Dry Weight Of Soil Research Articles

Stress-Strain Behavior of Soft Soil Stabilized with Nickel Slag, Limestone, and Aluminum Hydroxide

Soil stabilization by combining several minerals is a form of material engineering aimed at increasing the bearing capacity of the soil to a higher level. The development of waste-based materials and the utilization of local potential are part of environmentally conscious construction. This study aims to analyses the mechanical behaviour of soil stabilized with several pozzolanic materials derived from nickel processing waste and limestone, which are local materials with very large deposits. ASTM standards were used in this study for both physical and mechanical testing. Unconfined compressive strength (UCS) tests were conducted to compare the mechanical behaviour of stabilized soil with that of natural soil. The test samples used were cylindrical with a diameter of 35 mm and a height of 70 mm. The binding materials consisted of nickel slag, aluminium hydroxide, and limestone, with the amount of each material based on the dry soil weight (γdry). The addition of lime in this study was varied at 2%, 4%, and 6%. The test results generally show that lime variations and curing time affect the increase in unconfined compressive strength (qu), with the highest value of 30.91 kg/cm² observed at 6% lime content after 28 days of curing.

Dampak Penggunaan Abu Marmer terhadap Kuat Geser Tanah Lempung

Soil is an important part of the building structure because it has a function as a support for the building. Therefore, soil stability must be considered so that building construction is safe and durable. There are types of clay soils that have high plasticity values and low shear strength. Soils like this require stabilization with the addition of additives such as marble ash. The purpose of this study was to determine whether the addition of marble ash content has an optimal impact on improving the plasticity, density, and shear strength properties. The added material used was marble ash with a content of 3%, 6%, 9%, and 12% by weight of dry soil. The specimens were differentiated based on their curing age before being tested by triaxial. Based on the research results, it was found that the use of marble ash had the maximum impact on improving the plasticity properties and maximum density at an addition of 6%. This was followed by a significant increase in shear strength at the same addition. A good curing age for increasing the angle of internal friction in the soil was obtained at 14 days.

From environment to free-range chickens: Broad exposure to short- and medium-chain chlorinated paraffins in rural Tibetan Plateau, China

Chlorinated paraffins (CPs) are widely employed in various consumer products. Rapid socioeconomic development drives the elevation of CPs contamination by increasing the usage of modern lifestyle products, but limited information exists about their occurrence in remote rural areas. In this study, the occurrence, and profiles of short- and medium-chain CPs (SCCPs and MCCPs) in soils, plants, chicken feeds, eggs, and free-range chicken tissues in the rural Tibetan Plateau were investigated. The median concentrations of SCCPs and MCCPs were 108 and 141ng/g dry weight (dw) in soils, 1.76 × 103 and 1.16 × 103ng/g dw in plants, 43.6 and 24.3ng/g dw in chicken feeds, 299 and 251ng/g lipid weight in free-range chicken eggs, and 182−3.45 × 103 and 396−7.75 × 103ng/g lipid weight in chicken tissues, respectively. Correlation analysis demonstrated that soil was the primary source of CPs, and free-range chicken eggs were effective bioindicators for SCCPs and MCCPs contamination. Tissue distribution showed that SCCPs and MCCPs were highly accumulated in chicken tissues that local resident preferred to consume (such as muscle and stomach). Our findings lay the foundations for further evaluation of the potential risks of CPs on the ecosystem and human health in remote rural areas.

Morphophysiological and Histopathological Effects of Ammonium Sulfate Fertilizer on Aporrectodea trapezoides (Dugès, 1828) Earthworm.

