Cleaner Materials最新文献

The foundry industry is responsible for consuming large quantities of lining materials and generating significant amounts of waste. Silico-aluminous linings are used in the production of cast iron due to their compatibility with molten metal and slag. However, after use, these materials are typically disposed of in industrial landfills, creating an environmental liability. This study demonstrated a feasible alternative approach to repurpose silico-aluminous refractory wastes from induction furnaces and casting ladles from the foundry industry to develop new materials for refractory hydraulic binders for lining (refractory patch). The wastes were characterized using X-ray Diffraction, X-ray Fluorescence Spectrometry, Thermal Analysis, Scanning Electron Microscopy, and particle size distribution. The behavior of the lining wastes was found to be compatible with the proposed application, despite the expected contamination. There is potential for cost savings of at least 25 % and promoting a culture of recycling.

At present, nearly 85 % all of the requirement for MWFs are satisfied by the use of mixtures of petroleum by-products and synthetic substances with supplementary additives to enhance their properties. The demand for easily biodegradable, environmental friendly MWFs is a current requirement. COCOTP, a novel biodegradable MWF based on white (refined) coconut oil, developed by authors, had previously shown promising tribological properties for machining mild steel (MS) and stainless steel (SS) when used with the flooding method, but had fallen short of the performance of commercially available, non-biodegradable alternatives with MQL. Therefore in the current investigation, nano-particles were added to improve the performance of novel COCOTP MWF to use it with MQL conditions. Two nanomaterials nano-graphite and nano-Al₂O₃ were separately added to the base fluid in different concentrations as a monodispersed suspension. These nano enhanced fluids (NEFs) were subsequently used in straight turning experiments of two work materials AISI304 and SS400. Both the nano-enhanced fluids show convincing improvements over both COCOTP and mineral-oil based fluids in terms of surface roughness of the specimens regardless of the material being turned. However when machining SS 400, NEFs perform better only in lower speeds in terms of temperature. SS400 has a much higher thermal conductivity than AISI304 means that the quantity of residual heat remaining at the point of material removal which can be absorbed by the cutting fluid is lower in SS400. During machining SS400 under MQL lubrication 9.8 %, 26.8 % and 24 % reduction of surface roughness values (with respect to soluble oil) and during machining AISI304 55.3 %, 73.7 % and 70.4 % reduction of surface roughness values were obtained at 1175 rpm with COCOTP, NEF A and NEF G respectively. Based on the experimental results, the best-performing nano-enhanced fluids under MQL are 0.3 % (w/w) Al₂O₃ and 0.3 % (w/w) graphite.

This study focuses on the development of eco and user-friendly mechanochemically-activated geopolymeric stabilizers, surpassing the limitations inherent in traditional geopolymerization methods. A comparative analysis was undertaken with conventionally activated geopolymer stabilizers to establish benchmarks for effectiveness in soil stabilization applications. Additionally, the research delves into the impact of granulated blast-furnace slag (GGBS) content on the mechanical and durability properties of stabilized soil samples. In addition, the investigation focuses on the influence of the activation method on soil effectiveness and strength post-exposure to sulfate attack. The durability performance is rigorously assessed through the immersion of specimens in a 1 % magnesium sulfate (MgSO₄) solution for 60 and 120 days. The comprehensive evaluation includes visual appearance, mass changes, Ultrasonic Pulse Velocity (UPV), Unconfined Compressive Strength (UCS), and Fourier-Transform Infrared (FTIR) spectra of geopolymer-stabilized soil specimens. The results showed that before the exposure to the MgSO₄ solution, the UCS of mechanochemically activated geopolymer (MAG) samples was higher (12–45 %) than that of conventionally activated geopolymer (CAG)-stabilized soil. Furthermore, the strength of the geopolymer-stabilized soil improved by 114 %, 247 %, and 361 %, at 50, 75, and 100 % GGBS content, respectively. On the other hand, after exposure to the MgSO₄ solution, the results showed that the mechanochemically activated geopolymer-stabilized soil has better resistance to sulfate erosion than the conventionally activated geopolymer-stabilized soil. The residual UCS for MAG and CAG samples were 93 % and 89 % when exposed to 1 % magnesium sulfate solution for 60 days, whereas they declined to 70 % and 58 %, respectively, after 120 days of immersion.

