Dry Weight Of Soil Research Articles

Utilisation of Athel Leaves to Improve the Unconfined Compressive Strength of Soil

Athel Leaves (AL) are plentiful agricultural waste that might result in a detrimental effect on the environment owing to inadequate disposal. The purpose of this paper is to experimentally assess the impact of Athel leaves as a novel sustainable waste application on the unconfined compressive strength (UCS) of soil. For the purpose of fulfilling this main objective, five AL percentages (1%, 2%, 3%, 4% and 5% by dry weight of soil) and four curing periods (3, 7, 14 and 28 days) were selected. The failure pattern was also studied to better understand the ultimate behaviour of the improved soil. Assessment of the derived conclusions revealed that the inclusion of AL into soil enhanced the UCS. Careful inspection of the stress-strain relationships showed that inclusion of AL resulted in increased peak stress at large strains. Additionally, it was found that bulging and shear were the two patterns observed in this research. This study confirms the possibility of incorporating AL in geotechnical applications with significant environmental benefits.

Effects of Lime on Bagasse Ash-Stabilised Expansive Soils

Management of agricultural wastes and improvement of construction soils have become increasingly necessary for sustainable development. This study therefore stabilised selected expansive soils using bagasse ash (BA) and lime, with a view to determining the effect of lime on BA-stabilised soils. Two soil samples (identified as Sample A and Sample B) were collected from two identified locations characterised with expansive soils in Ile-Ife, Osun State, Southwestern Nigeria. Using standard procedures, the following preliminary and geotechnical tests were conducted on the soil samples in their natural state: moisture content determination, particle size analysis, specific gravity, Atterberg limits, compaction and unconfined compressive strength (UCS). BA was then introduced to the soils in 5 %, 10 % and 15 % proportions by weight of dry soil. Thereafter, Atterberg limits and UCS tests were conducted on the BA-stabilised soils. Also 2.5 % lime was introduced to each proportion of BA earlier used. Atterberg limits and UCS tests were then conducted on the BA-lime stabilised soils. Results showed that the two soils in their natural state have high plasticity and they both belong to the A-2-7 group. For both BA and BA-lime stabilised soil samples, plasticity reduced with increase in the stabilisers, which implies an improvement in the soil properties. Also, UCS of both BA and BA-lime stabilised soil samples increased with optimum values at 10 % BA content. Expectedly, addition of lime increased the values of UCS for each combination of stabilisers. It was concluded that BA could be used to improve the properties of expansive soils and that the addition of certain proportions of lime does not have a negative impact on the stabilisation properties of BA, but rather improves it.

A Study of the Effect of Addition of Nano SiO2 and Polyamide Fiber toward Swelling Potential Expansive Clay

Expansive clay with great swelling potential requires improvement or stabilization of the soil. It can be successfully done by mechanical and chemical stabilization techniques. This study aims to determine the effect of adding Polyamide (PA) fibre as the material for mechanical stabilization and nano SiO2 as the material for chemical stabilization. The expansive clay used in this study deployed a sample of clay containing mineral montmorillonite with the USCS classification in the high plasticity (CH) category. The mixed materials used include PA fibre with variations of 0.5%, 0.75% and 1% by weight of dry soil and nano SiO2 with variations of 1%, 2% and 3% by dry soil weight. To prove the effectiveness of using nano SiO2, this study compares the treatment with the use of micro SiO2 materials under the same comparison variations. This result indicates that the expansive clay that has been stabilized using PA fibre and nano SiO2 is capable of preventing the swelling potential.

Taxon-specific ability of saprophagous soil macrofauna to reintegrate carbon from agricultural waste into soil