The present study used the adult earthworm Aporrectodea trapezoides as a bioindicator species to look into the possible dangers of ammonium sulfate (AS) fertilizer. Two complementary toxicity tests were conducted to determine the LC50values, growth rate inhibition, morphological alterations, and histopathological texture of worms. The lethality test included four increasing concentrations of AS fertilizer (ranging from 2500 to 7500 mg/kg of dry soil weight (d.w.)), while sub-lethal concentrations were based on 10%, 30%, 40%, and 50% of the 14-day median lethal concentration (LC50), with a control group included for both tests. The LC(50) values for AS fertilizer were significantly higher at 7 days (4831.13 mg/kg d.w.) than at 14 days (2698.67 mg/kg d.w.) of exposure. Notably, earthworms exhibited significant growth rate inhibition under exposure to various concentrations and time durations (14/28 exposure days). Morphological alterations such as clitellar swelling, bloody lesions, whole body coiling and constriction, body strangulation, and fragmentation were accentuated steadily, with higher concentrations. Histopathological manifestations included severe injuries to the circular and longitudinal muscular layers, vacuolation, muscle layer atrophy, degradation of the chloragogenous tissue in the intestine, collapsed digestive epithelium of the pharynx with weak reserve inclusion, and fibrosis of blood vessels. These effects were primarily influenced by increasing concentrations of fertilizer and time exposure. The study highlights the strong relationship between concentration and exposure time responses and underscores the potential of A. trapezoides earthworms as valuable biological control agents against acidic ammonium sulfate fertilizer. Importantly, this research contributes to the use of such biomarkers in evaluating soil toxicity and the biological control of environmental risk assessment associated with chemical fertilizers.

Survival and reproduction tests using springtails reveal weathered petroleum hydrocarbon soil toxicity in boreal ecozone.

Survival and reproduction tests were conducted using two native springtail (subclass: Collembola) species to determine the toxicity of a fine-grained (< 0.005 - 0.425 mm) soil from an industrial site located in the Canadian boreal ecozone. Accidental petroleum hydrocarbon (PHC) release continuously occurred at this site until 1998, resulting in a total hydrocarbon concentration of 12,800mg/kg (soil dry weight). Subfractions of the PHC-contaminated soil were characterized using Canadian Council of Ministers of the Environment Fractions, which are based on effective carbon numbers (nC). Fraction 2 (> nC10 to nC16) was measured at 8400mg/kg and Fraction 3 (> nC16 to nC34) at 4250mg/kg in the contaminated soil. Age-synchronized colonies of Folsomia candida and Proisotoma minuta were subject to 0%, 25%, 50%, 75%, and 100% relative contamination mixtures of the PHC-contaminated and background site soil (< 100mg/kg total PHCs) for 28 and 21days, respectively. Survival and reproduction decreased significantly (Kruskal-Wallis Tests: p < 0.05, df = 4.0) in treatments of the contaminated site soil compared to the background soil. In both species, the most significant decline in survival and reproduction occurred between the 0% and 25% contaminated soil. Toxicity responses in the two springtails were ascribed to the standardized test design, short lifespans, and high fecundity in both species. This study showed that 25 + years of soil weathering has not eliminated the toxicity of fine-grained PHC-contaminated soil on two native terrestrial springtail species. Adverse effects to springtail health were attributed to exposure to soils dominated by genotoxic PHC Fraction 2 compounds and slow weathering processes due to the cold climate at the site.

Effect of kaolin-nano-silica mixture on geomechanical properties enhancement of soils

Weak soil is a major obstacle facing the urban development of any site with other exceptional merits. The current study aims to investigate the utilization of nano-silica in enhancing the mechanical properties of weak kaolin soils. Design mixes using different percentages of nano-silica were investigated in the range between 0.25–1.20% from the dry weight of the kaolin soil. Various chemical, physical, and mechanical properties of each mixture have been investigated. The obtained results indicated that nano-silica addition to such kaolin soils decreased the plasticity index and the maximum dry density while increasing the plastic limit, the Liquid limit, and the optimum moisture content. In different curing days of the tested mixtures, maximum dry density was decreased, while the optimum moisture content increased. The optimum value of added nano-silica was less than 1% of the soil dry weight. In the modified kaolin soil with 0.9% nano-silica, the plastic limit was increased by 29%, while the liquid limit decreased by 13% in comparison with the untreated sample. After 28 days of the cured sample, the unconfined compressive strength readings increased by almost 14% compared to its reading on day one. Also, the California bearing ratio results recorded significant enhancement with nano-silica additives in comparison with the untreated kaolin soil. After 28 curing days, the sonicated samples recorded enhancement in the unconfined compressive strength readings by more than 5% and 9% with the additive N-Si (0.3% and 0.9%), respectively, when compared with the unsonicated samples.Graphical

