Mechanical Properties Of Clayey Soil Research Articles

Experimental investigation of the effect of nano and micro Fe3O4 on the physical and mechanical properties of clayey soil

Experimental investigation of the effect of nano and micro Fe3O4 on the physical and mechanical properties of clayey soil

Influence of traditional and alternative additives on the physical and mechanical properties of clayey soil

Influence of traditional and alternative additives on the physical and mechanical properties of clayey soil

Optimizing the mechanical behavior of clay using cement and PVC aggregates with the application of a mixture design method

The present research work aims to use the mix design approach to develop some models that can predict the mechanical properties of clayey soil. For that, the proctor compaction test, direct shear test, and uniaxial compression test were performed on bentonite (B) and other mixtures incorporating different proportions of polyvinyl chloride (PVC) aggregates stabilized with cement (C). The experimental and modeling results indicated that a good correlation existed between the three factors (B, C, and PVC) and the values of the maximum dry density, cohesion, and compressive strength responses. It was also found that the majority of models gave relatively good correlation coefficients (R2 ≥ 0.90) for all the responses under study. The results obtained indicated that this bentonite had a compressive strength 180.24 kPa, with a cohesion 64.71 kPa, and a maximum dry density equal a 1.571 gr/cm3. In addition, the experimental and modeling findings showed that the mixture including C (55% ± 10%), PVC (35% ± 10%), and B (10% ± 10%) exhibited a quite high cohesion of 103 kPa (more than one and half times that of unreinforced samples), while the highest compressive strength of 445 kPa (two and half times more than that of unreinforced samples) was obtained for the mixture comprising of C (50% ± 10%), PVC (25% ± 10%) and B (25% ± 10%). In addition, it turned out that these results are very encouraging in terms of environmental protection because this technique allows recycling and valorizing huge quantities of PVC waste produced throughout the world. It has been revealed that PVC wastes can be utilized in the geotechnical field to improve the mechanical behavior for clay soils, and to assess the values of maximum dry density, cohesion, and compressive strength of mixtures not made in the laboratory using the derived statistical models.

Compressive and Tensile Strength of Nano-clay Stabilised Soil Subjected to Repeated Freeze–Thaw Cycles

Abstract Improvement of the mechanical properties of clayey soils by additional elements to enhance the strength under numerous freezing and thawing cycles has been considered as a serious concern for engineering applications in cold regions. The objective of the current study is to investigate the effect of nano-clay as a stabiliser on the mechanical properties of clay. To this end, the clay specimens were prepared by adding various percentages of nano-clay ranging from 0.5% to 3% by dry weight of soil and were experimentally tested under the uniaxial compression and tensile splitting tests under different curing times (0, 7 and 28 days) after experiencing various freeze–thaw cycles ranging from 0 to 11. It can be concluded from the results that nano-clay particles may be used as a stabiliser in geotechnical applications to improve soil property. The results indicate that the optimum moisture content (OMC) of specimens increases and the maximum dry density (MDD) decreases with the increasing nano-clay content. The specimens containing about 1% nano-clay recorded maximum values of unconfined compressive strength (UCS) as well as tensile strength. For example, the addition 1% nano-clay increased the UCS and tensile values of clay specimens under the curing time of 28 days by 34% and 247%, respectively. In addition, the long-term durability of specimens against freeze–thaw cycles increases further with the addition of nano-clay content ranging from 2% to 3%.

Influence of Stone Powder on the Mechanical Properties of Clayey Soil

In this experimental study, the use of stone powder as a stabilizer to the clayey soil studied. Tests of Atterberg limits, compaction, fall cone (FCT), Laboratory vane shear (LVT), and expansion index (EI) were carried out on soil-stone powder mixtures with fixed ratios of stone powder (0%, 5%, 10%, 15%, and 20%) by the dry weight. Results indicated that the undrained shear strength obtained from FCT and LVT increased at all the admixture ratios, and the expansion index reduced with the increase of the stone powder.

Mechanical Properties of Clayey Soil Reinforced with PET Considering the Influence of Lime-Stabilization

Reusing waste plastic can be considered as an important issue in terms of economical as well as environmental concerns. Stabilization of clayey soil is a well-utilized approach to improve the mechanical properties concerning the geotechnical aspects. Meanwhile, the effect of concurrent employment of both lime and waste plastic fibers with different contents and various shapes on mechanical properties of clay is not evident. This research presents the mechanical characteristics of clayey soil reinforced with Plastic Polyethylene Terephthalate (PET). Both unstabilized and lime-stabilized clay are considered as unreinforced materials and the plastic strips and pellets are separately utilized as reinforcement substances. Various tests namely standard Proctor compaction test, point load test (PLT) and drop-weight impact loading test are performed to assess the effect of reinforcement and stabilization on mechanical behavior of clayey soil. The concurrent influences of using PET and adding lime confirm that positive effect of lime stabilization on strength is more meaningful. Meanwhile, the limited content of 1.5% of PET shows the maximum strength for reinforced clayey soil. Generally, reinforcement with strips leads to the exhibition of higher strength based on the point load strength index and more flexibility based on the applied impact loads in comparison with pellet particles.

