Addition Of Blast Furnace Slag Research Articles

Synergistic reutilization of spent pot lining and water quenched blast furnace slag as mold flux

A treatment method that synergistic reusing spent pot lining (SPL) and blast furnace slag (BFS) as mold flux (a functional material used in steel enterprises) was developed to achieve the harmless treatment of hazardous substances and recycling of valuable resources in spent pot lining. Mold flux made of SPL and BFS shows outstanding metallurgical performance. More importantly, toxic fluoride and cyanide in SPL were effectively harmless-treated utilizing industrial waste heat after making mold flux. The fluorine leaching ratio of amorphous mold flux residual after a leach test for 128 h is 1.08 wt%, which is 1/24 of that of raw SPL. The microstructure characterization proved the addition of BFS enhanced the fluorine immobilization effect by optimizing the network structure of amorphous mold flux residue. Compared to the traditional landfill treatment, the estimated additional economic benefits of processing one ton of SPL with this method are approximately 1924 USD.

The influence of blast furnace slag on the mechanical properties and mesoscopic damage mechanisms of recycled aggregate concrete compared to natural aggregate concrete at different ages

To improve the mechanical property defects caused by recycled aggregate (RCA) in recycled aggregate concrete (RAC) as well as the effect of blast furnace slag (BFS) addition on the mechanical properties and microscopic damage mechanisms of natural aggregate concrete (NAC) and RAC at long ages. In this paper, the effects of different curing ages (T = 7d, 14d, 28d, 56d, 90d, and 150d) and blast furnace slag contents on the mechanical properties and microscopic damage mechanisms under uniaxial compression of NAC and RAC were investigated, where the cement substitution rate of BFS was 0 % and 35 % (water-cement ratio of 0.46, water-reducing agent dosage of 0.25 %), respectively. Nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM) were used to study the internal pore changes and the generation of hydration products in the specimens, and acoustic emission (AE) showed the microcrack development process. The results showed that the peak stress and modulus of elasticity of the specimens gradually increased with increasing age, the peak strain gradually decreased, and the internal porosity gradually decreased. It is worth noting that the addition of BFS caused the mechanical properties of RAC to decrease at 28 days but enhanced the mechanical properties of RAC at 56–120 days. This was attributed to the fact that the properties of BFS were not yet activated in the early stage, whereas it was activated in the later stage under an alkaline environment and reacted with CH to generate more C–S–H hydration products, which enhanced the interfacial transition zone and reduced the porosity. This highlights the potential of BFS to improve the performance of RCA over long periods of time. In contrast, BFS improved the mechanical properties of NAC throughout the age period and more significantly after 56 days. AE results showed that the peak ring counts lagged behind the peak stresses. Finally, combined with the statistical damage principal model, the fitting was performed by Matlab to analyze the microscopic damage mechanism of the specimen during uniaxial compression. It was found that the changes in the four characteristic parameters (εa, εb, εh and H) followed a certain regularity, reflecting the regular changes in fracture damage and yield damage. This revealed the intrinsic linkage between mesoscopic damage mechanisms and macroscopic mechanical properties. It was demonstrated that it was feasible to speculate on the law of the stress-strain curve at the macroscopic level by using the law of change of the four parameters (εa, εb, εh and H) at the microscopic level.

Synergistic treatment of blast furnace slag and basic oxygen furnace slag for efficient recovery of iron: Phase transformation and oxidation mechanisms

