Aggregation Of Particles Research Articles

The Application of Nano Zero-Valent Iron in Synergy with White Rot Fungi in Environmental Pollution Control.

Developing efficient and sustainable pollution control technologies has become a research priority in the context of escalating global environmental pollution. Nano zero-valent iron (nZVI), with its high specific surface area and strong reducing power, demonstrates remarkable performance in pollutant removal. Still, its application is limited by issues such as oxidation, passivation, and particle aggregation. White rot fungi (WRF) possess a unique enzyme system that enables them to degrade a wide range of pollutants effectively, yet they face challenges such as long degradation cycles and low degradation efficiency. Despite the significant role of nZVI in pollutant remediation, most contaminated sites still rely on microbial remediation as a concurrent or ultimate treatment method to achieve remediation goals. The synergistic combination of nZVI and WRF can leverage their respective advantages, thereby enhancing pollution control efficiency. This paper reviews the mechanisms, advantages, and disadvantages of nZVI and WRF in pollution control, lists application examples, and discusses their synergistic application in pollution control, highlighting their potential in pollutant remediation and providing new insights for combined pollutant treatment. However, research on the combined use of nZVI and WRF for pollutant remediation is still relatively scarce, necessitating a deeper understanding of their synergistic potential and further exploration of their cooperative interactions.

Integrating ANSYS Fluent Simulation and Aspen Plus for efficient heavy metal ion removal with de-oiled cake

In this study bio-flocculant extracted from the de-oiled cake, a common waste generated while producing oil was used to treat an electroplating industrial effluent. A comprehensive analysis of flocculation efficiency in a simulated reactor using ANSYS Workbench - Fluent, with a focus on optimizing impeller position was carried out. The findings reveal that the optimal impeller position is 2 cm from the tank base, where maximum turbulent kinetic energy (0.02577 m2/s2) and dissipation rate (22.19 m2/s3) were achieved at 200 RPM, enhancing flocculation efficacy. Furthermore, the study identifies 0.5 g L−1 as the optimal flocculant dosage, resulting in 72.70 % and 89.38 % removal of Ni(II) and Cr(VI), respectively. The flocculation process was determined to follow second-order kinetics, with significant improvements in collision efficiency and particle aggregation at the optimized dosage. Fourier Transform Infrared spectroscopy analysis confirmed chemical interactions leading to flocculation, while zeta potential and particle size distribution studies corroborated the stability and effectiveness of the process. A techno-economic analysis was conducted, estimating the total capital investment required for pilot and industrial-scale implementations, highlighting the feasibility and scalability of the proposed treatment method. A holistic framework for enhancing industrial effluent treatment processes by integrated computational fluid dynamics, kinetic studies, and economic evaluation, is the novelty of this research.

Chitosan enriched with ZnO[sbnd]nanoparticles fabricated using Synadenium glaucescens (Pax) aqueous leaf extract maintains postharvest quality of banana

Applications of edible coatings containing metallic nanoparticles for the preservation of post-harvest fruit quality have emerged as one of the most preferable strategies because of their enhanced antimicrobial properties. In the current study, zinc oxide nanoparticles were synthesized using Synadenium glaucescens leaf extract and added to chitosan for the post-harvest quality preservation of banana. The synthesized zinc oxide nanoparticles (ZnOSydlNPs) were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), elemental dispersive x-ray (EDX) and X-ray diffraction (XRD) techniques. The nanoparticles were found to form large particles due to aggregations of small particles of an average size of 11 ± 4 nm. The coating solution containing a mixture of chitosan and zinc oxide nanoparticles exhibited higher antimicrobial effects against Escherichia coli, Staphylococcus aureus, Puccinia asparagi and Candida albicans compared to chitosan. The inhibition diameters of chitosan and chitosan-ZnOSydlNPs against E. coli were 6 and 15 mm, respectively. Similarly, the average inhibition diameters of chitosan, chitosan-ZnOSydlNPs (0.1%) and chitosan-ZnOSydlNPs (0.3%) against Staphylococcus aureus, Puccinia asparagi and Candida albicans were 10 ± 2, 15 ± 0.5 and 16 ± 3 mm, respectively. The banana coated with chitosan-ZnOSydlNPs solutions exhibited higher titratable acid (maleic) than control and chitosan-coated samples. Additionally, banana coated with chitosan-ZnOSydlNPs films showed lower total soluble solids, weight loss and ripening index compared to chitosan-coated and control samples. The findings from the current study indicated that ZnOSydlNPs incorporated in polymeric materials (chitosan) could serve as a potential preservative of post-harvest qualities for banana and related fruits.