Saprophagous soil macroinvertebrates may potentially degrade agricultural wastes. However, it is not known, to what extent and representatives of which taxa may help reintegrating carbon from crop residues back into soil without triggering massive carbon release into the atmosphere. To tackle this problem, we conducted a three-month-long microcosm experiment with 21 different species of macrofauna (each treatment replicated four times) belonging to 13 families to test their ability to degrade wheat straw. Simultaneously CO2 release from the microcosms was measured. Five species did not survive under experimental conditions. Among the remaining 16 species, three significantly increased wheat straw decomposition with Oryctes nasicornis larvae having inflicted the highest straw mass loss (64%) in comparison with the control, where no animals were added (29%). None of the tested species increased cumulative CO2 evolution from the microcosms, while two species significantly reduced it. The reduction of carbon loss with aerobic respiration was recorded for Cetonia aurata larvae and the earthworm Dendrobaena veneta (respectively 2.5 and 2-fold in relation to the control – 53.8±4.6 mg CO2-C g−1 soil dry weight during the entire experiment). The original integrative Carbon Sequestration Index by Macrofauna (CSIM) calculated for both of the measured parameters suggests that the woodlouse Armadillidium vulgare and to a smaller extent the earthworm D. veneta appear to be the most promising organisms for industrial climate-friendly organic waste recycling in terms of survival, straw processing and simultaneous reduction of CO2 emissions from soil. Our results proved that the engagement of saprophagous macrofauna in crop residue decomposition is a viable technique of carbon reincorporation into the soil. It is accompanied with CO2 release mitigation into the atmosphere.

Landfill intermediate cover soil microbiomes and their potential for mitigating greenhouse gas emissions revealed through metagenomics

Landfills are a major source of anthropogenic methane emissions and have been found to produce nitrous oxide, an even more potent greenhouse gas than methane. Intermediate cover soil (ICS) plays a key role in reducing methane emissions but may also result in nitrous oxide production. To assess the potential for microbial methane oxidation and nitrous oxide production, long sequencing reads were generated from ICS microbiome DNA and reads were functionally annotated for 24 samples across ICS at a large landfill in New York. Further, incubation experiments were performed to assess methane consumption and nitrous oxide production with varying amounts of ammonia supplemented. Methane was readily consumed by microbes in the composite ICS and all incubations with methane produced small amounts of nitrous oxide even when ammonia was not supplemented. Incubations without methane produced significantly less nitrous oxide than those incubated with methane. In incubations with methane added, the observed specific rate of methane consumption was 0.776 +/− 0.055 μg CH4 g dry weight (DW) soil−1 h−1 and the specific rate of nitrous oxide production was 3.64 × 10−5 +/− 1.30 × 10−5 μg N2O g DW soil−1 h−1. The methanotrophs Methylobacter and an unclassified genus within the family Methlyococcaceae were present in the original ICS samples and the incubation samples, and their abundance increased during incubations with methane. Genes encoding particulate methane monooxygenase/ ammonia monooxygenase (pMMO) were much more abundant than genes encoding soluble methane monooxygenase (sMMO) across the landfill ICS. Genes encoding proteins that convert hydroxylamine to nitrous oxide were not highly abundant in the ICS or incubation metagenomes. In total, these results suggest that although ammonia oxidation via methanotrophs may result in low levels of nitrous oxide production, ICS microbial communities have the potential to greatly reduce the overall global warming potential of landfill emissions.

Compaction and strength characteristics of lead contaminated lateritic soil treated with eco-friendly biopolymer for use as road foundation material

Reuse of unwanted soil material due to contamination is one of the available alternative to mitigate the depletion of natural construction material like lateritic soil. Lateritic soil can become contaminated as a result of mining activities. However, assessment of such soil for adequate compaction and strength development is a critical requirement for establishing foundation for road pavement failure of which can result in rapid deterioration of structural integrity of pavement. The research paper investigated the efficacy of Gum Arabic biopolymer (GAB) as eco-friendly additive, in enhancing strength development of lead-contaminated lateritic soil (LCLS) for use as foundation material for road pavement. Varying contents of GAB up to 25% of the dry weight of soil in 5% succession was used in treating LCLS. Compaction characteristics, Maximum Dry Density (MDD) and Optimal Moisture Content (OMC), and California Bearing Ratio (CBR) with microstructural analysis of the treated soil were assessed using three distinct compactive efforts: British Standard Light (BSL), West African Standard (WAS), and British Standard Heavy (BSH). With increase in GAB content, there is a corresponding rise in MDD, while OMC decreased across all three compaction efforts. Optimal CBR values were obtained at 10% GAB content across the three compactive efforts. The Scanning Electron Microscopic (SEM) analysis revealed modifications in the surface morphology occurring at the peripheries of clay particles. The R-squared (R2) values of the regression models derived from statistical analysis of all dependent variables revealed that GAB, MDD, OMC and CE (compactive effort) collectively exert considerable significant effect over CBR values. However, the ultimate strength values fall short of the recommended thresholds for sub-base stabilization. This suggests that a GAB content of 10% enhances the characteristics of contaminated lateritic soil. However, it should not be employed as a sole stabilizer; instead, it could be considered as a potential admixture in cement stabilization.

