•HMA containing several contents of RCA from different sources were studied.•Results showed that the mixes with RCA exhibited a similar behavior to that of conventional HMA.•HMA mix-design with ...coarse RCA fraction satisfied the requirements of national specifications.•Performance of mixes with RCA was found to be highly dependent on the source and dosage of RCA.
The waste generated by the construction industry generally has an undesired negative impact on both human and animal life as well as the environment. Among these wastes, recycled concrete aggregate (RCA), due to its good residual physical, mechanical, mineralogical, and chemical properties, has attracted promising potential for re-use and incorporation in the construction of new infrastructural elements. These infrastructure applications include construction of sidewalks, curb and gutters, subbase/base layers, and/or as a partial replacement of natural aggregates (NA) in the production of hot mix asphalt (HMA) mixtures. In this laboratory study, experimental research work was conducted to evaluate the influence of RCA on the mechanical properties and performance of RCA modified HMA mixtures against a control HMA mixture without any RCA. RCAs were obtained from two different concrete sources, namely: (a) one from the demolition of a building (RCAB), and (b) another one from the rehabilitation of a Portland cement concrete pavement (RCAP). Both NA and RCA were characterized taking into account physical and mechanical properties. HMA mixtures were produced using the Marshall mix-design method by replacing 0.0% (control), 15%, 30%, and 45%, respectively, of the coarse NA fraction with RCA. Thereafter, laboratory testing (i.e., Scanning Electron Microscopy SEM, resilient modulus, indirect tensile strength, etc.) including material property characterization and performance evaluation were conducted on HMA samples. Overall, the laboratory test results showed that the RCA modified mixtures exhibited a similar behavior to conventional HMA mixtures, but with greater environmental benefits and potential cost savings through the recycling and reuse of waste concrete aggregates. However, it was observed that the laboratory performance of RCA modified mixtures is strongly dependent on the RCA source and dosage, with RCAP exhibiting superior performance over RCAB. HMA mixtures produced with RCA provided higher optimum asphalt-binder content (OAC) than that of mixes with NA.
•Crushed glass (CG) is added in alkali-activated binders (AABs) replacing fly ash.•CG showed a better release of silica at higher alkaline media compared to fly ash.•The addition of CG increased both ...workability and setting time of AABs.•CG-based AABs showed a gradual increase in strength at ambient conditions.•The addition of CG showed a dense microstructure with low porosity.
Alkali-activated binders (AABs) have the potential to consume various types of cementitious waste materials, including coal ashes, municipal solid waste incinerator ash, palm-oil fuel ash, steel slags, mine tailings, cement kiln dust, ceramic tile residue, rice husk ash, and waste glass. This paper presents a study of alkali-activated cement paste produced with the substitution of the cementitious waste material soda-lime glass, which makes up the major proportion of the general glass waste stream. In the alkali-activated cement paste, crushed soda-lime glass powder (CG) was used as a replacement for class F fly ash (FA) from 0 to 30% by total solid weight, keeping the ground granulated blast furnace slag (GGBFS) content constant at 50%. The influence of activator molarity (4–8 M), alkaline liquid/solid binder (L/S) ratio (0.4–0.5) and different curing conditions (ambient air curing, wet curing, and short-term heat curing) on the rheology, strength, and microstructure of CG-substituted AABs was investigated and optimum conditions are suggested. According to the experimental results, both the workability and strength (compressive and tensile) of the AAB gradually increased with increasing level of substitution of FA by CG. Significant improvement in flow and setting time was seen with the addition of CG, even in mixtures with a low L/S ratio of 0.4. Both ambient and wet curing had more influence on the strength gain of AABs, especially after 28 days. Short-term heat curing resulted in high early strength gain. The dissolution of CG increased with increasing molarity (from 4 to 8 M) of the alkaline solution, which improved both strength and microstructure with curing time. Morphological and elemental analysis indicated an improvement of the microstructure of AABs due to the increased formation of calcium-dominant hydration products and hence reduced porosity with the substitution of CG. However, undissolved large-sized CG particles agglomerated in the binder without participating in the alkaline reactions. These agglomerated particles may induce micro-cracks due to weak bonding between the cement matrix and the smooth CG interface, which reduces the durability of AABs. Therefore, the inclusion of waste soda-lime glass powder with a mean diameter of 10–15 µm as a precursor in FA/GGBFS-based AAB as a replacement for FA is feasible and provides a good solution for waste material recycling.
