名古屋大学博士学位論文 学位の種類:工学博士 (論文) 学位授与年月日:平成1年12月8日

Rapid development and growth of industrialization has brought immense enrichments in living standards of humans, however, improper planned development also brings along several environmental problems such as pollution of environment and excessive consumption of natural resources. Among all the others, uncontrolled utilization of water poses a severe threat to the coming generations. Past decades have witnessed water shortage in various countries of the world. Although about 80% of the earth’s surface is covered with water, around 97.2% of water is salty making it inappropriate for general usage. Among the rest of the 2.8%, which is present as fresh water on surface, a large proportion of it has been found to be severely polluted. The increasing demand of fresh water both for industrial and domestic usage adds great demand on the available groundwater. Moreover, the severe pollution of fresh water on the surface adds more stress on the available groundwater. In Australia, approximately 20% of water supply is from groundwater and in the case of Western Australia groundwater provides two thirds of its water supply needs. Thus, it is important to manage groundwater sources in Western Australia to achieve the optimum water utilization and maintain the water table and it is also essential to decide on an appropriate water budget. Groundwater flow modelling is an effective tool to get appropriate water distribution and, to examine effects from pumping on water levels and direction of groundwater flow paths, thereby helping in its proper management and utilization. Apart from monitoring the flow and utilization, groundwater flow modeling is also vital to keep the track of pollutant in the groundwater. Increasing surface pollution and landfill sites tend to pollute the groundwater due to leaching. / The above mentioned aspects formed the basis of the present research. A groundwater flow model was developed in Visual MODFLOW Premium to study the effect of three different types of soil in and around Perth region. This study also shows the hypothetical contaminated site model for benzene, toluene, ethylbenzene and xylene (BTEX) transport in Perth Superficial unconfined aquifer which includes three major aquifer sediments namely Bassendean Sand, Safety Bay Sand and Tamala Limestone. Among the four different contaminants it was observed that benzene is able to migrate quickly as compared to the other contaminants due to its smaller distribution coefficient. / This study also explored the major soil parameters such as effect of sorption, effective porosity and hydraulic conductivity on contaminant plume configuration and contaminants concentration for the three types of aquifer sediments. A critical comparison of the behaviour of the three different types of soils was also conducted. / Simulation results of sensitivity analysis have shown that sorption and hydraulic conductivity greatly affected the contaminant plume length and concentration of contaminants with much lesser effect shown by the effective porosity. The simulated results also showed that the movement of contaminant in Tamala Limestone is most rapid by comparing these three types of aquifer sediments together. Thus, it can be said that contaminated sites found in Tamala Limestone needs immediate remediation of contaminants to bring down the contaminants concentration in groundwater. / In brief, the thesis explores the current groundwater scenario in and around Perth region. Based on the information a hypothetical scenario simulation has critically analyzed the various parameters affecting the water and contaminant flow for the various soil parameters. The study is considered as a building block for further research on developing a remediation technique for groundwater contaminant treatment.

Este trabalho apresenta resultados de ensaios de fluência não confinada executados pelo modo convencional e acelerado. Foi possível avaliar alguns parâmetros que influenciam o fenômeno da fluência em geotêxteis não tecidos, e ainda comparar o comportamento de dois geotêxteis ensaiados, um de polipropileno e outro de poliéster. Construíram-se as curvas isócronas dos materiais estudados e as análises das mesmas mostram que os geotêxteis de poliéster sofrem menores reduções de rigidez quando submetidos a carregamentos constantes do que os geotêxteis de polipropileno, os resultados dos ensaios acelerados apresentam-se estaticamente compatíveis com os resultados convencionais, denotando a viabilidade do Stepped Isothermal Method (SIM) como ensaio de caracterização fluência não confinada para geotêxteis não tecidos. / This work presents results of conventional and accelerated unconfined creep tests. Some factors that influence the creep behavior of nonwoven geotextiles are evaluated. The performance of polypropylene and polyester geotextiles is also compared. Isochronous curves show that the polyester geotextiles have a smaller rigidity reduction when compared with the polypropylene geotextiles when submitted to constant loads. The results of the accelerated tests are statistically compatible with the results of conventional tests, indicating that the Stepped Isothermal Method is a feasible approach for characterizing the creep behavior of nonwoven geotextiles.

