جستجوی مقالات مرتبط با کلیدواژه « soil stabilization » در نشریات گروه « کشاورزی »

Considering the special position of biomass in providing energy in today's world and the increasing use of these renewable resources, it is expected that the production of ash will increase in the future. Therefore, the importance of biomass ash management and recycling regarding environmental and economic aspects has become more apparent. In this study, the properties of ash obtained from different lignocellulosic biomasses were investigated. For this purpose, two methods of electric furnace and open-air combustion are utilized to prepare ash from six types of lignocellulosic biomass, including rice husk, wheat straw, tree branches, MDF waste, recycled fibers from MDF waste and waste paper pulp. The content, dimensions, color, pH and chemical composition of different biomasses were investigated. The lowest content of ash was observed in recycled fibers and the highest amount of ash was observed in rice husk. All the ashes were alkaline. The color of the ashes obtained by the electric furnace method was brighter than that of open-air combustion. The smallest dimensions of the ash particles were related to the pulp ash of the electric furnace method and the largest dimensions were related to the branch ash obtained by the open-air method. The chemical compositions of the ashes were different. The obtained information is useful in determining the appropriate application of ashes.

Increased wind erosion and dust are the country's environmental issues, particularly in the border provinces. Every year, wind erosion and dust have several negative implications in the social, economic, cultural, and health. Dealing with these phenomena necessitates both short- and long-term planning. These phenomena can be controlled in a variety of ways. In this study, the performance of two biological (Microbial Induced Calcium Carbonate Precipitation) and chemical (polyvinyl acetate application) approaches was studied. Sampling was taken from one of the dust sources’ areas in Ilam province (0-30 cm depth). In this study, polymer polyvinyl acetate with five levels of zero (C0), 1 (C1), 1.5 (C2), 2 (C3), and 2.5 (C4), as chemical mulch and Bacillus sphaericus with three factors of bacterial strain (presence or absence of bacteria), nutrient content (with two levels of 0, 0.5 M) and volume of solution (123, 264 and 369 ml) as a factorial experiment in the form of the Completely Randomized Design with three repetitions have been used. The trays were placed in ambient conditions, and wind tunnel, penetration resistance, and aggregate stability tests were performed on all samples after 28 days. A double bacterial spray with 0.5 M of nutrients and a solution volume of 269 ml (BS2 C1 WC2) was shown the most efficient treatment for soil stabilization using the MICP approach. The best treatment for surface stabilization utilizing the chemical method was observed at 2.5 percent (C4). A comparison of these two methods showed that the rate of increase in penetration force, aggregate stability, and decrease in soil loss in the chemical method was higher than in the biological method. In a nutshell, the MICP approach is advised to manage dust storms in Ilam province.

Recently, conservation tillage (controlled) as a soil stabilization factor has been given much attention so that the soil is less disturbed and at least 30% of plant cover to remain on the soil surface. This greatly helps to maintain soil structure and moisture, especially in sloping fields. The fields of the Hezarjarib Behshahr region are steep, and due to the cold and dry climate and the wind blowing most of the year, it is very important to stabilize and maintain the soil moisture and structure and prevent it from being washed away by the wind. On the other hand, the sloping lands of this region are under dryland cultivation of wheat and barley, which have little income for farmers and require alternative crops. In this way, Black cumin (Nigella sativa) plant is a valuable substitute for them. Therefore, the purpose of this study was to investigate the effect of controlled tillage to cultivate black cumin plants on energy consumption, physical properties and soil protection, as well as plant performance in the sloping lands of Hezarjarib Behshahr region.

The investigated parameters included the required draft force by tillage tool, tractor fuel consumption, and changes in the degree of soil fragmentation and permeability before and after tillage. The input variables included root cutter supplement in two levels (without and with root cutter), tillage depth in two levels (35 and 28 cm for chisel) and forward speed in two levels (low gears 1 and 2). Considering 3 replications for each treatment, a total of 24 experimental plots with 2m width and 40m length were created with the random complete block design (RCBD) method and perpendicular to the slope. Regarding the yield and yield components of black cumin, after harvest, biological yield parameters, root weight, root length, root diameter, the width of root distribution, number of follicles per plant, number of seeds per follicle, thousand seed weight, plant height, stem diameter and performance were measured per unit area.

