Soil Improvement

Chalk breaks easily when subjected to human action such as mechanical handling, earthworks operations or pile instal- lation. These actions break the cemented structure of chalk, which turns into a degraded material known as putty, with lower strength and stiffness than the intact chalk. The addition of Portland cement can improve the behaviour of chalk putties. Yet, there are no studies determining the tensile strength of chalk putty–cement blends, the initial stiffness evolution during the curing time and other design parameters such as friction angle and cohesion of this material. This paper addresses this knowledge gap and provides an interpretation of new experimental results based on the dimensionless index expressed as the ratio between porosity and volumetric content of cement (g/Civ) or its exponential modification (g/ Civa). This index aids the selection of the amount of cement and density for key design parameters of compacted chalk putty–cement blends required in geotechnical engineering projects such as road foundations and pavements, embankments, and also bored concrete pile foundations.

This paper examines biocementation via the microbial-induced carbonate precipitation (MICP) process as an appropriate and promising new technology for stabilisation of loose sand and silty sand deposits as a method to mitigate wind erosion. The technique involves spray treating the sand surface layer with a mixture of cementation and bacterial-cell solutions, the ensuing reactions causing calcite precipitation to occur between the sand grains, thereby lightly cementing them together over time. The bench-scale experimental programme presented investigates the proposed technique's effectiveness for stabilisation of silica and carbonate sands with different gradations, determination of the optimal reagent concentrations, the time-dependent shear strength development for the crustal sand layer following single-and double-MICP spray treatments, as well as wind tunnel experiments. Of particular novelty were investigations of the effect of dew formation on crustal shear strength development with curing period and the efficiency of the MICP treatment for the outdoor environment compared to laboratory-controlled test conditions. The wind tunnel experiments demonstrated that 28-day cured singly MICP-spray-treated crustal sand layers were stable to simulated 20 m·s−1 winds measured at 20 cm above the layer surface.

Liquefaction is a hazardous seismic-based phenomenon, which causes an abrupt decrease in soil strength properties and can result in the massive destruction of the built environment. This research presents a novel approach to reduce the risk of soil liquefaction using jet-grouted micropiles in clean sands. The saturated soil profile of the study project mainly contains clean sands, which are suitable to more reliably employ simplified soil liquefaction analyses. The grouting is conducted using 420 micropiles to increase the existing soil properties. The effect of jet grouting on reducing the potential of liquefaction is assessed using the results of the cone penetration test (CPT) and the standard penetration test (SPT), which were conducted before and after jet grouting by implementing micropiles in the project sites. According to three CPT-based liquefaction analyses, the Juang method predicts the most effective improvement range of the factor of safety in the clean sand. The Boula...

Industrial waste is one of the most important sources of environmental pollution in the world and Egypt. Providing economic opportunities for recycling these wastes represent an essential solution to this problem to encourage waste producers to dispose it safely and to provide an added value for these wastes. This research work will study the feasibility of recycling certain industrial wastes for production low-cost building materials and improving the soil compaction characteristics. In this research work, the efficiency of recycling some common local industrial wastes in production of construction materials was explored. The selected wastes include cement kiln dust (i.e. bypass) and ceramics powder. Previous researches and the chemical analysis showed that both wastes are promising as cement replacement materials. However, this exploratory phase is an initial investigation targeting the chemical properties of theses wastes for efficient use of both wastes to replace cement – parti...

Soil improvement by means of stone column method is used to improve sabkha soils in order to limit total and differential settlement and to achieve the required bearing capacity. Full-scale plate test was performed on site to confirm the achievement of required bearing capacity at the specified settlement. Despite the fact that this technique is widely used to improve sabkha soils, there are no studies focusing on the behavior of stone columns in such problematic soils. Sabkha soils are known for its high compressibility, low strength and water sensitivity due to loss of salt cementation upon flooding during installation of stone columns. Numerical modeling of plate load test assist to understand complicated behavior of sabkha-stone column interaction. This paper presents a three-dimensional Finite element model, using PLAXIS 3D software, to simulate vertical plate load tests on a stone column installed in sabkha. The predicted settlement values are in reasonable agreement with the field measure values and the field load-settlement curve can be predicted with good accuracy.

The continuous growth in civilization and population have led to upsurge in generation of construction and demolition (C&D) wastes. A considerable part of C&D wastes is gypsum wastes that together with its derivatives are classified as a group of binding agents in soil stabilization and immobilization and upgrading soil durability. In this study, the possibility of using gypseous wastes as a binding agent was investigated. Moreover, soil stabilized with recycled gypsum was tested under different dry-wet cycles as well as multiple dry-rewetting to assess the stability of improved soil. Different amounts of gaseous waste (0, 5, 10, and 20%) and 5% cement and 5% lime were added to clay soil at various curing conditions (0, 7, 14, and 21 days). Then, durability of samples was tested by wetting/drying cycles (0, 1, 2, and 3 cycles). Soil characteristics including compaction, unconfined compression strength, Atterberg limits and soil durability were assessed for all samples. Results demonstrated significant increase of the unconfined compressive strength in clay by addition of gypsum waste, cement, and lime. However, we detected a significant reduction in the unconfined compressive strength of the samples in the third cycle of wetting-drying test.