Plasmonic Ag Nanoparticles: Correlating Nanofabrication and Aggregation for SERS Detection of Thiabendazole Pesticide.

The level of aggregation and aggregate morphology of metallic nanoparticles are factors that influence the SERS signal (surface-enhanced Raman scattering), affecting reproducibility and sensitivity. This study presents a systematic evaluation of the colloidal aggregation on the SERS signal by combining transmission electron microscopy and UV-vis extinction spectroscopy. It focuses on the effect of two methods of sample preparation ("external standard method-ESM" and "standard addition method-SAM") on the SERS signal using the fungicide thiabendazole (TBZ) in Ag colloid as a probe molecule. The TBZ critical concentration (concentration for which SERS reaches the maximum intensity) was 6.0 × 10-6 mol/L for ESM and 1.5 × 10-6 mol/L for SAM. Besides, TBZ exhibited a sigmoid-type isotherm for ESM, indicating formation of a TBZ first layer on Ag nanoparticles at lower concentrations (Ag aggregates more compact; size <500 nm) and TBZ multilayers at higher concentrations (Ag aggregates more branched; >2 μm). For SAM, the TBZ first layer formation was also observed at lower concentrations (Ag aggregates more branched; <2 μm). However, at higher concentrations, the Ag colloid degradation/precipitation was observed (Ag aggregates more compact; >2 μm). The Ag aggregation mechanisms align with reaction-limited colloidal aggregation at lower concentrations and diffusion-limited colloidal aggregation at higher concentrations. We believe these results contribute to the SERS research field despite all of the work already done over its 50-year history.

The role of nanomaterials in enhancing adhesion properties between bitumen and aggregate particles

During production and construction stages of asphalt mixtures, rheology of bitumen must be set at certain level. In addition, the adhesion strength between bitumen and the aggregate particles should be high enough so that during the service life of the pavement, asphalt mixture can resist various distresses. There are different methods of controlling rheological properties of bitumen binders and increasing adhesion properties of asphalt mixtures. One of the most effective methods of modifying bitumen binders of asphalt mixtures is using nanomaterials. In this research, two bitumen types of 60/70 and 85/100 penetration grades, three aggregate types (limestone, siliceous, and granite) and four nanomaterials types (nanohydrated lime NHL, nanosilica NSiO2, nanolime NCaCO3, and nanoclay bentonite NClay) were used at 2, 4, and 6% of the weight of bitumen. X-ray diffraction and X-ray fluorescence tests were performed and, microscopic images of thin-sections of aggregates and asphalt mixtures were taken with the aim of evaluating petrographic properties of aggregates and bonding characteristics of the bitumen binders with aggregate particles. Physical and rheological properties of the nano-modified bitumen binders were evaluated, performing dynamic shear rheometer and rotational viscometer tests. Boiling water and pull-off tests were also carried out in order to investigate the coating ability and the adhesion strength that is performed at the aggregate surface in the interface with the bitumen binders. Digital images were analyzed using Digimizer Software. The results indicated that the addition of nanomaterials at certain optimal percentage affected viscosity and improved rheological behavior of the bitumen binders at different temperatures, and increased adhesion properties of the bitumen coating the aggregate particles. Comparing the effects of different aggregates, it resulted that the binder coating the limestone aggregates performed better than the siliceous and the granite aggregates. The adhesion and the rheological properties of the 60/70 pen bitumen that was modified with nanomaterials were better than those of the 85/100 pen bitumen. Nano-modified binders at 4% NHL, or 2% NSiO2, or 4% NCaCO3, or 4% NClay exhibited the best behavior. Among these, the nano-modified binders containing 4% NHL resulted in better performance. Finally, the correlation between the adhesion and rheological behavior was suitable for nano-modified binders in order to improve the asphalt mixes' performance in operation and construction stages.