The results showed that the effect of the input variables was significant only on the required draft force by tillage tool and the tractor fuel consumption, in addition to the biological yield and the yield per unit area of black cumin. The use of a root cutter increased the required draft force by tillage tool and tractor fuel consumption, while harmed soil permeability and crushing, seed weight, biological yield and yield per unit area of black cumin. The use of higher forward speed leads to an increase in draft force and fuel consumption, and the absence of root cutter, leads to a decrease in soil permeability and fragmentation, biological performance and yield per unit area of the black cumin at a greater depth of tillage, while at a lower depth, no significant (5%) difference can be seen between the two speeds. Increasing the depth of tillage up to the range of vertical root growth due to the negative draft of the tillage tool has reduced the draft force and fuel consumption and had a positive effect on soil permeability and crushing plus crop yield.

The best-researched treatment was the used triple action tillage tool, without root cutter supplement, greater ploughing depth and forwarding with low gear 1. In this way, it will be possible to save 25% in fuel consumption due to the negative draft of the rotary plough, increase the depth of the plough and reduce the required draft force by 25%, increase the biological yield (straw) by 25% and increase the yield by 45%.

Since clay is widely used in most construction projects, the issue of improving clay soils has considerable importance. This study aimed to optimize the variables affecting the properties of geopolymer and improve their mechanical properties using Isfahan blast furnace slag. Taguchi's statistical design method was used to model three process variables (blast furnace slag, water, and alkali sodium hydroxide agent) with four different values in the mixing design. Geopolymer was used to optimize the uniaxial compressive strength. Sixteen geopolymer compositions determined by mini-tab software were prepared and their uniaxial compressive strength was measured. The obtained results were modeled by analysis of variance, and then the interactions of the three variables on the uniaxial compressive strength of geopolymer were investigated using two and 3D diagrams. Then, the variables were optimized and the proposed values for the optimal sample were examined at temperatures of 25, 50, and 70°C and at times of 3, 7, 14, and 28 days of operation. A comparison of the results predicted by the models and the results of the experiments confirmed the validity of the models. Also, the scanning electron microscopy (SEM) images showed that the porosity will reduce from 7 to 28 days. It indicated that the use of the geopolymerization method has a significant role in stabilizing weak clay soils with low plasticity. The effect of fibers and geopolymer to reinforce was also investigated and for better evaluation, it was compared with soil stabilization with Portland cement. The results showed that in the most optimal geopolymer composition, the bearing resistance of clay has increased by more than 3400%. Meanwhile, fibers along with geopolymer with optimal percentage and length (0.1% by weight of geopolymer composition and length of 12 mm) were able to increase the uniaxial compressive strength of clay by nearly 4000%, which shows the excellent effect of using cellular fibers parameter whit the geopolymer in this research.

The root of trees is one of the most important living materials for stabilizing and reinforcing the cut and fill slopes of forest road. This study was conducted to investigate the tensile strength of tree species according to changes in lignin, cellulose and root extracts content.

Darabkola forest in the southeast of Sari-Iran was selected for this study. To determine the tensile strength of tree roots, root samples from tress including the beech, hornbeam, alder, Zelkova carpinifolia, Persian Ironwood and oak were collected by soil profile trenching method and then the test of tensile strength was performed. The amount of lignin, cellulose and ash for the roots of different tree species was also measured in the laboratory. One-way anova was used to compare the means of roots tensile strength and also multivariate analysis was used to classification of species based on cellulose, lignin, ash and other extracts content.

The results showed that in beech, alder and Persian Ironwood, the measured rates of lignin were higher than cellulose levels. While in the Zelkova carpinifolia, the amount of cellulose was higher than others parameters, in beech and alder species (with higher lignin rate) the means of tensile strength was recorded less than other species, and for oak and hornbeam with higher cellulose levels, tensile strength was recorded higher than other species. The results of multivariate analysis based on tensile strength and numerical values of root decomposition showed three groups with high adaptability percentage (alder-beech, hornbeam-Zelkova carpinifolia and Persian Ironwood-oak).

According to the results, investigating the amount of lignin and cellulose in roots of different species as well as discriminant analysis with consideration of different factors can be a scientific method to select best species for soil bioengineering projects.