In light of the steel industry's rapid advancements, the availability of high-quality mineral resources is diminishing. Therefore, the recovery of iron from BOF slag is of great significance to the sustainability development. Considering the compositional characteristics of BOF slag, the transformation of the iron-containing phase into (Mn,Mg)yFe3-yO4 is the key step. Thus, a novel process for recovering iron resources by synergistic treatment of blast furnace slag (BFS) and BOF slag was proposed. This research employed FactSage thermodynamic simulation, XRD, SEM-EDS, XPS, and EPMA to analysis the impact of BFS addition (10–50 %), cooling methods (from water-cooling to furnace-cooling), and temperature (1400–1600 °C) on phase transformation and the RO oxidation mechanism, and the conditions of (Mn,Mg)yFe3-yO4 generation and enrichment was obtained. The results show that at BFS addition of 30 %, reaction temperature 1400 °C and furnace-cooling, the iron-containing phase (Ca2Fe2O5 and RO) was almost completely transformed into (Mn,Mg)yFe3-yO4. The oxidation mechanism of RO was formation of (Mn,Mg)yFe3-yO4 by cation diffusion. Under optimal conditions, the iron recovery rate and the grade reached 65.74 % and 32.07 %, respectively, which can be used as raw material for ironmaking. Meanwhile, the main phase of the tailing slag was β-Ca2SiO4, without f-CaO, which has the potential to be used in the cement and concrete industries with the advantages of both low cost and eco-friendly. Therefore, the process with green, efficient and low cost was provided, which is a feasible idea for the comprehensive utilization of industrial solid waste.

Comprehensive utilization of blast furnace slag, municipal sludge and kaolin clay in building brick manufacture: Crystalline transformation, morphology observation and property assessment

At present, the comprehensive utilization of bulk industrial solid waste has attracted wide attention. The recycling of industrial solid waste in building materials not only provides valuable insights for the management of solid waste, but also alleviates the over-exploitation of natural clay resources in the construction industry. In this study, municipal sludge (MS) and blast furnace slag (BFS) were incorporated into kaolin clay (KC) to synthesize sustainable composite bricks, and the sintering effects and engineering properties of bricks were adjusted by changing BFS dosages. The results indicated that the addition of BFS would promote liquid glassy phase production in bricks due to the higher content of alkali/alkaline-earth metal oxides, and the ingredient, viscosity and content of liquid glassy phases could also be regulated through varying the dosage of BFS (0-15%), thereby affecting the pore structure, particle arrangement/consolidation and performance of bricks. Among all synthesized bricks, the optimum dosages of BFS, MS and KC for satisfying the building standard thresholds were 10%, 40% and 50%, with corresponding linear shrinkage, porosity, density, water absorption, compressive and flexure strengths of 12.97%, 18.15%, 1.83 g/cm3, 0.82%, 15 MPa and 38 Mpa, respectively. Finally, mechanism analysis further demonstrated that the formation and evolution of liquid glassy phases were the key responsibility for adjusting the brick micromorphology and performance. Based on this study, using MS and BFS in brick manufacturing benefited the value-added utilization of industrial solid wastes, clean protection of environments and sustainable production of building materials, providing a reference for the process optimization and potential application of MS and BFS wastes in masonry construction.

Effects of blast furnace slag on the immobilization, plant uptake and translocation of Cd in a contaminated paddy soil

The potential toxicity of Cd to soil and rice plant severely threaten human health. This study was conducted to investigate the remediation effects of blast furnace slag (BFS) on the bioavailability of Cd in a contaminated paddy soil from a perspective of soil solution chemistry. Batch experiments, pot culture experiments, and principal analysis (PCA) were used to study the effects and mechanisms of BFS addition changing Cd chemical behavior and Cd toxicity. Results indicated that BFS facilitated Cd adsorption in soils, increased pH, Eh, and EC values in soil solution, whereas reduced dissolved Cd content. BFS amendment was efficient in decreasing root Cd intake and Cd upward transport in rice plant, with the Cd translocation factor in brown rice decreased by ∼ 75% (BFS treatment, 6‰ wt) relative to Cd treatment, which in turn increased rice biomass and grain yield. PCA indicated that the dissolved Cd concentration had a close relationship with soil pH and metal concentration in soil solution. Results from this study indicated that BFS had potential ability for either immobilization or remobilization of Cd in soils, and the findings have important implications for Cd-polluted soil remediation or other resource utilization with slag-based materials.