Investigating the radiative properties of large dust aggregate particles via the Monte Carlo ray tracing method

Understanding the radiative properties of particles is essential for interpreting and analyzing atmospheric remote sensing, target detection, combustion diagnostics, etc. At present, there is a relative lack of studies and understanding of the radiative properties of large aggregate particles. In this work, we comprehensively investigate the radiative properties of large dust aggregate particles via the developed Monte Carlo ray tracing method. Large dust aggregate models with monodisperse and polydisperse monomers are constructed, respectively. The effects of various factors on the radiative properties of large dust aggregate particles are analyzed. We find that the larger geometric standard deviation and the greater number of monomers lead to slightly larger backscattering and an increase of the overall radiative energy distribution on the receiving surface. With increasing the size parameter, the scattering phase function becomes smoother and the difference between the scattering phase function of spheres and aggregates diminishes. The absorptivity is proportional to the size parameter and inversely proportional to the number of monomers. At a size parameter of 100, the absorptivity and the peak of the radiative energy distribution of monodisperse monomer aggregates are higher than those of polydisperse monomer aggregates, and gradually converge with the increase of particle size parameter. Overall, this work helps to enhance the knowledge of the radiative properties of large aggregate particles.

Prolonged Skin Retention of Luliconazole from SLNs Based Topical Gel Formulation Contributing to Ameliorated Antifungal Activity.

The development of effective therapy is necessary because the patients have to contend with long-termtherapy as skin fungal infections usually relapse and are hardly treated. Despite being a potent antifungal agent, luliconazole (LCZ) has certainshortcomings such as limited skin penetration, low solubility in aqueous medium, and poor skin retention. Solid Lipid Nanoparticles (SLNs) were developed using biodegradable lipids by solvent injection method and were embodied into the gel base for topical administration. After in-vitro characterizations of the formulations, molecular interactions of the drug with excipients were analyzed using in-silico studies. Ex-vivo release was determined in contrast to the pure LCZ and the commercial formulation followed by in-vivo skin localization, skin irritation index, and antifungal activity. The prepared SLNs have an average particle size of 290.7nm with no aggregation of particles and homogenous gels containing SLNs with ideal rheology and smooth texture properties were successfully prepared. The ex-vivo LCZ release from the SLN gel was lower than the commercial formulation whereas its skin deposition and skin retention were higher as accessed by CLSM studies. The drug reaching the systemic circulation and the skin irritation potential were found to be negligible. Thesolubility and drug retention in the skin were both enhanced by the development of SLNs as a carrier. Thus, SLNs offer significant advantages by delivering long lasting concentrations of LCZ at the site of infection for a complete cure of the fungal load together with skin localization of the topical antifungal drug.

Photo-Induced liquid-based slippery materials for highly efficient particle aggregation

The drying of droplets containing non-volatile solutes presents significant potential for sensing applications, including disease diagnosis, and the detection of harmful substances. Colloidal droplets form various patterns on surfaces after evaporation, and controlling the deposited patterns to achieve the desired characteristics is crucial in sensing applications. In this study, we propose a novel approach that employs a slippery organogel (SOG) surface that can be rapidly fabricated based on a photo-induced process to enhance the sensitivity and reproducibility during detection. The SOG forms a thin lubricating layer on the surface, which reduces the pinning of the three-phase contact line, causing the aggregation of particles within a confined area. To analyze the aggregation characteristics of colloidal droplets on the SOG, we compared the deposited particles after evaporating four types of colloidal droplets on the following different surfaces: hydrophilic, hydrophobic, organogel (OG), and SOG. The SOG surface demonstrated a superior particle aggregation capability across various colloidal droplets, which is crucial for the future development of high-sensitivity detection technologies.