Desertification has become one of the main problems of human societies living in the vicinity of desert areas in recent years. One of the methods that have been considered in recent years and are rapidly expanding in the field of soil mechanics is the Microbial Induced Carbonate Precipitation (MICP). In this method, urea-positive organisms that are naturally present in the soil can stabilize the soil and improve its engineering parameters by using urea and calcium chloride. Recently, attempts have been made to use this method to create a crustal layer on the soil to prevent wind erosion. In the present study, the effect of environmental conditions in deserts such as temperature and sand bombardment on microbial soil treatment has been investigated using this new method. The soil of the Segzi region as one of the main centers of dust in the Isfahan region was studied in this research. Therefore, the improved samples are subjected to regional temperatures which increased the surface layer resistance with increasing temperature. Also, the sandstorm conditions of the region were simulated using three different grain sizes of sand inside the wind tunnel. The results of these experiments showed that stabilized soil could withstand the conditions at wind speeds of 7 and 11 m/s. However, by increasing the wind speed to 14 m/s and the grain size, the crustal layer destroys and increases the wind erosion of the soil. Also, the resistance of the surface layer increased by increasing temperature in the tested samples. This increase in resistance continued up to 24 degrees with a high slope, but from 24 degrees onwards, this slope decreases. Based on the results of this research, it can be said that the microbial improvement method can be used as an alternative method in the future to stabilize desert soils.

In order to strengthen and stabilize the soil masses in the range of soil till optimum, it should be used appropriate stabilization methods. The purpose of this study was to evaluate the effect of excess ash as an additive to soil and improve soil properties. To do this, 15 soil samples from the forest road fill slope were randomly selected combined with 3, 6, 9 and 12 weight percent logging residual ash. In order to investigate the effect of addition of stabilizing agents on the chemical and mechanical parameters of soil in the studied area, the experiments Atterberg limits, California bearing ratio, moisture as well as acidity, electrical conductivity, phosphorus, nitrogen, organic matter and carbon were carried out on control and treated soil samples. Data were analyzed using one-way ANOVA and Tukey tests were used to compare the averages. The results of the experiment show that the addition of logging residual ash increased plastic limit and California bearing ratio and reduced liquid limit and plasticity index. Also, the results of one-way ANOVA showed that the mean difference in moisture, acidity and nitrogen were not significant (P>5%) while electrical conductivity, phosphorus, potassium, organic matter and carbon showed significant differences.

The stabilization of the dried-up lakebeds is necessary. Recently, biocrust formation/ restoration through the microbial inoculation has been considered to stabilize the moving sands. Accordingly, this study planned to evaluate the possibility of using cyanobacterial inoculation and stimulation in stabilization of the moving sands beds of Lake Urmia at the laboratory conditions. To this end, the bulk samples were taken from Jabal-Kandi region (from Urmia) as a hotspot region for the moving sands, and the samples poured into the erosion trays. The most suitable existing cyanobacteria for the soil stabilization were selected, purified and proliferated from the origin soil. The stimulant nutrient (CHU10) was also prepared by dissolving various nutrients in sterile water. Then, the three treatments of control, stimulation of cyanobacteria, and inoculation of cyanobacteria were prepared by adding 1 l m-2 of sterile water, CHU10, and cyanobacterial solution at three replications. After 120 days, the wind (72 km h-1 for 30 min) was simulated on the trays. The rate of the wind-induced sand transport from the control, stimulated, and inoculated treatments were 1.58, 1.35, and 0.05 kg m-2 min-1, respectively. We found that both stimulated and inoculated methods significantly reduced (P< 0.01) the wind-induced sand transport by 14 and 96%, respectively, as compared to control. However, the inoculation of cyanobacteria was more effective than the stimulation of cyanobacteria. Assessing the scanning electron microscopy images from the soil surface also confirmed the ability of cyanobacteria in increasing the strong bindings between soil particles. Furthermore, inoculation of cyanobacteria increased the soil organic matter content and aggregate stability of the study soil, as important indicators of soil stability, by 162 and 106%, respectively. However, the inoculation of cyanobacteria under natural conditions is necessary to achieve an effective way in stabilizing dried-up beds of Lake Urmia.

