The use of various sustainable materials and cement is a frequent and successful strategy for stabilizing problematic soil. The current research discusses the potential use of discarded millet husk ash (MHA) and cement (C) as subgrade ingredients to improve the geotechnical qualities of soil (S). MHA and cement are mixed in different proportions and the engineering characteristics of the stabilized soil are studied. The study involves examining fundamental properties, such as specific gravity and Atterberg's limits, as well as engineering properties, including Unconfined Compressive Strength (UCS) and California Bearing Ratio (CBR) tests. These evaluations are conducted to assess the feasibility of using the MHA-cement blend as a construction material. Additionally, FTIR & SEM analysis shows the addition of MHA-cement blend effectively couples with the soil. The test findings demonstrate that adding MHA to soil lead to decreased liquid limits and plasticity indices. The maximum dry density (MDD) was observed to decrease when MHA was mixed with soil. When 8% cement was incorporated to the S:MHA (84.5:7.5) combination, the UCS value rose even higher reaching 1600.1 kPa. The S:MHA:C arrangement in the ratio of 84.5:7.5:8 had the greatest California bearing ratio (CBR). Fourier transform infrared spectroscopy (FTIR) elucidated the various types of bond formations present within the soil composite and deeper peaks depicted greater presence of cementitious compounds after curing period. SEM analysis exhibited a greater density of N-A-S-H and C-A-S-H gels in comparison to natural soil samples. The findings suggest that the MHA-cement blend can effectively enhance the geotechnical properties of problematic soils, while addressing issues of agricultural waste management. This research contributes to several Sustainable Development Goals (SDGs), including SDG 9 (Industry, Innovation, and Infrastructure) by promoting innovative construction materials.

The impact of the field conditions on needle-punched mulches made of cellulose fibres and PLA biopolymer during the 300 days of exposure was investigated. The study observed the degradation of nonwoven mulches during specific exposure periods (30, 90, 180 and 300 days), evaluating their mechanical, morphological and chemical properties. The impact of nonwoven mulches on soil temperature and moisture, consequently on the number of microorganisms developed beneath mulches after 300 days of exposure, were analysed and associated with obtained results complementing comprehension of nonwoven mulch degradation. The findings show that nonwoven mulches made from jute, hemp, viscose and PLA fibres change when exposed to environmental conditions (soil, sunlight, rainfall, snow, ice accumulation, air and soil temperatures, wind). The changes include alterations in colour, structure shifts and modifications in properties. The results highlight the degradation pathways of cellulose and PLA mulches, revealing that cellulose-based fibres degrade through the removal of amorphous components, leading to increased crystallinity and eventual structural breakdown. WAXD findings demonstrated that microbial and environmental factors initially enhance crystalline regions in cellulose fibres but ultimately reduce tensile strength and flexibility due to amorphous phase loss. FTIR analysis confirmed the molecular changes in cellulose chains, particularly in pectin and lignin, while SEM provided direct evidence of surface damage and fibre disintegration. Furthermore, it was found that fibre types of nonwoven mulch influence soil moisture retention and soil microbial activity due to a complex interplay of fibre composition, environmental conditions and nonwoven fabric characteristics. Comprehensive mechanical, morphological and chemical results of different types of nonwoven mulch during the 300 days of exposure to the field conditions provide valuable insights into sustainable practices for using nonwoven mulches for growing crops.

The impact of four distinct calcium sources on the microbial solidification of sand in the Kashi Desert, Xinjiang, was investigated. A wind tunnel test over a 60-day period revealed the cracking behavior of four different complex calcium nutrient solutions. By comparing the bearing capacity and the results from dry-wet cycling and freeze-thaw cycle tests, it was concluded that the sample treated with calcium gluconate exhibited superior sand fixation performance, whereas the sample treated with calcium acetate showed weaker sand fixation effects. The microstructure of the treated sand samples was analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Elemental analysis was conducted via energy dispersive spectroscopy (EDS), and functional groups were identified through Fourier transform infrared spectroscopy (FTIR). These experimental findings hold significant implications for soil remediation, pollutant removal in soil, enhancement of soil fertility, and desert soil stabilization.