Particle aggregation and the grinding limit in high energy ball mill

Dust aggregates — clusters of individual particles — are formed during mechanochemical processing of brown coal in a planetary ball mill. The aggregate structure can be identified by comparing the average sizes of aggregates and individual particles. We showed that dust aggregates are generally arranged in a regular way: the number of individual particles located along the aggregate coincides with the number of particles located across the aggregate. Power of power-law distribution of the monomers per aggregate revealed that individual particles stick together in extremely dense clusters. The average number of monomers per claster is ~104. In addition, it turned out that the dependence of the monomer's “stickiness” on applied energy dose has a kink simultaneously with other characteristics of the mechanochemical process (the monomer size and the chemical reaction depth). Speaking using mechanochemistry terms, it corresponds to transition from the brittle grinding mode to the plastic deformation mode after reaching the grinding limit.

Formulation and Evaluation of Glipizide-loaded Mucoadhesive Microparticle Using Salvia hispanica Seeds Mucilage as Co-polymer

Aims: Chia seed (Salvia hispanica L.) gum is a mucoadhesive, biodegradable polymer with sustained release properties. Objective: The objective of this study was to compare different formulations of glipizide-loaded microparticles using chia seed mucilage and sodium alginate, focusing on sustained release and mucoadhesive properties. Background: The present study aimed to comparatively evaluate various eco-friendly formulations of glipizide-loaded microparticles prepared using chia seed mucilage and sodium alginate. Materials and Methods: Gum was extracted from chia seeds and lyophilized, and preformulation studies were performed according to established protocols. Microparticles were formulated using the ionic gelation method, with sodium alginate as a copolymer and zinc chloride as a cross-linking agent. The prepared microparticles were evaluated using scanning electron microscopy (SEM) for size and particle aggregation, and Fourier Transform infrared spectroscopy (FTIR) for drug-polymer interaction, entrapment efficiency, swelling index, and in vitro drug release. Results: The % yield of chia seed mucilage was 27.35%. The pH of the mucilaginous suspension was 4.67 ± 0.50. The moisture content value was 14.56 % ± 0.50. The values of Carr's index and Hausner's ratio were 22.58 ± 1.89 and 1.38 ± 0.05, respectively. FTIR spectra showed no interaction between pure glipizide and chia seed mucilage, confirming no possible change in glipizide's pharmacology. SEM studies have confirmed the shape of the microparticles to be spherical, with average sizes ranging from 1235.18 ± 8.7 to 1423.25 ± 9.5 µm, and the drug entrapment efficiency ranged from 64.25 ± 2.52 to 81.82 ± 7.56%. The release of glipizide from the microparticles was sustained, and the Higuchi and Korsmeyer-Peppas models were found to be the best-fit kinetic models. Conclusion: The promising copolymer blend of chia seed mucilage and sodium alginate was used for the development of sustained-release dosage forms. A copolymer blend with a ratio of 1:1 produced glipizide-loaded microparticles with sustained release profiles and good mucoadhesive ability, along with a high percentage of drug entrapment efficiency.

Direct CO2 mineralization and evolution behavior of fine CaCO3 from ammonia-induced phosphogypsum mineral carbonation