Soft soils such as clay soils, mostly if they comprise swelling minerals may produce great damage to structures, particularly when these soils are exposed to wetting and drying situations. The geotechnical properties of soft soils could be enhanced by utilizing chemical additives. In this paper, granite waste dust was used to adjust the properties of clay soils. This paper investigates the effect of granite rock dust on the geotechnical properties of soft soil. The particle size distribution, Atterberg limits, compaction, California bearing ratio (CBR) and direct shear strength characteristics of the soil when blended with various percentages of granite dust were evaluated. The findings show a great increase in the maximum dry density, optimum water content, direct shear strength and CBR with increasing the amount of granite dust. The best results obtained for CBR values were when the soils mixed with 8% granite dust. Although these findings indicate great improvement in the geotechnical parameters of clayey soils, the higher strength established is not enough for the enhanced soil to be utilized as a base material in the construction of heavily-trafficked flexible pavements. However, this modified material can be used as a base material for moderate traffic roads and as a sub-base material for high traffic roads.

This study concluded the results of a research on the features of cement based permeation grout, based on some important grout parameters, such as the rheological properties (yield stress and viscosity), coefficient of permeability to grout (kG) and the inject ability of cement grout (N and Nc assessment), which govern the performance of cement based permeation grouting in porous media. Due to the limited knowledge of these important grout parameters and other influencing factors (filtration pressure, rate and time of injection and the grout volume) used in the field work, the application of cement based permeation grouting is still largely a trial and error process in the current practice, especially in the local construction industry. It is seen possible to use simple formulas in order to select the injection parameters and to evaluate their inter-relationship, as well as to optimize injection spacing and times with respect to injection source dimensions and in-situ permeability. The validity of spherical and cylindrical flow model was not verified by any past research works covered in the literature review. Therefore, a theoretical investigation including grout flow models and significant grout parameters for the design of permeation grouting was conducted in this study. This two grout flow models were applied for three grout mixes prepared for w/c=0.75, w/c=1.00 and w/c=1.25 in this study. The relations between injection times, radius, pump pressure and flow rate for both flow models were investigated and the results were presented. Furthermore, in order to investigate these two flow model, some rheological properties of the grout mixes, particle size distribution of the cement used in this study and some geotechnical properties of the sand used in this work were defined and presented.

The soil exploitation for intensive agricultural production such as tillage, chemical fertilizer and pesticide uses, monoculture cropping and continuously crop cultivation (without fallowing system) caused soil degradation and resulted some environmental pollutions. The application of green manure can be one of the alternatives in order to minimize the negative effects of some applications in intensive agriculture practices on the soil and the environment. The application of green manure increases soil organic matter and nitrogen and keeps the availability of other soil nutrients. The use of legume forage crops as green manure can increase the amount of nitrogen in the soil by atmospheric nitrogen fixation. This makes it more economically efficient than other green manure and chemical fertilizers. The legumes have a taproot that can absorb the nutrients from the deeper soil and improve the physical structure of the soil. For these reasons, this study discusses the importance of legume forage crops as green manure crops for the soil sustainabilities.

When predicting settlement in Texas Gulf Coast clays, engineers often use empirical relationships based on a series of 78 consolidation tests reported by . A study of consolidation characteristics of Gulf Coast clays. Proceedings of Texas Section of ASCE, Fall Meeting, San Antonio, Texas, September 18-21, 152-160. This paper provides an additional 156 consolidation tests on Gulf Coast clays and corresponding empirical relationships for predicting foundation settlement. This study shows that using data from the 156 samples results in predicted settlement that is three to five times that when using the relationships from the 1996 study and therefore gives engineers a more information when evaluating whether increased costs are justified for site-specific exploration programs.

Expansive soils are problematic due to the presence and consequent effect of their
clay mineral constituents, which makes them show the volume change characteristics.
The expansive and shrinkage behavior makes expansive soils unsuitable for direct
engineering application in their natural form. In an effort to make them more
practicable for different engineering applications, various additives and techniques
are employed to improve the soil properties. Stabilization of soil with lime, cement,
bitumen are expensive and therefore they are in need of an economic replacement.
Further, replacement of expansive soils with good quality soil is quite uneconomical.
The present investigation considers the effect of Egg Shell Powder (ESP) on expansive
soil. The ESP Eggshell is a desecrate material from domestic sources such as
poultries, hatcheries, homes and fast food hotels. Proper utilization of the ESP in
conjunction with soil, if proved effective, could mitigate environmental pollution to
larger extent. The Rock Dust (RD) which is being thought of as alternative to sand in
the construction field, has been used, in proportion of 10-30%, in combination with
optimum content of ESP for deriving maximum advantage of improving the
engineering characteristics of soil. The sample of expansive clay has been extracted
from Emani village of Duggirala Mandal of Tenali revenue division of Andhra
Pradesh. The laboratory tests were conducted to find out the effect of these additives
on consistency limits, compaction properties and California Bearing Ratio (CBR) at
soaked condition. The purpose of the study is essentially to suggest the optimum
combination to practicing engineers for use in various reengineering applications

The existing soils in the nature that is used for construction cannot necessarily bear the loadings on the structure. For example, in granular soils, the natural soil may be very loose and show a lot of elastic settlement. Sometimes, there are soft layers, saturated clay and swelling soils at the lower depths, which may cause significant settlement in the structure in terms of foundation load and clay layer thickness. To avoid such settlements, it is necessary to use certain techniques to improve
the soil condition. One of the methods that have recently been widely used to reduce the settlement of soft soils and swelling soils is stone columns or single piles. In this research, first of all, the parameters in need for the analysis will be gained by using the experimental data, and then, the static and dynamic behavior of the confined stone columns is examined with geotextile and without geotextile by a group and single manner as in two-dimensional form using Plaxis numerical method of the finite element and the impact of the following parameters will be investigated in both static and dynamic modes: Column length, column diameter, single and group behavior of columns, and soil cohesion effect on the behavior of the confined stone column in geotextile and reduction of soil settlement during use of stone columns. The results of this research indicate correct understanding of the use of geotextile (Woven Geotextile with a specific elastic normal strength) to prevent the camber and the settlement of the column and increase of the strength and bearing capacity of the column.