The effect of the addition of blast furnace slag on the wear behavior of heavy transport polymer-based brake pads

This study developed a new asbestos-free brake lining by including blast furnace slag. In addition to phenolic resin as the main binder, brass shavings, copper powder, alumina, and iron oxide powders as reinforcement material, graphite powder to increase friction stability, and calcium carbonate as filler were used. First, by applying a hot press and heat treatment, five samples were created in which these materials were used in various proportions. All samples were tested for tribological behavior and wear parameters, and wear surfaces were evaluated. According to the experimental results, the model containing 50% slag had the lowest wear rate (4.05 gcm3/Nm-6) and the highest friction coefficient (0.4552); yet it also had the most frictional irregularity. The sample containing 7.5% slag, 15% bronze chips, 15% copper powder, 20% phenolic resin, 15% graphite powder, 5% Alumina, 2.5% iron oxide and 20% calcium carbonate gave the best results. The average coefficient of friction for this sample was 0.4511 and the specific wear rate was 6.77 cm3/Nm-6. It has been proven that up to 7.5% slag in brake pads can be beneficial; however, it is not beneficial to use more than this ratio.

Production and Properties of Magnesium Potassium Phosphate Cements Containing Ash and Metallurgical Slag Additives for Radioactive Waste Immobilization

Magnesium potassium phosphate cements (MKPCs) are currently considered as the matrix materials for immobilization of radioactive waste of low and medium activity, as an alternative to Portland cements. At the same time, MKPC compound has the following advantages: fast hardening, high early strength, low shrinkage and high chemical resistance. Magnesium potassium phosphate cement is prepared at room temperature by an acid-base reaction between calcined magnesium oxide (MgO), potassium dihydrogen phosphate (KH2PO4) and water to form magnesium potassium phosphate hexahydrate MgKPO4 ∙ 6H2O known as K-struvite. To obtain MKPC, starting components of high purity and, accordingly, high cost are required. From an industrial point of view, this leads to an excessive price of the final product, and therefore, the use of inexpensive industrial waste as cement fillers is economically cost effective.
 In the present paper, the effect of fly ash and blast-furnace slag additives on the microstructure, compressive strength, and chemical resistance of MKPC samples was studied. The results indicate that particles of both ash and blast-furnace slag are involved in the reaction of MKPC obtaining with the formation of predominantly crystalline K-struvite. According to X-ray diffraction analysis, the content of K-struvite in samples with additives of both fly ash and blast-furnace slag is almost the same and amounts to 58–60 %. With the same addition of filler, samples with the addition of blast-furnace slag have a denser structure, which is formed due to the increased reactivity of blast-furnace slag particles. Moreover, MKPC samples with the addition of blast-furnace slag exhibit higher strength and better chemical resistance to leaching compared to MKPC samples with fly ash additions. The obtained results demonstrate the prospects of using industrial waste additives in the production of MKPC compounds characterized by high mechanical strength and chemical resistance.

Microscale and macroscale strength behaviors of blast furnace slag- cement based materials: Modeling and analysis

Blast furnace slag (BFS) is used extensively as a cement replacement material, improving both the microstructure and the mechanical properties. How to optimize the content of BFS used without losing the mechanical properties of the composite is a very important theoretical problem. Essentially, the strength evolution of BFS-cement based materials is mainly dominated by the hydration reaction of the cementitious material. The formed hydration products bind the dispersed aggregate particles together, so that the material exhibits a certain strength and stiffness on the macroscopic scale. Exploring the microstructural evolution of BFS-cement based materials contributes to the understanding of the failure and instability process under external stress loading, and the optimization of proportion ratios to achieve optimum mechanical properties. Consequently, a better understanding of the microstructure evolution of BFS-cement based material is required. In this study, the microstructure of the BFS-cement based material was modeled using the discrete element method in combination with techniques such as thermogravimetric (TG) analysis and X-ray diffraction (XRD). In addition, mercury intrusion porosimetry and uniaxial compressive strength tests were performed to verify the reliability of the model. Finally, a series of mechanical simulations were carried out using the model. The simulated porosity and compressive strength were compared with the relevant experimental data with an error rate of less than 10%, showing the strong simulation capability of the proposed model. Through representative elementary volume simulation analysis, it is shown that the 30 wt% addition of BFS had a more positive effect on long-term strength, with an increase of approximately 5% compared to that of pure cement sample. The proposed model exhibited that the slag hydration reaction consumes portlandite (CH) and produces more cementitious calcium silicate hydrate (CSH) particles, resulting in the simulated 28d strength starting to be larger than that of pure cement. The established microstructure model of BFS-cement based materials provides a basis for predicting the strength structural.

