Optimum Content Research Articles

Low-cost optimization of industrial textile landfill sludge re-dewatering using ferrous sulfate and blast furnace slag

This study was based on an industrial sludge landfill with a scale of 1 million cubic meters, which had been filled for more than 10 years. It focused on the secondary dewatering of industrial textile landfill sludge (LS) with a total organic carbon (TOC) content greater than 50% and a volatile suspended solids to suspended solids (VSS/SS) ratio of 0.59. A response surface methodology (RSM) model was established using the coagulant ferrous sulfate (FeSO4) and conditioning agents such as hydrated magnesium oxide (MgO), blast furnace slag (BFS), and calcium oxide (CaO). By solving the RSM equations for the respective indicators, the optimal dosages of FeSO4, MgO, and BFS were determined to be 90 mg/g of dry sludge (DS), and for CaO 174.85 mg/g DS. Further examinations of the dewatering performance, apparent properties, extracellular polymeric substances (EPS) components, rheological characteristics, moisture distribution, and pollutant content variation led to the development of a green waste-based dewatering agent composed of FeSO4 and BFS. In small-scale diaphragm plate and frame filter press tests, the optimal water content (WC) was 69.11%. In the final production-scale experiments, it was 65.72%, with the actual application cost being only 13.07 $/ton DS. Additionally, when FeSO4 and BFS were used together, the combined action of Fe and Si could significantly reduce the biotoxicity of heavy metals (HMs), cut down 75.2% of the LS's TOC, and effectively reduced the leaching of organic substances from the leachate, which was beneficial for subsequent disposal. In conclusion, the combined use of FeSO4 and BFS for the secondary dewatering of industrial textile LS was economically efficient, effective in dewatering, and had significant harm reduction effects, making it a worthwhile for waste treatment.

Optimization of mechanical properties and water resistance of sawdust-magnesium oxychloride cement composites based on orthogonal tests

Sawdust-magnesium oxychloride cement composites (SMOCC) are new low-carbon and environmentally friendly building materials. Its development not only reduces carbon dioxide emissions, but the use of sawdust can improve wood utilization rates and play important roles in protecting the environment. Nonetheless, SMOCC's performance is affected by various factors, and its overall sustainability remains to be comprehensively evaluated, which limits widespread application. For this reason, the effects of different factors (including MgO/MgCl2 molar ratio, MgCl2 solution concentration, and content of NaH2PO4) on the performance of SMOCC were initially obtained through single-factor experimental analysis. Next, multi-factor experiments were performed using the Taguchi orthogonal experimental method. The effects of different multifactor on the mechanical properties and water resistance of SMOCC were systematically investigated using response surface methodology, and relevant polynomial regression models were established and verified. Subsequently, the composition of the hydration products and the SMOCC's micromorphology were investigated using X-ray diffraction and scanning electron microscopy. The results indicated that the strength and water resistance of the SMOCC were affected by single factors as well as the interactions of multi-factor. The optimum contents of MgO/MgCl2 molar ratio, MgCl2 solution concentration, and content of NaH2PO4 were 11, 25 %, and 0.5 %, respectively, under which the SMOCC exhibited excellent strengths and water resistance. In addition, the proposed quadratic polynomial models accurately predicted the properties of SMOCC and reflected the effects of multi-factor interaction on the mechanical strength and water resistance of SMOCC.

Alternative concrete aggregates - Review of physical and mechanical properties and successful applications

Concrete is one of the most widely used construction materials, yet its production is associated with significant environmental impacts. One approach to mitigate such impacts is to use alternative aggregates. However, the limited knowledge about the availability and benefits of these unconventional materials, as well as concerns about their quality and performance, have hindered their adoption. This paper aims to analyse the potential benefits and limitations of using alternative aggregates in concrete by reviewing examples from three primary sources: construction and demolition waste (CDW), end-of-life materials (i.e., tyre rubber, glass, and plastic), and forest and agricultural waste (i.e., rice husk, wood, and hemp). First, the main sources and treatment needs are analysed. Then, a comprehensive macro analysis is provided on the physical and mechanical properties of concrete materials, discussing the results in terms of the aggregate nature and substitution ranges. The collected experimental data are also compared with estimations based on different models from two published codes, suggesting that more specific design-oriented models need to be developed to relate concrete's physical and mechanical properties using different waste-type aggregate replacements. Selected data analyses are presented to help the readers obtain the optimum content for specific structural or non-structural applications. Examples of successful application of alternative aggregates in construction projects and products are also provided and discussed.

