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The electrodes of industrial electrostatic precipitators degrade as a result of two phenomena: corrosion and erosion. The first is chemical degradation by highly reactive compounds formed during combustion, in particular, during the incineration of municipal or industrial wastes or high-sulfur coal. The degradation intensity of electrostatic precipitator electrodes depends on the chemical composition of the exhaust gasses. High concentrations of chlorides, fluorides, or sulfur in the exhaust gasses cause strong corrosion of the electrostatic precipitator elements. The second mechanism is the erosion caused by solid particles conveyed by the exhaust gas stream due to their collision with the electrodes. In this study, the analysis of the degradation of electrodes of an electrostatic precipitator downstream of an industrial waste incinerator was carried out. The industrial wastes of unknown sources were subjected to thermal degradation in a rotary kiln. The aim of this study was to provide fundamental knowledge about the mechanisms of electrode degradation located on the surface of discharge electrodes of electrostatic precipitators during the combustion of industrial wastes. [ABSTRACT FROM AUTHOR]

The utilization of industrial solid waste in mines is an important approach to resource utilization. The backfill material in mines is mainly composed of solid waste, which plays a supporting role. The excitation effect of lime on phosphogypsum and fly ash in backfill was studied in this paper. The macroscopic and microscopic characteristics of the backfill material were tested using uniaxial compression, nuclear magnetic resonance, scanning electron microscopy, and electrochemical techniques, and a relationship model was established between them. Furthermore, the influence of industrial solid waste on the properties of the backfill material under the action of lime and the hydration mechanism between different industrial solid wastes were studied. The results show that (1) under the action of lime, fly ash reacts with lime to produce C-S-H and C-A-H, and then C-A-H reacts with phosphogypsum to produce AFt. (2) The excess phosphogypsum also fills the pores. Therefore, 1.8% lime reduces the porosity of the backfill by 17.88% and increases the strength by 21.57%. (3) The cross-scale relationship shows that strength is inversely proportional to each type of pore content and fractal dimension, and it logarithmically increases with impedance at different frequencies. The lower the frequency, the stronger the relationship is. (4) This study indicates that industrial solid waste is a suitable cement replacement. [ABSTRACT FROM AUTHOR]

The intricate composition of wastewater impedes the recycling of agricultural and industrial effluents. This study aims to investigate the potential of sisal leaf wastewater (SLW), both water-treated (WTSLW) and alkali-treated (ATSLW), as a substitute for the alkali activator (NaOH solution) in the production of slag-powder- and fly-ash-based composites, with a focus on the effects of WTSLW substitution ratios and sisal leaf soaking durations. Initially, the fresh properties were assessed including electrical conductivity and fluidity. A further analysis was conducted on the influence of both WTSLW and ATSLW on drying shrinkage, density, and mechanical strength, including flexural and compressive measures. Microstructural features were characterized using SEM and CT imaging, while XRD patterns and FTIR spectra were employed to dissect the influence of WTSLW substitution on the composite's products. The results show that incorporating 14 wt% WTSLW into the composite enhances 90-day flexural and compressive strengths by 34.8% and 13.2%, respectively, while WTSLW curtails drying shrinkage. Conversely, ATSLW increases porosity and decreases density. Organic constituents in both WTSLW and ATSLW encapsulated in the alkaline matrix fail to modify the composites' chemical composition. These outcomes underscore the potential for sustainable construction materials through the integrated recycling of plant wastewater and solid by-products. [ABSTRACT FROM AUTHOR]

A steam jet mill (SJM), which employs industrial waste heat steam as a gas source, is a widely utilized apparatus for the pulverization of fly ash. To achieve elevated single-machine grinding capacity, efficiency improvement research based on structural optimization should be conducted. In this study, numerical simulations and industrial experiments are carried out on SJMs equipped with three and six nozzles (hereinafter referred to as N3 and N6, respectively) to study the influence of nozzle quantity on the flow field and grinding efficiency. The numerical simulation results indicate that, under the N3 structure, particles can achieve a higher impact velocity in the comminution area and improve the kinetic energy of a single impact. In the conveying area, the airflow diffusion is better, resulting in an upward flow field that is more uniform. The classification area shows an increase in the uniformity of the flow field and a significant reduction in the local vortex structure, which is beneficial for accurate particle classification. In the interim, industrial experiments demonstrate that the N3 structure can markedly enhance the processing capacity and energy efficiency of the system. The smaller the feed particle size, the more pronounced the efficiency improvement. [ABSTRACT FROM AUTHOR]

The utilization of CO2 mineralization fly ash (F) and coal gangue (G) technology is proposed in this research work to prepare underground backfilling materials. The test process can be divided into pre-treatment and post-treatment stages. In the pre-treatment stage, a sealed stirring vessel is used to conduct CO2 wet mineralization. The ratios of F and G were selected as follows: 20%:60% (F2G6), 30%:50% (F3G5), 40%:40% (F4G4), 50%:30% (F5G3), and 60%:20% (F6G2). The ratios were prepared into Φ50 mm × 100 mm cylindrical samples, with curing durations of 3 d, 7 d, 14 d, and 28 d. In the post-processing stage, the SANS microcomputer-controlled electronic universal testing machine and FLIR A615 infrared thermal imager were used to carry out uniaxial loading and temperature detection, respectively. The unconfined compressive strength (UCS), X-ray diffraction (XRD), average infrared radiation temperature (AIRT), variance of original infrared image temperature (VOIIT), and variance of successive minus infrared image temperature (VSMIT) of the samples were compared and analyzed. The results indicated that when curing reaches 14 d, the strength approaches its peak, with minimal changes in strength over a delayed period; furthermore, as the ratio of F to G continues to increase, the mineralization effect gradually strengthens, reaching its optimum level at a ratio of 5:3. However, when the ratio exceeds 5:3, signs of deteriorating mineralization effect start to appear. During the loading process, the AIRT of the mineralized samples showed a continuous increase, but the VOIIT and VSMIT of the mineralized sample both exhibited significant fluctuations or rapid increases during damage rupture. Moreover, the rise in the AIRT value was found to be linked to the increase in the ratio of F to G. This indicates that F has a higher thermal–mechanical conversion efficiency compared to G, so the temperature change will be greater during the loading process. The drastic changes in the VOIIT and VSMIT indicate that they can be used as sensitive response indicators for sample rupture, and can predict and warn of damage rupture in mineralized samples. Research work can provide practical guidance and reference for underground backfilling of CO2 mineralization industrial waste. [ABSTRACT FROM AUTHOR]

This study focuses on using activated fly ash to preparate silica aerogel by the acid solution–alkali leaching method and ambient pressure drying. Additionally, to improve the performance of silica aerogel, C6H16O3Si (KH-570) and CH3Si(CH3O)3 (MTMS) modifiers were used. Finally, this paper investigated the factors affecting the desilication rate of fly ash and analyzed the structure and performance of silica aerogel. The experimental results show that: (1) The factors affecting the desilication rate are ranked as follows: hydrochloric acid concentration > solid–liquid ratio > reaction temperature > reaction time. (2) KH-570 showed the best performance, and when the volume ratio of the silica solution to it was 10:1, the density of silica aerogel reached a minimum of 183 mg/cm3. (3) The optimal process conditions are a hydrochloric acid concentration of 20 wt%, a solid–liquid ratio of 1:4, a reaction time of two hours, and a reaction temperature of 100 °C. (4) The optimal performance parameters of silica aerogel were the thermal conductivity, specific surface area, pore volume, average pore size, and contact angle values, with 0.0421 W·(m·K)−1, 487.9 m2·g−1, 1.107 cm3·g−1, 9.075 nm, and 123°, respectively. This study not only achieves the high-value utilization of fly ash, but also facilitates the effective recovery and utilization of industrial waste. [ABSTRACT FROM AUTHOR]