Phytotoxicity Assay of Cu, Pb and Zn on Launaea cornuta and Sporobolus jacquemontii Grown in Heavy Metal contaminated soil

In this paper, a phytotoxicity assay is used to assess the harmfulness and tolerance of L. cornuta and S. jacquemontii in phytoremediation of heavy metal-contaminated soils. The effects of Pb, Cu, and Zn concentrations in the soil on the number of leaves generated, root and shoot growth, and tolerance indices of the investigated plant species were analyzed. The experimental plants were grown in soil with 0, 100, 300, 600, 1500, 2000, 2500, and 3000 mg/kg dry soil weight (DW for Pb, Cu, and Zn). Sample preparation and laboratory analysis followed the standard methods. Data were analyzed with one-way analysis of variance (ANOVA) using GraphPad Instat 3.1 software. The growth mean of different treatments was compared using Duncan’s Multiple Range Test at p < 0.05. Plants grown in soil containing more than 300/kg DW metal contents exhibited a significant effect on the growth of the root and shoot. Concentrations lower than 300 did not show any significant effects. At 1500 mg/kgDW, the numbers and sizes of leaves decreased very significantly, while at 2000 mg/kgDW both plants failed to survive. The toxic effects of the metals on biomass production showed inhibition in the following trend: Zn>Cu>Pb. The results suggest that hyper accumulator plants can also be affected by metals in the soils on which they grow. Therefore, the application of L. cornuta and S. jacquemontii as phytoremediation plants at higher metal soil concentrations requires the application of soil amendments to minimize the toxicity effect of metal on the plants.

Ridge with no-tillage facilitates microbial N2 fixation associated with methane oxidation in rice soil

Aerobic methane-oxidizing bacteria (MOB) play a crucial role in mitigating the greenhouse gas methane emission, particularly prevalent in flooded wetlands. The implementation of ridge with no-tillage practices within a rice-rape rotation system proves effective in overcoming the restrictive redox conditions associated with waterlogging. This approach enhances capillary water availability from furrows, especially during periods of low rainfall, thereby supporting plant growth on the ridges. However, the microbe-mediated accumulation of soil organic carbon and nitrogen remains insufficiently understood under this agricultural practice, particularly concerning methane oxidation, which holds ecological and agricultural significance in the rice fields. In this study, the ridge and ditch soils from a 28-year-old ridge with no-tillage rice field experiment were utilized for incubation with 13C-CH4 and 15NN2 to estimate the methane-oxidizing and N2-fixing potentials. Our findings reveal a significantly higher net production of fresh soil organic carbon in the ridge compared to the ditch soil during methane oxidation, with values of 626 and 543 μg 13C g−1 dry weight soil, respectively. Additionally, the fixed 15N exhibited a twofold increase in the ridge soil (14.1 μg 15N g−1 dry weight soil) compared to the ditch soil. Interestingly, the result of DNA-based stable isotope probing indicated no significant differences in active MOB and N2 fixers between ridge and ditch soils. Both Methylocystis-like type II and Methylosarcina/Methylomonas-like type I MOB catalyzed methane into organic biomass carbon pools. Soil N2-fixing activity was associated with the 15N-labeling of methane oxidizers and non-MOB, such as methanol oxidizers (Hyphomicrobium) and conventional N2 fixers (Burkholderia). Methane oxidation also fostered microbial interactions, as evidenced by co-occurrence patterns. These results underscore the dual role of microbial methane oxidation – not only as a recognized sink for the potent greenhouse gas methane but also as a source of soil organic carbon and bioavailable nitrogen. This emphasizes the pivotal role of microbial methane metabolism in contributing to soil carbon and nitrogen accumulation in ridge with no-tillage systems.