ПРИМЕНЕНИЕ ГРЕЧИХИ В РЕЦЕПТУРЕ ХЛЕБА

The purpose of research is to study the chemical composition of buckwheat varieties bred in the Republic of Bashkortostan and the influence of buckwheat flour on bread quality indicators. Objectives: to study the chemical composition of buckwheat varieties in the Republic of Bashkortostan, to identify varieties that have the highest nutritional value; to set parameters for soaking and germination of buckwheat grains; to carry out the selection of technological parameters for baking bread from composite flour (first grade wheat flour and buckwheat flour); to explore the quality indicators of bread. The study was carried out at the Department of Technology of Public Nutrition and Processing of Plant Raw Materials of the Fe¬deral State Budgetary Educational Institution of Higher Education "Bashkir State Agrarian University" and in the analytical laboratory of the Bashkir Research Institute of Agriculture UFITs RAS. The results of the chemical composition of buckwheat varieties Agidel, Zemlyachka, Ilishevskaya, Inzerskaya selection of the Republic of Bashkortostan for the 2019–2021 harvest, as well as the use of flour from sprouted buckwheat grains on the quality indicators of wheat bread are presented. Based on nutritional value, the buckwheat variety Inzerskaya was selected for the production of buckwheat flour for inclusion in the bread recipe. The physicochemical parameters of flour from sprouted buckwheat grain, as well as the content of flavonoids in buckwheat flour, were determined. Optimal parameters for germination of buckwheat grain have been identified, which prove an improvement in the physico-chemical parameters and antioxidant activity of the resulting flour, which confirms the need to use this flour in the bread recipe. The optimal content of flour from sprouted buckwheat grain as part of a composite mixture with first-grade wheat flour was identified, which was 10%, which improves the organoleptic and physicochemical properties of bread.

The Rheology of Polyether Ether Ketone Concentrated Suspensions for Powder Molding and 3D Printing.

The main goal of the work was to use rheological methods for assessing the properties of a composition based on polyether ether ketone (PEEK) to determine the concentration limits of the polymer in the composition and select the optimal content of this composition for powder molding. The rheological properties of highly filled suspensions based on PEEK and paraffin, as well as in paraffin-polyethylene mixtures at various component ratios, were studied. These materials are designed for powder injection molding and 3D printing. Suspensions with a PEEK powder content above 50% are not capable of flow and, with increasing pressure, slide along the surface of the channel. For compositions with a higher content (60 and 70 vol.%) PEEK, independence of the storage modulus from frequency is observed, which is typical for solids and confirms the assignment of such suspensions to elastic-plastic media. The introduction of high-density polyethylene into the composition helps improve the technological properties of suspensions, expanding the range of fluidity, although it leads to an increase in viscosity. In suspensions with a mixed composition of the liquid phase, with increasing temperature, a decrease in the storage modulus is observed at 120 °C and, on the contrary, an increase at 180 °C. The latter may be a consequence of the evaporation of paraffin and the softening of PEEK due to the approach to the glass transition temperature of the polymer. Suspensions with 40% PEEK content have an optimal set of rheological properties for powder injection molding. A 3D printing filament was also obtained from a composition with 40% PEEK, which had good technological properties for FDM 3D printing. Products of satisfactory quality from suspensions with 50% PEEK can be produced by powder injection molding, but not by 3D printing. The selected compositions were used to obtain real PEEK products for practical applications.