The huge demand for sand and gravel resources in road engineering construction leads to excessive consumption of resources and environmental damage. Recycling waste concrete and industrial solid waste as a road material is a promising alternative. In order to explore the application of these solid wastes in the road base, this paper studies the effect of adding lithium slag activated by an alkaline activator, fly ash (FA) and a combination of the two on the compressive strength, splitting strength and shrinkage performance of recycled cement-stabilized macadam mixture (RCSM). The optimum content of recycled aggregate (RA), alkali-activated lithium slag (AALS) and FA in composite-improved RCSM was optimized using a response surface method (Box–Behnken), and the microscopic characteristics of the mixture were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the optimum dosage of AALS, FA and RA determined by the response surface method is 15%, 10% and 40%, respectively. Compared with the cement-stabilized macadam mixture (CSM) with 40% RA, the 28 d compressive strength and 28 d splitting strength of the composite-improved RCSM are increased by 26.8% and 22.9%, respectively, and the dry shrinkage coefficient and average temperature shrinkage coefficient are decreased by 25.8% and 14.8%, respectively. Microscopic tests show that AALS and FA participate in the hydration reaction, generate more hydrated silicate (C-S-H) and ettringite (AFt), refine pores, effectively improve the performance of the internal interface transition zone of the mixture, make the microstructure of the mixture denser, and improve the strength and shrinkage performance of RCSM. This study provides technical support for the reuse of resources and the sustainable development of road construction. [ABSTRACT FROM AUTHOR]

Integrating waste and industrial by-products into concrete is an alternative way to reduce global cement consumption, enhancing its eco-friendliness. In this context, residues with fly ash have been increasingly utilised. Considering the vulnerability of concrete with fly ash to carbonation and, at the same time, its high resistance to chlorides, it is important to investigate the behaviour of these concretes under their combined actions. For this purpose, an experimental investigation was conducted, studying mortar and concrete specimens with 40% replacement of cement with fly ash. These specimens were subjected to a combination of actions (Cl− and CO2) in two phases: initially through immersion and drying tests, and subsequently through a combination of accelerated tests. Concerning the chloride impact study, free and total chloride profiles were studied. Concerning the impact of carbonation, colourimetric and chemical tests were used. The results demonstrate a significant influence of combined action not only on chloride penetration in cement-based materials with fly ash but also on the development of a carbonation front. Exposure of cement-based materials with fly ash to environments with high Cl− and CO2 content sequentially may lead, on the one hand, to an increase in carbonation resistance. However, on the other hand, it may result in a substantial reduction in chloride penetration resistance. [ABSTRACT FROM AUTHOR]

Wastewater discharges from industrial processes typically include elevated concentrations of contaminants, which largely consist of potentially harmful chemicals such as heavy metals. These contaminants are characterized by their slow rate of decomposition. Hence, the removal of these metallic ions from effluents poses a challenge. Among different treatments, the adsorption approach has considerable potential due to its ability to effectively eliminate both soluble and insoluble pollutants from effluent, even at lower levels of concentration. Of various wastes, fly ash (FA) material has been the subject of attention because it is abundant, has favorable qualities, and contains a high percentage of minerals. This review investigates multiple facets, with a specific focus on the application of FA, an industrial byproduct, as an adsorbent in removing heavy metals. A comprehensive examination was conducted on a range of concerns pertaining to the pollution caused by metallic ions, including the underlying causes, levels of contamination, health implications of heavy metals, and removal methods. Multiple factors were found to affect the adsorption process. Of all the factors, the pH value considerably influences the elimination of heavy metals. An acidic pH range of 2.5–4.5 was found to be optimal for achieving the highest possible elimination of As(V), Cu(II), Hg(II), and Cr(VI). The latter elimination rate reached 89% at the optimal pH level. Most heavy metals' adsorption isotherms conformed to the Langmuir or Freundlich models, while the pseudo-second-order kinetics provided a satisfactory match for their removal. Using a raw FA, adsorption capacities were achieved in the removal of metallic ions, Ni(II), Pb(II), and Cr(VI), that ranged from 14.0 to 23.9 mg g−1. Meanwhile, the FA-zeolite showed a remarkable capacity to adsorb ions Mn(II), Ni(II), Cd(II), Cu(II), and Pb(II), with values ranging from about 31 to 66 mg g−1. The cost analysis showed that the treatment of FA is economically advantageous and may result in significant cost reductions in comparison to commercial adsorbents. In summary, FA is an inexpensive waste material with potential for water treatment applications and several other purposes due to its excellent chemical and mineralogical composition. [ABSTRACT FROM AUTHOR]

In light of the urgent need to develop environmentally friendly materials that, at some point, will allow the reduction of concrete and, consequently, cement consumption—while at the same time allowing the reuse of waste and industrial by-products—alkali-activated fly ash (AAFA) geopolymer composite emerges as a material of great interest. The aim of this study was to investigate the physico-mechanical performance of composites based on AAFA binders and the effect of different types of aggregates on these properties. The experimental results indicate variations in flexural and compressive strength, which are influenced both by the nature and particle size distribution of aggregates and the binder-to-aggregate ratio. The analysis of the samples highlighted changes in porosity, both in distribution and pore size, depending on the nature of the aggregates. This supports the evolution of physico-mechanical performance indicators. [ABSTRACT FROM AUTHOR]

Artificial aggregate (AF), i.e., silico manganese (SiMn) slag aggregate, is a byproduct of ferromanganese and silico manganese alloy production. The utilization of industrial waste and industrial byproducts in construction has increased the aim of conserving natural resources to nurture a pollution-free environment. The current study examines the performance of the use of artificial aggregate (AF) and partial replacement of cement with fly ash (FA). The properties of fresh concrete, as well as the compressive and flexural strength and split tensile strength of concrete were evaluated. Seven mix proportions were prepared for M30-grade concrete. The first was a control mix (with 0% AF and FA), three other mixes contained varying amounts of AF (20%, 40%, and 60%) as a partial replacement of CA with AF. The average compressive strength of the control SCC was found to be 32.87 MPa (megapascals) at the age of 28 days, and after replacing 20% natural aggregate with artificial aggregate, the compressive strength increased by 8.27%, whereas for 40% and 60% replacement, it decreased by 4.46% and 12.55%, respectively. Further investigation was performed on the optimum value obtained by replacing 20% of CA with AF. At this percentage, cement was replaced by FA at (15%, 25%, and 35%) where at 15%, the average compressive strength increased by 7.41%, whereas for 25% and 35% replacement, it decreased by 7.47% and 17.19%, respectively. For SCAF20 and SCF15, all strengths were at maximum due to the increase in its density. The findings show that the development of advanced construction materials is environmentally sustainable. [ABSTRACT FROM AUTHOR]

The purpose of this study is to synthesize geopolymer binders as an environmentally friendly alternative to conventional cement using available local raw materials. Waste materials such as chalcedonite (Ch), amphibolite (A), fly ash from lignite combustion (PB), and diatomite dust (D) calcined at 900 °C were used to produce geopolymer binders. Metakaolin (M) was used as an additional modifier for binders based on waste materials. The base materials were subjected to fluorescence X-ray fluorescence (XRF) analysis and X-ray diffractometry (XRD) to determine chemical and phase composition. A laser particle size analysis was also performed. The various mixtures of raw materials were activated with a 10 M solution of NaOH and sodium water glass and then annealed for 24 h at 60 °C. The produced geopolymer binders were conditioned for 28 days under laboratory conditions and then subjected to microstructural analysis (SEM) and flexural and compressive strength tests. The best compressive strength results were obtained by the Ch + PB samples—more than 57 MPa, while the lowest results were obtained by the Ch + D+A + M samples—more than 20 MPa. On the other hand, as a result of the flexural strength tests, the highest flexural results were obtained by D + A + M + PB binders—more than 12 MPa, and the lowest values were obtained by binders based on Ch + D+A + M—about 4.8 MPa. [ABSTRACT FROM AUTHOR]