An environmentally friendly approach to soil improvement with by-product of the manufacture of iron

Blast furnace slag has been used for many years in various applications related to civil engineering. Many studies have created a wide variety of cost-effective and environmentally friendly solutions for this industrial by-product. This study aims to contribute to the performance evaluations of the usability of the blast furnace slag for soil improvement and the effects of the additive ratio and curing time. Bentonite samples were prepared with the addition of blast furnace slag at 5%, 10%, 15%, and 20% ratios by weight at optimum water content (wopt). Results were evaluated using the liquid limit, plastic limit, unconfined compressive strength, and swelling tests performed after 1, 7, 14, and 28 days of curing time. Results revealed that the liquid limit value decreased, and the unconfined compressive strength increased with increasing curing time and blast furnace slag ratio in the mixture. Additionally, swelling pressure generally decreased with increasing slag contribution and curing time. The lowest values of the unconfined compressive strength were observed on the 7th day of curing time, and the minimum value was obtained at 10% mixing ratio. The highest unconfined compressive strength values were observed on the 28th days of curing time. The optimum mixing ratio was 5%.

Consolidation of phosphorus tailings and soluble fluorine & phosphorus with calcium carbide residue-mirabilite waste as a green alkali activator

Two alkalis of industrial solid wastes, calcium carbide residue-mirabilite (CCRM), were used as a green combined activator to consolidate phosphorus tailings and soluble phosphorus as well as fluorine through the alkaline activation process. The results based on XRD, FTIR, 29Si NMR and SEM indicated that most of the blast furnace slag (BFS) forms gels to consolidate phosphorus tailings, and the calcium silicate hydrate (C-S-H) gel dominated mechanical properties and immobilization of soluble phosphorus and fluorine. Comparing with the classical alkaline activators Na2SiO3 and NaOH, the CCRM activated materials displayed great competitiveness in mechanical properties with the order of NaOH < CCRM < Na2SiO3. Its maximum compressive strength reached to 10.9 MPa, and the compressive strength increased greatly with certain increasing content of BFS. In addition, the toxicity characteristic leaching procedure (TCLP) tests found the consolidation of risky soluble fluorine and phosphorus ions in the alkaline activation materials (AAMs) presented in the trend of CCRM > NaSiO3 > NaOH, and the tendency enlarges with increasing BFS addition, over 93.1 % and 98.9 % of soluble fluorine and phosphorus ions could be well fixed. Considering on the environmental and economic efficiency, mechanical properties, soluble phosphorus and fluorine immobilization, the CCRM is found a quite potential solid waste alkali activator for phosphorus tailings and soluble fluorine & phosphorus solidification.

Effects of admixtures on the mechanical characteristics and microstructure of coral aggregate mortar

Coral mortar is often used to reinforce building foundations in island-reef engineering. To enhance the mechanical characteristics of coral aggregate mortar, and hence facilitate the development of ocean engineering, this paper studies the influences of silica fume (SF), metakaolin (MK), blast furnace slag (BFS) and fly ash (FA) on the workability, uniaxial compression process and microstructure of coral aggregate mortar (CAM). Ultrasonic pulse velocimetry is used to investigate the effects of various additives on ultrasonic propagation speed and cumulative voltage energy (CVE). The microstructure and hydration products of different CAMs are analyzed using scanning electron microscopy. Experimental results show that silica fume is more effective than blast furnace slag and fly ash in improving density and water retention of CAM. Silica fume can promote the consumption of calcium hydroxide crystals and the formation of calcium silicate hydrate, thus improving the compressive strength of CAM. There is a good correlation between S-wave velocity and elastic modulus in CAM. The CVE of the P-wave in CAM with external admixture is significantly higher than that in ordinary CAM. Addition of blast furnace slag and fly ash makes the CVE of the ultrasonic wave in CAM decrease earlier and faster. The results provide a guide for the improvement of the strength of CAM.