Implementing Internet of Things for Real-Time Monitoring and Regulation of Off-Season Grafting and Post-Harvest Storage in Citrus Cultivation: A Case Study from the Hilly Regions of Nepal

Citrus fruit cultivation, especially mandarin oranges, is crucial to the economy of Nepal’s hilly regions due to their ideal geoclimatic conditions. Despite its economic importance, the sector faces several challenges, such as inadequate grafting techniques, low-quality saplings, and ineffective post-harvest storage. This paper explores these issues and proposes innovative solutions through the use of Internet of Things (IoT) technology. To address these challenges, we identified key areas for improvement. First, we focused on extending grafting practices during the off-season to ensure a higher success rate and better-quality saplings. Second, we examined different post-harvest storage methods to determine their effectiveness in terms of shelf life, decay loss, and quality of fruit. In addition to exploring post-harvest strategies, this paper provides preharvest recommendations for farmers, emphasizing methods to enhance fruit quality and longevity through effective pre-storage practices. Our IoT-based approach introduces off-season grafting in polyhouses and advanced monitoring for post-harvest storage. The results are promising: We achieved grafting success rates of 91% for acid lime and 92% for local mandarin orange varieties. Additionally, our research compared different post-harvest storage methods for mandarin oranges, including room, cellar, and cold chamber. We assessed these methods based on shelf life, physiological weight loss, and the total soluble solids (TSS) to titratable acidity (TA) ratio. The cold chamber proved to be the most effective method, offering superior conditions for storing mandarin oranges. The IoT-based monitoring system played a crucial role in maintaining optimal temperature, humidity, and gas content within the cold chamber, resulting in reduced post-harvest losses and extended shelf life. These findings highlight the transformative potential of IoT technology in mandarin orange cultivation and post-harvest storage.

Regularities in mercury cation sorption by a lignin-based sulfur-containing sorbent

The unfavorable environmental situation in the town of Usolye-Sibirskoye (Irkutsk Oblast, Russia) determines the relevance of investigating and applying a new lignin-based sulfur-containing sorbent for purification of groundwater from mercury compounds. The sorbent was synthesized on the basis of waste products of epichlorohydrin (1,2,3-trichloropropane), sulfur, and lignin. The IR spectrum of the sorbent under study showed the presence of an S–S bond in the region of 445–465 cm-1. Intensive absorption of Hg2+ ions in the regions of 2800–2950 cm-1 (valence vibrations of C–H bonds in CH and CH2 groups) and 1460 cm-1 (deformation vibrations in CH2 group) was observed. Absorption of Hg2+ ions by lignin fragments was accompanied by a change in the vibration band of S–S bonds, which splits into two bands of higher frequencies than the νS–S band in the original sorbent. The optimum sulfur content, which ensures the maximum sorption activity of the sorbent, was found to be 53.25%. The mercury sorption isotherms at 20 and 60 °C are described by parabolic dependencies with determination coefficients of 98.9 and 98.6 %, respectively. The kinetic curve at 20 °C and 40 °C is approximated by a hyperbola and a cubic polynomial with determination coefficients of 97.9 and 96.2 %, respectively. The reaction order (first order at 20 °C and second order at 40 °C) and the reaction rate constant (0.0876 min-1 at 20 °C and 0.00014 min-1 at 40 °C) were determined. At 20 °C, the sorption rate of Hg2+ was established to be significantly higher and the sorption time to be faster than those at 40 °C. Therefore, mercury sorption by the proposed sorbent should be carried out at 20 °C in order to reduce energy consumption.

Enhancement of porous asphalt mixtures modified with various fibers and ethylene–vinyl acetate polymer

Porous asphalt mixture is conventional hot mix asphalt (HMA) with substantially decreased fines, which produces an open-graded mixture that enables the water to flow through an interconnected void space. Porous asphalt is a permeable system that has a lot of benefits. However, because of its open structure, the durability of this mixture decreases, and both its stability and resilient modulus are much lower compared to the dense conventional asphalt mixtures. Also, the high void percentage may lead to an increase in the draindown proportion. Fibers (cellulose or mineral) and polymer-modified binders are recommended for porous asphalt mixtures, especially in hot and moderate climates. The objective of this study is to improve the porous asphalt mixture's performance by using ethylene–vinyl acetate (EVA) polymer-modified bitumen. Two types of fibers (cellulose fibers and glass wool fibers) were used, separately to determine the control mixture. Four different proportions of EVA polymer were added to the bitumen (1%, 2%, 3%, and 4%) and Scanning Electron Microscopy (SEM) was used for better investigating of the bitumen microstructure, then The Marshall mix design was used to determine the optimum EVA content (OEC) for the porous asphalt mixture. Several performance tests were conducted to investigate the characteristics of the porous asphalt mixture, such as the infiltration rate, binder draindown, the wheel track and the cantabro abrasion tests. The findings of the study conclude that the addition of EVA polymer to the porous asphalt mixtures enhances the performance as it increases stability by 20.8% and the infiltration rate by 20.6%. It decreases binder draindown proportion by 33.3%, cantabro abrasion loss by 25.1% and the rut depth at 5,000 cycles and 10,000 cycles by 29.8% and 19.7%, respectively.

