and soil geopolymerization. Different water-diluted solutions containing 50, 35, 20 wt% sodium silicate were prepared and sprayed over the soil surface while various specifications of the stabilized part were evaluated. It was found that interparticle cohesion, shear strength, and wind erosion were affected by sodium silicate content, as explained through a series of immersion, direct shear, and wind tunnel tests. A combination of mechanical and chemical forces can explain the interparticle cohesion since no chemical bonding was established between silica gel and soil particles, as described in Fourier-transform infrared spectroscopy analysis. Scanning electron microscopy coupled with energy-dispersive spectroscopy and thermogravimetric experiment displayed soil particles’ aggregation without mineralogical alteration. The achieved results implicate sodium silicate’s promising role as a stabilizer to bind the soil particles and control wind erosion.

Optimal formulation design of polymer-modified cement based grouting material for loose deposits

Due to material requirements for grouting in loose deposits, a new polymer-modified cement grout (PMCG) material was designed by addicting polyethylene glycol (PEG), polycarboxylate superplasticizer (PS) and sodium silicate into the cement grout. Then, the properties of PMCG were predicted statistically by using the response surface method (RSM) and the effects of the four parameters (w/c, PEG content, sodium silicate content and PS content) as well as their interaction on the response variables (fluidity, bleeding rate, gel time, and early strength) were investigated. Furthermore, the optimal formulation of PMCG (w/c of 0.9, 8.7% sodium silicate, 4% PEG and 1% PS) can be obtained using a multi-objective optimization technique considering the multi-performance requirements of grouting material in loose deposit. Finally, the macro-performance of the grouting material formed by optimal formulation was validated by a set of experiments. The results demonstrated that the proposed designing method can work effectively in determining the optimal formulation of the grouting material to meet various engineering demands.

Effects of activator content on properties, mineralogy, hydration and microstructure of alkali-activated materials synthesized from calcium silicate slag and ground granulated blast furnace slag

Calcium silicate slag (CSS) is the solid waste of the alumina recovery from high-alumina fly ash project based on combined pre-desilication and lime-soda sintering process. Alkali-activated materials (AAMs) were synthesized from calcium silicate slag (CSS), ground granulated blast furnace slag (GGBFS) in this study. The properties, mineralogy, hydration and microstructure of AAMs with various content of activator (sodium silicate) were investigated. The results show that the AAMs synthesized from 70 wt% CSS, 30 wt% GGBFS and sodium silicate solution with a Na2O/H2O mass ratio of 0.15 reached an optimal compressive strength over 65.0 MPa at 28 d. The reaction products of AAMs synthesized from CSS, GGBFS and sodium silicate are C(N)-(A)-S-H gels. The properties of CSS-based AAMs varied with the activator content - The increasing sodium silicate content is favorable to the hydration, microstructure and strength development. However, as the Na2O/H2O ratio of alkaline solution exceeded 0.15, the significant increase of the viscosity inhibited the hydration and the removing of air bubbles during preparation. This consequently decreased the compactness and compressive strength of CSS-based AAMs.

Investigation of the Nucleation and Initial Growth of Nanosilica Using In Situ Small-Angle X-ray Scattering and Reactive Molecular Dynamics Simulation

A method based on the combination of in situ small-angle X-ray scattering (SAXS) and reactive molecular dynamics (MD) simulation is proposed to investigate the nucleation and initial growth of nanosilica. The formation and significant growth of silica nuclei within 1 s can be observed using in situ SAXS in a custom-designed sample cell. Meanwhile, reactive MD simulation confirms that the nucleation and initial growth take place over a very short time period and quantitatively describes the morphology of the formed particles. Both the experimental and simulation methods reveal changes in the particle size and number. A sudden increase in particle size is observed in the experiment, which corresponds to a decrease in particle number, indicating the transformation of the growth mode from ortho-silicic acid attachment to particle coalescence. The simulation snapshots also captures the process of particle coalescence, confirming the existence of this growth mode. The effects of the synthesis conditions, including temperature, sodium silicate concentration, and pH value, are studied and discussed in detail. The results show that the combination of in situ SAXS and reactive MD simulation is a useful method that provides detailed information on the preparation of precipitated silica and its regulatory mechanism.