Heavy-metal contamination in soils has become a serious environmental problem. Among all metals, excessive amount of zinc was released to soils over the years. Zinc is not only toxic to human being, but also to plants. High concentration of zinc is extremely phytotoxic. Currently, the most popular method to remediate heavy-metal contaminated soils is stabilization/solidification (S/S) technique as it is cheaper, faster and more effective to remediate heavy metals than other remediation methods. Portland cement is the most-used binder in S/S technique. However, the production of Portland cement has released a significant amount of carbon dioxide, which strongly contributes to global warming. In addition, zinc retards the setting and hydration of Portland cement, which would require more Portland cement to remediate zinc-contaminated sites. Therefore, researchers are looking for new materials to improve the performance of Portland cement in zinc-contaminated soils. In recent years, the application of graphene-based materials in concrete had proved to be effective. Due to relative cost-effectiveness and comparable properties, multi-layer graphene, known as graphene nanoplatelets, may show a promising potential in construction. Moreover, research has reported that graphene nanoplatelets can be exfoliated from graphite and potentially scaled up for full-scale applications. At present, there is no application of graphene nanoplatelets in the S/S of contaminated soils and the roles of graphene nanoplatelets in cement-stabilized zinc-contaminated clay remained unknown. In this research, graphene nanoplatelets were dispersed in solution with a high-shear mixing apparatus. Dispersed graphene nanoplatelets solution was then applied to zinc-contaminated soil along with cement. To evaluate the efficacy of this S/S method, various influencing factors such as mixing sequence, graphene nanoplatelets content, zinc content, cement content, and curing time were studied. An optimum graphene nanoplatelets content was determined through the unconfined compressive strength (UCS) of the stabilized/solidified samples. It was found that at the optimum content, the unconfined compressive strength of cement-stabilized zinc-contaminated clay was improved by 22.3% with the addition of graphene nanoplatelets. Also, graphene nanoplatelets were effective at moderate zinc content and low cement content. Graphene nanoplatelets accelerated cement hydration effectively at early ages. Microstructural analyses indicated that more hydration products were developed in samples with graphene nanoplatelets. At current stage, it is still expensive to apply graphene nanoplatelets in S/S technique; however, it is possible to exfoliate graphite into graphene nanoplatelets in future research. / Graduate / 2022-05-12

Sulfide soils are silty soils, often found in saturated conditions, under the groundwater level. Characteristics of these soils, including particle size distribution and consistency limits along with chemical composition and environmental properties, cause excavation to be necessary for construction purposes. The excavated sulfide soil usually is transported and deposited in landfills. These soils are either deposited in saturated conditions or chemical buffers are added to the soil to prevent acidification. Special conditions of these landfills complicate the disposal procedure and the landfill maintenance which makes those financially expensive. Reusing sulfide soil in construction is a solution to reduce the expenses related to the management of sulfide soils. Since the mechanical properties of these soils are not suitable for construction purposes, the first step is to improve soil characteristics to the level that fulfills the needs of construction applications. One solution to improve the mechanical properties of the soil is adding a binder to the soil. The main focus of the research was to improve the mechanical properties of soil. The research activities were divided into two parts. The first part was conducted in a laboratory environment to develop mixtures, while the second focused on transferring the results to field conditions. The laboratory tests included mixing soil and binder i.e., cement was added to the soil at different percentages to evaluate the soil improvement. An unconfined compressive strength (UCS) test was conducted on the stabilized sample to evaluate the efficiency of the stabilization. The resultsof UCS for the stabilized samples were compared. Since the soil contains a high amount of water, the traditional sample preparation was not suitable. Therefore, an alternative method was developed and evaluated. Moreover, the effect of curing time on the strength and consistency limit of stabilized samples was evaluated. At last, the effect of different variables, including porosity, binder content and initial water content, on the UCS of soil was investigated to identify potential correlation between UCS and different soil variables. The results of the tests showed that adding a binder, regardless of the type of sulfide soil, positively affects the UCS of prepared samples and increasing the curing time increased the UCS of the samples. At higher cement content, the effect of curing time was more significant. Also, it was shown that at higher water content, the effect of binder is lower in comparison with the same soil at lower water content. By lowering the water content, the strength of stabilized soil reaches a maximum and drying further the soil, below the optimum water content, led to strength reduction. A correlation between UCS of sample and porosity/binder ratio was employed to predict the strength behavior of stabilized soil based on variables such as porosity, initial water content and binder dosage. In order to evaluate if laboratory results can be applied to geotechnical applications, the second part of this research included a field mixing experiment for a large-scale mixture of soil and cement. The effect of the mixing procedure with common equipment on the homogeneity of industrial-size mixture was investigated. A sampling strategy for collecting representative samples of mixture was selected and assessed. the number of mixing steps and the effect of binder dosage on the uniformity of samples were studied. Results of UCS of samples prepared from field and laboratory mixture were compared and evaluated. A field evaluation was conducted to determine the quality of the mixture and how many mixing steps are required to reduce variability between samples. Two different percentages of binder were added to the 5 Tons of soil. The UCS test samples were prepared from the soil-cement mixture in the same way as they were prepared in the laboratory and cured for a specific time. The UCS test was conducted on cured samples. The test results were compared to evaluate the mixture homogeneity in the field. The results showed that homogeneous mixtures can be obtained in the field with the available equipment. Assessing the sampling strategy showed that increasing the sampling sections from 5 to 12 and preparing single UCS sample from the collected soil provides representative samples from the soil mixture pile. Additionally, it was shown that by increasing mixing steps from 2 to 3, it was possible to eliminate samples with notable lower strength than average UCS. A greater number of mixing steps improves homogeneity while reducing the average UCS. It was found that mixing soil and binder in the laboratory improves strength better than mixing them in the field. When applying laboratory results to field design, this point must be taken into account.