Recently, there has been considerable interest in utilizing various forms of graphene derivatives for producing high-strength concrete. Among these derivatives are superstructure of graphene quantum dots (GQDs), particularly in their assemblies of carbon dots, which is innovative in cement. This research investigates the impact of graphene derivatives known as supra-GQDs on the mechanical properties and microstructure analysis of cement composites, compared with the control mixture and GQDs solution. The results found that supra-GQDs exhibit enhanced mechanical characteristics. The composite containing 1.2 % supra-GQDs had higher compressive and flexural strengths than the control by 40 % and 108 %, respectively. The study also identified a microstructural bridging mechanism involving the seeding and crystal growth of the C-S-H phase, leading to refined pore structure and less nano-, meso-, and micro-pores. The measured total pore volume reduced by 30 % when compared to GQDs solution. This investigation provides novel insight into the potential of utilizing supra-GQDs in cement composites, opening promising possibilities for high-performance concrete in the construction industry.

The hike in CO₂ emission from the cement industry calls for an alternative binder to cement. On the other hand, construction and demolition waste management is a global concern. This research aims to demonstrate the complete applicability of brick-based demolition wastes in geopolymer mortar and concrete. Ground Granulated Blast Furnace Slag (GGBS) was used with brick waste to improve performance. 3 M, 4 M and 6 M NaOH were used for mortar preparation, and 6 M NaOH was used for concrete tests. The performance of the geopolymer binder and mortar was compared with the control specimen. 5 % to 20 % incorporation of demolition waste powder (DWP) with GGBS was explored to find the optimum binder combination. A 10 % incorporation for 3 M and 15 % for 4 M and 6 M was found optimum. Then, 10 % to 100 % incorporation of brick sand was studied to examine the influence of brick-based demolition waste on the fresh and hardened properties of mortar. Sand: Binder: Alkaline activator was taken 3.375: 1: 0.45 for mortar. The workability of mortar varied with the increase of brick sand content. The flexural and compressive strengths were decreased with an increase in brick sand content for all molarities of NaOH; consequently, the water absorption increased with brick sand content. The maximum mortar compressive strength of 27 MPa was found for 10 % demolished sand with a 6 M alkali concentration. However, consistent results were obtained with a 4 M concentration. Geopolymer concrete from brick-based demolition waste was prepared using 6 M NaOH. The UPV result indicates the regular quality of the concrete cube, with acceptable capillary water absorption after 24 h. However, the compressive strength of geopolymer concrete could be useful for non-structural works, and therefore, further studies with higher strength of NaOH for geopolymer concrete are recommended.

Rubberized geopolymer concrete (RuGPC) is a new, environmentally safe building material requiring less energy and carbon footmark than normal cement-based systems, which can significantly reduce global warming concerns. Using waste rubber tyres by incorporating them in concrete as a substitute for natural aggregate, helps to reduce pollution and depletion of natural resources. Research shows that incorporating waste crumb rubber in geopolymer concrete (GPC) can reduce carbon dioxide emissions by 90% compared to ordinary Portland cement (OPC) and attain sufficient and mechanical properties and durability. This paper reviews the material properties of RuGPC and the possible structural application. It can be concluded, that RuGPC can substitute normal concrete (NC) particularly due to its impact resistance, and energy absorption performance. However, more research still needs to be conducted to be able to come up with practical design standards and conduct full-scale studies on RuGPC elements structurally to promote its practicability.

To avoid climate change, the world must reach net-zero carbon emissions by 2025 to achieve the goal of a sustainable environment. Improving resource efficiency is one of the important strategies to achieve a sustainable environment. Effectively recycling resources and reducing energy consumption have become important international issues today.

Therefore, this research was to recycle waste oyster shells, combined it with geopolymer technology, and added foaming agents to create an innovative building material that is 100% recyclable after use – “Foam heat-insulating bricks”, thereby reducing carbon emissions and building energy consumption. Through physical properties (apparent density, porosity, water absorption, etc.) and mechanical properties (compressive strength and flexural strength), discussed factors such as lime-sand ratio, alkaline solution concentration, foaming agent, etc., effected on the heat-insulating performance and environmental protection performance of foam heat-insulating bricks. The newly prepared foam heat-insulating bricks were also evaluated for their environmental and economic aspects according to relevant standards.

The results show that::(1) The higher the concentration of alkaline solution and the greater the proportion of lime-sand, which the mechanical properties of the finished product were the higher. Samples 10 M−55, 10 M−64 and RWITGP-60 can meet the G2 lightweight bricks standard; Samples WITGP-46, WITGP-55 and WITGP-64 can meet the roof heat-insulating brick standard. (2) The better the foaming performance, the higher the porosity and water absorption, which the thermal heat-insulating effect were better, but the worse the compressive strength and flexural strength. The foaming performance of the foaming agent is Sodium-perborate(NaBO₃) > Aluminum(Al) > Nothing-added(WITGP). (3) Oyster shell foamed heat-insulating bricks are 100 % recyclable, have better performance after remanufacturing, and have extremely high development potential. (4) It could pass the “Toxicity Characteristics Leaching Procedure” test and comply with Taiwan's general specifications for green building materials. (5) The heat flow resistance of adding different foaming agents is aluminum with the greatest benefit, and the order is: Aluminum (Al = 133.4)W/m² > Sodium-perborate (NaBO₃ = 93.6)W/m² > Nothing-added (WITGP = 90.6)W/m² > Concrete (CON = 68.2)W/m². (6) The oyster shell heat-insulating bricks produces 0.473 kg of carbon dioxide. Compared with concrete heat-insulating bricks, it can reduce carbon emissions by 48.7 % and save an economic price of 451.15 yuan/brick.