EXPERIMENTAL EVALUATION OF EXPANSIVE SOIL STABILIZED WITH WHEAT HUSK ASH AND SISAL FIBER

Everything starts with soil. Being a civil engineer, we are aware of how essential soil is to construction, as everything is dependent on it. Before building any kind of structure on top of soil, we examine the soil's characteristics and behavior to determine its strength and ability to support the weight of the structure to be built on top of it. In this study work, we used agricultural waste materials, such as wheat husk ash (WHA), as a stabilized material in soil at different percentages of 5%, 10%, and 15% to perform various tests on the soil to determine its qualities or strength. Sisal fibers are inexpensive, readily available locally, and environmentally benign, making them an excellent choice for enhancing soil properties. The stabilizing effect of sisal fiber on soil characteristics has been experimentally investigated in this work. In light of this, an experimental study is carried out using pricey, locally accessible soil that has been blended with various percentages of sisal fiber. In the CBR mold and UCS sampler, soil samples are prepared at their maximum dry density (MDD) matching to their optimum moisture content (OMC) both with and without Sisal Fiber and WHA. In the laboratory, CBR and UCS tests are carried out in accordance with the proportion of Sisal Fiber by dry weight of soil, which is determined to be 1%, 1.5%, or 2%. According to test results, the amount of sisal fiber in the soil increases with its saturated CBR and UCS value. When wheat husk ash and sisal fiber are added, the CBR of the mix increases and the pavement thickness decreases, resulting in lower construction costs and ultimately, more economical highway building. Key Words: Compaction test, CBR, UCS, WHA, Sisal Fiber

Integrating automated machine learning and metabolic reprogramming for the identification of microplastic in soil: A case study on soybean

The accumulation of polyethylene microplastic (PE-MPs) in soil can significantly impact plant quality and yield, as well as affect human health and food chain cycles. Therefore, developing rapid and effective detection methods is crucial. In this study, traditional machine learning (ML) and H2O automated machine learning (H2O AutoML) were utilized to offer a powerful framework for detecting PE-MPs (0.1 %, 1 %, and 2 % by dry soil weight) and the co-contamination of PE-MPs and fomesafen (a common herbicide) in soil. The development of the framework was based on the results of the metabolic reprogramming of soybean plants. Our study stated that traditional ML exhibits lower accuracy due to the challenges associated with optimizing complex parameters. H2O AutoML can accurately distinguish between clean soil and contaminated soil. Notably, H2O AutoML can detect PE-MPs as low as 0.1 % (with 100 % accuracy) and co-contamination of PE-MPs and fomesafen (with 90 % accuracy) in soil. The VIP and SHAP analyses of the H2O AutoML showed that PE-MPs and the co-contamination of PE-MPs and fomesafen significantly interfered with the antioxidant system and energy regulation of soybean. We hope this study can provide a reliable scientific basis for sustainable development of the environment.

Vertical movement of microplastics by roots of wheat plant (Triticum aestivum) and the plant response in sandy soil