Performance of Nickel Slag as a Stabilization Material for Soft Soil

The chemical soil stabilization method is an effort to improve soil bearing capacity according to soil work specifications in construction. The use of conventional stabilization materials, such as cement and lime, is considered environmentally unfriendly. Utilizing by-products from the mining industry becomes an alternative that can be developed in soil improvement efforts. This research aims to examine the influence of nickel slag on the enhancement of soil bearing capacity as observed through its unconfined compressive strength value. In this study, the concentration of added nickel slag as a stabilization material is 3%, 6%, 9%, and 12% by dry soil weight. The test specimens used are cylinders with a diameter of 5 cm and a height of 10 cm. Unconfined compressive strength testing is conducted after the specimens are cured for 14 days. The results of this study indicate that the clay soil used is classified as organic clay with high plasticity based on the USCS classification, with an unconfined compressive strength value of 0.2 kg/cm2. The addition of nickel slag with concentrations of 3%, 6%, 9%, and 12% results in respective increases in unconfined compressive strength by 46%, 50%, 68%, and 47%. These findings demonstrate that the optimum nickel slag content of 6% provides the maximum unconfined compressive strength. Therefore, it can be concluded that nickel slag, as a source of silica, has the potential to be used as an alternative material in soft soil improvement.

The stabilisation of clayey soil by using sawdust and sawdust ash

ABSTRACT Soil stabilisation by waste materials has been recently employed to enhance soil engineering properties. The purpose of this study is to compare the impact of utilising sawdust in its raw form versus sawdust ash as a soil stabiliser. This is to determine if sawdust (SD) can be considered as a substitute for sawdust ash (SDA) in order to reduce incineration and air pollution. To fulfil this aim, the Atterberg limits, modified Proctor test, and Direct Shear test were performed on both stabilised and non-stabilised mixtures of clayey soil. The soil was treated with 2%, 5%, 8%, 12%, 15%, and 20% by soil dry weight of both SD and SDA. The findings show that the use of SD and SDA leads to a reduction in the plasticity index and the maximum dry unit weight of the soil while increasing its optimum moisture content. The bearing capacity of the soil was greatest at 5% for both SD and SDA, with SD exhibiting a greater enhancement (31.89%) than SDA. Therefore, it is recommended to utilise SD instead of SDA for soil stabilisation due to its superior effectiveness and less harmful environmental impact.

Effects of polystyrene nanoplastics (PSNPs) on the physiology of Allium sativum L.: Photosynthetic pigments, antioxidant enzymes, phytohormones, and nutritional quality

Nanoplastics (NPs) arouse increasing attention recently. Many studies have shown possible negative effects on plants exposed to NPs, but more data are needed on various species of plants to elucidate the potential phytotoxicity mechanisms of NPs. In this work, a pot experiment was conducted to analyze toxicity induced by polystyrene nanoplastics (PSNPs; particle size, 75.10 nm) at diverse doses (0.05, 0.1, 0.25, 0.5, 1.0 mg/g dry soil weight) to seedlings of garlic (Allium sativum L.). The photosynthetic pigments, antioxidant enzyme activities, common phytohormones and styrene contents, and nutritional quality of leaves of A. sativum seedlings were determined. Results showed that the toxic effects of PSNPs on plants at 42 days after exposure were stronger than those at 28 days. Chlorophyll a, chlorophyll b, as well as carotenoids levels within A. sativum leaves treated with PSNPs for 42 days decreased, with the highest decreasing rates of 40.22%, 41.29%, and 27.38%, respectively. The malondialdehyde (MDA) level within A. sativum leaves was noticeably up-regulated at 0.5 and 1.0 mg/g of PSNPs. Furthermore, the guaiacol peroxidase (POD) and catalase (CAT) activities and the abscisic acid (ABA) contents increased significantly with increasing the concentrations of PSNPs. After exposure for 42 days, allicin, soluble sugar and soluble protein levels decreased with increasing the concentration of PSNPs. The highest styrene content in leaves of A. sativum was obtained for the treatment group of the 0.5 mg/g PSNPs, showing an increase of 23.73% relative to control. Collectively, PSNPs were translocated into the leaves of A. sativum from roots, significantly affected the photosynthetic pigments contents, and significantly induced oxidative stress in A. sativum. Furthermore, high doses of PSNPs exposure impaired the A. sativum’s nutritive quality. These research results can provide basic data for accurately evaluating the ecological toxicity of NPs on crops.