Enhanced performance of graphene-incorporated electrodes for solid-state lithium-sulfur batteries through facilitated ionic diffusion pathways

Significant progress has been achieved in advancing all-solid-state lithium-sulfur batteries through the development of sulfide solid electrolytes. Nonetheless, a challenge lies in creating a percolated ion–electron conduction path with intimate contact between charge carriers throughout the cathode which is crucial for enhancing overall efficiency and addressing issues related to slow kinetics and impedance during battery operation. This study introduces a framework elucidating how the integration of graphene enhances electrode performance by refining ionic diffusion pathways. An idealized ionic diffusion pathway characterized by a continuous ionic network, facilitating minimum diffusion distances, is proposed. Through a parametric study substituting portions of ionic and electronic conductive agents with graphene, the impact on total ionic and electronic conductivity of positive electrodes was comprehended. The findings underscore the critical role of optimum graphene content, which fills the gaps between ionic conductive materials and creates the shortest diffusion paths for ions and electrons. While incorporating graphene into cathode electrodes is not novel, it is noteworthy that graphene, as a mixed ion–electron conductive material, significantly enhances ion mobility due to its 2D structure, addressing a crucial aspect of cathode performance. Upon achieving optimum composite formulation, empirical findings demonstrate substantial performance improvement, including a 17.7% increase in initial capacity and a remarkable 21% enhancement in capacity retention compared to electrodes without graphene.

Comparative study on agronomic and physiological performance of gerbera (Gerbera jamesonii) under drip and aggregate wick systems

Aggregate wick system (AWS) or capillary action technique is a kind of sub-surface irrigation system gaining popularity owing to its profound advantages of improved water and nutrient use efficiency resulting in superior plant growth and development. However, its effect on growth and physiology of gerbera crop has not been studied yet. Therefore, an experiment was conducted during 2021–23 at ICAR-Indian Institute of Horticultural Research, Bengaluru, Karnataka to assess the effect of aggregate wick system on growth, flowering, vase life, yield and physiological aspects of gerbera var. Arka Nesara as compared to the conventional drip systems. It was apparent from the results that higher overall factor productivity in terms of number of leaves/plant (12.92), earlier first flower harvest (149.80 days) and copious flower production (38.58/plant/year) with enhanced chlorophyll content and optimal starch content were observed with AWS on the soil bed. However, AWS with pots on the ground resulted in extended vase life (9.20 days) with enhanced leaf area (115.31 cm2), chlorophyll-b, reducing sugars and decreased total and non-reducing sugars in leaves. Therefore, it can be concluded that the improved flower yield and vase life of gerbera in aggregate wick systems might be attributed to the greater chlorophyll production and reducing sugars in the leaves, respectively.

Optimal Limestone Content on Hydration Properties of Ordinary Portland Cement with 5% Ground Granulated Blast-Furnace Slag.

In this study, the effect of limestone content on the mechanical performance and the heat of hydration of ordinary Portland cement (OPC) was investigated. Changes in the phase assemblage were analyzed through XRD and thermodynamic modeling. The purpose of the study was to identify the optimal limestone content in OPC. As a result of the experiment, all samples were found to have equal fluidity. Increasing the limestone content accelerated the hydration of the cement before approximately 13 h and shortened the setting time due to the acceleration of the initial hydration reaction. The compressive strength of the cement mortar showed a dilution effect, with lower compressive strength compared to the reference sample at an early age, but it gradually recovered at a later age. This is because, as shown in the XRD and thermodynamic modeling results, the carboaluminate phases formed due to the chemical effect of limestone contributed to the development of compressive strength. As a result, within the scope of this study, it is believed that maintaining the limestone content in OPC within 10% is optimal to minimize quality degradation.

Effects of Silicone Rubber on Rheological Properties and Aging Characteristics of Asphalt Binder.