Blast furnace slag has been used for many years in various applications related to civil engineering. Many studies have created a wide variety of cost-effective and environmentally friendly solutions ...for this industrial by-product. This study aims to contribute to the performance evaluations of the usability of the blast furnace slag for soil improvement and the effects of the additive ratio and curing time. Bentonite samples were prepared with the addition of blast furnace slag at 5%, 10%, 15%, and 20% ratios by weight at optimum water content (wopt). Results were evaluated using the liquid limit, plastic limit, unconfined compressive strength, and swelling tests performed after 1, 7, 14, and 28 days of curing time. Results revealed that the liquid limit value decreased, and the unconfined compressive strength increased with increasing curing time and blast furnace slag ratio in the mixture. Additionally, swelling pressure generally decreased with increasing slag contribution and curing time. The lowest values of the unconfined compressive strength were observed on the 7th day of curing time, and the minimum value was obtained at 10% mixing ratio. The highest unconfined compressive strength values were observed on the 28th days of curing time. The optimum mixing ratio was 5%.
•Microparticles prepared from biochar originated from different waste materials.•Microparticles were effective adsorbents for organic contaminant, methylene blue.•Feedstock and method of production ...affected adsorption properties of biochar.•Biochar from paper is an effective adsorbent even with absence of well-defined pores.
Biochar microparticles were prepared from three different types of biochar, derived from waste materials, such as pine wood (BC-PW), pig manure (BC-PM) and cardboard (BC-PD) under various pyrolysis conditions. The microparticles were prepared by dry grinding and sequential sieving through various ASTM sieves. Particle size and specific surface area were analyzed using laser particle size analyzer. The particles were further characterized using scanning electron microscope (SEM). The adsorption capacity of each class of adsorbent was determined by methylene blue adsorption tests in comparison with commercially available activated carbon. Experimental results showed that dye adsorption increased with initial concentration of the adsorbate and biochar dosage. Biochar microparticles prepared from different sources exhibited improvement in adsorption capacity (7.8±0.5mgg−1 to 25±1.3mgg−1) in comparison with raw biochar and commercially available activated carbon. The adsorption capacity varied with source material and method of production of biochar. The maximum adsorption capacity was 25mgg−1 for BC-PM microparticles at 25°C for an adsorbate concentration of 500mgL−1 in comparison with 48.30±3.6mgg−1 for activated carbon. The equilibrium adsorption data were best described by Langmuir model for BC-PM and BC-PD and Freundlich model for BC-PW.
In the present study, an attempt has been made to utilise spent alumina catalyst (SAC) and carbonised eggshell (CAES) in the fabrication of AA5052-based composite material. Cr was also added to ...further enhance the tensile strength, hardness and corrosion resistance of the material. Results showed that by adding 4.5% SAC, 4.5% CAES and 1.5% Cr in aluminium alloy, mechanical properties such as tensile strength, hardness and compressive strength enhanced significantly. Tensile strength, hardness and compressive strength increased by about 11.98%, 37.22% and 23.06%, respectively, concerning the base material. However, the toughness and ductility of composite have been reduced. Microstructure results of Al/4.5% SAC/4.5% CAES/1.5% Cr composite showed uniform. Corrosion weight loss and thermal expansion behaviour of composite have been also investigated to observe the SAC, CAES and Cr addition effect in the aluminium alloy.
•Synthesis of activated porous carbon from bio waste.•Symmetric super capacitor based on the activated porous carbon attributes excellent electrochemical performance.•The symmetric super capacitor ...device and the carbon itself evinced excellent long cycle stability and high cell voltage.•High specific energy and specific power are realized in super capacitor analysis.•The system potential is calculated by utilizing the upper limit of the capacitive potential value.
Rechargeable energy storage systems are highly demandable in the present scenario. Willing to engineer economical energy storage applications using environmentally sustainable technology, a high-temperature controlled heating process has synthesized activated porous carbon in an inert atmosphere with the bio-waste materials' KOH activation process. X-ray diffraction analysis confirms the phase and field emission scanning electron microscopy characterize the morphological features. Electrochemical studies are evaluated in envisaging the prospective approach of that system in the energy storage devices. This activated porous carbon has a mean pore size of 1.81 nm and a specific area of 811.8 m2g−1, which is high. The specific capacitance is evaluated to be 565.2 Fg−1. The porous carbon exhibits 98% stability up to 10000 cycles with high specific energy of 21 Whkg−1 at the specific power of 5000 Wkg−1. Assembled solid-state symmetric supercapacitor depicts 96% capacity retention with a high specific energy of 24.5 Whkg−1 at the specific power of 801.82 Wkg−1. The large surface area with porosity that enhanced the amount of charge storage can boost an electrical double-layer capacitor. The high value of specific capacitance and long cycle stability makes it a prospective candidate to attain the urge for the establishment of new functional materials for energy storage.
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Sustainable development becomes an important parameter for human civilization these days. Development of sustainable material requires the introduction of advanced technological solutions along with ...beneficial economic effects which take care of comfort and health of consumers, decreasing the harmful effect of the materials on the environment. Natural fiber as reinforcement in composites has numerous advantages over synthetic fibers. They are biodegradable, renewable and have a high strength to weight ratio. The addition of waste materials in the natural fiber reinforced polymer composites not only reduce the disposal problems associated with them but also offer superior properties over conventional materials. The present study gives a review of recent work on natural fiber reinforced polymer composites modified with waste material. The physical, mechanical and wear properties of these composites along with potential applications are also discussed.