Blast Furnace Slag, Post-Industrial Waste or Valuable Building Materials with Remediation Potential?

In recent years, the construction industry has struggled with a variety of issues such as material availability, supply channel management, and the increasing cost of construction materials. These issues have encouraged the search for replacements and substitutes for existing construction materials. Blast Furnace Slag is used in the construction industry as a mineral amendment or aggregate. Their use in Earth Construction, due to their post-industrial origin, may be associated with increased levels of potentially toxic elements (PTE) in the soil. This study aimed to evaluate the effectiveness of the immobilization potential of Blast Furnace Slag and to compare it with the addition of Blast Furnace Slag with Activated Carbon using different concentrations of these amendments. We were able to determine the concentrations of selected PTE (zinc, copper, nickel, cadmium and lead) in the soil, roots and aerial parts of Lolium perenne L., using different concentrations of Blast Furnace Slag (3%, 5% and 10%), and Blast Furnace Slag with Activated Carbon (3% and 5%) as soil amendments. Measurements were carried out with Flame Atomic Absorption Spectrometry (FAAS). Both the addition of Blast Furnace Slag and Activated Carbon with Slag increased plant biomass. The addition of slag effectively reduced the zinc, copper, cadmium and lead content of the soil, while the addition of Activated Carbon slag significantly increased the content of selected PETs in the roots and aerial parts of plants. It was considered reasonable to use Blast Furnace Slag with the addition of Activated Carbon in supporting the processes of the assisted phytostabilization of PTE polluted soils.

Cement based-thermal energy storage mortar including blast furnace slag/capric acid shape-stabilized phase change material: Physical, mechanical, thermal properties and solar thermoregulation performance

Solar thermal energy efficiency of cementitious mortar is enhanced by introducing a phase change material (PCM) with thermal energy harvesting/releasing ability. Within this framework, a new type of cement based-thermal energy storage mortar (CBTESM) was developed by substituting blast furnace slag (BFS)/capric acid (CA) shape-stabilized PCM (SSPCM) with 15%, 30% and 45 wt% of sand. The results of XRD indicated that crystalline structure of CA was not affected with addition of BFS. The results of SEM/EDS confirmed successful impregnation of the melted CA into the BFS as carrying material thanks to the capillary forces. DSC analysis indicated that melting temperature and latent heat of fusion for SSPCM is 28.0˚C and 55.5 J/g while they are 28.52˚C and 13.8 J/g for CBTESM containing 45 wt% SSPCM. When 45 wt% SSPCM was added to mortar, bulk density (1.45 g/cm3), compressive strength (8.16 MPa) and thermal conductivity (0.601 W/m.K) decreased by 28.57%, 85.37% and 41.25%, respectively. The CBTESM sample including 15 wt% SSPCM additive (22.51 MPa) can meet the standard conditions in terms of compressive strength. Thermoregulation performance test under actual ambient conditions demonstrated that the developed CBTESM considerably reduced the indoor temperature. Theoretical calculations showed that a 13.5 kWh energy saving can be achieved by using 1 kg CBTESM in a wall having size of 3 × 4 × 0.2 m. Also 36.67, 35.73 and 5.87 kg-CO2 reduction in carbon emission would be reduced as per 1 kWh coal, natural gas and electricity consumptions, respectively.