Construction of proper foundation for water structures such as canals increases their long life. One of the effective factors in this issue is soil strength condition. Chemical compounds of the soil affect its strength and change its bearing capacity. Sodium and Calcium are the most important cations in the soil and water resources. In recent years, because of its environmental compatibility and economic advantages, fine sand has been used widely as an additive amendment for soil remediation. In this research, the effect of calcium chloride and sodium chloride as well as fine sand, as additive material, on the strength characteristics of clay soil have been investigated. In this regard, the additive materials (salt and sand) were added to the clay soil at four different levels (0, 5, 10, 20 and 0, 5, 10, 15 percent of the soil dry weight, respectively) and specimens were provided by static compaction method. The specimens were subjected to an unconfined compressive strength test after two curing times of 7 and 28 days.  The results showed increasing sodium chloride decreases the strength characteristics of the soil and adding fine sand does not have any significant effect on this trend. Also, adding 5 percent sand and calcium chloride to the clay soil caused to obtain maximum unconfined compressive strength and elasticity module of it. On the base of the results, adding calcium chloride improve soil strength relatively but not as much as other common additives, such as lime. Moreover, for increasing the strength of soils with large amounts of sodium chloride, soil leaching is suggested as a proper solution before foundation construction of the structures.

Nowadays, the destructive phenomenon of desertification and wind erosion is one of the most important environmental crises in the world, which are serious challenges to sustainable production and agricultural land management. In the present study, the effect of microbial precipitation of calcium carbonate has been studied as a biological reformer and compatible for controlling wind erosion and soil stabilization. For this purpose, erosion rate of bio-cemented samples was investigated through ….in a wind tunnel under the condition of wind velocity of (0 to 98 km hr-1) in two soil types with sandy and silty texture in a completely randomized design in three replications. Investigation of the threshold velocity of soil particle movement revealed that air dried soil particles begin to move at the velocity of 8 and 10 km hr-1 in the silty and sandy soils respectively, however, in all biological samples (MICP) particles did not move at 97 km.hr-1. The results also indicated that the weight loss of all MICP treatments at different wind velocities were significantly reduced as compare to the control. The amount of the soil loss among biological cemented samples and control treatments were dramatically different at higher velocities. So that, at velocities more than 57 km/h, soil losses indicated significantly enhancement in control, whereas in the soils which are treated by bacteria, soil losses were insignificant and approximately 2.5 kg.m-2.hr-1. The results also showed that the equal's amount of calcium carbonate and the penetration resistance of the soil surface increased significantly in MICP treatments as compare to control treatments, this event indicated the formation of a surface-resistant layer on bio-treated cement samples. In this study, the comparison of used bacteria also showed that Bacillus infantis and Paenibacillus sp3 have high efficiency in controlling wind erosion. Therefore, it seems that cementation by biological methods could be an effective way to stabilize surface particles and control soil erosion.

In this research, laboratory studies were carried out to improve a clay soil by adding calcium ion through Electrokinetic method Experiments were performed in a special device using distilled water firstly, as the reference test and calcium chloride solution with the concentration of 0.25, 0.5, 1 and 1.5 molar secondly, as an anode reservoir fluid under the influence of 52-volt voltage during 7 days. During the experiment, the pH value was measured for electrolyte at the anode and cathode reservoir. Also, volume of water discharged from the cathode reservoir was measured at a given time interval. After the tests, shear strength of the soil was measured at different distances from the anode. The results showed that the calcium injection into the soil increases shear strength of the soil, and its amount depends on the concentration of calcium chloride solution, so shear strength increases by increasing concentration of the calcium chloride solution.

In this study, Nano-polymer CBR PLUS is sued for soil stabilization in forest roads. Tests were carried out to identify the texture, Atterberg limits, compaction and CBR on the control and treated soil samples with different percentage of 0.25%, 0.50%, 0.75% and 1%. In order to study the mechanical characteristics of upper layer, five plots including one control plot (untreated) and four sample plots were carried out on forest road. The results showed that the Nano-polymer reduced liquid and plastic limits. By increasing the percentage of CBR PLUS, the soil fine particles decreased in control and treated samples, in which that 1% treatment has the minimum content in weight percent of soil fine particles and maximum content in coarse particles compare to other treatments. Also soil treated with CBR PLUS, reduces the optimum moisture content and increases maximum dry density and California Bearing Capacity (CBR). Investigation of chemical properties showed that the amount of Calcium, Magnesium and Potassium increased in runoff. It was concluded that 1% of Nano-polymer CBR PLUS acted better in comparison with other treatments.