In addressing eutrophication and enhancing water quality, this study builds upon previous research involving the development of an Efficient Phosphorus Removal Composite (EPRC), a material created using modified industrial wastes (steel slag and fly ash) as adsorbent substrates, supplemented with a binder and porosity-forming agent. In this investigation, the EPRC was further enhanced through the addition of zirconium oxychloride octahydrate, resulting in the production of Zr-EPRC particles as reinforced phosphorus removal materials. Comparative experiments were conducted to assess different methods for preparing Zr-EPRC, the static adsorption performance, and dynamic adsorption behavior. The optimal preparation of Zr-EPRC was achieved by separately modifying the base materials, steel slag and fly ash. Loading with mass ratios of zirconium chloride octahydrate to fly ash and steel slag at 0.4 and 0.6, respectively, for a duration of 12 h at a pH of 10 yielded the best results. In static adsorption experiments conducted at temperatures of 15 °C, 25 °C, and 35 °C, Zr-EPRC exhibited saturated phosphorus adsorption capacities of 11.833 mg/g (variance = 0.993), 12.550 mg/g (variance = 0.993), and 13.462 mg/g (variance = 0.996), respectively. Zr-EPRC emerges as a cost-effective and readily available solution with promising stability for general wastewater treatment applications, contributing significantly to the mitigation of eutrophication and the improvement of water quality. [ABSTRACT FROM AUTHOR]

Sustainable zero cement-based one-part ambient cured alkali-activated engineered composites (AAECs) are developed. The durability and microstructural characteristics of developed AAECs using 2% v/v polyvinyl alcohol (PVA) fibers, silica sand, binary or ternary combinations of precursors (fly ash class C 'FA-C', fly ash class F 'FA-F' and ground granulated blast furnace slag 'GGBFS') and two types of powder form alkaline reagents (Type 1 and Type 2) are evaluated compared to conventional engineered cementitious composites (ECCs) and alkali-activated mortars (AAMs) without fiber. AAECs developed satisfactory compressive strength ranging from 34 MPa to 46 MPa. Expansion/shrinkage and mass change (loss/gain) behaviors are affected by binary/ternary combination of source materials, reagent types and curing regimes (water or ambient) for both AAMs and AAECs. The binary (FA-C + GGBFS) and reagent 2 (calcium hydroxide + sodium sulfate) composites demonstrated lower shrinkage due to formation of crystalline C-A-S-H/C-S-H binding phases than their ternary (FA-C + FA-F + GGBFS) and reagent 1 (calcium hydroxide + sodium metasilicate) counterparts which formed amorphous N-C-A-S-H/N-A-S-H phases. The matrix densification due to the formation of reaction products and fiber-induced micro-confinement leads to lower shrinkage and mass change of AAECs compared to their AAM counterparts. Composites exhibited lower or comparable secondary sorptivity indices compared to control ECC, indicating their superior permeation performance. All AAECs had a relative dynamic modulus of elasticity (RDME) greater than 90% at 300 cycles (comparable to control ECC), exhibiting satisfactory freeze–thaw resistance with reagent 2 mixes showing better performance compared to those with reagent 1. The production feasibility of strain hardening AAECs with powder form reagents having satisfactory mechanical and durability properties is confirmed. [ABSTRACT FROM AUTHOR]

In order to raise the utilization rate of industrial waste and mitigate issues involving land resource occupation and environmental damage, in this study, industrial-waste-based artificial aggregates (IWAAs) were fabricated using steel slag powders, fly ash, and cement. They were processed under accelerated carbonation and were utilized in a bitumen mixture. During the experiment, the micromorphology, internal structure, and phase composition of IWAAs before and after accelerated carbonation were characterized using X-ray phase analysis, thermal analysis, and scanning electron microscopy (SEM); concurrently, the possibility of IWAAs being used as a partial substitute for natural aggregate to prepare bituminous mixture was qualitatively and quantitatively analyzed based on Marshall's design procedure in combination with road performance tests and microcosmic analyses. The results indicated that the presence of carbonate crystals brought about by accelerated carbonation was the main phase composition inside the IWAAs, enhancing the microstructure densification and diminishing the immersion expansion and crushing values; this is due to the depletion of the interior Ca-based (e.g., f-CaO and Portlandite) and Mg-based (e.g., periclase and brucite) compounds together with the formation of cement hydration products. Additionally, the 12 h carbonation time obtained the optimum CO2-sequestration efficiency on the premise of satisfying the performance standard. The expansion rate and crushing value of the IWAAs decreased by 82.21% and 41.58%, respectively, whilst the anti-rutting properties, the moisture damage resistance, and the skid resistance rose by 31.92%, 5.59%, and 10.00%, respectively, in the IWAAs–bituminous mixture. This study lays a foundation for research on the CO2 sequestration and resource utilization of industrial wastes in bitumen mixtures. [ABSTRACT FROM AUTHOR]

For decades, a significant amount of research has been conducted on the vitrification of mixtures of all kinds of industrial wastes, especially fly ash, both from thermal power plants and municipal waste incinerators. Although the possibility of creating glass from all types of fly ash has been proven through such research, these studies barely focused on the emission of volatile components that takes place during vitrification processes at high temperatures. This is why, after identifying the types of volatilisation that can occur, we characterised the gasses that are emitted during the vitrification of some types of fly ash and other waste in a laboratory furnace. In order to do so, we analysed the Cl2 and SO2 gasses emitted using the DTA/TG/FTIR techniques, as well as the losses of H2O and CO2. The authors also measured the volatilizations directly from the mouth of the furnace using gas chromatography syringes and analysed the possible emission of dioxins. This study is the first analysis of volatile elements of this kind, after numerous vitrifications in recent decades which ignored the volatilisations that occur when using fly ashes. Although the various types of fly ash used generate emissions of Cl2 and SO2, their use as a by-product on an industrial level could be recommended if previous thermal and washing treatments are conducted. These would minimise the above emissions, enabling the use of said fly ash in the production of glasses for commercial frits, even if an efficient industrial-scale gas cleaning system would apply. Furthermore, an appropriate optimised design of its formulation would make it possible to structurally link some of these gaseous components to the glass structure. These types of results will make it possible to calculate the volatilization when vitrifying certain types of industrial waste on an industrial level, although these studies would require prior assessment in a pilot plant. [ABSTRACT FROM AUTHOR]

Industrial secondary products (e.g., fly ash, blast furnace slag, and silica fume) have found extensive application as alternative construction materials in conventional manufacturing methods to reduce carbon emissions due to cement usage and solve the waste management problem. To date, additive manufacturing or 3D printing has been massively developed for every material, including cement-based materials. Some possibilities have arisen to incorporate industrial wastes in cement mixtures in 3D printing applications. However, a comprehensive study about fly ash (FA), ground granulated blast-furnace slag (GGBFS), and silica fume (SF) usage in 3D-printed materials needs to be conducted. This paper shows that some aspects of 3D printing, such as printability, buildability, and rheological properties, need to be considered, and waste materials affect these fresh mixture properties. Applying waste materials as supplementary cementitious materials also gives different mechanical properties and durability performances. Furthermore, the environmental and economic benefits of 3D-printed and conventional materials are compared. The results show that 3D printing methods can enhance the environmental and economic benefits while maintaining the performance of materials created using traditional methods. Studying industrial waste application in 3D printing has become a promising way to develop sustainable materials in this digitalization era. [ABSTRACT FROM AUTHOR]

In the context of the circular economy and the adoption of one of its business models, namely "resource recovery", this study presents an opportunity to valorize industrial and urban wastes using alkaline activation technology to produce hybrid binders. Several alkali-activated binders were produced using response surface methodology based on a mixture of 45/45/10 clay brick waste, fly ash, and Portland cement. The compressive strength and setting time of each were evaluated. The hybrid cementitious pastes achieved up to 45 MPa after 28 days of setting. Based on the experimental data, two binders were selected as the cementitious matrix for composites, with paper sludge as the lightweight aggregate. Incorporating up to 45% volume of paper sludge allowed extrusion of the materials. The addition of paper sludge reduced the compressive and flexural strength. These results were explained by the decrease in density and the increase in porosity. However, there was an improvement in the thermal properties of the composites; in particular, the thermal conductivity range between 0.35 and 0.49 W/mK. Finally, it was found that the composites with 25% volume of paper sludge had the best combination of properties, positioning them as potential construction materials. [ABSTRACT FROM AUTHOR]