The construction of railway embankments on loose beds using reinforcing elements results in a modification of the embankments slope, which significantly reduces the amount of earthworks. In addition, reinforcement of both bed and embankment is essential to increase the load-bearing capacity and control the settlements. A solution for high railway-embankment stabilization and enhancing the operational axle load is the use of micropiles in the embankment toe to transmit the applied loads to the firm underlying layers and avoid the deep sliding of loose subgrade. This paper presents three experimental models of embankments of 10 m in height on a scale of 1=20 to set up a number of loading tests: one based on a non-reinforced embankment and two others based on reinforced embankments that are stabilized with two different arrangements of micropiles. During laboratory tests, the data, including the load-bearing capacity of embankments, displacements of embankment crest and bed surface, and axial strain of micropiles were measured using the instrumentation tools. In the next step, three numerical models were developed by using the PLAXIS-3D code based on the FEM. Then, a comparison was made between the experimental and numerical data to verify the outputs of the numerical analyses. In the procedure of numerical analyses, elastoplastic behaviors of embankment material and bed were defined based on the Mohr-Coulomb failure criterion, and micropiles were considered as linear elastic elements. Finally, after accomplishing a series of sensitivity analyses on the geometric parameters of micropiles, their efficiency factor was classified in the process of arrangement optimization.

Strengthening beach sand using enzyme induced carbonate precipitation (EICP) was demonstrated. Enzyme induced carbonate precipitation (EICP) is an emerging biologicallybased ground improvement technique that precipitates calcium carbonate within the pores of a granular soil via hydrolysis of urea catalyzed by free urease enzyme. In this study, samples of a natural beach sand were treated using an EICP solution at one, two, and three cycles of treatment (one pore volume per treatment cycle). Strength and carbonate content of the treated specimens were measured using unconfined compressive strength (UCS) testing and acid digestion. X-ray diffraction analysis and scanning electron microscopy (SEM) were used to evaluate the morphology of the precipitates. The treated specimens showed average UCS of 145 kPa, 241 kPa, and 483 kPa at average carbonate content of 1.96%, 2.98%, and 3.69% (corresponding to one, two, and three cycles), respectively. Calcite was observed to be the main crystal ...

The degree of consolidation is usually used as one of the criteria for assessing the effectiveness of soil improvement work using the fill surcharge or vacuum preloading method. It is also often used as a design specification in a soil improvement contract. Degree of consolidation is normally calculated using settlement data. However, as the effect of vacuum preloading is controlled largely by pore water pressure changes, it is necessary to analyze the pore water pressure variations and to assess the degree of consolidation using pore water pressures. In this paper, the problems involved in the estimation of degree of consolidation using settlement data are discussed. A method to estimate the average degree of consolidation using pore water pressure data is suggested. Two case studies are presented to examine the characteristics of the pore water pressure variation of soil under vacuum loading. The degree of consolidation achieved in each of the two cases is assessed using pore water pressure data and compared with that estimated using settlement data. Factors affecting the degree of consolidation assessment are discussed.

Subsurface tile drains were installed at a farm of 15 feddan, situated at Senores district, El-Fayoum depression. This area had gone out of cultivation due to the problems of waterlogging and salinity. This work was conducted to study the feasibility of installing tile drainage at farm level and using gypsum and deep ploughing to improve soil properties and productivity. The drainage pipes were laid at a depth of 1.25m from ground surface and 35m between drain spaces. The experiment was laid in a completely randomized design with four replicates; the plots were treated with four treatments as follows: plots without treatments (T1), applying a full gypsum requirement for the upper 15 cm soil (T2), deep ploughing up to 50 cm depth (T3) and gypsum applications combined with deep ploughing (T4). On the other hand, time as a limit factor in soil reclamation was taken into account, where all the studied measurement were periodically determined at zero time (initial) 3, 6, 9 and 12 month of the experimental start time. 
The application of full gypsum requirements and deep ploughing process as a secondary tool plays an important role in accelerating the improvement rates in soil hydro-physical and chemical characteristics.
The highest average values of water table draw down and drainage intensity factors "a" were observed under gypsum combined with deep ploughing (T4). Benefits claimed include increased infiltration rate, enhanced quickly drainable pores and decreased soil bulk density. Chemically, soil salinity and alkalinity values were reduced below the save limits (ECe less than 4 dS/m and ESP less than 15).
The beneficial effect of the primarily and secondly drainage treatments is remarkable and is reflected in soil productivity. The maximum yield of corn and wheat were produced under the combination of the gypsum application and deep ploughing. These studies show the feasibility of tile drainage associated by gypsum and deep ploughing effectiveness to maximize crop productivity at El-Fayoum problematic soils.