This paper presents research findings on the influence of tyre-derived rubber particle size on the mechanical properties of rubberised syntactic foam manufactured through stir casting. The study examined how the rubber particle size affected the shear, in-plane compression, and through-thickness compression properties, as well as the flexural properties of sandwich composites with rubberised syntactic foam core. Rubber particles of various sizes (<150 µm, 150–250 µm, 250–425 µm, and >425 µm) were integrated into the syntactic foam at both low (9 wt%) and high (23 wt%) concentrations. Rubber particles measuring less than 150 µm, promoted agglomeration and increased void volume due to elevated viscosity, leading to a reduction in the mechanical properties of the rubberised foam. Conversely, larger rubber particles exceeding 425 µm reduced the mechanical properties of the syntactic foam due to debonding at the matrix/rubber interface. This study identified the optimal rubber particle size for achieving the highest mechanical properties in rubberised foam, which falls within the range of 150–425 µm. This research demonstrates the sustainable development of multifunctional composites from recovered waste tyres.

Increasing the number of residential buildings due to rapid urbanization growth has led to the massive consumption of concrete materials and significant negative environmental impacts worldwide. Properly selecting green concrete (GC) materials in residential projects can promote sustainable construction practices and achieve a circular economy (CE). This paper aims to identify and analyze the parameters affecting GC material selection based on CE principles by developing a system dynamic (SD) model to investigate the environmental and economic benefits during the construction process. The system dynamic-based framework (SD-BF) is used to investigate the simulation interaction of the variables between the GC original scenario and several hypothetical scenarios through the simulation process, including fly ash concrete (FA) and recycled aggregate concrete (RAC). The causal loop diagrams (CLD) and stock and flow (SF) diagrams are created to investigate the inner relations among the GC variables that can achieve CE. The SD model was applied for a residential building case study in New Cairo City, Egypt, using Vensim to simulate and analyse the most appropriate GC scenarios regarding cement, natural aggregate, CO₂ emissions, cost-effectiveness, and waste generation. The results showed that using various concrete scenarios could enhance the GC selection for CE principles, in which cement reduction is the most effective variable, and the reduction reached 19.8% and 11.4% in the most optimum scenarios, while the natural aggregate (NA) reduction reached 19.1% compared with the original scenario. This development is vital for achieving CE and closing the concrete materials loop, which helps construction decision-makers select suitable concrete materials for future residential projects.

People discover various materials from time to time that break the boundaries of traditional materials. Plastic is a revolutionized material, and is referred to as “a material with 1,000 uses”. This review summarized up-to-date research on plastic and its waste pollution. Plastic has a domain throughout human life with its versatile properties such as lightweight, high durability, flexibility, and low production cost. This article describes the applications, benefits, production, consumption, and classifications of plastics. Plastic commercialization began with the Second World War and grew all over the world within less than a century. The global annual production of plastic is more than 359 million tons. Despite all the benefits, plastics cause severe environmental and public health issues. Accordingly, this study addresses the major issues of plastic waste on the environment and human health. Plastics can degrade into micro to nano sizes, and those fine particles are more spreadable in air, water, and soil. Therefore, both terrestrial and aquatic animals go through various negative impacts such as ingestion, entangling, ulcers, low reproduction, and oxidative stress. Microplastics also degrade human health due to cardiovascular diseases, chronic kidney disease, birth defects, cancer, etc. The closing contains the developed end-of-life options (e.g., recycling and reprocessing, incineration with energy recovery, modification reuse, value addition, and landfilling) of biodegradable and non-biodegradable plastic wastes. Several international, regional/national level legislations and policies/concepts (e.g., plastic trade, 3R policy, and circular economy) are available to manage plastic and plastic waste generation. Plastic waste management is also discussed offering practical insights and real-world scenarios. Solutions and challenges in effective plastic waste management guide to create a more sustainable and environmentally responsible approach. Finally, this review article highlights the importance of judicious decisions and the involvement of all stakeholders to overcome the plastic waste crisis.