Industrial waste usage in the technology of construction materials is currently in a relevant and promising direction. Materials made of industrial waste have a lower cost and are highly environmentally friendly. The objective of this study is to develop effective compositions of sulfur concrete based on the maximum possible number of various wastes of the local industry for this and to investigate the characteristics of this composite. Test samples of sulfur concrete were made from sulfur, fly ash, mineral aggregates and bitumen additive. The dosages of fly ash, sand and bitumen varied, while the content of sulfur and crushed stone remained constant. The following main characteristics of sulfur concrete were determined: density; compressive strength; and water absorption. Tests of sulfur concrete were carried out after 1 day and 28 days of hardening. The best values of compressive strength (24.8 MPa) and water absorption (0.9%) were recorded for the composition of sulfur concrete at the age of 28 days with the following content of components: sulfur—25%, modified with 4% bitumen of its mass; fly ash—10%; crushed stone—40%; and sand—25%. The optimal composition of modified sulfur concrete showed compressive strength up to 78% more and water absorption up to 53% less than the control composition. The characteristics of the sulfur concrete samples after 28 days of hardening differ slightly from the values after 1 day of hardening (up to 1.8%). An analysis of the structure confirmed the effectiveness of the developed composition of sulfur concrete in comparison with the control. [ABSTRACT FROM AUTHOR]

In order to solve the global problem of bridge head jumping caused by the insufficient compaction of the roadbed in the transition section of highways and bridges, a desulfurization gypsum–fly ash flowable lightweight soil without vibration, capable of self-compaction, low bulk density, and economic and environmental protection, has been developed. This study selected low-grade cement, industrial waste (fly ash and desulfurization gypsum), and Yellow River silt as the raw materials for the design of the mix ratio of a desulfurization gypsum–fly ash flow-state lightweight soil mix. Through multiple indoor experiments, the influence of cement content, silt content, and the fly ash/desulfurization gypsum quality ratio on its fluidity and mechanical properties was systematically studied. The stress–strain relationship under uniaxial compression was analyzed and the strength formation mechanism was revealed through scanning electron microscopy (SEM). The results show that the mechanical properties of the prepared desulfurization gypsum–fly ash flowable lightweight soil meet the engineering requirements. Increasing both the cement and fly ash content results in the decreased fluidity of the desulfurization gypsum and fluidized fly ash. However, as the mass ratio of fly ash to desulfurization gypsum increases, the fluidity reaches its maximum when the mass ratio of fly ash to desulfurization gypsum is 2:1. Based on the stress–strain relationship test results, a uniaxial compressive constitutive model of the desulfurization gypsum–fly ash flowable lightweight soil was proposed. The model was fitted and analyzed with the test results, and the correlation was greater than 0.96. The high degree of agreement showed that desulfurization gypsum can promote the disintegration of fly ash, thereby increasing the specific surface area. This provides more contact points, promotes the hardening process, and enhances the interlocking force between particles and the formation of cementitious substances, further enhancing strength. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of alum sludge as an alternative to fly ash in fabricating geopolymer paste and mortar. The blending of this industrial waste (alum sludge and fly ash) is not only for the benefit of sustainable construction and disposal of industrial waste but also for the reduction of CO2 emissions due to the increasing production of Portland cement from the cement production industry. A laboratory investigation was carried out on the workability and mechanical properties of geopolymer paste and mortar produced with alum sludge replacement in different proportions (0, 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100). A combination of an alkaline solution of sodium silicate and sodium hydroxide of 14 molarity was employed as an activator for the manufacturing of both paste and mortar geopolymer specimens. It was observed from the findings that geopolymer paste and mortar was flowable and workable when alum sludge is replaced for fly ash at higher replacement content. The addition of alum sludge to the mix improved some properties such as density, strength, water absorption, and the elevated temperature behavior. It was observed that the addition of alum sludge was optimum at the 50% replacement level. The addition of alum sludge up to 50% significantly increased the compressive strength of mortar (up to 80% increase in 28 days strength). The compressive strength of the paste and mortar increased with an increase in curing age. Thus, alum sludge and fly ash can be employed together in the production of eco-friendly cementing material for environmental sustainability. [ABSTRACT FROM AUTHOR]

Fly ash is one of the industrial waste residues with significant emissions in China, and its rational utilization has important economic significance and environmental value. Due to the similarity in properties between fly ash and limestone mineral powder, it is possible to replace the mineral powder filler in asphalt concrete with fly ash. This article explored the feasibility of replacing the mineral powder with fly ash in an asphalt mixture through the study of fly-ash-modified asphalt mastic. Firstly, the microstructures and elemental compositions of fly ash and mineral powder were studied using scanning electron microscopy (SEM) and X-ray diffraction (XRD) tests. Then, the rheological properties of asphalt mastics with different fillers were studied using dynamic shear rheological (DSR) tests. The results show that when the stress level was 3.2 kPa, the change in the Jnr value was different from that at 0.1 kPa, indicating that after increasing the stress level, the Jnr of fly ash asphalt mastic was smaller, and fly ash can improve the high-temperature creep performance of asphalt mastic. Replacing mineral powder with fly ash can improve the high-temperature rheological properties of asphalt mastic, but this damages the elastic and crack resistance properties of the asphalt mastic. In practical applications, partial substitution of mineral powder can be considered for the preparation of an asphalt mixture. [ABSTRACT FROM AUTHOR]

This research investigates the feasibility of developing clay composites using natural materials and incorporating waste by-products suitable for plastering diverse support structures. The study identified a versatile composition suitable for a wide range of support materials and explored the potential of revaluing industrial waste and by-products by reintegrating them into the Circular Economy. The experimental investigation outlines the process of evaluating the influence of different raw materials on the performance of the clay composite. The findings confirm that using limestone sludge and fly ash as additives to clay contributes to reducing axial shrinkage and increasing mechanical strengths, respectively. The optimal percentage of additives for the clay used are identified and provided. Using hydraulic lime as a partial substitute for clay reduces the apparent density of dried clay composites, axial shrinkage, and fissures formation while improving adhesion to the substrate. Introducing dextrin into this mix increases the apparent density of the hardened plaster while keeping axial shrinkage below the maximum threshold indicated by the literature. Mechanical strengths improved, and better compatibility in terms of adhesion to the support was achieved, with composition S3 presenting the best results and a smooth, fissure-free plastered surface after drying. [ABSTRACT FROM AUTHOR]

The utilization of carbon dioxide and combustion products in cost- and energy-efficient technologies is an important element of creating sustainable energy systems, particularly in the transition period towards carbon neutrality and in light of the latest political developments, when solid fuels are still competing for a dominant role in securing energy supplies. Within the study presented, bituminous coal-derived fluidized bed fly ash samples of high calcium content, treated using a dry carbonation method under ambient conditions, were tested in terms of their specific properties to determine their usability in the preparation of injection mixtures for the filling of voids after shallow mining activities and other selected geo-engineering techniques. The study goes beyond the existing literature in terms of the carbonation method used, alkaline earth metal source, scale of the experiment, process conditions employed and product application studied. The results showed that the bituminous coal-derived fluidized bed fly ash, carbonated using the direct method adopted, may be successfully employed as the main solid component (over 82% w/w) of the injection mixtures for filling voids after shallow mining activities. The achievable compressive strength of a few MPa makes these materials applicable also in terms of ground strengthening in case it is required in light of the expected land development options to be employed. All principal materials used in the injection mixtures developed (carbonated fluidized bed fly ash, carbon dioxide, bottom ash) are industrial waste, and the carbonation method employed is simple and performed under ambient conditions, which reduces the required energy and cost input of filling mixture production, avoids the surface waste storage requirements, and contributes to the development of low energy-intensive carbon dioxide utilization and solid waste valorization methods. [ABSTRACT FROM AUTHOR]