The mineral carbonation of phosphogypsum (PG) presents considerable potential for simultaneous CO2 sequestration and high-value utilization of PG. Variations in carbon footprints are crucial for enhancing carbonation efficiency and regulating product formation. This study explores the mechanism of direct CO2 mineralization by PG and the evolution of the resulting product. The results demonstrate that 97.14% of the CaSO4·2H2O in PG can be converted to calcite under conditions including a nitrogen–sulfur molar ratio of 3, a liquid–solid ratio of 6, a CO2 flowrate of 0.4 L/min, and a stirring rate of 800 rpm for 60 min. The carbonation rate exhibits significant variation with time, occurring in three distinct stages. Initially, CO2 reacts with ammonia to form (NH4)2CO3, releasing greater heat. This heat inhibits the dissolution of Ca2+ from PG, resulting in a lower carbonation efficiency, as only a limited amount of Ca2+ reacts with CO32– to preferentially form amorphous CaCO3 (ACC). As CO32– formation reaches equilibrium, the endothermic properties of the reaction between CaSO4 and (NH4)2CO3 promote the dissolution of Ca2+ from PG, further accelerating CO2 mineralization and resulting in significant increases in carbonation efficiency and ACC production. The ACC is rapidly transformed into calcite via a “dissolution-reprecipitation” mechanism. However, the carbonation rate of PG decreases as saturation is approached, mainly resulting from the aggregation of fine CaCO3 particles on the PG surface. As a result, the direct CO2 sequestration process by PG follows a carbon footprint sequence of “CO2–(NH4)2CO3–ACC–calcite”. This study provides significant insights into the mechanisms of direct CO2 mineralization and product evolution and offers a basis for optimizing carbonation processes enhancement and regulating product phases.

Process-induced protein aggregates influenced pea globulins’ structure formation upon heating

Pea protein ingredients play key role in formulations of plant-based foods. However, functional properties of pea ingredients are inconsistent depending on extraction process. Protein aggregation occurs simultaneously during protein extraction, thus examining the protein aggregated states as induced by processing is essential for better process design. This study investigated the influence of process-induced protein aggregated states on structure formation upon heating of pea protein ingredients. Combining rheological, spectroscopic, and microscopic techniques, the mechanisms underlining heat-induced structure formation have been unveiled from microscopic to macroscopic scales. The salt-extracted isolate (PPI*) where protein aggregation was minimized, developed mesh-like structure through intermolecular protein-protein interaction upon gelling similar to commercial protein concentrate (PPC). In turn, commercial isolate (PPI) as appeared as microscopic particles, formed gel through accumulation of protein particles with no structure development. The aggregated states of PPI* and PPI seemed to dictate vicilin and legumin purification by means of anion exchange chromatography. Purification process promoted intermolecular protein aggregate structures. However, these purified fractions regardless of parent isolates showed similar structure development as PPC and PPI* during gelling. Monitoring protein aggregation during extraction process can be a key to limit functional property variation in pea protein ingredients.

Performance analysis and accuracy of numerical methods for solving simultaneous nonlinear particulate processes with multi-dimensional extension

The simultaneous population balance equation (PBE) incorporating diverse particulate process aggregation, breakage, growth, nucleation and source is a long-standing and significant problem in the field of particulate sciences such as pharmaceutical industry, chemical engineering, astrophysics and biology. Owing to the complex and nonlinear nature of the governing equations, finding an analytical solution is quite challenging for empirical kernels. In this work, simultaneous PBEs are solved using sectional and semi-analytical techniques. The performance, adaptability and accuracy of both methods for solving simultaneous PBEs are discussed in detail. The iterative semi-analytical scheme for solving simultaneous PBE is introduced, and a detailed convergence analysis using Banach fixed point theory is also presented. Both the schemes are further extended to solve simultaneous PBE in multi-dimensions. Performance analysis is also executed for multi-dimensional models. This article is a comprehensive study on various solution techniques for solving simultaneous PBEs. Therefore, it will be beneficial for the researchers working in industry and computational fluid dynamics modelling to identify the best method according to their requirements.