Microplastics persist as a challenging pollutant in agroecosystems, posing potential risks to soil health and crop productivity. Root growth, elongation and expansion may significantly influence the vertical transport and infiltration of microplastics into the soil profile. Wheat plants (Triticum aestivum) grown in 70 cm deep rhizotrons were investigated for their influence on the vertical movement of two prevalent microplastic shapes, polyester fibres and polyvinyl chloride (PVC) fragments. Wheat was chosen for its dense and extensive fibrous and fine root system, which is a robust model for studying root-soil-microplastic interactions. Microplastics at a 0.24% w/w dry soil weight concentration were homogeneously distributed in the topsoil (0–20 cm). Infiltration of polyester fibres up to 50 cm into the soil profile was discerned as strong adherence to plant roots. PVC fragments exhibited greater mobility, reaching depths of 70 cm in the presence and absence of wheat plants. Plant growth response on exposure to microplastics appeared in the form of increased root branching and decreased shoot biomass, indicating a stress response in wheat plants. The results prove the vertical movement of microplastics, while the infiltration depth was influenced by microplastic shape. Movement was detected as either strong adherence of polyester fibres to plant roots or infiltration of PVC fragments. PVC fragments may have infiltrated through preferential flow paths in soil pores and the fissures created by root elongation and water movement.

Investigating the Impact of Ground Granulated Blast Furnace Slag (GGBS) and Cement Kiln Dust (CKD) on fine grained Soil Subgrade in Al Hillah City

Abstract In many parts of the world, fine grained soils are regarded as one of the major concerns for civil engineering projects. To mitigate these problems, fine grained soils are typically replaced with stronger materials. However, due to the high cost of this approach, various researchers have tried alternative approaches, the most popular of which is soil stabilization. This method could be deemed suitable for pavements. The research focuses on stabilizing fine soil through the utilization of cement kiln dust (CKD) and ground granulated blast slag (GGBS). This research involves treating fine soil with 10% of the total binder consist from (GGBS+CKD), with the amount of GGBS to CKD determined by dry soil weight as follows: (10% GGBS + 0% CKD), (8% GGBS + 2% CKD), (6% GGBS + 4% CKD), (2% GGBS + 8% CKD), and (0% GGBS + 10% CKD). The compaction parameters, consistency limitations, and the findings of the Unconfined Compressive Strength (UCS) test were used to assess the enhancement levels. In addition, specimens were subjected to UCS testing after (7-28) days of curing. The findings demonstrated that the combination of GGBS activated by CKD notably enhanced the physical characteristics of fine soil. The Plasticity Index (PI) decreased from 7.4 for untreated soil to 4.8 for a mixture containing 10% binder, comprised of 2% GGBS and 8% CKD, and to 4.25 for a single-binder mixture with 10% CKD. Furthermore, the unconfined compressive strength test (UCS) results indicated that a 10% binder mixture of 8% GGBS and 2% CKD increased the UCS by 2.9 to 5.9 times compared to untreated soil after 7-28 days of curing.

Expansive clay subgrade soil improvement using municipal solid waste fly ash: Experimental and numerical approach

The expansive soil under investigation has caused damage to lightweight structures due to its swelling and shrinkage characteristics in response to changing moisture content. The study aims to assess the impact of municipal solid waste (MSW) fly ash on the engineering properties of subgrade expansive soils and its influence on pavement structure deformation. The influence of municipal solid waste fly ash on expansive soils was evaluated using laboratory tests and finite element methods. The Abaqus software was used to investigate the effects of MSW fly ash on pavement structure deformation. The input parameters employed for this analysis were elastic modulus, Poisson ratio, load, contact area dimension, and pavement layer thickness. To mitigate this issue, MSW fly ash was used as a stabilizing agent at varying percentages (5 %, 10 %, 15 %, 20 %, 25 %, and 30 % of the dry mass of the soil sample).According to the AASHTO soil classification, the soil is classified as A-7, has a high free swell, a low soaked CBR value, and a high soaked CBR swell, and does not meet the ERA manual standard for subgrade materials. The laboratory tests shown several improvements in the engineering properties of expansive soil when MSW fly ash were mixed. These improvements included a reduction of soaked CBR swelling, free swell index, plasticity index, specific gravity, optimum moisture content. Additionally, the maximum dry density and soaked CBR values increased. Numerical analysis using Abaqus software focused on vertical deformation of the pavement structure. The results showed that as the percentage of MSW fly ash in form 0 % to 25 % of soil dry weight, the vertical deformation of the pavement structure decreased from 0.84 mm to 0.67 mm. This demonstrates that the addition of MSW fly ash reduced the deformation of expansive sub-grade soil and improved the engineering qualities of pavement structure. In conclusion, the study revealed that the use of MSW fly ash as stabilizing agent effectively reduced the deformation of expansive subgrade soil and improved the engineering qualities of pavement structure.