Ferrihydrite-mediated methanotrophic nitrogen fixation in paddy soil under hypoxia.

Biological nitrogen fixation (BNF) by methanotrophic bacteria has been shown to play an important role in maintaining fertility. However, this process is still limited to aerobic methane oxidation with sufficient oxygen. It has remained unknown whether and how methanotrophic BNF proceeds in hypoxic environments. Herein, we incubated paddy soils with a ferrihydrite-containing mineral salt medium to enrich methanotrophic bacteria in the presence of methane (20%, v/v) under oxygen constraints (0.27%, v/v). The resulting microcosms showed that ferrihydrite-dependent aerobic methane oxidation significantly contributed (81%) to total BNF, increasing the 15N fixation rate by 13-fold from 0.02 to 0.28μmol 15N2 (g dry weight soil) -1 d-1. BNF was reduced by 97% when ferrihydrite was omitted, demonstrating the involvement of ferrihydrite in methanotrophic BNF. DNA stable-isotope probing indicated that Methylocystis, Methylophilaceae, and Methylomicrobium were the dominant methanotrophs/methylotrophs that assimilated labeled isotopes (13C or 15N) into biomass. Metagenomic binning combined with electrochemical analysis suggested that Methylocystis and Methylophilaceae had the potential to perform methane-induced BNF and likely utilized riboflavin and c-type cytochromes as electron carriers for ferrihydrite reduction. It was concluded that ferrihydrite mediated methanotrophic BNF by methanotrophs/methylotrophs solely or in conjunction with iron-reducing bacteria. Overall, this study revealed a previously overlooked yet pronounced coupling of iron-dependent aerobic methane oxidation to BNF and improves our understanding of methanotrophic BNF in hypoxic zones.

Optimization of the Atterberg Limits on expansive soil stabilized with chitosan biopolymer

Pavement deterioration can be caused by expansive road subgrade material. Swelling properties are one of the problems on expansive soils. The swelling properties can be decreased by stabilization using additives. The potential of using chitosan biopolymer for soil improvement is attractive due to environmental friendliness and sustainability. This research was conducted to determine the effect of chitosan biopolymer from shrimp shell waste on the Atterberg Limits of expansive soil. This test can be used as an initial assessment of soil strength and stiffness parameters. The Atterberg Limits test was carried out by mixing chitosan biopolymer with a ratio of 0.05%; 0.10%; 0.15%; and 0.20% to the dry weight of the expansive soil. The study’s results showed that adding chitosan biopolymer with a ratio of 0.1% was the most effective in reducing the plasticity index by up to 67% and increase in the shrinkage limit value which is greater than 12%, making the degree of expansion non-severely. The use of chitosan biopolymer is also expected for soil pollution control and remediation.

Improvement of the Bearing Capacity and Swelling of Ciampel Expansive Soil using Waste Foundry Sand

Road construction on expansive soil often suffers damage because of large shrinkage properties due to changes in water content. This study aims to analyze the bearing capacity and swelling of expansive soils stabilized using WFS as an effort to find solutions for improving expansive soils by utilizing local materials based on industrial waste. In this study, the soil was mixed with waste foundry sand as an additive material with a concentration of 2.5%, 5%, 7.5%, and 10% of the soil dry weight. Tests carried out included Compaction, California Bearing Ratio, and Swelling Potential based on ASTM standards. The soil stabilized with 10% WFS showed a significant increase in CBR value with changes of 64.89% (unsoaked) and 438.69% (soaked) to the original soil CBR value. WFS 10% in the soil was able to suppress the expansion value of the expansive soil by 93.16% to the swelling value of the original soil. WFS content of 10% in the soil can be recommended as an expansive soil stabilization material because it can increase the bearing capacity of the soil and reduce the level of swelling of the soil.