Variasi metode perbaikan tanah sudah sangat berkembang belakangan ini. Setiap metode perbaikan tersebut tentunya harus bertujuan untuk meningkatkan kekuatan dari tanah, mengurangi pemampatan yang mungkin terjadi dan mengurangi tingkat permeabilitas dari tanah. Pemilihan metode perbaikan tanah tersebut sangat tergantung dari kondisi geologis dari tanah, karakteristik dari tanah, biaya yang dikeluarkan untuk perbaikan, pengadaan bahan perbaikan tanah serta pengalaman dalam hal pelaksanaan di lapangan. Bergado dkk (1996) membagi pemilihan metode perbaikan tanah menjadi 2 kategori. Kategori pertama adalah termasuk metode untuk menggunakan material baru/material tambahan dilapangan dan pengadaan material perkuatannya. Metode ini temasuk penggunaan perkuatan tanah dengan stone column, creep piles maupun dengan stabilisasi tanah menggunakan bahan kimia. Kategori yang kedua adalah dengan proses dewatering pada tanah dengan menggunakan metode preloading yang dikombinasi dengan vertical drains. Pada bab ini pembahasan hanya dikhususkan kepada perkembangan dan penggunaan PVD dan sedikit akan dibahas pre-loading sebagai metode perbaikan tanah lunak.

In this thesis, it is aimed to contribute to train soil improvement specialists by
explaining soil improvement techniques which become a common need in today’s
civil engineering applications. In accordance with this purpose, first of all
classification of the soil improvement techniques of the problematic soils is
mentioned. Selected classification principles for categorizing the techniques which
mentioned in the thesis are explained. The subjects are emphasized such as the soils
on which the techniques can be applied, the applications of the techniques in civil
engineering, the special equipments required for the applications, the construction
methods of the application, advantages and disadvantages of these applications.
Besides, the theories- related to design of the methods- are explained with sample
problems. Some cases in which the techniques have been applied in Turkey and the
World are presented as case studies. Finally, in an attempt to make easier the
selection of appropriate technique among the mentioned ones, a guideline has been
developed by considering parameters such as the purpose of improvement,
appropriate soil type, applicable effective depth, applicable economic area, advantages, disadvantages, seismic performance and costs of the methods

Most buildings and other civil engineering construction projects are started as raw land. The first step to be performed is site investigation in order to know the situation of the site. It is difficult to find location that has perfect soil properties. One of the alternative to handle this problem is by modifying the existing soil. Hausmann (1990) distinguished the ground improvement or modification or stabilization into four groups, one of them is modification by inclusion and confinement or it is called as soil reinforcement. The concept of this method is by utilizing the properties of the materials used to resist tensile stress. There are several materials that can be used in this group, such as fiber. Two types of fiber-reinforcing soil based on the distribution of fiber within the soil, pattern-fibrous and randomly-distributed. In this paper, randomly distributed-reinforced soil is discussed.

Liquefaction adalah suatu kejadian dimana suatu massa tanah mengalami kehilangan kekuatan mekanisnya pada kondisi tanah yang jenuh air, pada jenis tanah yang non-kohesif yang disebabkan oleh kenaikan nilai pore water pressure (tegangan air pori) pada saat mengalami beban dinamis. Menurut Sladen dkk, (1985), Liquefaction adalah suatu fenomena dimana massa tanah mengalami kehilangan nilai shear resistance karena adanya suatu kondisi yang bersifat monoton, berulang, siklik dan beban yang mengagetkan (shock loading) sehingga bersifat seperti suatu cairan yang mengalir hingga shear stress yang terjadi pada massa tanah tersebut bernilai sama rendahnya dengan nilai berkurangnya shear resistance. Namun secara garis besar, liquefaction dapat diartikan sebagai perubahan suatu sifat masa tanah yang awalnya bersifat solid berubah menjadi bersifat seperti liquid yang disebabkan oleh meningkatnya nilai tegangan pori dan berkurangnya nilai tegangan efektif pada tanah. (“Definition on terms..” 1978).