The purpose of this research was to investigate the effects of reclaimed asphalt pavement (RAP) content and cement content on the strength and durability of recycled aggregate base materials. Specifically, the unconfined compressive strength (UCS) and final dielectric value in the Tube Suction Test (TST) were measured in a full-factorial experimental design including five RAP contents, five cement contents, and three replicate specimens of each possible treatment. Specimen mixtures consisted of 0, 25, 50, 75, or 100 percent RAP and 0.0, 0.5, 1.0, 1.5, or 2.0 percent Type I/II Portland cement. Both the RAP and base materials were sampled from the I-84 pavement reconstruction project performed in Weber Canyon near Morgan, Utah, during the summers of 2004 and 2005. The laboratory testing procedures consisted of material characterizations, specimen preparation, and subjection of the specimens to strength and durability testing, and the data were evaluated using analysis of variance (ANOVA) testing. Both the RAP and base materials included in this research were determined to be non-plastic, and the AASHTO and Unified soil classifications for the RAP material were determined to be A-1-a and SM (well-graded sand with gravel), respectively, and for the base material they were A-1-a and SW-SM (well-graded sand with silt and gravel), respectively. The optimum moisture contents (OMCs) for the blended materials were between 5.6 and 6.6 percent, and maximum dry density (MDD) values were between 129.7 and 135.5 lb/ft3. In both cases, decreasing values were associated with increasing RAP contents. The results of the ANOVA performed on the UCS data indicate that UCS decreases from 425 to 208 psi as RAP content increases from 0 to 100 percent and increases from 63 to 564 psi as cement content increases from 0.0 to 2.0 percent. Similarly, the final dielectric value decreases from 14.9 to 6.1 as RAP content increases from 0 to 100 percent and decreases from 14.0 to 5.8 as cement content increases from 0.0 to 2.0 percent. With design criteria requiring 7-day UCS values between 300 and 400 psi and final dielectric values less than 10 in the TST, the results of this research suggest that milling plans should be utilized to achieve RAP contents in the range of 50 to 75 percent, and a cement content of 1.0 percent should be specified for this material. Cement contents less than 1.0 percent are not sufficient to stabilize the material, and greater cement contents may cause cracking. Because control of the actual cement content in the field depends on the contractor's equipment and skill, inspection protocols should be implemented during construction to ensure high-quality work. Additional recommendations are associated with the construction process. The specimens prepared in this research were compacted to relative densities of 100 percent using modified Proctor energy. Therefore, field compaction levels must approach these density values if the same material properties are to be achieved. In addition, all specimens tested in this study were cured at 100 percent relative humidity. Following compaction in the field, cement-treated layers should be moistened frequently during the first few days after construction or promptly sealed with a prime coat or wearing surface to ensure that the cement continues to hydrate. Variability in RAP and cement contents should also be minimized to achieve consistent material properties.