High-Density Polyethylene (HDPE) PE is one of the primary contributors of long-lasting and prolonged pollution in the environment. In this study, more than three hundred marine isolates collected off the Gujarat Sea coast were tested for HDPE plastic utilizing ability. Among fifty-one positive noted isolates, RS124 as a potential strain was identified as Micrococcus flavus (accession is PP858228) based on 16 S rRNA gene sequencing and total cellular fatty acid profiling. Initial bacterial adherence on the film surface was shown in a scanning electron microscopy (SEM) image as a key step to biodegradation. Moreover, atomic force microscopy (AFM) shows that the film surface became more fragile, damaged, and rougher than untreated films. Shifts and alterations in peak transmittance with emergence of two new shouldered peak in degraded HDPE observed by fourier transform infrared spectroscopy (FTIR) was associated to chemical and mechanical alteration. Thermogravimetric analysis (TGA) analysis designated larger difference in percent weight loss provisions thermal instability. In the enzymatic study, the highest activity of peroxidase and dehydrogenase was recorded on the 3rd and 4th weeks of treatment with strain, respectively, during co-incubation. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis disclosed the presence of a distinct 19 kDa size protein, uncovering its role in the colonization of bacteria on the hydrophilic HDPE surfaces. About 1.8% weight reduction in HDPE was recorded as a result after 30 days of bio-treatment with M. flavus. Hence, the entire observed results reveal that the M. flavus RS124 could be effectively applied for the degradation of HDPE. This is the first report on M. flavus that it exhibits plastic degrading characteristic ever, which may allow for green scavenging of plastic waste.

Background This study investigated the effect of B. Subtilis bacteria on the properties of cement mortar. This was done by using soil samples from Sharkia, Egypt, to isolate 48 bacterial strains, after which they were cultured using the Johnson method and various media. Bacteria were then added to the cement mortar in amounts of 5% and 10% by weight to evaluate their effect on the mechanical and chemical properties of the modified mortar. Results The study examined the compressive and flexural strength of the modified mortar over time, as well as its microscopic properties and chemical composition after 28 days. The results indicated that bacterial additions of 5% and 10% increased the compressive strength of the mortar after 28 and 56 days compared to the control. A 5% bacteria concentration resulted in significant improvements in strength, showing the best concentration for increasing mortar strength. The addition of 5% bacteria significantly enhanced the early flexure strength, while the 10% showed superior long-term strength after 56 days. Scanning electron microscopy (SEM) revealed high CaCO3 deposits in the bacterial samples, indicating microbial-induced calcite precipitation that filled the small cracks and increased strength. Fourier-transform infrared spectroscopy (FTIR) confirmed the presence of hydroxyl, carbonate, and silicate groups, with bacterial samples having a higher carbonate content, indicating an increase in calcium carbonate formation and microstructure. Conclusions The ideal bacterial concentration was 5% as it improved the compressive and flexural strength while also promoting a more flexible microstructure. This study supports the employment of microorganisms in the production of more durable and environmentally friendly building materials, enhancing the sustainability of building practices.

The presence of drying cracks can significantly affect soil hydromechanical behavior, which has effects on soil performance in civil engineering. One innovative approach that has received much interest in the last decade is using microbially induced calcium carbonate precipitation (MICP) for soil reinforcement and stabilization. A series of clay specimens with varying moisture levels and concentrations of cementation solution were carefully prepared. All these samples were subjected to a series of mechanical tests to assess the improvement in the clay's mechanical characteristics. These tests covered various conditions, ranging from unsaturated to saturated states of the clays. The results showed that the strength of clays was significantly improved, and the most significant increase in mechanical strength was observed with the 1.4 M MICP solution. The precipitation of CaCO3 was quantified using a calcimeter. In addition, composition analysis by X-ray diffraction and attenuated total reflectance infrared spectroscopy confirmed the presence of calcium carbonate crystals and indicated residual urea and calcium acetate.

Escalating usage of non-degradable plastics is raising significant concern. The search for bio-based degradable alternatives commenced far back, and the burgeoning progress in the development of bioplastics is featured as a critical solution to ongoing plastic pollution. Bioplastics are becoming a promising substitute for petroleum-based plastics, depending on the production source and post-use disposal management. Among all the promising materials, microbially produced polyester and polyhydroxybutyrate (PHB) belong to the polyhydroxyalkanoate (PHA) family and are biocompatible and non-toxic. PHB has remarkable thermal and mechanical properties, making it a potential replacement for ubiquitous plastics. In this study, PHB-producing bacteria were isolated from mangrove soil and checked for PHB accumulation using preliminary and confirmatory staining. Out of a total 25 isolates, 13 were found positive for PHB accumulation. Dairy wastewater was used as a cultivation medium for PHB production; the potential PHB-producing strain was selected for morphological and biochemical characterization up to the genus level and was found to be Bacillus sp (3.6 +/- 0.15g/L). Extracted PHB was characterized using FTIR, XRD, and TGA; in FTIR, the characteristic peak was recorded at 1724 cm-1, and XRD showed the crystallinity of PHB. outcome of the present study shows that dairy wastewater is an indispensable medium for PHB production in an eco-friendly way.