In the scope of this study, selection process of ground improvement methods for soils, which has bearing capacity, settlement, liquefaction, permeability, stability, swelling or subsidence problems, are investigated. Soil improvement methods are investigated in detail. All improvement methods can be classified as surface and deep according to depth, mechanical, hydraulical, physical, chemical, biotechnical and reinforcement according to the method of application, for clayey soils, for sandy soils and for all soils according to the soil types, and reinforcement, improvement and treatment according to application for tunnels, underwater constructions, historical buildings, and other superstructure and infrastructure projects. In this study, soil improvement methods are classified according to depth and the soil improvement methods are explained under two main headings as surface and deep soil improvement methods that improve bearing capacity, settlement, liquefaction, permeability, stability, swelling and subsidence problems. Under surface ground improvement and deep ground improvement methods, improvement by reinforcement, improvements with admixtures, surface drainage, surface compaction methods are mentioned as surface improvement methods and biotechnical, deep dynamic compaction, deep drainage, deep mixing, deep dynamic modification, electrical signal compaction, grouting, hydro-blasting compaction, thermal treatment, improvement piles, jet grouting, sand compaciton pile (SCP), microbic methods, blasting, stone column were mentoined as deep improvement methods. Moreover, most used methods, which are jet grouting, cement grouting and stone column, were examined in detail.
Commonly used ground improvement methods jet grouting, cement grouting and stone column applications’ effects on soil behaviour were investigated. Improvement effects of these three methods on same soils were estimated. Jet grouting, cement grouting and stone column methods were modelled for a site where bored piles were applied. On this site, soil profiles which have bearing capacity and potential settlement problems were determined according to the available soil investigation report. Jet grouting, cement grouting and stone column materials were designed for these profiles. All these design parameters should be checked on site. Design parameters of jet grouting, cement grouting and stone column materials were used in empirical and Plaxis software analysis which use finite element methods. All the analysis were done on Profile 1, Profile 2 and Profile 3 which are determined as having porential bearing capacity and settlement. Profile 1 includes low plasticity clay and clayey gravel, Profile 2 includes high plasticity clay, low plasticity silt and clayey sand, and Profile 3 includes silty and clayey sand. First, lengths of columns and piles were optimized for these three soil profiles. Jet grouting, cement grouting and stone column applications were investigated in 3.4 m and 13 m excavation depths, different column lenghts, and 3 D (%8.7), 2 D (%19,6) and 1,5 D (%34,9) column spacings (improvement rates) whereby empirical and numerical analysis using Plaxis program column and composite soil, Terzaghi and Meyerhof bearing capacity theories and Bowles settlement theory. According to this, each soil improvement methods has an effective column length that change with soil samples and lengths. Even though, almost all the improvement methods’ bearing capacity and settlements were affected positively with increase of improvement ratio, however, there were also rare negative effects like settlement increase of stone column in sandy soil.
In terms of bearing capacity, stone column method gave better results than jet grouting and cement grouting applications. Although, in the application of stone column, in sand, bearing capacity has increased, increase of bearing capacity for jet grouting application gave far better results. Cement grouting, which is applicable only to sand on Profile 3, increased bearing capacity significantly. However, the effect of cement grouting on the bearing capacity was less than stone column and jet grouting applications.
Furthermore, jet grouting application affect settlements far possitively for clayey, silty and even sandy soils than the other methods, moreover, the settlement problem beneficially. Stone column method, which is applied through substitution is not rigid, and cause less settlements for clayey and silty soils, but settlements were increased in sandy soils. This situation could be better when alternative compacted stone column methods are applied. Moreover, cement grouting affected settlements well, but it could not be as much as jet grouting effects.
On the other hand, there were distinct results according to analysis types. It was observed that calculated empirical bearing capacity values were higher than the one’s found the other methods. Moreover, bearing capacity that calculated according to composite soil theory is higher than calculated value by Plaxis program. Also, empirical calculation of settlements is lower than calculated value by Plaxis program. Bearing capacity of stone columns calculated by using the composite soil theory gave high bearing capacity values on the internal friction angle is high. Bowles settlement theory results gave less settlement values than the one calculated by Plaxis program. Plaxis column calculations can be considered better due to the reason that column can be evaluated separate or group.
In addition, the stone column usage in the clay and silt soils gave better results than sand. As long as cement injection can be applied, it has been observed that it contributes to the bearing capacity of loose sands and improved to settlement behaviour. Also, jet grouting method contributed significantly to settlements including clayey, silty and sandy soils, however, it did not demonstrate a good performance in bearing capacity. Jet grouting method has been shown to contribute positively to the bearing capacity on clayey and silty soils, but it has not been able to make much contributions to settlement. As a result, jet grouting method can be effective in all soil types, and it can make significant contributions to settlements in all types of soil and has a positive effect on all soil types. Stone column method has positive effects on settlements on clayey and silty soils and contributes significantly to bearing capacity in all types of soils. Although, cement grouting method has narrow application area, it contributes to the bearing capacity and settlement of loose sand.
Finally, only jet grouting application has provided sufficient bearing capacity and limit settlement values in profile 3. While the jet grouting improvement was insufficient in profile 1 and profile 2, and stone column and cement grouting were not sufficient in all profiles. The bored pile method applied can be used as an alternative to soil improvement methods under high superstructure loads. Soil improvement can be preferred for soils that are under low loads.

This study investigates the combined efficacy of waste-tire-derived aggregate (TDA) materials and hydrated lime on the compactability, compressive strength and swelling potential of a highly expansive soil from South Australia. A total of 21 mix-designs, covering a comprehensive range of soil-TDA-lime combinations, were examined through standard Proctor compaction, unconfined compressive strength (UCS) and oedometer swell tests. The mobilized UCS exhibited a 'rise-fall' behavior, peaking at 5% TDA content and subsequently decreasing (monotonically) for higher inclusions of TDA. Increasing the TDA mean particle size (from 1.67 to 3.34 mm) also contributed positively to the UCS development. Addition of TDA to the soil/soil-lime-blends produced notable reductions in the swelling potential; the reduction was primarily governed by higher TDA contents, and, to a lesser degree, for larger TDA mean particle sizes. However, the role of TDA particle size in reducing swelling was found to be more significant than that of enhancing the UCS. As expected, lime treatment of the soil-TDA blends provided major further improvements to the UCS and swelling potential reduction; the achieved UCS improvements being positively proportional to the lime content and curing time. In view of the experimental results, soil-lime blends containing TDA to soil-lime mass ratios of up to 10% (preferably employing coarse-sandsized equivalent TDA) can be deemed as suitable choices (capable of adequately mitigating the swelling potential, while simultaneously enhancing the UCS).