Influence of the Addition of Blast Furnace Slag to Alkali-Activated Mixtures Based on Natural Zeolites

This study focuses on a comparison of alkali-activated materials based on natural zeolites without and with the addition of blast furnace slag and their subsequent modification by acid leaching. The addition of slag to alkali-activated mixtures is generally used to increase the strength. The subsequent modification of its chemical, textural and mechanical properties by acid leaching makes this material usable in other industries, especially in the chemical industry. This study aimed to examine the influence of the addition of blast furnace slag to alkali-activated mixtures based on natural zeolites and observe the effect of subsequent acid leaching on the chemical, textural and mechanical properties and CO2 adsorption capacity of these materials. The modification of alkali-activated materials was carried out by acid leaching using 0.1 M HCl and then using 3 M HCl. The properties of these materials were determined using N2 physisorption, Hg porosimetry, XRF, XRD, DRIFT, TGA and strength measurements. The results showed that the addition of blast furnace slag significantly increased the cutting-edge strength of the obtained materials and affected the textural properties, especially in leached samples. The presence of blast furnace slag generated a higher proportion of mesopores, which are attributed to the presence of the calcium silicate hydrate (C–S–H) phase and are easily removed by leaching, as shown by the XRF results. The obtained data showed an improvement in properties and extension of the potential applicability of these materials in the chemical industry, especially for catalytic and adsorption applications.

Recycling of Blast Furnace and Coal Slags in Aided Phytostabilisation of Soils Highly Polluted with Heavy Metals

(1) Background: The growing demand for developing new methods of degraded land remediation is linked to the need to improve the soil environment, including post-industrial soils. Biological methods such as the aided phytostabilisation technique are the most common methods applied to achieve effective remediation. This study aimed to determine the technical potential of methods using novel or yet not used soil amendments, such as blast furnace slag (BFS) and coal slag (CS), with Dactylis glomerata L. as a test plant. (2) Methods: The experiment was conducted on post-industrial area soil with high concentrations of Cu (761 mg/kg), Cd (23.9 mg/kg), Pb (13,539 mg/kg) and Zn (8683 mg/kg). The heavy metal content in roots and the above-ground parts of plants and soil was determined by flame atomic absorption spectrometry. (3) Results: The addition of BFS to the soil was the most effective in increasing Dactylis glomerata L. biomass yield. The Cu, Cd, Pb, and Zn concentrations were higher in the roots than in the above-ground parts of the plants. BFS and CS induced a considerable increase in soil pH, compared to the control treatment. The addition of BFS also produced the greatest significant decrease in the Pb content in soil following the phytostabilisation process. (4) Conclusions: In view of the above, the use of BFS in the aided phytostabilisation in soils contaminated with high levels of Cu, Cd, Pb, and Zn can be recommended for larger-scale in situ projects.

Microstructure, Durability and Mechanical Properties of Mortars Prepared Using Ternary Binders with Addition of Slag, Fly Ash and Limestone

In order to improve the contribution to sustainability of cement production, several strategies have been developed, such as the incorporation of additions as clinker replacement. Regarding the production of commercial cements with additions, those made with binary binders are mostly produced. However, the use of ternary binders for manufacturing commercial cements is still very low, at least in Spain, and they could also be an adequate solution for producing eco-friendly cements. The objective of this research is to study the effects in the long term produced by ternary binders which combine the additions of blast furnace slag, fly ash and limestone in the microstructure, durability and mechanical performance of mortars, compared to mortars without additions and mortars made with binary binders. The ternary and binary binders accomplished the prescriptions for a cement type CEM II/B. The microstructure was characterized using mercury intrusion porosimetry, electrical resistivity and differential thermal analysis. Absorption after immersion, diffusion coefficient, mechanical strengths and ultrasonic pulse velocity were studied. The best performance was noted for ternary binder with both slag and fly ash, probably produced by the synergetic effects of slag hydration and fly ash pozzolanic reactions. These effects were more noticeable regarding the compressive strength.