Cement Stabilization of soft soil subgrade and Cost Analysis

The soft soil when present in subgrade creates a lot of problem in highways. Due to soft soil subgrade, the rutting is predominant cause of flexible pavement failure all around the world. This kind of soil is either replaced or modified prior to construction of other layers of road to minimize the formation of rut. This study deals with stabilization of soft soil subgrade by cement. The sample was collected from a depth around existing road subgrade. A series of laboratory tests on untreated soil sample was first done to determine the competency of soil as a subgrade layer followed by preparation of sample with varying stabilizer content i.e. 4%, 6% and 8% cement by weight of dry soil, to determine the optimum stabilizer content. Samples with varying cement content were also prepared for California Bearing Ratio (hereafter, CBR) and Unconfined Compressive Strength (hereafter, UCS)with different curing periods i.e. 7 days for CBR and 3, 7, 14 and 28 days for UCS. UCS test on these sample showed a significant improvement over the values of natural soil without stabilizer. CBR showed a similar trend and the resulting modified soil was competent enough to be used as a subgrade for heavy traffic condition. The pavement was modelled using Kenpave for 30 and 50 million standard axle (msa) traffic intensity to determine the ideal pavement section for two types of pavement used in this study. In addition, the cost of construction for replacement method and for cement stabilization are determined using norms of Department of Road and District rate of Kathmandu and are compared. The cement stabilized soil with optimum content is found to be cheaper than conventional method of replacement.

Pengaruh Aplikasi Biochar Tempurung Kelapa dan Pupuk Anorganik terhadap Serapan N P K dan Hasil Tanaman Jagung Manis pada Tanah Gambut

Maize (Zea may ssaccharata) is the horticulture in demand current society this. Limited avalability of land productive agriculture causes agricultural development, especially maize plant using peat soil media. Peat soil are low acidity, and nutrient content macro N, P, K available to plant also low. Attempts made for increasing the productivity of peat soils is by giving biochar and proper fertilization. Provision of biochar and inorganic fertilizer in addition to being a source of nutrients for plants, can also improve the physical, chemical and biological properties of the soil. This study aims to determine the influence of the application of coconut shell biochar and inorganic fertilizers on N P K nutrient uptake and maize crop yields. Research using Complete Random Design (CRD) factorial consists of two factors treatment and three replications. The first factor, namely coconut shell biochar which consist of 3 levels. The second factor, namely inorganic fertilizer consisting of 3 levels so there are 27 experimental units consisting of 2 sets of plants. Based on the results of variance, interaction of coconut shell biochar administration and inorganic fertilizer no significantly influence on all treatments. Whereas the administration of coconut shell biochar has no significant influence on soil pH, K uptake and cob weight, but significantly affected the wet weight, dray weight, N uptake and K uptake. Inorganik fertilizer has no significant influence on soil pH, wet weight, dry weight, N uptake and cob weight, but has a significant influence on P uptake and K uptake. The best cob weight is at A1B3 treatment (biochar coconut shell 55 gram/polybag + inorganic fertilizer 5,1 gram/polybag).

Bacteria degrading both n-alkanes and aromatic hydrocarbons are prevalent in soils

This study was undertaken to determine the distribution of soil bacteria capable of utilizing both n-alkanes and aromatic hydrocarbons. These microorganisms have not been comprehensively investigated so far. Ten contaminated (4046–43,861 mg of total petroleum hydrocarbons (TPH) kg−1 of dry weight of soil) and five unpolluted (320–2754 mg TPH kg−1 of dry weight of soil) soil samples from temperate, arid, and Alpine soils were subjected to isolation of degraders with extended preferences and shotgun metagenomic sequencing (selected samples). The applied approach allowed to reveal that (a) these bacteria can be isolated from pristine and polluted soils, and (b) the distribution of alkane monooxygenase (alkB) and aromatic ring hydroxylating dioxygenases (ARHDs) encoding genes is not associated with the contamination presence. Some alkB and ARHD genes shared the same taxonomic affiliation; they were most often linked with the Rhodococcus, Pseudomonas, and Mycolicibacterium genera. Moreover, these taxa together with the Paeniglutamicibacter genus constituted the most numerous groups among 132 culturable strains growing in the presence of both n-alkanes and aromatic hydrocarbons. All those results indicate (a) the prevalence of the hydrocarbon degraders with extended preferences and (b) the potential of uncontaminated soil as a source of hydrocarbon degraders applied for bioremediation purposes.