•Foam stability is crucial for obtaining the desired properties of LWFC.•The utilization of industrial by-products with low specific gravity as pozzolans results in a density reduction in LWFC.•Use ...of fine waste materials increase water and paste requirements due to their larger specific surface area.•The increased water absorption is a result of porous industrial by-products and agro waste as lightweight aggregates.
This comprehensive investigation explores the potential application of agro and industrial by-products in the development of lightweight concrete (LWC), with a specific emphasis on lightweight foamed concrete (LWFC). Recognizing the value of limited natural resources, such as fine and coarse aggregates, commonly utilized in concrete within the construction sector, this study addresses the global concern of managing and disposing of by-products. While previous research has explored the integration of waste materials into pre-foamed concrete, a lack of comprehensive knowledge regarding their utilization and impact on foamed concrete has hindered widespread adoption and further advancement. Therefore, this study aims to analyze and evaluate the viability of various industrial and agricultural by-products, as well as quarry and construction sector wastes, as alternative cementitious materials and aggregates in concrete. The focus of this review lies in examining the characteristics of LWC, which encompasses autoclaved and foamed concrete and utilizes diverse industrial and agricultural by-products as substitutions for cementitious materials and aggregates. Detailed analysis is provided on the influence of cement and aggregate substitutions on key concrete properties, including density, compressive strength, flexural strength, splitting tensile strength, workability, porosity, and water absorption. When agricultural and industrial by-products are incorporated into LWFC, it results in a reduction in the dead load of constructions due to their lower density, along with increased compressive strength, flexural strength, and splitting tensile strength. At larger replacement ratios, however, detrimental impacts on fresh and hardened characteristics were seen. By investigating the utilization of waste materials and agricultural by-products in lightweight concrete, this study contributes to addressing resource scarcity and waste management challenges in the construction sector. The findings shed light on the potential benefits and limitations of incorporating such materials into concrete production, paving the way for sustainable and environmentally friendly construction practices.
Advanced materials design based on waste wood and bark Wenig, Charlett; Dunlop, John W C; Hehemeyer-Cürten, Johanna ...
Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences,
09/2021, Letnik:
379, Številka:
2206
Journal Article
Recenzirano
Odprti dostop
Trees belong to the largest living organisms on Earth and plants in general are one of our main renewable resources. Wood as a material has been used since the beginning of humankind. Today, forestry ...still provides raw materials for a variety of applications, for example in the building industry, in paper manufacturing and for various wood products. However, many parts of the tree, such as reaction wood, branches and bark are often discarded as forestry residues and waste wood, used as additives in composite materials or burned for energy production. More advanced uses of bark include the extraction of chemical substances for glues, food additives or healthcare, as well as the transformation to advanced carbon materials. Here, we argue that a proper understanding of the internal fibrous structure and the resulting mechanical behaviour of these forest residues allows for the design of materials with greatly varying properties and applications. We show that simple and cheap treatments can give tree bark a leather-like appearance that can be used for the construction of shelters and even the fabrication of woven textiles. This article is part of the theme issue 'Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 1)'.
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•Newly formulated hydrogels made of whey protein isolate and bioactive glass were created.•Heat-induced gelation technique used allowed generation of ready-to-use, sterile ...materials.•Bioactive glass particles were homogenously distributed in the hydrogel matrix.•Hydrogels showed a high capacity for mineralization and antioxidant activity.•Materials were cytocompatible and supported MG-63 osteoblastic cell functions.
This study deals with the design and comprehensive evaluation of novel hydrogels based on whey protein isolate (WPI) for tissue regeneration. So far, WPI has been considered mainly as a food industry by-product and there are very few reports on the application of WPI in tissue engineering (TE). In this work, WPI-based hydrogels were modified with bioactive glass (BG), which is commonly used as a bone substitute material. Ready-to-use, sterile hydrogels were produced by a simple technique, namely heat-induced gelation. Two different concentrations (10 and 20% w/w) of sol–gel-derived BG particles of two different sizes (2.5 and <45 µm) were compared. µCT analysis showed that hydrogels were highly porous with almost 100% pore interconnectivity. BG particles were generally homogenously distributed in the hydrogel matrix, affecting pore size, and reducing material porosity. Thermal analysis showed that the presence of BG particles in WPI matrix reduced water content in hydrogels and improved their thermal stability. BG particles decreased enzymatic degradation of the materials. The materials underwent mineralization in simulated biological fluids (PBS and SBF) and possessed high radical scavenging capacity. In vitro tests indicated that hydrogels were cytocompatible and supported MG-63 osteoblastic cell functions.
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