Pebax/NC-PCL membrane containing well-distributed PCL grafted biodegradable nano-chitosan particles for CO2 separation

This study presents a novel method to improve carbon dioxide (CO2) separation performance in mixed-matrix membranes (MMMs) by incorporating polycaprolactone (PCL) grafted biodegradable nano-chitosan (NC) particles into a Pebax membrane matrix. Adding NC particles strengthens the interaction between the polymer mixed-matrix and CO2 molecules through functional groups on the NC particles via a facilitated transport mechanism. Grafting NC particles with PCL prevents the aggregation of particles by introducing steric repulsive forces between them, ensuring a well-dispersion of NC particles within the polymer matrix. Gas separation tests revealed that the membrane containing NC-PCL particles at a 1:1 ratio achieved a superior CO2 permeability of 99.8 Barrer and a CO2/N2 selectivity of 234.9. This performance marks a moderate increment of 20.7% in CO2 permeability and a substantial 413% increase in CO2/N2 selectivity compared to the neat Pebax membrane. Overall, the membranes managed to exceed the Robeson upper bound line by enhancing both CO2 permeability and CO2/N2 selectivity simultaneously, thereby better balancing the trade-off effect between selectivity and permeability.

Characterization of Discharge Associated With Fiber Particle Aggregation in Oil Streams Under High-Voltage Direct Current Field

Characterization of Discharge Associated With Fiber Particle Aggregation in Oil Streams Under High-Voltage Direct Current Field

Encapsulation of Cu/Fe3O4 With RT‐COF‐1 for Improved Stability in Water–Gas Shift Reaction

AbstractStability is crucial for the practical application of heterogeneous catalysts, particularly in industrial processes, where catalyst deactivation often occurs due to factors such as sintering, poisoning, and active site degradation. This study investigates the effectiveness of utilizing covalent organic frameworks (COFs), specifically RT‐COF‐1, to enhance the stability of Cu/Fe3O4 catalysts in harsh water–gas shift (WGS) reaction environments. By encapsulating Cu/Fe3O4 with trace RT‐COF‐1, we aimed to preserve the structural integrity and active interfaces between the metal components during catalytic reactions. Characterization techniques, including X‐ray photoelectron spectroscopy, nitrogen sorption, and high‐angle annular dark‐field scanning transmission electron microscopy, confirmed the successful COF coating and its role in preventing particle aggregation and maintaining active site structures over extended catalytic tests. Notably, Cu/Fe3O4@COF demonstrated significantly enhanced stability during a continuous 24‐h WGS test compared to uncoated catalysts, which exhibited rapid deactivation. Mechanistic insights indicated that COF coating reduced the number of active sites while preserving the overall morphology of the catalyst, contributing to its robust performance. Ultimately, this work highlights the potential of COF encapsulation as an effective strategy for enhancing the durability and efficacy of multifunctional catalysts in challenging reaction conditions.

The impact of particle size and concentration on the characteristics of solid–fluid two-phase flow in vertical pipe under pulsating flow

Vertical pipe hydraulic conveying is currently considered the most promising method for deep-sea mining. The conveying velocity at the inlet of the vertical pipe is often close to a pulsating form due to the influence of the flexible pipe and the marine environment. This study employs a combined Computational Fluid Dynamics (CFD) and Discrete Element Method (DEM) approach to investigate the impact of various particle sizes and concentrations on the flow behavior of solid–fluid two-phase flow in a vertical pipe under pulsating flow. The study reveals that fluid velocities exhibit periodic fluctuations within the vertical pipe under pulsating inlet flow. Moreover, the periodic phenomenon of local increases in particle velocity and concentration becomes more pronounced as particle size and concentration increase. Larger particle sizes increase particle inertia, reducing the ability to follow the fluid and leading to more localized particle aggregation. Therefore, the flow pattern within the vertical pipe transitions from homogeneous flow to plug flow as particle size increases. Variations in fluid–solid interaction forces and particle collision forces are explored to explain this phenomenon. When the particle size exceeds a critical threshold, the collision force surpasses the fluid–solid interaction force, leading to the transition.