Silicone rubber (SR) is a kind of polymer insulation material with excellent performance. With the service life of silicone rubber products reaching the limit, how to dispose of waste silicone rubber is an urgent problem to be solved. In this paper, silicone rubber-modified asphalt binder (SRMA) was prepared by SR and 90# base asphalt binder. The simulated short-term aging and long-term aging tests of SRMA were carried out using the thin film oven aging test (TFOT) and pressure aging vessel test (PAV). The rotary viscosity test and dynamic shear rheological test (DSR) were applied to the rheological properties of SRMA before and after aging. The degradation degree and chemical composition changes of SR were explored by the toluene insoluble matter test, Fourier transform infrared spectroscopy (FTIR), and a Fluorescence microscope (FM). The results demonstrate that SR can significantly affect the aging resistance, fatigue life, and high-temperature stability of SRMA. As the content of SR rose, the elastic component in SRMA increased, leading to a nice performance in stability at high temperatures and fatigue resistance. However, excessive content (14%wt and 16%wt) had a negative influence on the performance of SRMA. So, the optimal content was speculated to be between 12% and 14%. Furthermore, SR and asphalt binder would be aged and degraded together in the aging process, and this phenomenon was more obvious during long-term aging.

Mechanical, Thermal and Performance Evaluation of Hybrid Basalt/Carbon Fibers Reinforced Bio-Based Polyethylene Terephthalate (BioPet) Composites

Looking at the dynamically developing market of engineering materials, there is a need to create newer functional composites. Today's economic situation related to high energy prices and environmental threats force industry to conduct sustainable production. Polymer composites based on plant raw materials are increasingly appearing on global markets, which are light, have good mechanical properties and are also pro-ecological. This work involved the production of hybrid composites based on bio-based poly (ethylene terephthalate) by means of injection molding. Two types of fibers were used simultaneously as the reinforcement phase: basalt fibers and carbon fibers in the amount of 5, 7.5, and 10 wt% of each. The produced materials were subjected to a wide range of mechanical, thermal, and functional characteristics. The experimental data were compared with the theoretical results which were calculated from different micromodels. The studies showed that with the addition of the filler, the mechanical properties of the produced composites increased, but the optimal content was found for composites with 7.5/7.5 wt% addition of fibers, where the improvement was – 81%, 337%, and 25%, for tensile strength, Young's modulus, and impact strength, respectively. In the produced materials, the thermal properties of composites were also improved, where the shrinkage decreased by min. half, and linear coefficient at least 3 times. Sufficient adhesion between the fibers and the matrix was confirmed by SEM images and mechanical micromodels, which confirmed the highest efficiency of reinforcement with a total content of 15 wt% of fibers. To assess the influence of extreme conditions on the behavior of composites, hydrolytic degradation was carried out, which showed that the addition of fibers will not increase water absorption. The mechanical tests of the incubated materials lead to the conclusion that the produced materials could be successfully used in long-term applications because the properties obtained during the tensile test have deteriorated by only max. 5%. The work showed for the first time the modification of bioPET using two types of fibers introduced simultaneously. Hybridization of bioPET with basalt and carbon fibers has shown that it is possible to create very durable composites with a high Young's modulus. The work showed that different fibers are responsible for increasing other parameters – basalt fibers increase strength, while carbon fibers increase Young's modulus. The research may contribute to the popularization of bio-based polymer composites that have high strength for low weight and are a cheaper equivalent than polyamide-based composites.

Study on the Performance Degradation of Membrane Electrode Assembly in Proton Exchange Membrane Fuel Cell Caused by Freeze–Thaw Cycles

ABSTRACTDurability of membrane electrode assembly (MEA) is a serious problem to be overcome in the commercial development of proton exchange membrane fuel cell (PEMFC). The change in volume due to water–ice conversion has an irreversible effect on the MEA, which affects the performance of PEMFC. For investigating the optimal initial water content of MEA that minimizes the impact on PEMFC performance after freeze–thaw (F/T) cycles, this study first measured the high‐frequency resistance to determine the water content of MEA, and then subjected five MEAs with different water contents to 60 F/T cycles at −20°C to 30°C. The fuel cell output performance of five MEAs was found to be inconsistently degraded by polarization curve tests, with the cells of the two MEAs with the lowest and highest water contents exhibiting the worst output performance. Electrochemical impedance spectroscopy curves proved that the difference in resistance change after F/T cycles is one reason why the cell output performance is degraded differently. Finally, the degradation of cell performance was further explained by cyclic voltammetry. These results indicate that MEA has the best output performance for F/T cycles at an initial water content of 3.0.