Today, the use of the biological stabilizers of soil such as ashes and nano-particles has been concerned to accelerate and improve the stabilizing process of the swelling soil of road bed. In this study the swell soil was brought from the routes of recommended forest road in district two of Bahramnia forest management plan in Golestan province according to the appearance and performance properties of soil. At first, for preparing the soil stabilization treatments the mixtures of 0.5% montmorillonite nano clay and 2% reed ash (Phragmites australis (Cav.) Trin. ex Steud.), 1% nano clay and 4% ash, 1.5% nano clay and 6% ash and 2% nano clay and 8% ash were added to soil and then mixed for 5 minute to access homogenous mixture without lump. After the curing time of 7, 14 and 28 days from the stabilization time, the Atterberg limit, standard proctor, unconfined compressive strength and Californian bearing ratio tests were done for 4 replications on mixtures of soil and control sample. Results showed that adding reed ash and nano clay increased the plastic limit and decreased the liquid limit and plastic index. Moreover, with increasing the amount of additive materials in the soil, the maximum dry density of the mixture decreased and optimum moisture content increased. The CBR and unconfined compressive strength of the mixture increased considerably until adding 1.5% nano clay and 6% ash and then adding more additive materials didn’t change the soil strength. In this study increasing the curing time, caused that the maximum dry density and soil strength to increase, whereas the plastic index of the mixture decrease. So, the optimal treatment of 1.5% nano clay and 6% ash and curing time of 28 day is recommended for stabilization of clay soil in study area

Using some additive materials to gypsum soil can increase its compressive strength and erosion and make it fit for civil projects in irrigation networks. In this study, (Journal No. 268., 2003) five levels of cement (5, 8, 10, 12 and 15 % to dry soil) and three levels of micro silica (0, 5 and 10 % cement) were added to the local soil. The processing of soil samples were conducted in two temperature (27 and 400C) and their compressive strength was studied and analyzed via SAS statistical software. In the present research, the best combination, with the minimum addition and a high compressive strength, was reached by adding 10% cement and 10% micro silica to the soil. In order to evaluate the sample’s erosion potential, it was exposed to water jet plane in four angles (Ө = 0,30,60, 90), five speeds (V = 2, 4, 6, 8 and 8.64 m/s) and three times (T =4,8 and 12 hr) and the highest weight loss erosion (dw) was observed between the speed of 4 to 8 m/s and the time of 8 hours later in a horizontal state (0 Ө =). .

Sugarcane bagasse is one of the agro-industry wastes that its maintenance and disposal makes some problems for the factories managers. In this research, the effects of lime and bagasse fly ash on the strength characteristics of a clayey soil were studied. For this purpose, 20 treatments were made by adding of different amounts of lime and bagasse fly ash to a high plastic clayey soil. In such a way four levels of lime including 0, 1, 3 and 4percent and five levels of bagasse fly ash including 0, 2, 5, 8 and 12 percent by dry weight of soil. In addition and bagasse were added to the soil with percentages of 2, 5, 8 and 12 for bagasse ash. Then, considering two curing times (7 and 28 days) and three replications, 6 specimens for each treatment and totally 120 specimens were made by using of Harward miniature compaction apparatus. The prepared samples were then tested for unconfined compressive strength at their curing ages. The results showed that the adding of Bagasse fly ash and lime increases the optimum water content and reduces maximum dry density of the clayey soil. It is also found Furthermore,The combination of 8% sugarcane bagasse ash with clayey soil has increased the compressive strength of soil by 92%. Moreover, addition of bagasse ash to the mixture of clayey soil-lime reduces the amount of unpressurised compressive strength and of the elastic modulus. According to the experimental mixtures, the combination of 2% sugarcane bagasse ash with 4% lime was obtained as the optimum composition.