The use of recycled concrete material (RCM) as pavement base material is a promising but unproven technique for road rehabilitation and construction. A telephone survey conducted to investigate the state of the practice concerning RCM usage in Utah County revealed that RCM is infrequently used in this application due primarily to a lack of practical knowledge about the engineering properties of the material. Therefore, this research was aimed at evaluating the physical properties, strength parameters, and durability characteristics of both demolition and haul-back sources of RCM available in Utah County for use as pavement base material. The study included extensive laboratory and field testing. Laboratory tests included California bearing ratio (CBR), unconfined compressive strength (UCS), stiffness, freeze-thaw cycling, moisture susceptibility, abrasion, salinity, and alkalinity evaluations. Non-destructive testing was utilized in the field to monitor seasonal variation in stiffness of an RCM pavement base layer over a 1-year period. The testing included a dynamic cone penetrometer, ground-penetrating radar, a heavy Clegg impact soil tester, a soil stiffness gauge, and a portable falling-weight deflectometer. The laboratory testing indicated that the demolition material exhibited lower strength and stiffness than the haul-back material and reduced UCS loss after freeze-thaw cycling. However, the demolition material received a moisture susceptibility rating of good in the tube suction test, while the haul-back material was rated as marginal. Both materials exhibited self-cementing effects that led to approximately 180 percent increases in UCS over a 7-day curing period. Seven-day UCS values were 1260 kPa and 1820 kPa for the demolition and haul-back materials, respectively, and corresponding CBR values were 22 and 55. The field monitoring demonstrated that the RCM base layer was susceptible to stiffness changes due primarily to changes in moisture. In its saturated state during spring testing, the site experienced CBR and stiffness losses of up to 60 percent compared to summer-time values. RCM compares well with typical pavement base materials in many respects. Given the laboratory and field data developed in this research, engineers should be able to estimate the strength and durability parameters of RCM needed for pavement design.

Frost heave is a primary mechanism of pavement distress in cold regions. The distress exhibited is dependent on the frost susceptibility of the soil within the depth of frost penetration, the availability of subsurface water, and the duration of freezing surface temperatures. Cement stabilization is one technique used to mitigate the effects of frost heave. The tube suction test (TST) is one possible method for determining the frost susceptibility of soils in the laboratory. The purpose of this research was to assess the utility of the TST for identifying non-frost-susceptible (NFS) materials stabilized with cement. This research investigated two aggregate base materials from Alaska that have exhibited negligible frost susceptibility in the field. The unconfined compressive strength (UCS), final dielectric value in the TST, and frost heave at three levels of cement treatment and in the untreated condition were evaluated for both materials. The data collected in this research indicate that, for the two known NFS materials included in this study, the TST is a good indicator of frost heave behavior. The total heave of the untreated materials was approximately 0.15 in. at the conclusion of the 10-day freezing period, which classifies these materials as NFS according to the U.S Army Corp of Engineers. Both materials had final dielectric values of less than 10 in the TST, indicating a superior moisture susceptibility rating. The results of this research suggest that the TST should be considered for identifying NFS materials, including those stabilized with cement. Additional testing should be performed on known NFS materials stabilized with cement and other additives to further assess the validity of using the TST to differentiate between frost-susceptible and NFS materials. Consistent with previous studies, this research indicates that, once a sufficient amount of cement has been added to significantly reduce frost heave, additional cement has only a marginal effect on further reduction. Therefore, to avoid unnecessary expense in construction, the minimum cement content required for preventing frost heave should be identified through laboratory testing and specified by the engineer. In this work, UCS values ranging between 200 psi and 400 psi after a 7-day cure were typically associated with this minimum cement content. Because the scope of this research is limited to two aggregate base materials, further testing is also necessary to validate this finding.