Mussel-inspired co-deposition of catechol-amine and graphene oxide (GO) modified anion exchange membranes (AEMs) for antifouling

Mussel-inspired co-deposition has many applications in surface modification of polymer membranes. Organic fouling of ion exchange membranes is one of the common issues that hinder electrodialysis treatment of industrial wastewater. In this work, anion exchange membranes were surface-modified by the mussel-inspired co-deposition of catechol-amine and graphene oxide (GO) nanosheets. Results showed that co-deposition with catechol (CA) and m-phenylenediamine (MPD) as reactant monomers rapidly generated modifying layer on the AEM surface. And the addition of GO into co-deposition helped improve the homogeneity and reduce polymer particle aggregation. The synergistic effect of catechol-amine and GO nanosheets was beneficial to form uniform modifying layer with improved hydrophilicity and negative charge density of membrane surface. In eletrodialysis experiments with sodium dodecyl benzene sulfonate (SDBS) as model foulants, GO-CA-MPD-3h modified AEM maintained high desalination rate close to that without folants, indicating good modifying antifouling performance. Mussel-inspired co-deposition of catecholamines and functional materials give new insights into membrane modificatin through a feasible and cost-effective method

Investigation of static mechanical characteristics and numerical simulation of fractal gangue cemented backfill materials

This study investigated the static mechanical responses of gangue cemented backfill materials (GCBM) with aggregate particle size distribution (APSD) satisfied fractal grading theory. The recycling of gangue in GCBM alleviates gangue accumulation pollution and improves mining production efficiency. Macroscopically, uniaxial compression experiments regarding various loading strain rates (ε̇) on gangue cemented backfill specimens (GCBS) were conducted. Acoustic emission monitoring and digital image correlation technique were employed to reveal crack activities and strain field evolution in real time. Microscopically, scanning electron microscopy and numerical specimens considering APSD were utilized to analyze the microstructure and damage process. The deterioration mechanisms and quantified number of cracks were explored at the micro level. The conclusions are as follows: (1) The axial stress (σ) of GCBM increased with fractal dimension (D) of APSD and ε̇. For the same σ, cumulative AE counts decreased with increasing ε̇ and D. (2) The main failure mode of the GCBS under static loading was tensile failure, exhibiting tensile cracks initiating at the bonding–aggregate interface. (3) The increase in the proportion of fine aggregate contributed to the optimization of the microstructures of the GCBS (4) An increased proportion of fine aggregate in the GCBS improved the synergistic load-bearing capacity between the cementing and aggregate mediums, leading to an enhancement in the σ.

Optimizing multi-recycled concrete for sustainability: Aggregate gradation, surface treatment methods and life cycle impact assessment

Utilizing demolished waste as recycled aggregate in concrete is a sustainable practice, however, the concerns over inconsistent quality, such as hardened mortar content and water absorption, hinder global adoption. This study evaluates the physical, microstructural properties and gives insights into Life Cycle Impact Assessment of three generations of recycled aggregate concrete. The microstructure analysis yielded compelling insights into the role of Interfacial Transition Zone (ITZ) of reclaimed aggregate on concrete. The study demonstrated that the effective proportioning of coarse and fine aggregate particles using Compressible Packing Model (CPM), resulted in a reduction of dosage of cement in concrete volume, reducing the Binder Intensity Index (BII), and an improvement in the strength and stability of concrete. Additionally, surface treatment methods, including water soaking, mechanical, and thermo-mechanical treatments, were explored. The thermo-mechanical treatment method proved to be effective in reducing 40–60 % of residual mortar. Life cycle assessment of treated and untreated recycled aggregate concrete was performed, considering five environmental impact indicators viz., Global Warming Potential (GWP), Acidification Potential (AP), Eutrophication Potential (EP), Abiotic Depletion Potential (ADP) and Human Toxicity (HT). These indicators illustrated that CPM method of mix proportioning accompanied with thermo-mechanical treatment of repurposed aggregate resulted in lowering environmental impact. These findings underscore the potential for sustainable concrete construction through the use of treated recycled aggregate, offering valuable insights into methods for augmenting its quality and performance.