Potential application of sludge pond ash as a novel additive for clay stabilization

Clays often have unfavorable geotechnical properties that limit construction applications on them. There is a need for sustainable soil improvement techniques to enhance the strength and stiffness of clays. While previous studies have explored clay stabilization with common supplements like cement, lime and fly ash, the utilization of sludge pond ash (SPA) as a sustainable additive has been limited and there is a lack of understanding of the interactive effects of SPA proportion, moisture content, and curing time on the mechanical behavior of clay. The objective of this study is to examine the mechanical properties of clay enhanced with SPA under different curing conditions. To achieve this, different proportions of SPA were mixed with the clay to obtain accurate findings on the efficacy of SPA addition on compaction and unconfined compressive strength (UCS) of the clay to determine mechanical properties. Scanning electron microscopy (SEM) provided imaging of clay improved with SPA to evaluate the microstructural changes in soil texture. Firstly, the sludge from a pond burned at 1000 °C (the optimal temperature determined by microstructural X-ray diffraction (XRD) analysis) was added to the mixture as 0, 2, 4, 6, 8 and 10% of the soil's dry weight, respectively. The studied samples were prepared with the same energy (equivalent to the standard Proctor test) at different moisture contents and were tested in a uniaxial device at 7, 28 and 56 days of curing. It was found that adding SPA to the base soil decreased the maximum dry unit weight (MDUW). On the other hand, it increased the optimum moisture content (OMC) of the compacted mixture. The study examined the combined effects of moisture content and curing time on the compounds, revealing that these factors induced a decrease and an increase in the UCS, respectively. The addition of SPA as an additive material to the clay mixture was found to exert a significant effect on the strength properties of the clay, with an optimal percentage of around 10%. Empirical correlations were also developed to predict the UCS of the SPA-improved clay with high precision. Furthermore, SEM analyses show that SPA acts as a glue gel between aggregate in the mixture and coat clay particles that changes the blend texture and alters weak bonding to aggregate-like particles. The results of both macro- and micro-scale analyses collectively confirm the superior efficacy of the optimal SPA replacement in enhancing various strength and stiffness properties of the clay.

Feasibility of Strengthening Sandy Soils Using Industry Waste as Geo-Fiber

Abstract Re-using waste generated from daily domestic usage to improve weak soils such as dune sand gives a profitable solution to both environment and the construction sector. In this paper, weak sandy soil was modified with two types of fibers derived from daily domestic use. Plastic bottle waste fiber and tainted polypropylene sediment filter fiber were embedded in the sandy soil with a rate of (0.5%,1%,1.5%, and 2%) by weight of dry soil. Toward this, the direct shear test was conducted to confirm the optimum fiber content and evaluate other parameters such as shear strength, normalized ultimate shear strength, angle of internal friction, and adhesion. The results showed that the 1.5% fiber content showed higher values of angle of internal friction and the normalized ultimate shear strength for both types of fibers. The reinforcement with plastic bottle waste fiber and tainted polypropylene sediment filter fiber enhanced the shear strength parameters and normalized ultimate shear strength. Significant improvement was noticed in the adhesion value with the addition of 2% of tainted polypropylene sediment filter fiber. finally, the effect of fiber addition on the Mohr-coulomb failure envelope was discussed.

The Strength Behaviour of Cement-Treated Clay at Different Moisture Content and Curing Time

This study involves the study on the properties of clay samples from Pagoh at natural state and stabilized state with Portland cement. The main objective of the study is to identify the unconfined compression strength of original and stabilized clay at different moisture content and curing time. The tests carried out include proctor test, moisture content and unconfined compression test (UCT). Therefore, clay was mixed with Portland cement at a concentration of 10 % by weight of dry soil for the proctor test. The original and stabilized samples were tested in an UCT at different curing period of 14 and 28 days. At the end, the actual result shows that the unconfined compressive strength of the stabilized clay is higher than the original. It is believed that the value of strength is highly affected by the different moisture content and curing time. Therefore, the control of water content and treatment time is essential to produce a strong and safe foundation for any construction purpose. As a result, new stabilization methods to prevent landslides in natural and developed quick clay slopes will be developed. In conclusion, cement stabilization improves the workability of clay.