Analysis of Bound Water and Its Influence Factors in Mixed Clayey Soils

Bound water is an important factor in controlling the physical, chemical and mechanical properties of clayey soils, and it plays an important role in geotechnical engineering disaster prevention and environmental protection. There are many factors (such as soil texture, mineral composition, specific surface area (SSA), organic matter content, porosity and so on) that affect bound water in natural clayey soils. However, the main factors are mineral composition and specific surface area (SSA). Experimental tests on specific surface area and isothermal adsorption of a series of artificial mixed clayey soils were carried out to determine the different types of bound water. On this basis, the relationship between the bound water of mixed clayey soils and influencing factors of mineral composition and specific surface area are discussed. The results show that relative humidities of RH = 0.90 and 0.98, in an isothermal adsorption method, are the boundary-dividing points between strongly bound water and weakly bound water, and between weakly bound water and free water, respectively. The bound water content of the mixed clayey soils increased linearly with the montmorillonite content and specific surface area. Clay’s mineral composition (montmorillonite) was found to be the most fundamental influencing factor.

Reuse of waste tyre products as a soil reinforcing material: a critical review.

All over the globe, the generation of industrial waste has been increased due to the increasing demand for modern civilisation. In the developing countries like India, it is growing vigorously which eventually increases the production of vehicles and results in the more number of waste tyres. Despite the dumping such hazardous waste in landfills, stockpiling, and burning, their feasible utilisation in the modification of soil and concrete can be a good alternative option for their disposal. This paper enlightens the published work carried out by various researchers to enhance the mechanical properties of clayey soil using various forms of waste tyres. The effects of different forms of waste tyres on consistency limits, compaction characteristics, strength characteristics, compressibility characteristics, permeability and California-bearing ratio of cohesive soils have been reviewed. The review results show that the use of waste tyre products in ground improvement can be an economical solution for the construction industries and optimistic future as its disposal option. Still, further investigations and more research studies are required to consolidate the remarks drawn by the past researchers for its utilisation in the construction of highway/railway embankments and other field applications.

Effect of adding cement and nanocement on mechanical properties of clayey soil

Improving the soil behavior, using additives, has considered by a lot of researchers in geotechnical engineering as one of the effective methods to improve various soil behavior parameters. However, nanomaterials have received less attention in geotechnical engineering despite having unique characteristics and causing fundamental changes when being used in other branches of engineering. The present study investigated the effect of adding cement and nanocement for improving the mechanical behavior of clayey soil. For this purpose, cement and nanocement with the dry soil weights of 1, 2, 3 and 4% were mixed with the clay soil and the Atterberg limits, standard compaction and unconfined compressive strength tests were performed on the samples. The samples were cured by within 42 days. The results showed that with the addition of cement and nanocement, the optimum moisture content, liquid limit and plastic limit increased, while the maximum dry density and plasticity index decreased. Also, as a result of the stabilization with cement and nanocement, the increase in the uniaxial compressive strength was observed about 10 and 12 times more than the unstabilized sample, respectively. It should be noted that the increase in the strength in the samples with stabilized nanocement was higher than that in the cement-containing samples. For example, the uniaxial strength of the unstabilized sample was obtained 200 kPa after 42 days of curing, while with adding 4% of cement and nanocement after 42 days of curing, the UCS of 2113 and 2416 kPa were obtained, respectively.

Mechanical Properties and Microstructure of Fibre-Reinforced Clay Blended with By-Product Cementitious Materials

Clayey soils endure adverse changes in strength and volume due to seasonal changes in moisture content and temperature. It has been well recognised that high cement content has been successfully employed in improving the mechanical properties of clayey soils for geotechnical infrastructural purposes. However, the environmental setbacks regarding the use of high cement content in soil reinforcement have necessitated the need for a greener soil reinforcement technique by incorporating industrial by-product materials and synthetic fibres with a reduced amount of cement content in soil-cement mixtures. Therefore, this study presents an experimental study to investigate the mechanical performance of polypropylene and glass fibre-reinforced cement-clay mixtures blended with ground granulated blast slag (GGBS), lime and micro silica for different mix compositions and curing conditions. The unconfined compressive strength, linear expansion and microstructural analysis of the reinforced soils have been studied. The results show that an increase in polypropylene and glass fibre contents caused an increase in unconfined compressive strength but brought on the reduction of linear expansion of the investigated clay from 7.92% to 0.2% at fibre content up to 0.8% for cement-clay mixture reinforced with 5% Portland cement (PC). The use of 0.4–0.8% polypropylene and glass fibre contents in reinforcing cement-clay mixture at 5% cement content causes an increase in unconfined compressive strength (UCS) values above the minimum UCS target value according to American Society for Testing and Materials (ASTM) 4609 after 7 and 14 days curing at 20 °C to 50 °C temperature. Therefore, this new clean production of fibre-reinforced cement-clay mixture blended with industrial by-product materials has great potential for a wide range of applications in subgrade reinforcement.