The construction of railway embankments on loose foundations using reinforcing elements results in improvement of the embankments' slope stability, which significantly reduces the amount of earthworks. In addition, reinforcement of foundation and embankment is essential to increase bearing capacity and minimise settlements. In this study, a preliminary numerical analysis was performed to design and set up a series of experimental tests for investigating the efficiency of micro piles in reinforcing the high railway embankments on loose foundation. To this end, two experimental models of embankment were explored: one without reinforcement and another reinforced with micro piles to stabilise the embankment slope. The minimised arrangement of micro piles to reinforce the experimental model was obtained according to the results of the preliminary numerical simulation using Plaxis-2D finite-element code. The experimental data included bearing capacity of the embankment, displacement of foundation and embankment and axial strain of the micro piles. Finally, the efficiency of micro piles in reinforcing high embankments on loose subgrades was assessed by comparing the experimental data of non-reinforced and reinforced embankments.

The study evaluated the effects of Coconut Husk Ash (CHA) as a stabilizer of fine-grained soil for subgrade/subbase purposes. The CHA with size less than No. 200 sieve with a specific gravity of 0.66 was able to improve soil strength parameters; the effects, however, was sensitive. Maximum Dry Density which is also associated with higher CBR rating was achieved for clay and silt-clay soils at 5.0% CHA content, while silt soil gained its maximum MDD at 2.5% CHA. The data is, however, insufficient to conclude the range of quantity that results into better CBR rating. A similar study may be conducted with an improved number of trials.

The hemp plant is not only the most useful plant in the world, hemp is also a potential climate saver and can even significantly reduce global warming, climate crises and land degradation with appropriate applications. Greening Deserts projects such as the Greening Camps and research stations will use bamboo, hemp and other key plants extensively to improve soil quality and water quality.
The groundwater is protected by hemp cultivation, sustainable agriculture, organic farming and innovative water management. Only natural fertilizers are used and pesticides are avoided, there are many good alternatives. Different bamboo and hemp sorts can be used in almost every climate and under all possible conditions or events. Global hemp cultivation can generally contribute to climate, soil and water improvement as well as for a better cultivation of crops and a variety of afforestation or reforestation. The founder and project developer of Greening Camp projects has been developing these innovative and sustainable solutions for years.
Various greenhouses and research fields can be established together with the camps for education, research and product development, the projects also serve the climate, nature and environmental protection. At each camp can be special biotopes, botanical gardens, greenhouses and parks for endangered species - especially for cultivating or saving plants, insects and other animals of each climate zone or region. Climate protection, nature conservation, species protection and plant science are a few of the primary tasks.

Cation binding by organic matter content (OMC) in soils has consequences for the behaviour of the organic compounds themselves, influencing adsorption, aggregation, and solubility, and thereby soil structure, translocation of organic matter within soils, and transport to waters. The study reported here involved a number of experiments using composition of alkaline earth metals grout to treat organic soils, in order to provide a better understanding of the engineering behaviour of this soil after stabilization. Besides, it provides a series of the laboratory mix design and testing which in turn provide an essential guide regarding the choice, dosage and economical amount of chemical binders. We carried out a series of batch test using composition of sodium silicate system binders to find their effects on physic-chemical properties of the organic soil. The results show that in the batch tests unconfined compressive strength (UCS), increases of up to 220% of the soil’s baseline strength can be achieved by adding the 3 mol/L Na2Sio3, while UCS results enhanced to 270% having an activator CaCl2 and/or Al2(SO4)3 additives. Moreover, using higher molarities of CaCl2 (for example, 1mol/L) did not show any remarkable effect on the UCS results.

Soil stabilization using nanomaterials is an emerging research area although, to date, its investigation has mostly been laboratory-based and therefore requires extensive study for transfer to practical field applications. The present study advocates nano-calcium carbonate (NCC) material, a relatively unexplored nanomaterial additive, for stabilization of low-plasticity fine-grained soil having moderate organic content. The plasticity index, compaction, unconfined compressive strength (UCS), compressibility and permeability characteristics of the 0.2%, 0.4%, 0.6% and 0.8% NCC-treated soil, and untreated soil (as control), were determined, including investigations of the effect of up to 90-d curing on the UCS and permeability properties. In terms of UCS improvement, 0.4% NCC addition was identified as the optimum dosage, mobilizing a UCS at 90-d curing of almost twice that for the untreated soil. For treated soil, particle aggregation arising from NCC addition initially produced an increase in the permeability coefficient, but its magnitude decreased for increased curing owing to calcium silicate hydrate (CSH) gel formation, although still remaining higher compared to the untreated soil for all dosages and curing periods investigated. Compression index decreased for all NCC-treated soil investigated. SEM micrographs indicated the presence of gel patches along with particle aggregation. X-ray diffraction (XRD) results showed the presence of hydration products, such as CSH. Significant increases in UCS are initially attributed to void filling and then because of CSH gel formation with increased curing.

The properties of soil play a major effect on the design of road pavements. Thus, using waste materials to develop the characteristics of weak soil is being progressively necessary for industrial constructions. In past years, several pieces of research have been done to show the significance of these waste materials on the strength of the soil. This research aims to focus on the impact of granite powder on the behavior of the soil subjected to loading. Therefore, soils blended with several amounts of granite powder i.e. 4%, 8%, 12%, 16%, and 20% of the total weight were examined. The CBR, compaction and direct shear tests were executed to evaluate the performance of the untreated and treated soils. The findings proved that adding granite dust increased noticeably the shear strength, CBR and dry density of the soils. It was found that an addition of 8% granite dust to the natural soil yields the most appropriate results among other contents of granite dust. Hence, it is concluded that the granite dust has good potential to be used as an additive for improving the engineering properties of clayey soil.