The recycling of hazardous industrial waste into high-tech materials with desired properties is of considerable interest since it provides optimal alternatives for its final disposal. Coal fly ash, the major waste generated by coal-fired power plants, contains significant quantities of dispersed microspheres with a diameter smaller than 10 μm, which are anthropogenic atmospheric pollutants PM10. Due to their composition and fine-grained powder morphology, they can be converted into sintered products. In this study, dispersed microspheres from class C fly ash were directly sintered without any additive to form high-strength glass-ceramics with magnetic properties. The optimum processing conditions were achieved at a temperature of 1200 °C, at which samples with a compressive strength of 100.6 MPa were obtained. Sintering reduces the quantity of the glass phase and promotes the formation of larnite, Fe-spinel, ye'elimite, and ternesite. Mössbauer measurements show that the relative concentration of the magnetic phase compared to the paramagnetic one rises almost in order. The sintered sample demonstrates a narrower distribution of the hyperfine magnetic field and a significantly lower value of the coercive field of 25 Oe, which allows proposing such materials as soft magnetic materials. The presented results demonstrate promising industrial applications of hazardous PM10 to minimize solid waste pollution. [ABSTRACT FROM AUTHOR]

In recent years, the reuse of industrial waste has become increasingly important for sustainable development. Therefore, this study investigated the application of granulated blast furnace slag (GBFS) as a cementitious replacement material in fly-ash-based geopolymer mortar containing silica fume (GMS). The performance changes in the GMS samples manufactured with different GBFS ratios (0–50 wt%) and alkaline activators were evaluated. The results indicated that GBFS replacement from 0 wt% to 50 wt% significantly affects GMS performance, including improving the bulk density from 2235 kg/m3 to 2324 kg/m3, flexural-compressive strength from 5.83 MPa to 7.29 MPa and 63.5 MPa to 80.2 MPa, respectively; a decrease in water absorption and chloride penetration, and an improvement in the corrosion resistance of GMS samples. The GMS mixture containing 50 wt% GBFS demonstrated the best performances with notable results regarding strength and durability. Owing to the increased production of C-S-H gel, the microstructure of the GMS sample containing more GBFS was denser, as obtained via the scanning electron micrograph analysis results. Incorporating the three industrial by-products into geopolymer mortars was verified when all samples were determined to be in accordance with the relevant Vietnamese standards. The results demonstrate a promising method to manufacture geopolymer mortars that aid sustainable development. [ABSTRACT FROM AUTHOR]

The carbonation of alkaline industrial wastes is a pressing issue that is aimed at reducing CO2 emissions while promoting a circular economy. In this study, we explored the direct aqueous carbonation of steel slag and cement kiln dust in a newly developed pressurized reactor that operated at 15 bar. The goal was to identify the optimal reaction conditions and the most promising by-products that can be reused in their carbonated form, particularly in the construction industry. We proposed a novel, synergistic strategy for managing industrial waste and reducing the use of virgin raw materials among industries located in Lombardy, Italy, specifically Bergamo–Brescia. Our initial findings are highly promising, with argon oxygen decarburization (AOD) slag and black slag (sample 3) producing the best results (70 g CO2/kg slag and 76 g CO2/kg slag, respectively) compared with the other samples. Cement kiln dust (CKD) yielded 48 g CO2/kg CKD. We showed that the high concentration of CaO in the waste facilitated carbonation, while the presence of Fe compounds in large amounts caused the material to be less soluble in water, affecting the homogeneity of the slurry. [ABSTRACT FROM AUTHOR]

Traditional silicate cement materials produce a large amount of CO2 during production, making it urgent to seek alternatives. Alkali-activated slag cement is a good substitute, as its production process has low carbon emissions and energy consumption, and it can comprehensively utilize various types of industrial waste residue while possessing superior physical and chemical properties. However, the shrinkage of alkali-activated concrete can be larger than that of traditional silicate concrete. To address this issue, the present study utilized slag powder as the raw material, sodium silicate (water glass) as the alkaline activator, and incorporated fly ash and fine sand to study the dry shrinkage and autogenous shrinkage values of alkali cementitious material under different content. Furthermore, combined with the change trend of pore structure, the impact of their content on the drying shrinkage and autogenous shrinkage of alkali-activated slag cement was discussed. Based on the author's previous research, it was found that by sacrificing a certain mechanical strength, adding fly ash and fine sand can effectively reduce the drying shrinkage and autogenous shrinkage values of alkali-activated slag cement. The higher the content, the greater the strength loss of the material and the lower the shrinkage value. When the fly ash content was 60%, the drying shrinkage and autogenous shrinkage of the alkali-activated slag cement mortar specimens decreased by about 30% and 24%, respectively. When the fine sand content was 40%, the drying shrinkage and autogenous shrinkage of the alkali-activated slag cement mortar specimens decreased by about 14% and 4%, respectively. [ABSTRACT FROM AUTHOR]

Waste incineration is a widely used treatment method, and sustainable approaches are required to properly recycle large volumes of incineration ash to reduce environmental impacts and landfill space consumption. Studies have focused on the potential of recycling incineration ash as a replacement for natural aggregates in civil engineering applications, such as road construction. However, industrial waste incineration ash, such as waste tire incineration ash, contains hazardous heavy metals, such as lead and zinc that pose potential environmental threats. Moreover, few studies have investigated the leachability of these hazardous metals after long-term natural aging. This study investigates the long-term evolution of leachate chemistry, mineralogical transformation, and heavy metal fixation performance of a recycled roadbed material using ash from industrial waste incineration of waste tires and biomass (SFA). Additionally, field samples from a five-year pilot test site utilizing SFA were also examined. Regulatory leaching tests showed that the concentrations of Cd, Pb, As, T-Cr, and Ni were all below permissible limits even after five years of utilization. Long-term column leaching experiment results indicated that, compared to the total content of the SFA material, the leaching ratios of Pb, T-Cr, Cu, and Zn were 27%, 12%, 5%, and 0.1%, respectively. The SFA pH-stat leaching test results demonstrated that the mass release of the total content of heavy metals was relatively minimal, even under acidic pH conditions (pH < 4). Finally, profiles of pH and major ions in leachate from the column leaching experiment were simulated using HYDRUS HP1, implementing a dual-porosity modeling approach. In conclusion, despite containing hazardous heavy metals, SFA exhibits significantly low leaching rates over a long-term period. [ABSTRACT FROM AUTHOR]

There is an ever-growing interest in recovering and recycling waste materials due to their hazardous nature to the environment and human health. Recently, especially since the beginning of the COVID-19 pandemic, disposable medical face masks have been a major source of pollution, hence the rise in studies being conducted on how to recover and recycle this waste. At the same time, fly ash, an aluminosilicate waste, is being repurposed in various studies. The general approach to recycling these materials is to process and transform them into novel composites with potential applications in various industries. This work aims to investigate the properties of composites based on silico-aluminous industrial waste (ashes) and recycled polypropylene from disposable medical face masks and to create usefulness for these materials. Polypropylene/ash composites were prepared through melt processing methods, and samples were analyzed to get a general overview of the properties of these composites. Results showed that the polypropylene recycled from face masks used together with silico-aluminous ash can be processed through industrial melt processing methods and that the addition of only 5 wt% ash with a particle size of less than 90 µm, increases the thermal stability and the stiffness of the polypropylene matrix while maintaining its mechanical strength. Further investigations are needed to find specific applications in some industrial fields. [ABSTRACT FROM AUTHOR]

This paper presents experimental investigations on epoxy mortar produced using industrial wastes. In some recent studies, coal bottom ash and polyethylene terephthalate (PET) waste have been chosen as a filler to replace sand, and fly ash and silica fume have been chosen as micro fillers for epoxy mortar production; enhanced results in terms of compressive and tensile strengths and durability have been achieved. However, these approaches failed to boost the strength and durability compared to the epoxy steel slag, epoxy sand, epoxy marble dust, and epoxy polyvinyl chloride (PVC) waste. This present research work has investigated the influence of waste filler on the mechanical properties and microstructure of epoxy mortar, produced by using sand and industrial wastes, i.e., steel slag, marble dust, and polyvinyl chloride waste. Based on the composition ratio, the prepared samples of epoxy resin mortar containing 25% epoxy binder (epoxy resin plus epoxy hardener) and 75% filler (1:3) were compared to the cement mortar. However, each specimen of epoxy resin mortar was prepared by mixing with different fillers. The properties such as compressive strength, tensile strength, and microstructural changes were measured using different characterization techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared radiation spectroscopy (FTIR), and scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDX). From the obtained results, it was found that the strength of the specimens increases when blended with steel slag and marble dust, which is attributed to their peak densities and enhanced particle interactions. The XRD, SEM, FTIR, and SEM-EDX analyses showed the formation of calcium, magnesium, and other phases in the microstructure of epoxy resin-based mortars. This resulted in lower water absorption and porosity, as well as improvements in both compressive and tensile strengths. This research can help in understanding the important role of different industrial wastes as feasible fillers in epoxy resin-based composites. [ABSTRACT FROM AUTHOR]