Effect of alkaline rice straw fibers content and curing ages on static mechanical properties of cemented lithium mica tailings backfill

Alkaline rice straw fibers (ARSF), as a widely available and recyclable plant fiber source, can provide new insights for improving the mechanical properties of backfill and the treatment of agricultural waste resources research. Different amounts of ARSF were prepared to enhance the cemented lithium mica tailings backfill (CLMTB), and uniaxial compression strength (UCS) tests and Brazilian splitting tensile strength tests were conducted to study the influence of ARSF on the static mechanical properties of CLMTB samples. Firstly, the flowability of mortars with different ARSF content was tested, the results showed that the flowability decreased by a maximum of 5.4 %, which met the construction requirements of cement mortar in the construction process. The UCS showed an increasing trend and then reduced with the increased ARSF content, with 0.15 % being the optimal content, showing a maximum increase of 14.2 %. Under Brazilian splitting loading conditions, the tensile strength gradually increased with the increased ARSF content, with 0.60 % being the optimal content. The UCS of the CLMTB samples showed exponential growth with increased curing age. Additionally, there was a linear functional relationship between the curing age and the tensile strength of the CLMTB samples. The experimental results indicate that the ARSF improved the toughness and changed the failure mode of the CLMTB samples. In the meantime, it increased the residual bearing capacity and the peak tensile strain of the CLMTB samples.

Effect of magnetite and graphene nanoplatelets on mechanical properties and thermal stability of thermoplastic elastomer

ABSTRACT Functional nanocomposites have garnered considerable attention due to their ability to exhibit multifunctional properties and achieve exceptional performance. This current paper aims to analyze the individual and combined effects of magnetite (Fe3O4) and Graphene nanoplatelets (GNPs) on the mechanical, thermal, and morphological properties of a blend consisting Thermoplastic elastomer (TPE) which is made up of Natural rubber (NR) and Polyaniline (PANi). Both nanocomposites were fabricated via melt blending method using an internal mixer, followed by compression via hot/cold pressing. The incorporation of Fe3O4 was observed to consistently enhance the flexural and impact properties compared to GNP-based nanocomposites. Notably, the nanocomposites filled with 6 wt% Fe3O4 displayed the highest flexural strength (2.1 MPa), flexural modulus (31.1 MPa), and impact strength (4.4 kJ/m2). Results from thermogravimetric analysis and differential scanning calorimetry demonstrated a significant improvement in thermal stability within the nanocomposites. The introduction of nanoparticles led to a delay in decomposition and melting processes. The hybridization of Fe3O4 and GNP proved effective in synergistically enhancing both mechanical performance and thermal stability. At optimum content, scanning electron microscopy micrographs revealed a uniform dispersion of Fe3O4/GNPs within the TPE-PANi blend, accompanied by strong interactions between the components.

Effect of different fibers and fiber contents on the mechanical properties and failure behavior of early age cemented lithium feldspar tailings backfill

The cemented lithium feldspar tailings backfill (CLFTB) samples with different fiber types and contents were prepared and subjected to uniaxial compression tests. The results show that glass fiber had the best improvement effect on UCS. With the increase in fiber content, the UCS showed a trend of first increasing and then decreasing, increasing from 1.138 MPa to 2.017 MPa and then decreasing to 1.907 MPa, with the optimal content being 0.6%. The relationship between the strength gain percentage (SGP) and the peak strain gain coefficient γ with fiber content was analyzed. As the fiber content increased, SGP first increased and then decreased while γ gradually increased. Fibers enhanced the ductility, peak load-bearing capacity, and dissipative energy required for the failure of CLFTB. Furthermore, showing greatly enhanced crack resistance in FRCLFTB, evidenced by an increase in the number of fine cracks and a decrease in fragment detachment.