Compressed stabilised earth block synergistically valorising municipal solid waste incinerator bottom ash and sisal fiber: Strength, durability and life cycle analysis

Compressed stabilized earth blocks (CSEB) represent an eco-friendly substitute for traditional building materials, predominantly utilizing earth. Municipal Solid Waste Incineration Bottom Ash (MSWIBA) is a by-product of municipal waste treatment that can be creatively repurposed in construction projects. This research explores integrating MSWIBA as a substitute for Earth in CSEB production to conserve natural resources and repurpose waste, potentially reducing its landfill disposal. The sisal fibers (SF), often regarded as by-products of agricultural processes, offer an intriguing research material. The SF was treated with a 5 % NaOH alkaline solution to improve the CSEB bonding, increasing the flexural strength. The study aims to determine the optimal mix of stabilizers, in addition to a 10 % cement content, using various percentages of MSWIBA (10–40 % by weight of dry sand) and SF content (0.25–1 % by weight of dry soil). These blocks undergo comprehensive tests to determine their strength and durability. Wet and dry compression, flexural tests and indirect tensile tests were used to assess strength qualities, while wetting-drying cycles and acid exposure were used to determine durability. MSWIBA replaces 20 % sand in CSEB satisfying the strength. However, exceeding this amount increases void content and lowers strength, emphasizing the importance of balanced proportions for best performance. The 20 % MSWIBA and 0.75 % SF combination enhanced the compressive strength by 6.45 MPa, flexural strength by 0.92 MPa and water absorption by less than 18 %. The durability test displayed increases in compressive strength of 14.7 % and flexural strength of 93.48 % and optimized water absorption rate. Furthermore, microstructural analysis has been performed on CSEBs and the results highlight the importance of balanced cement and SF proportions for structural integrity. Life Cycle Analysis (LCA) investigation shows that construction costs using CSEB are 12.24 % higher than those with FCBs. Additionally, the study suggests that CSEB with MSWIBA and SF will be an environmentally sustainable construction material, considering factors such as energy usage, Global Warming Potential, and other environmental considerations

STUDY ON ENGINEERING PROPERTIES OF SOIL USING STONE DUST AND BAGASSE ASH

In the discipline of civil engineering, soil stabilization is the process of enhancing and improving the engineering qualities of soil so that it can support large loads without failing. The safe and efficient disposal of waste material without causing harm to society is a significant concern in a well-managed ecosystem. Utilizing solid waste products to stabilize soil has become more popular recently as a successful way to manage trash from many sectors. This paper reviews the usage of various solid waste items that have been applied to stabilize soft soils. However, there are numerous approaches and strategies for stabilizing this soil. This research offers a method for stabilizing soft soil using waste products. An investigation into the stabilizing potential of bagasse ash and sisal fiber for highly compressible clayey soil has been prompted by the rising expense of building traditional stabilizers and the necessity of inexpensively consuming industrial and agricultural wastes for value trade. There is a growing demand for sustainable construction, which is why recent research has concentrated on sustainable resource consumption trends. We can employ natural and biodegradable resources, as well as waste products, to obtain. This study was a large-scale laboratory experiment to explore the use of natural fibers, industrial waste, and agricultural waste to improve the engineering qualities of moderately compressible clay. The purpose of this study was to determine whether Stone Dust and Bagasse Ash were suitable for stabilizing clayey soil. The results of testing for consistency limits, maximum dry density, optimal moisture content, UCS, and (soaked) CBR were obtained using percentages of 10%, 15%, and 20% by weight of dry soil for Bagasse Ash and 6%, 8%, and 10% for Stone Dust. In this work, expansive soil was stabilized using Stone Dust and Bagasse Ash. Bagasse Ash was fixed at 15%, after that Stone Dust was changed to 3%, 6%, and 9%. Key Words: Compaction test, CBR, UCS, Stone Dust, Bagasse Ash