Poland is a country where the commercial power industry mainly uses coal to produce energy. As a result of energy production processes, by-products of combustion are generated, primarily fly ashes. In Poland, these are mostly obtained from conventional coal combustion boilers. Fly ashes from coal combustion account for 1.2% of all industrial waste generated in Poland. In addition, fly ashes are produced by fluidized-bed boilers. These are classified as a mixture of fly ashes and solid calcium-based reaction waste from flue-gas desulphurization, and constitute almost 2% of Polish industrial waste. This paper describes the amounts of fly ashes generated in Poland and considers activities related to their recovery and disposal. The high recovery levels of fly ashes (about 90%) and fluidized ashes (about 98%) mean that these waste products can also be considered anthropogenic raw materials. The use of these materials in the cement industry is an example of industrial symbiosis. Such usage benefits not only the economy but also the environment and, therefore, society as a whole. To describe the use of recovered fly ashes in cement plants, the authors use the anthropogenicity index, which characterizes the level of technological advancement and the substitutability of primary raw materials for secondary raw materials. [ABSTRACT FROM AUTHOR]

To reduce the harm caused by industrial solid waste to the environment, and solve the problem of excavated soil disposal in buried pipeline management projects, this study proposes a method to produce soil-based controlled low strength materials (CLSM) by using industrial solid wastes (including fly ash and red mud) as partial replacements for cement. The properties of CLSM were characterized in terms of flowability, unconfined compressive strength, phase composition and microstructure. The test results showed that fly ash could significantly improve the flowability of CLSM, while red mud had more advantages for the strength development. When 20% fly ash and 30% red mud were combined to replace cement, the fluidity of CLSM was 248 mm, and the unconfined compressive strength (UCS) at 3, 7 and 28 days was 1.08, 1.49 and 3.77 MPa, respectively. The hydration products of CLSM were mainly calcium silicate hydrate gels, ettringite and calcite. Fly ash provided nucleation sites for cement hydration, while the alkali excitation of red mud promoted the dissolution of SiO2 and Al2O3 in fly ash. The filling and gelation of hydration products make the microstructure dense, which improves the mechanical properties of the mixture. [ABSTRACT FROM AUTHOR]

Water is a resource that is essential to almost all phases of industrial and manufacturing operations globally. It is important to handle the wastewater generated professionally. The textile industry is one of the major global polluters, with textile producers responsible for one-fifth of all industrial water pollution worldwide. In contrast, heavy metal contamination has developed into a critical, expanding global environmental problem. Geopolymer is a cementitious constituent of amorphous aluminosilicates derived from natural or industrial wastes. It is produced using the polymerization of aluminosilicate raw ingredients in an alkaline atmosphere. The aim of this study is to evaluate the application of eco-friendly geopolymer cement in the immobilization technique for the treatment of wastewater including heavy metals and dyes. Geopolymer cement pastes were organized using slag and fly ash as an aluminosilicate source, (1:1) sodium silicate and sodium hydroxide 15 wt.% as an alkali activator in the presence of organic dye pollutant reactive red 195, and Cu2+ ions (700 ppm) at different hydration times for up to 28 days. The physicochemical and mechanical properties of the prepared geopolymer cement mixes were further examined in relation to reactive dye pollutant and Cu2+ ions. The hydration characteristic was examined using the compressive strength and % of total porosity tests, as well as FTIR and XRD studies. Our findings support the 100% immobilization of both Cu2+ ions and organic dye pollutants in prepared geopolymer pastes for up to 28 days of hydration. Additionally, adding both Cu2+ ions and dye pollutants to the prepared geopolymer paste improves its mechanical properties, which is also supported by FTIR data. XRD and FTIR studies showed that the Cu2+ ions and dying bath effluent addition have no influence on the kind of hydration products that are produced. On the other hand, the geopolymerization process is negatively impacted by the presence of Cu2+ ions alone in the geopolymer paste. [ABSTRACT FROM AUTHOR]

Mining is a primary sector for the national economy of many countries, but exploiting these natural resources causes negative impacts on the environment. Tailings produced during mining, called mine tailings, have to be disposed of, and for that purpose, they are often mixed with Portland cement to control environmental toxicity and improve their mechanical properties. However, the high environmental impacts of producing Portland cement are well known. In this sense, sustainable binders based on the alkaline activation of industrial wastes have been studied as an alternative to using Portland cement. This study focused on applying a sustainable binder based on the alkaline activation of fly ash to improve the mechanical performance of a mine tailing from a mine located in Portugal. Geotechnical tests and chemical analysis were conducted to characterize the mine tailing and fly ash used in the alkaline activation process. In addition, triaxial tests were performed to evaluate the mechanical performance of the specimens, with both natural and stabilized tailings. The developed study proved that stabilized tailing with activated fly ash shows promising mechanical performance showing that this approach can be an excellent alternative to using Portland cement. [ABSTRACT FROM AUTHOR]

Cementitious material based on synergistic industrial wastes can be used as a new product for low-carbon transformation. It can aid in resource recycling and suitable consumption and utilisation of various industrial wastes. The proposed material can reduce a large amount of CO2 emitted during calcination in cement production and the decomposition of raw limestone. In addition, the material exhibits high durability and high resistance to corrosion in the marine environment that can further reduce CO2 emissions over the lifecycle of the carbon footprint of the building. Currently, many similar chemical kinetic processes and mineralogical reaction processes of particle migration and rebinding exist in the hydration and hardening reactions, service processes and durability evolution of different industrial waste cementitious systems for low-carbon production. The theoretical basis of preparing various low-carbon cementitious materials (LCCMs) with industrial waste systems is discussed herein, including the two theories of 'complex salt effect' and 'isomorphic effect from tetrahedral coordination of silicon-oxygen'. Further research on LCCM is based on the theoretical foundation of 'passive hydration kinetics'. Furthermore, this study presents the CO2 reduction potential of LCCM prepared using industrial wastes and provides future research directions in this regard. [ABSTRACT FROM AUTHOR]

Currently, there is an increasing industrial demand for rare earth elements (REE) as these elements are now integral to the manufacture of many carbon-neutral technologies. The depleting REE ores and increasing mining costs are prompting us to consider alternative sources for these valuable metals, particularly from waste streams. Although REE concentrations in most of the alternative resources are lower than current REE ores, some sources including marine sediments, coal ash, and industrial wastes, such as red mud, are emerging as promising with significant concentrations of REE. This review focuses on the alternative resources for REE, such as ocean bottom sediments, continental shelf sediments, river sediments, stream sediments, lake sediments, phosphorite deposits, industrial waste products, such as red mud and phosphogypsum, coal, coal fly ash and related materials, waste rock sources from old and closed mines, acid mine drainage, and recycling of e-waste. Possible future Moon exploration and mining for REE and other valuable minerals are also discussed. It is evident that REE extractions from both primary and secondary ores alone are not adequate to meet the current demand, and sustainable REE recovery from the alternative resources described here is also necessary to meet the growing REE demand. An attempt is made to identify the potential of these alternative resources and sustainability challenges, benefits, and possible environmental hazards to meet the growing challenges of reaching the future REE requirements. [ABSTRACT FROM AUTHOR]