Desiccation Cracking Behavior of Clayey Soils Treated with Biocement and Bottom Ash Admixture during Wetting–Drying Cycles

Desiccation cracking considerably impairs the hydraulic and mechanical properties of clayey soils that are critical to the long-term performance of infrastructure foundations and earth structures. Typical crack remediation methods are associated with high labor and maintenance costs or the use of environmentally unfriendly chemicals. Recycling waste materials and developing biomediated techniques have emerged as green, sustainable soil stabilization solutions. The objective of this study was to investigate the feasibility of soil crack remediation through use of bottom ash admixtures and microbial-induced calcite precipitation (MICP). We carried out cyclic wetting–drying tests to characterize the effects of bottom ash and MICP on the desiccation cracking behaviors of bentonite soils. Two groups of soil samples that contained different percentages of bottom ash (0%, 20%, 40% by weight) were prepared for cyclic water and MICP treatments, respectively. The desiccation cracking patterns captured by a high-resolution camera were quantified using image processing. We also employed scanning electron microscopy for microstructural characterizations. Experimental results revealed that cyclic water treatment resulted in more cracking, whereas cyclic MICP treatment improved soil strength owing to the precipitation of calcite crystals on the soil particle surface and inside the interparticle pores. Adding bottom ash to bentonite reduced the plasticity of the mixture, promoted the flocculation of clay particles by cation exchange, and also provided soluble calcium to enhance calcite precipitation. This study demonstrates the potential of bottom ash and MICP for crack remediation and brings new insights into the design and assessment of sustainable infrastructures under climate changes.

The Analysis of The Impact of Liquid Limit on Mechanical Properties of Clayey Soil

This article introduces the importance of the liquid limit of soil. The liquid limit largely determines the plasticity index and liquidity index of soil, which directly affects the classification and denomination of the soil. It also makes an analysis of the impact of liquid limit on the state of clayey soil and its mechanical indicators. Even if the water content is high and the porosity is large, as long as the water content does not exceed the liquid limit, it cannot be named silt soil. Under the same conditions, the higher the liquid limit, the harder the state of the soil, the higher the undrained strength and bearing capacity, and the smaller the coefficient of consolidation, but the liquid limit has less impact on the compression coefficient and compression modulus.

Effect of the Curing Time and Combination of Corncob (Zea Mays L.) Ash With Swelling Clay on Mechanical Properties of Soil in Forest Road

ABSTRACT Swelling soil such as clay soil is known as unsuitable material for forest transportation due to the high volume change and mechanical defects. The aim of this study was to investigate the effects of corncob ash as a biologic additive on mechanical properties of clayey soil in forest roads of Bahramnia forestry plan in Golestan province. Different content of corncob ash and curing time were the treatments of study. Corn wastes were collected from farmlands and nodes of corncob with high silica content were used to produce ash. Soil samples were collected from the road construction area to conduct testing. First set of soil samples without additives and second set contained 5%, 10%, 15%, and 20% of corncob ash. Atterberg limits, standard proctor, and unconfined compressive strength were carried out on 7, 14, and 28 days curing times. Findings showed that the plastic index decreased by increasing corncob ash to 5%. Adding ash up to 5% can cause dramatic increase in plastic index. Addition of ash to the soil decreased dry bulk density and increased optimum moisture content. Maximum dry density (1.73 g cm−3) was recorded in optimum moisture of 28.5% and ash content of 5%. Unconfined compressive strength of samples increased until adding 5% of ash, and then the compressive strength decreased by increasing the ash content. There wasn’t significant difference between the curing times of 14 and 28 days in mechanical properties of soil samples. It was concluded that ash content of 5% and curing time of 14 days were the optimum values which maximum improvements in mechanical properties of swelling clay soil are occurred.