Climate change in edaphic systems – Impact of salinity intrusions in terrestrial invertebrates

Amongst climate change’s impacts a major concern is salinization of soils, for example due to saltwater intrusion. The aim of the present study was to investigate in a standard field soil the impacts of soil salinity increase. The purpose was to study this in two soil invertebrates that are key model ecotoxicology test-species, Enchytraeus crypticus and Folsomia candida as surrogate representatives of the soil ecosystem. The exposure followed the standard ecotoxicity OECD (Organization for Economic Cooperation and Development) test guidelines, and the assessed endpoints were survival, reproduction and size. Exposure done in LUFA 2.2 soil, spiked with 0,0.6,1,2,3,4,5,6,8 g NaCl/kg soil dry weight (DW) for E. crypticus (21 days) and 0,0.06,0.6,1,2,3,4,5,6 g NaCl/kg soil DW for F. candida (28 days). There was a similar impact for both species in terms of survival (LC50=4.2 g NaCl/kg soil DW), whereas at the reproductive output level of F. candida (EC50=2.1 g NaCl/kg soil DW) was more sensitive than E. crypticus (EC50=2.4 g NaCl/kg soil DW). Further, size was impacted for F. candida in a monotonic dose-response curve for both adults (EC50=3.5 g NaCl/kg soil DW) and juveniles (EC50=2 g NaCl/kg soil DW), whereas for E. crypticus there was an increase in reproductive output at lower concentrations (0.6–1 g NaCl/kg soil DW). This increased reproduction was associated with a larger size of adults within the same concentration range. Considering the prediction from the climate models, the soil invertebrate community will be affected. As upper soils are likely to have the highest salinity increase due to evaporation, soil surface species, such as the collembolan tested here, are at higher risk. Negative population effects were occurring within salinity levels predicted by climate change models.

Effects of poly‐γ‐glutamic acid addition on the transformation and distribution of soil nitrogen under different water conditions

AbstractThe impact of external poly‐γ‐glutamic acid (γ‐PGA) on soil nitrogen (N) transformation and distribution remains unclear, despite its contrasting effects on N use efficiency. Therefore, soil culture and soil column experiments were conducted using three different γ‐PGA addition rates (0%, 4% and 8% of dry soil weight, w/w) under different soil water contents (40%, 60% and 80% of field water capacity) and dry–wet cycles (0, 2, 4 and 8 times cycles; a single dry–wet cycle involved reducing soil water content from 80% to 40% of field water capacity) in sandy loam soil. The results of soil culture experiment showed that the γ‐PGA significantly increased soil –N and –N contents, as well as nitrification and transformation rates. However, these effects were observed to be influenced by both the culture time and soil water content. In addition, the results of soil column experiment showed that γ‐PGA not only significantly enhanced the soil inorganic nitrogen content within the 0–20 cm soil layer, but also improved water retention capacity. However, the differences between the γ‐PGA treatments gradually diminished with an increase in dry–wet cycle times. These results indicate that γ‐PGA addition enhanced soil inorganic N content and soil water retention by influencing soil N transformation and water distribution. However, the impact of γ‐PGA addition on soil improvement was regulated by soil water content, which should be taken into full consideration in agricultural practices.