Geocell, which is one of the increasingly used geosynthetic materials in recent years, limits the lateral movement of the ground with its three-dimensional honeycomb structure. Thanks to this new technique, the cost of the soil improvement methods and the construction time are reduced. Even though various researchers have performed laboratory, field, and numerical studies, the factors affecting the working mechanism and performance of the geocells are not fully explained. With this review study, geocell history, usage areas, parameters affecting performance and working mechanism are explained.

Four organic fertilizer made from pineapple stubble were evaluated as an alternative for biomass control and nutrient cycling in a farm. Three compost mixes were made, one with pineapple leaves and two combining pineapple stubble with mountain microorganisms (MM) and chicken manure. The composting process lasted 60 days, the temperature was determined every three days, the ratio C:N and nutrient content every 20 days. Overall, the compost that had a higher quality was the combination of pineapple leaves with chicken manure. It kept the temperature and moisture within the optimum range. The C:N ratio at the end of the process was less than 10, indicating their potential to mineralize N once incorporated to the soil. It also submitted an acceptable nutritional quality. Nutrient content was within the lower range recommended for organic fertilizers. The compost of pineapple leaves and pineapple with MM, are not considered of quality. Excessive moisture had a negative effect on the composting process of the compost mentioned above. The leachate contained soluble nutrients and it show as an alternative method for short term fertilization.

Liquefaction is one of the cardinal concern to the geotechnical engineers as well as those involved in the building and development of structural foundations. To strengthen the subsoil properties in terms of its bearing capacity, shear strength, and settlement; ground improvement techniques are often used. This paper reviews three ground improvement techniques suitable for remedial work near existing structures. Three techniques includes- compaction grouting, permeation grouting, and jet grouting. Suitable method can be selected according to loading conditions, characteristics of soil, project type and cost. The factors which influence the efficacy of a particular technique are identified. From the advantages and drawbacks stated, a combination of techniques may provide the most cost-effective ground improvement solution for preventing damage to existing lives resulting from liquefaction-induced settlement and uplift.

Consolidation characteristics are one of the prime considerations for any structure constructed above clay soil. This behavior of soil is mainly responsible for the settlement of a clay layer. Structure may be penetrated considerably in the soil; roadway may be undulated due to this settlement problem. Moreover, differential settlement causes excessive damage to the structure. Therefore it is required to understand the process properly which will eventually help to mitigate the problems related to the settlement. For this purpose, a wide range of consolidation tests were performed in the laboratory to understand the settlement characteristics and to improve the condition by soil stabilization with different percentage of lime. Lime is a natural rock which can be used as an effective soil stabilizer to improve workability and load bearing capacity of soil. The study covers the improvement of consolidation characteristics to reduce the settlement of clay soil by using lime. In investigation 4% lime was found to be the optimum percentage for soil stabilization which improves the settlement behavior of the soil. This composition of lime and soil can be used to treat the foundation soil of any structure which may decreases the possibility or risk of differential
settlement.

Liquefaction is one of the cardinal concern to the geotechnical engineers as well as those involved in the building and development of structural foundations. To strengthen the subsoil properties in terms of its bearing capacity, shear strength, and settlement; ground improvement techniques are often used. This paper reviews three ground improvement techniques suitable for remedial work near existing structures. Three techniques includescompaction grouting, permeation grouting, and jet grouting. Suitable method can be selected according to loading conditions, characteristics of soil, project type and cost. The factors which influence the efficacy of a particular technique are identified. From the advantages and drawbacks stated, a combination of techniques may provide the most cost-effective ground improvement solution for preventing damage to existing lives resulting from liquefaction-induced settlement and uplift. KeywordsGround Improvement, Compaction Grouting, Permeation Groutin...

As we know the road development is one of the major parts of growing infrastructure & Nepal, which is expanding at a very fast rate, the construction of roads is of major concern. As per IRC recommendation, California Bearing Ratio (CBR) value of subgrade is used for design of flexible pavements. The CBR test may be done either in Soaked Specimen or in Unsoaked Specimen. But the standard test requires soaked test, hence in this experiment Soaked Specimens are prepared and tested for CBR values. Also as fly Ash is one of the abundant forms of Solid Waste produced at thermal power plants. Its disposal is a big problem. keeping both these concerns in mind it was tried to come out with a project which will integrate Road development and Fly ash disposal. Thus, in this project we intend to calculate and compare CBR values of natural soil with soil mixed of Lime and fly ash in the ratio 1:3 and then calculated their respective pavement thickness.

The ground is a natural grand system; it is composed of myriad constituents that aggregate to form several geologic and biogenic systems. These systems operate independently and interplay harmoniously via important networked structures over multiple spatial and temporal scales. This paper presents arguments and derivations couched by the authors, to first give a better understanding of these intertwined networked structures, and then to give an insight of why and how these can be imitated to develop a new generation of nature-symbiotic ground engineering techniques. The paper draws on numerous recent advances made by the authors, and others, in imitating forms (e.g. synthetic fibres that imitate plant roots), materials (e.g. living composite materials, or living soil that imitate fungi and microbes), generative processes (e.g. managed decomposition of construction rubble to mimic weathering of aragonites to calcites), and functions (e.g. recreating the self-healing, self-producing, and self-forming capacity of natural systems). Advances are reported in three categories of Materials, Models, and Methods (3Ms). A novel value-based appraisal tool is also presented, providing a means to vet the effectiveness of 3Ms as standalone units or in combinations.

