No description available.

The aim of the present investigation is to improve the geotechnical properties of dispersive soil by reducing their dispersivity after elucidating the important mechanisms controlling the dispersivity of the soils. Dispersive soils have unique properties, which under certain conditions deflocculate and are rapidly eroded and carried away by water flow. These soils are found extensively in the United States, Australia, Greece, India, Latin America, South Africa and Thailand. The mechanism of dispersivity of soils is a subject matter of great interest for geotechnical engineers. In the earlier days clays were considered to be non erosive and highly resistant to water erosion. However, recently it was found that highly erosive clay soils do exist in nature. Apart from clayey soil, dispersivity is also observed in silty soils. The tendency of the clays to disperse or deflocculate depends upon the mineralogy and soil chemistry and also on the dissolved salts in the pore water and the eroding water. Such natural dispersive soils are problematic for geotechnical engineers. They are clayey soils which are highly susceptible to erosion in nature and contain a high percentage of exchangeable sodium ions, (Na+). It is considered that the soil dispersivity is mainly due to the presence of exchangeable sodium present in the structure. When dispersive clay soil is immersed in water, the clay fraction behaves like single-grained particles; that is, the clay particles have a minimum of electrochemical attraction and fail to closely adhere to, or bond with, other soil particles. This implies that the attractive forces are less than the repulsive forces thus leading to deflocculation (in saturated condition).This weakens the aggregates in the soil causing structural collapse. Such erosion may start in a drying crack, settlement crack, hydraulic fracture crack, or other channel of high permeability in a soil mass. Total failure of slopes in natural deposits is initiated by dispersion of clay particles along cracks, fissures and root holes, accelerated by seepage water. For dispersive clay soils to erode, a concentrated leakage channel such as a crack (even a very small crack) must exist through an earth embankment. Erosion of the walls of the channel then occurs along the entire length at the same time. Many slope and earth dam failures have occurred due to the presence of dispersive soils. Unlike erosion in cohesionless soils, erosion in dispersive clay is not a result of seepage through the pores of clay mass. However, the role of type of clay and its Cation exchange capacity in the dispersion of soil is not well understood. Data on the presence, properties, and tests for identification of dispersive clays is scarce. Hence, an attempt is made, in this thesis, to develop reliable methods to identify these soils and understand the extent of their dispersivity as well as to develop methods to control their dispersivity. The present study deals with the characterization of a local dispersive soil collected from southern part of Karnataka State. This study has focused on comprehensive tests to assess the dispersivity of the soils by different methods and to methods to improve geotechnical properties by reducing the dispersivity of the soil. An attempt is made to reduce the dispersivity of soil by using calcium based stabilizers such as lime, cement and fly ash. The mechanism of improvement in reducing the dispersivity of the soil with calcium based stabilizers has been studied. One of the important mechanism by which the dispersivity of the soil is reduced is by inducing cementation of soil particles. The differences in effectiveness of different additives are due to their differences in abilities to produce cementitious compounds. Although all the additives increased the strength of the soil and reduced the dispersivity of the soil, cement was found to significantly reduce the dispersivity of the soil, compared to the other two additives lime and fly ash. Cement is more effective as sufficient cementitious compounds are produced on hydration without depending on their formation. A detailed review of literature on all aspects connected with the present study is given in Chapter 2. A comprehensive description of dispersive soils present worldwide has been brought out in this section. Based on this survey, the scope of the present investigation has been elaborated at the end of the chapter. To understand the reasons for dispersivity of the soil and to estimate its degree of dispersivity, it is essential to assess standard methods to characterize the soil. Chapter 3 presents a summary of material properties and testing programs. The results of geotechnical characterization of the soil, the index properties of the soilspecific gravity, sieve analysis, Atterberg’s limits are discussed in Chapter 4. The physico chemical characteristics play an important role in determining the amount of dispersivity of the soil. Dispersive soils have two main characteristics which define its dispersivity chemically. These are Sodium Adsorption Ratio (S.A.R) and Exchangeable Sodium Percentage (E.S.P). The two characteristics are determined from the Cation exchange capacity of the soil. Exchangeable Sodium Percentage is defined as the concentration of sodium ions present in the soil with respect to the Cat ion exchange capacity of the soil. And Sodium Adsorption Ratio is used to quantify the free salts present in the pore water. Since Atterberg’s limits