Concrete is a versatile construction material used along with a reinforcement. Concrete is made up of binder materials and aggregates. Cement is a primary binder material used to produce conventional concrete. Carbon dioxide emissions in the atmosphere are a symptom of the issue related to Portland cement manufacture. It is estimated that one ton of cement produced releases an equal amount CO2 into atmosphere. On other hand, many industrial wastes are dumped in open spaces, leading to land pollution. Researchers have developed a construction material known as geopolymer concrete that uses industrial waste materials as a binder material to address these two issues. Excellent mechanical and durability characteristics are displayed by geopolymer concrete. For the creation of geopolymer concrete, fly ash is employed as a binder material. The drawback of utilizing fly ash is the curing method. Due to increased setting time, concrete samples require either heat curing or oven-curing. Geopolymer paste preparation is based on the type of binder materials used. In this study, GGBS is partially added with fly ash to cure specimens in ambient temperature due to presence of a higher amount calcium in GGBS. The present study investigates the consistency of geopolymer pastes, their workability, and the compressive strength of cement mortars by varying the amount of binder content (360 kg/m3 & 400 kg/m3). The molarity of NaOH was varied from 8 to 12. The ratio between binder material and alkaline to binder ratio were 0.45 and 0.50, respectively. The specimens were cured in both ambient and oven temperatures to study their strength development caused by temperature. A total of 396 specimens were cast to study the behavior of geopolymer concrete made with fly ash and GGBS (FAG). The test results revealed that the substitution of 50% GGBS with fly ash exhibited better strength properties during curing. Additionally, by increasing the binder content to 400 kg/m3, the results of 80% GGBS and 20% fly ash revealed excellent consistency among all other mixes. The oven-cured specimens showed more strength compared to specimens cured in ambient temperature, but the ambient cured specimens (ACS) attained the required strength. It was also not practically possible to cure the structural members by oven-curing in the field. The mix with 80% of GGBS and 20% fly ash can be used for construction. The required strength can also be achieved by increasing the molarity ratio. [ABSTRACT FROM AUTHOR]

The protection of the environment must be a priority in our society, and the construction sector can contribute significantly to this goal. Construction, being one of the industrial sectors that is more demanding in terms of raw materials, must reinforce its effort to implement, in a more profound and systematic way, the paradigm of the circular economy. In this sense, in recent years several studies have been trying to contribute solutions aimed at reintroducing industrial by-products or residues in new products for the construction industry. It should be noted that nowadays it is increasingly important to introduce a higher percentage of recycled materials in concrete. In this context, the present work addresses the appropriateness of a design procedure proposed to maximize the content of electric arc furnace slag (EAFS) and include recycled tire steel fibers (RTSF) in the production of more sustainable structural concretes. For this, the properties of various concrete mixtures at the fresh and hardened state, obtained by the substantial substitution of coarse and fine natural aggregates by EAFS and fly ash (FA), were investigated. The design of EAFS mixtures was based on two conventional reference mixtures (REF1 and REF2), and by using the modified Andreasen and Andersen particle packing model, these were optimized to achieve maximum packing density. Compressive strength, modulus of elasticity behavior, and fresh and physical properties were assessed in order to define the best mix proportions with respect to the predefined requirements of ordinary mixtures. Untreated recycled tire steel fibers (RTSF) were included in the developed sustainable concrete to perform a comparison of the physical properties with unreinforced concretes developed with natural aggregates (REF2) and with EAFS aggregates (EAFS8D1). This incorporation was intended to improve the physical behavior of unreinforced concretes with EAFS aggregates. Mixtures with high percentages of waste aggregates up to 70% (in weight), and 10% (in weight) of FA were obtained, showing competitive mechanical behavior compared to REF1 and REF2. These concrete compositions showed minimum and maximum compressive strengths between 9 MPa and 37 MPa, respectively. This study coverd the two major classes of concrete used as structural material, namely structural concrete and fiber reinforced concrete. [ABSTRACT FROM AUTHOR]

In order to alleviate the shortage of sand resources for construction, make full use of industrial waste and promote the development of green lightweight aggregate concrete in the desert and surrounding areas, this paper proposes a new lightweight ceramsite concrete, fly ash cenospheres and desert sand ceramsite concrete (FDCC). An orthogonal test was conducted to analyze the effects of the desert sand (DS) replacing ratio, fly ash cenosphere (FAC) replacing ratio and polymer emulsion (PLE) addition on the damage patterns, slump, apparent density and compressive strength of the FDCC. The results showed that the most influential factors for the slump, apparent density and compressive strength of the FDCC were the FAC replacing ratio, FAC replacing ratio and DS replacing ratio, respectively. Meanwhile, the PLE addition had little effect on the workability or mechanical performance of the FDCC. With the increase in the DS replacing ratio, the slump decreased rapidly and the compressive strength reached its peak value, increasing by 20.6% when the DS replacing ratio was 20%. With the increase in the FAC replacing ratio, the slump increased by 106%, the apparent density decreased gradually and the compressive decreased and then increased, reaching its lowest value when the FAC replacing ratio was 20%. According to the synthetic evaluation analysis, the optimum DS replacing ratio, FAC replacing ratio and PLE addition of the FDCC were 20%, 30% and 1%, respectively. [ABSTRACT FROM AUTHOR]

The direction of construction science that is associated with the development of the theory and practice of creating a new generation of foam concrete is particularly interesting and relevant. The development of improved structural foam concrete using polypropylene fiber and industrial waste, namely fly ash (FA), is prompted by the existing environmental threat posed by FA; this threat is a result of the operation of the fuel energy industry, as well as the possibility of using foam concrete not only as thermal insulation, but as the main material for load-bearing structures that have a certain level of responsibility. The aim of this work was to create and optimize the recipe technological parameters to produce non-autoclaved fiber foam concrete (FFC) using FA as a component. The study used standardized methods for assessing the properties of FFC, and the method of optical microscopy to analyze the structural characteristics of the material. It has been revealed that the replacement of cement with FA in an amount of 10% to 40% helps to reduce the dry density (DD) of FFC. The lowest DD was recorded for samples with 40% FA. The best results for the compressive strength (CS) and flexural strength (FS) were recorded for FFC samples with 10% FA instead of cement. The increase in CS was 12%, and the increase in FS was 23%. The best thermal insulation properties of FFC, and in terms of resistance to freezing and thawing, were recorded in samples with a 10% replacement of cement with FA. The maximum decrease in thermal conductivity was 14%. [ABSTRACT FROM AUTHOR]

Nowadays, the environmental impact of plastic waste is crucial, and in the energy industry, fly ash, a type of solid waste, has also prompted severe ecological and safety concerns. In this study, we synthesised composite material from two industrial wastes: recycled polyethylene terephthalate (rPET) as the matrix and fly ash as the filler. The effect of different fly ash loadings on the thermal behaviour and microstructure of the composite material using rPET were evaluated. Various loading amounts of fly ash, up to 68%, were added in the rPET mixtures, and composites were made using a single-threaded bar's barrel extruder. The feeding zone, compression zone, and metering zone made up the three functional areas of the extruder machine with a single-flighted, stepped compression screw. The composite materials were subjected to DSC and SEM equipped with EDX spectroscopy tests to examine their thermal behaviour and microstructural development. It was found that the thermal behaviour of rPET improved with the addition of fly ash but degraded as the fly ash loading increased to 68%, as confirmed by the DSC study. The composites' microstructural development revealed an even filler distribution within the polymer matrix. However, when the fly ash loading increased, voids and agglomeration accumulated, affecting the composites' thermal behaviour. [ABSTRACT FROM AUTHOR]

In recent years, due to the reduction in available natural resources, the attention of many researchers has been focused on the reuse of recycled materials and industrial waste in common engineering applications. This paper discusses the feasibility of using seven different materials as alternative fillers instead of ordinary Portland cement (OPC) in road pavement base layers: namely rice husk ash (RHA), brick dust (BD), marble dust (MD), stone dust (SD), fly ash (FA), limestone dust (LD), and silica fume (SF). To exclusively evaluate the effect that selected fillers had on the mechanical performance of asphalt mixtures, we carried out Marshall, indirect tensile strength, moisture susceptibility, and Cantabro abrasion loss tests on specimens in which only the filler type and its percentage varied while keeping constant all the remaining design parameters. Experimental findings showed that all mixtures, except those prepared with 4% RHA or MD, met the requirements of Indian standards with respect to air voids, Marshall stability and quotient. LD and SF mixtures provided slightly better mechanical strength and durability than OPC ones, proving they can be successfully recycled as filler in asphalt mixtures. Furthermore, a Machine Learning methodology based on laboratory results was developed. A decision tree Categorical Boosting approach allowed the main mechanical properties of the investigated mixtures to be predicted on the basis of the main compositional variables, with a mean Pearson correlation and a mean coefficient of determination equal to 0.9724 and 0.9374, respectively. [ABSTRACT FROM AUTHOR]