Bu çalışmada, derin zemin karıştırma tekniği ile zemin iyileştirmesi çalışmaları için arazideki durumu temsil edecek nitelikte gerçekçi laboratuvar örnekleri hazırlanması amaçlanmıştır. Bu kapsamda İzmir İli, Meles Deltasında bulunan bir bölgede uygulanması düşünülen derin zemin karıştırma çalışmasına veri sağlamak amacı ile araziden numune alınmış ve çeşitli bağlayıcı yüzdeleri kullanılarak örnekler hazırlanmıştır. Laboratuvarda örnek hazırlanması sırasında karışımlar derin karıştırma tekniğine paralel olarak sıkıştırılmadan ve arazideki doğal su içeriği ve birim hacim ağırlık değerleri hedeflenerek kalıplara yerleştirilmiştir. Numunelerin rijit kalıplar içerisine hava boşluksuz yerleştirilmesi tabakalar halinde serme, şişleme ve darbe vurmak suretiyle yapılmıştır. Kür süreleri boyunca suya batık ve şişmelerine izin verilmeden tutulan örnekler daha sonra kalıplardan çıkartılarak su içerikleri ve birim hacim ağırlıkları belirlenmiştir.

Loess as a type of collapsible soils is a well-studied Aeolian deposit, which is characterized by some specific engineering properties including high initial void ratio, relatively low initial density, low water content, and a high percentage of fine-grained particles. Collapsible soils such as loess, sustain substantial stress under dry condition. However, they experience a high and sudden decrease in their volume by reaching to their critical moisture content. As a result, their natural condition is not suitable for construction works if the possibility of the exposure of the soil to excessive water is present.
This research presents the utilization of an innovative method for stabilization and improvement of Gorgan loessial soil. This method uses Electrokinetics and Nanomaterials as an in-situ remedial measure to instigate additives to move through soil pores through ion migration phenomena. In order to assess the deformation and strength behavior of improved collapsible soil and comparing with those of unimproved soil, several Unsaturated Oedometer tests under constant vertical stress and varying matric suction were performed.
The result showed the effect of matric suction on the behavior of both improved and unimproved samples. The resistant of the soil was highly dependent on the water content and matric suction. The Oedometer tests on samples improved by 3% Lime and 5% nanomaterials showed considerable improvement of Collapse potential. Results also showed that stabilized samples experienced notably lower volume decrease under the same induced stresses.

Swelling soils account for large volume of the ground. These soils are Swelled due to moisture changes in different seasons of the year which leads to damage and Crack to structures built on these soils and considerable financial loss would be incurred. Thus this phenomenon may be described as dangerous like other natural disasters. Soil Stabilization is a good technique for reducing such loss. Mechanical techniques such as Concentration leads to improved soil characteristics. However, authors have concluded that chemical stabilization of the soil is more effective. In this paper, lime is used as a Stabilizing chemical for swelling soils. Soil samples with plasticity index 31.1were used in experiment. Plasticity characteristics of clay soils in the region regarding mentioned samples are studied and compared using combination of various percentages such as 2%, 4%, 6% and 8% of lime. From the observation author find 4%lime as
modifying agent to optimize plasticity index value.

The main purpose of this experimental study is to know the effect of improvement of soft soil by mixing it with granular materials on the properties of soft soil. The soil model was brought from a one construction project in Karbala, Iraq. Routine tests were carried out on the soft soil model alone, as well as for soft soil with specific percentage of granular materials. The model of cylindrical shape laboratory dimensions of 250 mm in diameter with a height of 300 mm. Eight different shear strength were used for laboratory model tests. Static loading tests were carried out on these model tests. It was found from results of model tests of improved soil that the averaged value of settlement reduction is 0.61 for all model tests, where the bearing capacity is increased by 31%.

Studies of surface improvement have been carried out in Georgia-Poti in order to decrease surface deformations since surface conditions of railway line that comes from the harbor are too poor. Stone column and jet grouting methods were evaluated together as surface improvement methods. As engineering parameters on the surfaces which are applied, jet grouting are higher than the other method, it was decided to improve the line within project with this method. This study was carried out in order to present surface parameters obtained with seismic refraction data carried out together with surface improvement practices. Findings show that parameters of shear wave velocity, amplification rate and bearing power obtained with jet grouting practices are higher than those of stone column practices.

Construction of railway embankments on loose beds without using any methods of soil improvement (e.g. stone columns in silt and clay beds, deep soil mixing method, jet grouting and also using micropiles individually or in groups form) leads to reduction of embankment slope gradient, which significantly increases the volume of soil operation. Generally, micropile as a reinforcing element with the main characteristics of improving the mechanical-physical properties of soil, is a proper methodology for the aim of improving loose earth with low bearing capacity and intensive settlement characteristics. This paper explores numerical models of non-reinforced and reinforced railway embankments (with the height of 10 to 25 m) rested on loose beds that simulated and analyzed by SLIDE software. It should be considered that in order to reinforce the embankments using different arrangements of micropiles. In addition, the non-reinforced and reinforced embankments were analyzed against different load combinations that consist of railway operational load, permanent weight of the rail line and intense earthquake load. It should be mentioned that LM71 standard load was used as operational load during the simulations. The main purpose of this paper is finding the optimum arrangement of micropiles to reinforce the high railway embankments on loose beds. Therefore, according numerical analyses procedure, it was resulted that the use of micropiles exactly between toe and 1/3 to 1/2 length of the embankment slope is the optimal way to reinforce the embankments on loose beds.