Plastics are extensively used in agriculture, but their weathering and degradation generates microplastics (MPs) that can be carried by runoff into water bodies where they can accumulate and impact wildlife. Due to its physicochemical properties, biochar has shown promise in mitigating contaminants in agricultural runoff. However, few studies have examined its effectiveness at removing MPs. In this study, we assessed MP pollution (>30 mu m) in runoff from a farm in the Mississippi Delta and examined the effectiveness of biochar (pinewood and sugarcane) to remove MPs from aqueous solutions. Using micro-Fourier Transform Infrared spectroscopy (mu -FTIR), we observed an average of 237 MPs/L (range 27-609) in the runoff, with most particles identified as polyethylene, polyamide, polyvinyl chloride, polyurethane, acrylonitrile butadiene styrene, and polyarylamide. Biochar columns effectively removed MPs from runoff samples with reductions ranging from 86.6% to 92.6%. MPs of different sizes, shapes, and types were stained with Nile red dye (to facilitate observation by fluorescence) and quantified their downward progress with multiple column volumes of water and wet/dry cycles. Smaller MPs penetrated the columns further, but >= 90% of MPs were retained in the similar to 20 cm columns regardless of their shape, size, and type. We attribute these results to physical entrapment, hydrophobic behaviors, and electrostatic interactions. Overall, this proof-of-concept work suggests biochar may serve as a cost-effective approach to remove MPs from runoff, and that subsequent field studies are warranted.

For evaluating the resistance performance of cement-stabilized soils in cold regions, the variation of the strength of the cemented sand-gravel (CSG) mixture concerning the hydration process should be explored. This paper aims to study the effect of freeze-thaw (F-T) cycles on the strength and microstructure of a CSG mixture with 10% cement that is subjected to 12 cycles of freezing at a temperature of -23 degrees C for 24 h and then melted at room temperature of 24 degrees C for the next 24 h. The uniaxial compressive strength (UCS), California bearing ratio (CBR), and weight volume loss of the samples were measured after individual F-T cycles. Furthermore, the change in the microstructure of the CSG mixture in various F-T cycles was explored. The results showed a considerable reduction in the UCS up to Cycle 3, then a slight increase for Cycles 3-6, and finally a gradual decrease for further cycles. However, the CBR and weight loss slightly fluctuated up to Cycle 6, and then gradually decreased for subsequent cycles. The majority of compounds of hydrated cement were damaged in the first three cycles. In the following cycles, between Cycles 3 and 6, the portlandite compound was dissolved and recrystallized within the microvoids. Depending on the environmental conditions, carbonation may be generated from the hydrated cement fraction, which fills the microvoids and improves the strength and structure of the mixture. During further cycles after the sixth cycle, the mechanical action of the ice lenses coupled with the disintegration of the hydrate compounds imposed many new microvoids and cracks with considerable length and width, which intensified the strength reduction of the moisture and weakened the adhesion between grains. Since cement is widely used in pavement and dam engineering for stabilizing soils, the durability of cemented soils is of prime concern. This study may help improve the durability and resistance of cemented soils in cold climates. The F-T action not only influences the macrostructure of cement-stabilized soils by imposing a wide crack and ice lens but also induces a considerable change in the complexes existing in the hydrated cement paste of the mixture. Three patterns govern the change of the mixture microstructure in various F-T cycles that correspond to the observed trend in strength. The mentioned trend for the microstructure change and, consequently, the strength variation of the CSG mixture are associated with many factors such as pH, cement content, CO2 content, moisture content within the mixture, and relative humidity within the environment. Accordingly, the pattern of microstructural changes in the CSG mixture after the middle F-T cycles may vary depending on environmental conditions.

Freeze-thaw cycles significantly impact construction by altering soil properties and stability, which can lead to delays and increased costs. While soil-stabilizing additives are vital for addressing these issues, stabilized soils remain susceptible to volume changes and structural alterations, ultimately reducing their strength after repeated freeze-thaw cycles. This study aims to introduce a different approach by employing magnesium chloride (MgCl2) as an antifreeze and soil stabilizer additive to enhance the freeze-thaw resilience of clay soils. We investigated the efficiency of MgCl2 solutions at concentrations of 4%, 9%, and 14% on soil by conducting tests such as Atterberg limits, standard proctor compaction, unconfined compression, and freeze-thaw cycles under extreme cold conditions (-10 degrees C and -20 degrees C), alongside microstructural analysis with SEM, XRD, and FTIR. The results showed that MgCl2 reduces the soil's liquid limit and plasticity index while enhancing its compressive strength and durability. Specifically, soil treated with a 14% MgCl2 solution maintained its volume and strength at -20 degrees C, with similar positive outcomes observed for samples treated with 14% and 9% MgCl2 solutions at -10 degrees C. This underlines MgCl2's potential to enhance soil stability during initial stabilization and, most importantly, preserve it under cyclic freeze-thaw stresses, offering a solution to improve construction practices in cold environments.