This paper presents the results of an experimental program developed to investigate the effect of an additive agent branded CBRPLUS on the mechanical behavior of a forest soil with high plasticity. Various experiments consisting of Atterberg limits, standard compaction, California bearing ratio (CBR), swelling potential and swelling pressure were conducted on natural soil and soil stabilized with various percentages of CBRPLUS. The results indicated that the addition of this material (at the rate of 0.05%), significantly changes the physical and mechanical properties of rehabilitated soil, including, reduction of the liquid limit (at least 6%), plasticity index (at least 9%), swelling potential (at least 27%), and swelling pressure (at least 45%), and also increasing the bearing capacity of soil (at least 53%); hence, the improvement of soil properties is a function of mass percentage of CBRPLUS. Furthermore multiple regression models were developed for CBR, swelling potential and swelling pressure as a function of additive agent percentage, plasticity index and maximum dry unit weight with accuracy and a high degree of agreement between experimental and predicted values. In addition a sensitivity analysis was also performed to investigate the effect of various parameters on CBR, swelling potential and swelling pressure values.

Application of chemical polymers is one the effective methods for stabilization of soils. In this research, the effects of Polyvinyl Acetate Polymer on stabilization of soils and erosion control has been investigated. To do this, three different soils types were treated with five levels of Polyvinyl-Acetate emulsion and cured for three ages. Thus, considering three replication for each samples totally 135 specimens were prepared and tested for determination of their compressive strength. Statistical analysis of the results showed that the adding of polymer increases the compressive strength of the samples significantly, where the rate of increase depends on soil texture and varies from 15 % in clayey samples to 400 % in sandy soils. Furthermore, the compressive strength of the samples significantly affected by the age of the samples and deacreased upto 15 and 28 percet after 3 and 6 months respectively. Also based on durability tests, addition of polymer to the samples makes the sandy samples durable but has no effect on the durability of clay samples. Finally, application 25 g of polymer per square meter of soil was determined as the optimal treatment to stabilize the studied soil.

Mulch is one of the most common materials for soil stabilization which prevents wind erosion and dust emissions. In this respect, the sustainability of mulches against corrosive environmental factors is important for selection. In this study, the resistance of some abiotic mulches was examined in simulated desert conditions against pressure by pocket penetrometer at different temperatures. Also, to evaluate the amount of surface leaching, the mulches were tested against spraying water as well. Treatments include 13 types of mulches, nano-polymer mulch, sand, stone powder, sludge and clay soils. Two types of eroded soils including moderate and severe soil erosion and three levels of temperature including ambient temperature, 50 ºC, 60 ºC all of them with three replications were studied. The results showed that sprayed polymers on severe soil erosion and under both 50 ºC and 60 ºC temperatures had the maximum compressive strength. Also the results of spraying water on the treatments showed that polymeric mulch was more resistant against leaching than others.

Stabilization، alter and improvement of engineering properties of soil are for providing predetermined goals. The most important aim of soil stabilization is increasing long term soil strength، but in very wet and loos lands the other aim of soil stabilization، is to decrease plasticity characteristic of soil، which are tested by Atterberg limits tests. Since the road soils of Namkhane District of Kheyrud forest، have fine grained texture، with high clay content and high plasticity، it''s necessary to attempt to improve the mechanical properties and stabilize the soil، before road construction work starts. Nowadays with new technologies، polymer materials have been released. In the present study، compaction and Atterberg limits tests on samples of natural soil and treatment soils with different percentages of 2 types of polymer material CBRPLUS and RPP were studied. Also due to determine the effect of time on performance of these polymer material، samples treated with 0. 05% CBRPLUS and 0. 03% RPP prepared، stored for 7 and 14 days and then Atterberg limits tests were conducted on these samples. Result showed that with the addition of difference percentage of CBRPLUS to soil، liquid limit was changed between 3. 27 and 22. 05 and plastic limit was changed between 0. 94 and 6. 97. The plasticity index decreased between 4. 8 and 32. 5. Adding RPP decreased the liquid limit between 4. 93 and 14. 27، plastic limit between 3. 14 and 8. 57 and plasticity index between 13. 22 and 24. 03. The results of Atterberg limits indicate that add this material causes improvement of plasticity properties of soil، and treatment time technical has no significant influence on plasticity properties of soils. Also results of compaction test indicate that add CBRPLUS to soil، increase maximum dry density between 1. 58 and 9. 85 and optimum moisture between 3. 57 and 23. 21. Adding RPP، somewhat (0. 75 and 1. 58%) improve the maximum dry density of soil. It has no effect on optimum moisture. Generally according to achieved results، add this material to soil cause relative improvement of soil characteristics.