and grain size analysis do not help in identifying dispersive soils or in quantifying its dispersivity, two other tests- Emerson Crumb test and double hydrometer test were carried out on the soil. Emerson crumb test is a simple way for identification of dispersive soils. In this test, a crumb of soil measuring about 1mm diameter is immersed in a beaker containing distilled water and the subsequent reaction is observed for 5 minutes. It is solely based on direct qualitative observations. Depending on the degree of turbidity of the cloud formed in the beaker, the soil is classified in one of the four levels of dispersion in accordance with ASTM-D6572. Since this test is mainly a qualitative test and does not help in quantifying the dispersivity, it cannot be depended upon completely in identifying a dispersive soil. Another test double hydrometer test, which helps in quantifying the dispersivity of the soil, was also conducted on the soil. This test involves in conducting the particle size distribution using the standard hydrometer test in which the soil specimen was dispersed in distilled water with a chemical dispersant. A parallel hydrometer test was conducted on another soil specimen, but without a chemical dispersant. The dispersing agent used for the experiment was sodium hexametaphosphate. The percent dispersion is the ratio of the dry mass of particles smaller than 0.005 mm diameter of the test without dispersing agent to the test with dispersing agent expressed as a percentage. The double hydrometer test was carried out according to Double Hydrometer Test (ASTM D4221). Apart from the conventional tests, attempts are made to consider shrinkage limit test and unconfined compression test to determine the dispersivity of the soil. For this purpose, the shrinkage limit of the soil was determined with and without dispersing agent. The initial shrinkage limit of the untreated soil reduced on treating it with dispersing agent, thus indicating that the soil had further dispersed on addition of dispersing agent. In order to carry out the unconfined compression strength, the maximum dry density and optimum moisture content was determined through the compaction test. The soil was then treated with dispersing agent and compacted at the optimum moisture content. The soil exhibited high degree of dispersion through the strength test. Hence it is necessary to stabilize the soil with additives. Detailed experimental program has been drawn to find methods to improve the geotechnical properties and to reduce the dispersivity of the soil. Chapter 5 presents the investigations carried out on the dispersive soil with lime. The importance of lime stabilization and the mechanism of lime stabilization have been discussed initially. Commercially obtained hydrated lime was used in the present study. The soil was treated with three different percentages of lime 3, 5 and 8. The curing period was varied from one day to twenty eight days. The effect of addition of lime on various properties of the soil such as pH, Atterberg’s limits, compaction test and unconfined compression test is elaborated in chapter 5. The pH of the soil was maximum on addition of 3% lime. On further addition, the pH decreased and remained constant. The liquid limit of the soil increased on adding 3% lime and decreased with further lime content. The compaction test conducted on the soil showed an increase in maximum dry density of the soil and reduction in optimum moisture content with 3% lime content. On further increase in the lime content, the soil showed a decrease in the maximum dry density and increase in optimum moisture content. The unconfined compressive strength of the soil also increased on increasing lime content upto 5%. The variation in strength of the soil with respect to curing period was also compared. Optimum lime content arrived at based on the above conducted tests was 3%. The effect of lime in reducing the dispersivity of the soil through shrinkage limit test and unconfined compression test is also presented in this chapter. Details of the efforts made on the soil with fly ash are presented in Chapter 6.The fly ash used for stabilization of Suddha soil was of Class F type. This type of fly ash contains low reactive silica and lime. The effect of varying fly ash content on the properties of Suddha soil by varying the percentage of fly ash from 3 to 10 percentages is discussed in this chapter. The tests conducted on fly ash treated Suddha soil were pH test, compaction test, Atterberg’s limits and unconfined compression test with varying curing period. The fly ash treated Suddha soil was cured from one day to twenty eight days for the unconfined compressive strength analysis. The pH of the soil system increased with increasing percentage of fly ash. The increase in liquid limit was marginal on addition of fly ash. The maximum dry density of fly ash treated Suddha soil decreased continuously and the optimum moisture content of the treated soil increased with increasing fly ash content. The unconfined compressive strength of Suddha soil increased with increase in fly ash content upto 8% and then decreased for fly ash content of 10%. For all the percentages of fly ash added, the strength of the soil increased with increase in the curing period. The effect of fly ash in reducing the dispersivity of the soil was carried out using shrinkage limit and unconfined compression test. It was seen that on increasing the fly ash content, the soil treated with dispersing agent