Improving the geotechnical properties of soft clay with nano-silica particles

This paper reports on an investigation into the effect of using nano-silica particles to improve the mechanical properties of clayey soil with low and high liquid limits. The engineering properties studied included Atterberg limits, maximum dry unit weight, optimum moisture content, California bearing ratio, consolidation and unconfined compressive strength. Nano-silica to soil ratios of 0·5, 0·7 and 1·0% were used. Both the Atterberg limits and California bearing ratio values improved with increasing nano-silica content. Increasing ratios led to a reduction in the plasticity index and an increase in the shrinkage limit. The reduction in soil settlement was attributed to a viscous gel in the soil–additive interaction, which resulted in an increase in the pre-consolidation stress of the stabilised soil. The test results showed that the viscous gel caused an increase in initial pre-consolidation stress of 70 kN/m2 for a soft clay soil to 300 kN/m2 for a soil stabilised with 0·7% nano-silica. Undrained compressive strength also increased by up to 56%. An increase in nano-silica content led to a reduction in failure strain but an increase in the elastic modulus of soils. Based on the results, it can be concluded that the addition of nano-silica improves the mechanical properties of clay significantly.

Settlement control by deep and mass soil mixing in clayey soil

This paper discusses the influence of adding various amounts of cement to and changing the water content of clayey soil and their effects on controlling the settlement of a superstructure with various improvement area ratios (IARs). As a first step, the physical and mechanical properties of clayey soil from Bandar Imam Port, Iran, with 4, 6, 8 and 10% cement content and various water contents (30, 48 and 70%) were determined. Sample preparation was carried out using the wet deep soil mixing (DSM) method. The relationship between secant modulus at 50% strength (E50) and curing time for various cement contents was determined. In addition, different DSM column patterns with IARs of 0, 0·2, 0·3, 0·4 and 0·5, considering floating and end bearing DSM columns, were modelled using the finite-element method. Soil improvement by mass mixing of layers 2–7 m thick was also studied. The optimisation of various IARs and DSM characteristics and patterns enables production of a chart guide for preliminary design.

Physical, Hydraulic, and Mechanical Properties of Clayey Soil Stabilized by Lightweight Alkali-Activated Slag Geopolymer

AbstractLightweight cement materials are extensively used in the infrastructure construction. Geopolymer is a low-carbon and environmentally friendly cementitious material. This paper presents an investigation on the physical, hydraulic, and mechanical characteristics of lightweight geopolymer stabilized soil (LGSS) and a comparison with lightweight cement stabilized soil (LCSS). Measurements of volumetric absorption (VA) of water, hydraulic conductivity (k), and unconfined compressive strength (qu), scanning electron microscope (SEM) observation, mercury intrusion porosimetry (MIP) test, and thermogravimetric analysis (TGA) are conducted. The results show that LGSS has higher VA than LCSS. The k of LGSS is one order of magnitude higher than that of LCSS. The qu of LGSS is 2–3.5 times of that of LCSS. Microstructurally, the VA and k of LGSS are found to be positively correlated with the volume of large air pores (>10 μm). Higher qu of LGSS than LCSS is attributed to more hydration products that fill up t...

Study of Barium Cation Effects on Mechanical Characteristics of the Kahrizak Clay

Some recent research has indicated that certain alkaline contaminations may adversely affect mechanical properties of clayey soils. To examine the potential impact of alkaline divalent barium on the swelling characteristics of KAHRIZAK clay, the major solid-waste landfill at south of Tehran, a systematic set of experiments was conducted. Observations indicated that the swelling in the studied soil that belonged to the CH-MH group with a PI of 28.44, was reduced by about 17, 37, 48 and 54 percent, and swelling pressure by about 41, 55, 65 and 67 percent, respectively, after addition of barium chloride solutions to concentrations of 0.25, 0.5, 0.75 and 1.25 molal. It was also found that addition of barium chloride solutions to concentrations of higher than 1 molal had a little effect on reduction of swelling and swelling pressure.

Relation Between Ultrasonic Pulse Velocity and Some Mechanical Properties of Clayey Soil Treated with Lime

Relation Between Ultrasonic Pulse Velocity and Some Mechanical Properties of Clayey Soil Treated with Lime

Effect of fibres on the mechanical properties of clayey soil

This paper presents the effect of short, discrete, randomly oriented fibres (natural and synthetic) on the mechanical properties of clayey soils. The mechanical properties investigated include peak unconfined compressive strength, stiffness and ductility. Three types of clayey soil were obtained from the eastern part of Irbid city in northern Jordan. Two types of fibre were used in this study: nylon and palmyra fibres, with aspect ratios (L/d) equal to 75. The clayey soils were mixed with fibres at five different percentages by volume of solid soil particles: 1%, 2%, 3%, 4% and 5%. The results showed that the peak unconfined compressive strength, stiffness and ductility of the clay–fibre mixture increased with fibre content. The post-peak softening in compression resistance decreased with increasing fibre content. The relative unconfined compressive strength increased with fibre content. Palmyra fibre showed a higher increase in the relative unconfined compressive strength than nylon fibre when mixed with clayey soil, for all fibre contents. Furthermore, the clayey soil with a high activity index showed greater improvement when mixed with fibres than that with a low activity index.

Effects of Aluminum on Mechanical Properties of Clayey Soils

Effects of Aluminum on Mechanical Properties of Clayey Soils