Incessant generation and mismanagement of industrial waste, resource scarcity, and environmental degradation have created non-sustainability in human life. Though industrial wastes are hazardous or non-hazardous in nature based on their source, open dumping disposal is commonly done for both types of waste. The adversity associated with waste enhances the environmental and health impacts. However, this waste has the potential to recycle and minimize resource scarcity. The circular economy works on the concept of reuse, recycling, and recovery to convert waste into a resource. Thus, industrial waste can benefit the environment and economic growth to build industrial ecology. However, the opportunities and challenges associated with industrial ecology for the reuse and recycling of waste have to be identified and preserved. Therefore, this study has identified challenges associated with waste, analyzed their impact, and industrial regulations, prioritized their criticality, and developed solution strategies to alleviate them. Two case studies on industrial byproducts, i.e., fly ash and red mud, based on different income groups are discussed in this study. It highlights the circular economy has minimized waste generation and enhanced the recovery of secondary resource materials. In addition, this study supports achieving the sustainable development goals (SDGs) 11 and 12 to build a sustainable industrial ecosystem. [ABSTRACT FROM AUTHOR]

This study was conducted in a fluidized-bed incineration plant, evaluating the formation, emission and flux of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from industrial-organic-solid-waste (IW) incineration. The results revealed that both the total (or I-TEQ) concentrations of toxic and 136 total PCDD/Fs in flue gas (FG), fly ash (FA) and bottom ash (BA)were ramped up to a higher level than those during municipal-solid-waste (MSW) incineration. A possible explanation was the chlorine (Cl) content of IW. However, the emitted PCDD/Fs in FG (FA/BA) still fulfilled the criteria. Subsequently, similar distribution patterns of PCDD/F isomers were observed in subsystems, indicating a unified formation-pathway. De novo synthesis was detected as the dominant formation-pathway of PCDD/Fs, while high-temperature and precursor syntheses were excluded. DD/DF chlorination formed PCDD/Fs to some extent. Furthermore, the mass flow chart indicated that PCDD/Fs output in primary FG was significantly strengthened (>1000 times) by de novo synthesis, from 1.25 μg I-TEQ/h to 1.67 mg I-TEQ/h. With effective cleaning by APCS, 99.6% of PCDD/Fs in FG were purified. PCDD/Fs in the gas phase were finally emitted at a discharge rate of 7.25 μg I-TEQ/h. However, accumulated FA took most PCDD/Fs into the environment (>99%), reaching 3.56 mg I-TEQ/h. [ABSTRACT FROM AUTHOR]

Each year, China produces a substantial amount of municipal sludge, industrial waste (slag, fly ash, and desulfurized gypsum), and construction waste, while its recycling rate is low. If not disposed in a properly and timely manner, this inequity can have serious environmental impacts. This study aimed to prepare a new type of modified sludge material with high strength, low shrinkage, and low permeability by curing municipal sludge with industrial waste (slag, desulfurized gypsum, and fly ash) and powdered construction waste. At specific maintenance ages, the modified sludge material was examined for shrinkage deformation, water content, compressive strength, and hydraulic conductivity. The modified sludge material was also tested by scanning electron microscopy (SEM + EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) tests. The hydration products, micromorphology, and elemental composition of modified sludge were also analyzed at specific maintenance ages. These analyses revealed the mechanism of solidification of municipal sludge by industrial waste and powdered construction waste and the changes in the microstructure of the sludge. The results showed that the compressive strength of the modified sludge ranged from 3.83 to 8.63 MPa, volumetric shrinkage ranged from 2.12 to 12.68%, and hydraulic conductivity ranged from 1.65 × 10−8 to 2.21 × 10−7 cm/s after 28 d of maintenance. The active substances, such as SiO2, Al2O3, and CaO, in the industrial waste, powdered construction waste, and municipal sludge were subjected to a hydration reaction in an alkaline environment to produce dense blocks, agglomerates of C-S-H, ettringite, gismondine, and other hydration products. The compressive strength of the modified sludge increased, and its internal structure was dense. [ABSTRACT FROM AUTHOR]

Introduction: the article discusses the effect of the complex of active mineral additives consisting of silica and fly ash, and a fine aggregate, including finely ground natural-white quartz sand for partial replacement of river sand, on the mechanical properties of high-strength concrete containing steel fiber. Materials and methods: high-strength concrete containing Dramix®3D 65/35 steel fiber in the amount of 100 kg per 1 m3 of concrete mixture was suggested where 22% to 100% of river sand was replaced by finely ground white natural sand of the particle size of 5 to 1800 μm and containing the complex of active mineral additives for partial replacement of cement as part of a multicomponent binder, consisting of low-calcium fly ash of thermal power plants and silica and containing, respectively, 20, 30, 40% fly ash and from 5 to 15% silica by weight of the binder. Results: research results have shown that 100% replacement of river sand with finely ground natural white sand, in concrete containing 20% of the mass as part of a multicomponent binder, fly ash and from 5 to 15% by weight of silica, contributes to the increase of its strength properties: the values of concrete compressive strength after 28 days were in the range from 118.5 to 128 MPa, tensile strength during bending and splitting, respectively, from 18.8 to 25.4 MPa and from 10.2 to 11.9 MPa, which is higher than the strength of concrete samples containing river sand. Conclusions: the achieved results have demonstrated the efficiency of using finely ground natural white sand as an alternative to river sand for producing high-strength concrete, thus helping to save the river sand resources in Vietnam. The use of fly ash and micro silicon, which are power and metallurgy wastes, as part of a multicomponent binder in order to partially replace cement reduces the carbon footprint in the production of binders and will also have a beneficial effect on environmental protection against industrial waste pollution. [ABSTRACT FROM AUTHOR]

The following article introduces, in a thorough manner, how the chemical pozzolanic reaction takes place in cement composites containing the fly ash (FA) additive. In the research part, however, the development of phases in the structure of the cement paste in the initial period of its curing and after 28 days from its preparation was traced. For this purpose, a Scanning Electron Microscope (SEM) was used. In order to accurately highlight all the characteristic stages of the formation of the structure of the composite containing FA, an analysis of the cement matrix was carried out between 0.5 and 28 days of their curing. Microstructural studies were complemented by tests of pozzolanic activity of FAs used. In order to conduct a full analysis of this feature, experiments were carried out using two types of research methods, i.e., chemical and physical. On the basis on the conducted studies it was found that: in cement composites with the addition of FA, in the period until the third day of curing, the development of the material structure is mainly the result of the hydration reaction, and between the seventh and fourteenth day after sample preparation, the first signs of the pozzolanic reaction on FA grains are visible; however, in the period between 14 and 28 days, there is a clear homogenization of the structure of the cement composite with the addition of FA, resulting from the change of disordered phases into compact and homogeneous forms and filling in the composite of porous places with pozzolanic reaction products. The use of cement composites based on materials whose application makes it possible to reduce GHG emissions to the atmosphere, reduce energy consumption, and reduce industrial waste landfills leads towards the development of ecological and sustainable building engineering. [ABSTRACT FROM AUTHOR]

The paper presents the results of research on a composite mixture intended for use in road construction. The purpose of developing the mixture is to be able to use large amounts of industrial waste to produce building material. The waste used are coal slate from the mining industry, shredded rubber waste from used passenger car tires and fly ash from power plants. The mixture (SRFC) consists of unburnt coal-mining slate (S), shredded rubber waste (R), fly ash (F) and cement(C). A test under cyclic loading conditions was carried out on samples prepared from the SRFC mixture, in which the global deformations and local strains caused on the samples were measured. A measurement system using digital image correlation was used for the research. On the basis of the conducted research, it was found that the content of shredded rubber waste significantly influences the deformability of the tested mixtures and allows for the extension of the scope of elastic deformation in which the tested samples work. [ABSTRACT FROM AUTHOR]