Evaluating the Geotechnical Properties of Stabilized Problematic Soil by Utilizing Reed Ash and Lime Mixture

Stabilization of problematic soil poses a significant challenge in civil engineering projects, especially in regions with prevalent soft clay soils. This study was carried out to study the impact of using a blend of reed ash and lime on improving and stabilizing problematic soil. A sample of soil was obtained from a location in the south of Iraq, specifically in Al-Muthanna Governorate. The treatment involved adding different proportions of reed ash (3%, 5%, 7%, and 9.0% of the soil's dry weight) along with 5% lime, which was determined as the optimal percentage based on previous research. Various laboratory tests were conducted to assess the characteristics of the treated soil, including compaction and unconfined compressive strength (UCS). The findings indicated a notable enhancement in UCS and the maximum dry density (MDD). It was observed that UCS and MDD increased with increasing the reed ash and lime mixture proportion, reaching an optimal level. Beyond this percentage, the strength started to decline. It was found that the incorporation of lime and reed ash (5% lime and 7% reed ash) into the treated soil significantly improved its strength, up to about 10 times compared to untreated soil after 28 days of curing. This approach offers additional benefits, such as reducing environmental pollution by decreasing CO2 emissions during phases of production and providing cost savings because of the affordability of the materials used.

Stabilization of Pavement Subgrade Clay Soil Using Sugarcane Ash and Lime

Soft to medium clay soil possesses major sources of damages to the pavement layers overlying them because of their potential failure under moisture changes and external heavy traffic load. In such situations, soil stabilization methods can be used to improve the soil properties and satisfy the desired engineering requirements. This study presents the use of sugarcane bagasse ash (SBA) and lime as chemical stabilizers for a clay soil subbase. Sugarcane bagasse ash and lime are used individually and as mixtures at varying percentages to stabilize a clay soil from Taxila, Pakistan. Various geotechnical laboratory tests such as Atterberg limits, compaction test, and California Bearing Ratio (CBR) are carried out on both pure and stabilized soils. These tests are performed at 2.5%, 5%, and 7.5% of either SBA or lime by weight of dry soil. In addition, mixtures of lime and SBA in ratios of 1:1, 2:1, 3:1, 1:2, and 1:3 are used in 5%, 7.5%, and 10% of dry soil weight, respectively. Results indicate that soil improved with 7.5% SBA showed a 28% increase in the liquid limit, while soil mixed with 2.5% lime in combination with 7.5% SBA showed an increase of 40% in the plastic limit. For the plasticity index, the soil mixed with 7.5% SBA showed an increase of 42%. Moreover, 2.5% lime in combination with 2.5% SBA showed the best improvement in soil consistency as this mixture reduced the soil plasticity from high to low according to the plasticity chart. Furthermore, 2.5% SBA in combination with 5% lime demonstrated the largest improvement on the CBR value, which is about a 69% increase above that of the pure soil. Finally, the cost analysis indicates a promising improvement method that reduces pavement cost, increases design life, and mitigates issues of energy consumption and pollution related to SBA as a solid waste material.

A review on Comparative study of using Silica Fume and Areca Fiber on Soil Stabilization

Abstract The rapid expansion of urban areas and the rise in construction activities have led to a shortage of land with suitable soil conditions. This has forced people to utilize weak soils available locally for construction purposes, employing various stabilization techniques. Urban expansion and construction demand the utilization of local weak soils for building, necessitating the application of soil stabilization techniques. These methods enhance soil strength by altering its properties. This study evaluates silica fume and areca fiber as stabilizers. Silica fume is a pozzolanic and supplementary cementitious material that enhances material properties such as strength, durability, and resistance to chemical attacks and abrasion. Few studies have examined areca fiber as soil reinforcement. Areca fiber (20-30 mm in length) upto 0.6% of dry weight of soil significantly improves engineering properties of soil. Varied weight ratios of silica fume and areca fiber are used based on soil type for optimal conditions. Silica fume stabilizes, and areca fiber reinforces problematic soil, as demonstrated through compaction, UCS, and CBR tests. Utilizing such waste materials is a cost-effective and more sustainable approach in the field of engineering. This research investigates the compaction and strength properties of various problematic soils stabilized with silica fume and areca fiber, providing a comprehensive review of the findings.