Control of the setting reaction and strength development of slag-blended volcanic ash-based phosphate geopolymer with the addition of boric acid

This work aimed to evaluate the role of the addition of blast furnace slag for the formation of reaction products and the strength development of volcanic ash-based phosphate geopolymer. Volcanic ash was replaced by 4 and 6 wt% of ground granulated blast furnace slag to accelerate the reaction kinetics. Then, the influence of boric acid for controlling the setting and kinetics reactions was also evaluated. The results demonstrated that the competition between the dissolution of boric acid and volcanic ash-slag particles is the main process controlling the setting and kinetics reaction. The addition of slag has significantly accelerated the initial and final setting times, whereas the addition of boric acid was beneficial for delaying the setting times. Consequently, it also enhanced the flowability of the paste. The compressive strength increased significantly with the addition of slag, and the optimum replaced rate was 4 wt% which resulted in 28 d strength of 27 MPa. Beyond that percentage, the strength was reduced because of the flash setting of the binder which does not allow a subsequent dissolution of the particles and their precipitation. The binders formed with the addition of slag and/or boric acid are beneficial for the improvement of the water stability of the volcanic ash-based phosphate geopolymer.

Co-disposal of MSWI fly ash and spent caustic through alkaline-activation consolidation

This work investigates spent caustic as an alkaline activator for the consolidation of municipal solid waste incineration (MSWI) fly ash through the alkaline activation process. The effects of comparable alkalinity of NaOH solution and spent caustic, and the addition of blast furnace slag (BFS) on consolidation MSWI fly ash were investigated. Compressive strength measurement for alkali-activated MSWI fly ash-based mortars was characterized to evaluate the consolidation effect. The microstructure of mortars was characterized by XRD, FTIR, 29Si NMR, and SEM measurement. It was found that the compressive strength of spent caustic-activated mortars was higher than that of NaOH-activated mortars. The formation of ettringite and more C-(A)-S-H, and the presence of carbonate and organics in spent caustic-activated mortars enhanced the compressive strength. This work found an emerging cost-efficient alkaline activator in waste management through alkaline activation and could achieve environmentally sustainable.

Development of Cleaner One-part geopolymer from lithium slag

In this study, lithium slag waste was utilized for the development of eco-friendly ambient cured one-part geopolymer. Lithium slag and blast furnace slag were employed as alumino-silicate precursors and anhydrous sodium silicate as alkaline activator. Fresh properties were assessed using setting time and flowability tests, while compressive strength, flexure strength, water absorption and drying shrinkage tests were performed to evaluate hardened properties of newly developed geopolymer mix. X-ray Diffraction analysis (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy examination (SEM) were performed to evaluate the chemical functional groups and microstructure of the mix. The environmental impact analysis was determined through measurement of carbon dioxide equivalent (CO2-e) of constituents. The experimental investigation revealed that blast furnace slag addition in lithium slag based geopolymers improved its reactivity and hardening was achieved at room temperature. The 57 MPa compressive strength was achieved, which is comparable with other one-part geopolymers prepared using similar precursors. The improvement in mechanical strength can be attributed to enhanced geopolymerization reaction and improvement in gel structure as observed through microstructural testing.

Mixed Alkali and Mixed Alkaline-Earth Effect in Ceramic Sanitaryware Bodies Incorporated with Blast Furnace Slag

Raw materials and energy are among the most important costs in ceramic sanitaryware production. With the decrease in raw material sources and increasing costs of energy in recent years, researches on alternative raw materials and energy have started to gain importance. In this study, blast furnace slag and spodumene were used to reduce both energy and raw material costs. In standard vitreous china ceramic sanitaryware, a maximum of 15% blast furnace slag and 4% spodumene was used instead of sodium feldspar. In this study, the effects of CaO, MgO, and Li2O on microstructure, technological properties such as flexure strength, water absorption, porosity, bulk density; and also, thermal properties such as sintering analysis were investigated by using a non-contact optical dilatometer and thermal expansion. The dry strength and flexure strength of fired samples increased. The increase in dry strength was approximately 47%. The increase in flexure strength was approximately 67%. The reduction in the thermal expansion coefficient values was approximately 17%, which is also important in terms of stability of the final product. As a result, the use of blast furnace slag and spodumene will result in a reduction in both energy and raw material costs. The spodumene and BFS provided a reduction in sintering temperature at a rate of approximately 60 °C. The flue gas emissions may also reduce because flue gas emissions are higher as the temperature inside the furnace is higher. The spodumene and blast furnace slag addition provide a decrease in the peak of sintering temperatures so that flue gas emissions will reduce.