Performance evaluation of flexible pavement using polyethylene terephthalate (PET)

In this study, the benefits and feasibility of incorporating Polyethylene Terephthalate (PET) into Flexible pavement were evaluated. The study aims to identify new ideas on recycling plastic wastes and thereby improving overall sustainability. The Samples were prepared by adding PET with an increasing concentration level along with optimum asphalt content with a percentage by weight of 3.5%, 4.0%, 4.5%, 5.0%, 5.5% and 6%. Multiple tests were conducted on Natural aggregates including Resistance to degradation of aggregates by Abrasion and Impact, Specific Gravity and Abrasion of coarse aggregates, and Impact Value of Aggregates. Similarly, the tests conducted on asphalt include the specific gravity of semi-solid bituminous material, the ductility of bituminous material, the flash point and softening point of asphalt, and the penetration grade of bituminous material. Rutting potential of the optimum asphalt, Plastic mix Was evaluated by increasing the frequency of load cycles from 0 to 5000 cycles. Furthermore, the effect of asphalt and plastic content on the density, Flow, voids, and stability were also analysed. It was found that the addition of PET resulted in improved stability by more than 50% specifically 52%, while 70% improvement was observed in flow characteristics of Hot Mix Asphalt. However, a slight change in density was observed. The sample also showed a reduction in rut depth by more than 40% of the mix.

Statistical model and fracture behavior of manufactured sand concrete with varying replacement rates and stone powder contents

Manufactured sand (MS) is considered a reliable alternative to natural sand (NS) in concrete due to its wide availability and cost-effectiveness. In this study, the influences of water-cement ratio (0.41, 0.44, 0.47), replacement rate of MS (20 %, 60 %, 100 %) and stone powder content (0 %, 5 %, 10 %) on the mechanical and fracture characteristics of manufactured sand concrete (MSC) were investigated. Statistical model of mechanical properties (compressive strength, flexural strength and flexural toughness) of MSC was constructed based on response surface methodology (RSM). Acoustic emission (AE) technology was used to monitor the MSC fracture process in real time. The correlation between the cumulative AE parameters and the strength of MSC was analyzed. The results showed that the compressive strength, flexural strength and flexural toughness of MSC were negatively correlated with water-cement ratio while positively correlated with the replacement rate of MS. The optimum stone powder content can be determined for MSC to reach its maximum compressive strength. The coupling effects of water-cement ratio and replacement rate of MS was the most significant. This was followed by the coupling effect of water-cement ratio and stone powder content. The coupling effect of stone powder content and replacement rate of MS was the weakest. Moreover, AE analysis on the fracture process of MSC indicated that the AE parameters were more active when the water-cement ratio increased. As the replacement rate of MS increased, the AE parameters were smoother and the specimens were less damaged. The stone powder content played greater role in affecting the AE parameters in compression, while the effect of stone powder content on the four-point bending test was not significant. The cumulative AE parameters were linearly related to the strength of MSC. The cumulative AE parameters can reflect the strength of MSC.

Compaction behaviour of a sandy road base contaminated with microplastics from vehicle tires

AbstractDisintegrated tire particles can easily be transferred into the road bases because of the abrasion of vehicle tires on roads. The fragmented tire particles that have a grain size of smaller than 5 mm can be expressed as microplastics. In order to simulate the tire chip microplastic concentration in a sandy road base and assess the effect of microplastics on the compaction degree of the road base, standard Proctor compaction tests were performed on 0.05%, 0.1%, 0.2%, 0.4%, 1%, 2%, 4% and 8% tire chip microplastics‐amended sandy soil by dry mass. Results showed that maximum dry unit weight (ɣdmax) of the sand increased from 16.04 to 16.99 kN/m3 as the tire chip microplastic concentration increased up to 0.4%. Further increase in the microplastic concentration resulted in a decrease in ɣdmax. Contrarily, optimum water content (wopt) decreased from 15.9 to 12.5% as a result of the tire chip microplastic addition up to a concentration of 0.4%. An additional increase in the microplastic concentration led to an increase in wopt. By considering these results, a concentration of 0.4% tire chip microplastics was found to be the optimum amount that enhanced the degree of compaction. Besides contributing to the stabilization of a sandy road base, tire chip microplastics can also be assessed in terms of environmental protection. These microplastics are forced to be stacked in the sand because of compaction. As a result, they cannot easily be transferred to water resources or agricultural products that may threaten human health and cause environmental contamination.