Full-depth reclamation (FDR) is an increasingly common technique that is used to rehabilitate flexible pavements. Implementation of FDR on rehabilitation projects produces several desirable benefits. However, these benefits are not fully realized due to the fact that state department of transportation specifications typically limit the reclaimed asphalt pavement (RAP) content of pavement base material to 50 percent. The objective of this research was to evaluate the effects of RAP content, cement content, temperature, curing time, curing condition, and moisture state on the strength, stiffness, and deformation characteristics of cement-treated base (CTB) mixtures containing high percentages of RAP.For this research, one aggregate base material and one RAP material were used for all samples. RAP content ranged from 0 to 100 percent in increments of 25 percent, and low, medium, and high cement levels corresponding to 7-day unconfined compressive strength (UCS) values of 200, 400, and 600 psi, respectively, were selected for testing. Moisture-density, UCS, resilient modulus, and permanent deformation tests were performed for various combinations of factors, and several statistical analyses were utilized to evaluate the results of the UCS, resilient modulus, and permanent deformation testing.The results of this work show that CTB containing RAP can be made to achieve 7-day UCS values approaching 600 psi regardless of RAP content. With regards to stiffness, the data collected in this study indicate that the resilient modulus of CTB containing RAP is affected by temperature in the range from 72 to 140°F for the low cement level. Permanent deformation of CTB containing RAP is significantly affected by RAP content and cement level at the test temperature of 140°F. At the low cement level, temperature is also a significant variable. As the 7-day UCS reaches approximately 400 psi, permanent deformation is reduced to negligible quantities. The results of this research indicate that the inverse relationship observed between permanent deformation and 7-day UCS is statistically significant.Given that the principle conclusion from this work is that CTB with high RAP contents can perform satisfactorily as a base material when a sufficient amount of cement is applied, agencies currently specifying limits on the percentage of RAP that can be used as a part of reclaimed base material in the FDR process should reevaluate their policies and specifications with the goal of allowing the use of high RAP contents where appropriate.

The Deep Mixing Method (DMM) is a widely used, in-situ ground improvement technique that modifies and improves the engineering properties of soil by blending the soil with a cementitious binder. Laboratory specimens were prepared to represent soil improved by the wet method of deep mixing, in which the binder is delivered in the form of a cement-water slurry. To study the influence of curing temperature on the strength of the treated soil, specimens were cured in temperature-controlled water baths for the desired curing time. After curing, unconfined compressive strength (UCS) tests were conducted on the specimens. To investigate the optimum mix design for the wet method of deep mixing, UCS tests were performed to measure the strength of cured specimens, and laboratory miniature vane shear tests were conducted on uncured specimens to measure the undrained shear strength (su), which is used to represent the consistency of the mixture right after mixing. The consistency is important for field mixing because a softer mixture is easier to mix thoroughly. Based on the UCS test results, an equation that can provide a good fit to the strength data of the cured binder-treated soil is proposed. When the curing temperature was changed during curing, the UCS of the specimen cured at a low temperature and then cured at a high temperature was greater than the UCS of the specimen cured at a high temperature first. This seems to be due to different effects of elevated curing temperatures at early and late curing times on the cement reaction rates, such that elevating the curing temperature later produces a more constant reaction rate, which contributes to the reaction efficiency. An optimum mix design that minimizes the amount of binder while satisfying both a target strength of the cured mixture and a target consistency of the uncured mixture can be established by using the fitted equations for UCS and su. The amount of binder required for the optimum mix design increases as the plasticity of the base soil increases and the water content of the base soil (wbase soil) decreases. / Master of Science / The Deep Mixing Method (DMM) is a ground improvement technique widely used to improve the strength and stiffness of loose sands, soft clays, and organic soils. The DMM is useful for both inland and coastal construction. There are two types of deep mixing. The dry method of deep mixing involves adding the binder in the form of dry powder, and the wet method of deep mixing involves mixing binder-water slurry with the soil. The strength of the cured mixture is significantly influenced by the amount of added cement and water, the curing time, and the curing temperature. This research evaluates the influence of curing temperature on the strength of cured cement-treated soil mixture. Mixture proportions and curing conditions also influence the consistency of the mixture right after mixing, which is important because it affects the amount of mixing energy necessary to thoroughly mix the binder slurry with the soil. This research developed and evaluated fitting equations that correlate the cured mixture strength and the uncured mixture consistency with mixture proportions and curing conditions. These fitting equations can then be used to select an economical and practical mix design method that minimizes the amount of binder needed to achieve both the desired cured strength and uncured consistency. The amount of binder required for the optimum mix design increases as the plasticity of the base soil increases and the water content of the base soil (wbase soil) decreases.