Effects of Particle Gradation, Relative Density and Curing on the Strength of Silicate Grouted Sand

This research paper presented the influence of variables such as sand gradation, relative density, curing time and condition and sodium silicate content on the strength characteristics of sodium silicate-formamide injected sand. To start with, the viscosity, gel time, and syneresis of sodium silicate-formamide grouts were studied. With the increase of sodium silicate content in the grout mix, the setting time of sodium silicate-formamide solutions decreased but the viscosity increased. Additionally, an increase in silicate content increased the amount of syneresis of grouts up to a specific point. The grouts with various silicate contents successfully penetrated the sand specimens with different grain size distributions and relative densities. The wet-cured and the air-dried samples were subjected to unconfined compressive (UC) and undrained-unconsolidated (UU) triaxial tests at various time intervals. The UC strengths of wet-cured as well as the air-dried specimens varied from 0.11 to 0.80 MPa and from 0.48 to 2.52 MPa respectively at the end of the 150th day. Moreover, as the internal friction angles of wet-cured and air-dried specimens ranged from 36° to 43° and from 41° to 50° the cohesion intercepts of wet-cured and air-dried specimens varied from 40.78 to 161.68 kPa and from 85.84 to 348.62 kPa respectively at the end of 150th day. As the silicate content of grouts increased, UC and UU strengths of air-dried and wet-cured samples increased. The UC and UU strengths of injected sand specimens under wet-cured condition reduced with time owing to syneresis. However, the UC and UU strengths of grouted specimens under air-dried condition increased with time. Though the strength of grouted sand samples was slightly increased with the increase of relative density, it was found to be highly variable with the grain size distribution.

Testing stabilization of high-plasticity clays used in sloping terrain by adding sodium silicate

High-plasticity clays can be stabilized by the addition of a small percentage of sodium silicate. Sixteen mixtures of 4000 g with different concentrations of sodium silicate at difference percentage were designed, to which were carried out physical, mechanical and chemical characterization tests that allowed to analyze the behavior at intervals of time. Physical, mechanical and chemical properties of the soil were evaluated. Using stabilization with sodium silicate in high plasticity clays, changes in the physical, mechanical, and chemical parameters of the soil were achieved. Having satisfactory results with 3% saturation, optimal concentration, at time intervals of 2 days and 1 month; Then as time passes the soil tries to return to its initial properties, which establishes that the concentration of the Silicate and its effect on the physical and mechanical properties of the soil should be checked over a longer time interval. Studying the physical, mechanical, and chemical parameters of high plasticity clays by adding multiples mixtures of sodium silicate contributes to the understanding of the soil behavior on the pressure condition.

Formation Kinetics of the Dielectric Coatings on Iron Powders for the Fabrication of Soft Magnetic Composite Materials

The topicality and efficiency of applying a silicate-containing inorganic coating as an electric insulator when producing soft magnetic composite materials (SMCMs) from iron powders are substantiated. The influence of the sodium silicate (Na2O–SiO2) concentration in an aqueous solution on the formation kinetics of the dielectric coating on iron powders of various brands is shown as well as on their weight increment, average coating thickness, and physical and manufacturing characteristics. It is established experimentally that the influence of particle morphology of iron powders and surface-tension coefficient at the liquid–solid interface on the coating thickness can be indirectly evaluated by wettability characteristics, in particular, by the contact angle. The peculiarities of formation of interlayer SMCM boundaries are considered. Elemental mapping using an energy-dispersive microanalyzer shows that the coating thickness changes after sample compaction under a pressure of 600 MPa and subsequent heating in a range of 400–600°C, and silicon partially redistributes in the dielectric layer. This is caused by the fact that silicon, having a higher oxygen affinity when compared with iron, actively reacts with oxygen arranged on the surface of iron particles and/or reduces iron oxides, forming SiO2 dioxide in the form of a dense film, which, on the one hand, protects iron particles against oxidation, and on the other hand, the dielectric layer affecting specific magnetic losses is formed in the contact zone of iron particles. It is established that the distinctive feature of densification of iron powders with the coating is the prevalence of the structural deformation under compacting, because the coating reduces the internal friction coefficient. It is shown that the developed SMCM corresponds to modern requirements demanded of soft magnetic composite materials in regards to its magnetic characteristics.