Responses of soil aggregation and aggregate‐associated nitrogen to straw return in China: Evidence from a meta‐analysis and a pot experiment

AbstractEnhancing soil structure and soil nitrogen availability is the key to sustainable agricultural development in global cropping systems. Straw return can affect soil aggregation, but the results of recent studies on the influence of straw return on soil aggregation are not consistent, and the distribution and availability of straw‐derived nitrogen in soils are still unclear. Here, a meta‐analysis of the effects of straw return on soil aggregation was conducted based on 57 studies published in China over the past 10 years. Moreover, combined with a pot experiment, the distribution and transfer characteristics of the two main wheat (Triticum aestivum L.)‐preceding crops, corn (Zea mays L.) and soybean (Glycine max L.) straw‐derived nitrogen in the soils were studied by using the 15N‐tracer method in the main wheat‐producing areas of China. 15N‐labeled straw was introduced into soils in pots at rates of 0.3% and 0.5% of the soil dry mass and incubated 60%–70% of the field water capacity throughout the entire growth period of wheat (220 days). A meta‐analysis revealed that straw return significantly improved the mass ratio of large macro‐aggregates (LM%) and small macro‐aggregates (SM%) but significantly decreased the mass ratio of micro‐aggregates (MI%) and silt plus clay‐size particles (CS%), with mean effect sizes of 36.27%, 9.06%, −8.26%, and −21.32%, respectively. The mean weight diameter (MWD) and geometric mean diameter (GMD) also increased by 21.48% and 15.64%, respectively. Compared with SM%, LM% made a greater contribution to the stability of soil aggregates. Moreover, only LM% showed a significant positive correlation with the corresponding aggregate‐associated nitrogen content, which was an important reason for the improvement in soil nitrogen availability after straw return. The positive effect of straw return on soil aggregation was greatest when the soil pH was close to 6.5–7.5, the average annual temperature was greater than 15°C, and the average annual rainfall was close to 800–1000 mm. The results of the pot experiment revealed that the proportions of straw‐derived nitrogen in &gt;2 mm aggregates were 1.21–1.28, 1.50–2.23, and 1.34–1.74 times greater than those in 0.25–2, 0.053–0.25, and &lt;0.053 mm aggregates, respectively. Moreover, the proportion of straw‐derived nitrogen content of aggregates of different particle sizes showed that the proportion of straw used to reach 0.5% of the soil dry weight was greater than 0.3%, which was 1.09–1.66 times greater, and that of soybean straw was significantly greater than that of corn straw, which was 1.50–2.28 times greater. At application rates of 60 g pot−1 and 100 g pot−1 straw, the absorption of soybean straw‐derived nitrogen by wheat was 1.83 and 2.15 times greater than that of corn straw‐derived nitrogen, respectively. In conclusion, straw return effectively improved soil aggregate stability and nitrogen availability, which was closely related to the increase in soil LM%. Soybean straw can stabilize soil aggregates better than corn straw, and its straw‐derived nitrogen is an important nitrogen source for subsequent wheat crops.

Uptake of technetium-99 by food crops under field conditions

Long-term field experiments have been carried out in the Chornobyl Exclusion zone to determine parameters describing technetium (99Tc) transfer into five food plants (Lettuce, Radish, Wheat, Bean, and Potato) from four types of soil, namely Podzoluvisol, Greyzem, Phaeozem, and Chernozem. Technetium was added to the soils under field conditions in a pertechnetate form. In the first two years, soil type had little effect on Tc uptake by plants. In the first and second years after contamination, the concentration ratios (CR), defined as 99Tc activity concentration in the crop (dry weight) divided by that in the soil (dry weight), for radish roots and lettuce leaves ranged from 60 to 210. For potato tubers, the CR was d 0.4–2.3, i.e., two orders of magnitude lower than for radish and lettuce, and for summer wheat grain it was lower at 0.6 ± 0.1. After 8–9 years, root uptake of 99Tc by wheat decreased by 3–7 fold (CR from 0.016 ± 0.005 to 0.12 ± 0.034) and only 13–22 % of the total 99Tc added remained in the upper 20 cm soil layers. The time taken for half of the added 99Tc to be removed from the 20-cm arable soil layer due to vertical migration and transfer to plants was short at c. 2–3 years.