showed an increase in the shrinkage limit. Also, the same trend was observed for the unconfined compression strength to determine dispersivity. Optimum fly ash was determined as 8% with the help of all the tests conducted on the soil. Since the improvement in the properties of the soil with lime and fly ash was not very high, Cement was also considered as another additive used for stabilization of Suddha soil. It is known that soil with lesser amount of clay content will respond well with cement. The effect of cement addition on various properties of Suddha soil has been brought out in Chapter 7. It was found that addition of cement had positive effects on all the properties of Suddha soil. The pH of the soil increased for all the percentages of cement addition. The liquid limit of the soil increased on increasing the cement content. The shrinkage limit also showed a similar trend. The optimum moisture content of the soil decreased on increasing the cement content for Suddha soil and the maximum dry density increased for cement treated Suddha soil. The soil showed the maximum dry density at 8% cement content. The unconfined compression strength conducted on cement treated Suddha soil increased significantly for higher cement contents and also with curing period. Suddha soil when treated with 8% cement content exhibited maximum strength in comparison to other percentages. Also, the effect of cement in reducing the dispersivity of the soil was carried out using shrinkage limit and unconfined compression test. The shrinkage limit of the soil increased for all percentages of cement content, even in the presence of dispersing agent. Through the unconfined compression strength for dispersivity, it could be seen that 8% cement treated Suddha soil had the least dispersion. Optimum cement content was derived as 8% with the help of the tests conducted on the soil. A comparison of effect of all the additives on the strength of the soil as well as effect of the additives in reducing the dispersivity of the soil is discussed in Chapter 8. The effect of additives on the shrinkage limit of the soil with and without dispersing agent has been compared. The variation in shrinkage limit of the soil when treated with the additives was due to the different mechanisms involved in reducing the dispersivity by each additive. The effect on the unconfined compression strength of the soil treated with the additives with and without dispersing agent is also brought out in this chapter. It was noted that the dispersion exhibited through shrinkage limit test was lesser as compared to the percentage dispersivity exhibited through unconfined compression test. Hence it could be said that dispersion of the soil is due to loss of cohesion than volume change behavior. Also, the unconfined compression strength of the soils with respect to curing period is compared. The percentage dispersivity calculated through these tests is summarized and compared. With the help of this it could be said that to control the dispersivity of the soil, it is necessary to enhance the strength of the soil. The general summary and major conclusions drawn from the thesis are presented in Chapter 9.

O objetivo principal desta dissertação é determinar, a partir de ensaios de laboratório, o comportamento mecânico de misturas constituídas com solos lateríticos arenoso e argiloso e emulsão asfáltica, visando a sua utilização na construção rodoviária. Utilizou-se na compactação a energia normal do Proctor, e analisaram-se os efeitos do tipo de solo, o teor e tipo de emulsão, tipo de cura pré e pós-compactação, tempo de cura e a imersão em água na resistência e rigidez das misturas. Foram realizados ensaios para a determinação da resistência à compressão simples, resistência à compressão diametral, módulo de resiliência, índice de suporte Califórnia e variação volumétrica durante a cura e imersão dos corpos-de-prova. Os resultados mostraram que as misturas com emulsão apresentaram resistência e rigidez superiores às dos solos in natura, e ainda menores variações volumétricas decorrentes da secagem e da imersão dos corpos-de-prova em água. Finalmente, concluiu-se que o uso das emulsões asfálticas é promissora na área de pavimentação, dado que proporciona às misturas propriedades físicas e mecânicas para estas serem aplicáveis na construção rodoviária. / This work has the main objective of studying, based on laboratory tests, the mechanical behavior of sand and clay lateritics soils and the asphalt emulsion in focus mixtures, seeking their utilization in road construction. Were compacted at the normal Proctor energy, analyzing the soil type, the asphaltic emulsion rate and type, the curing pre and pos- compactation, the curing time and the effect of the immersion in water to the mixtures strength and rigidity, afterwards they were submitted to tests to the determination of unconfined compressive strength, indirect tensile strength, modulus resilient, California bearing ratio and volumetric variability of specimens when immersed in water. The results showed that the addition of asphaltic emulsion to soils improve the strength and rigidity of in natura and reduction of the volumetric variability caused by drying and immersion in water soils. Finally, it concludes that bituminous emulsion provides to soils qualities that could be qualified for use in road construction.

The objectives of this research were to 1) measure the extent to which water vapor movement results in water accumulation in freezing base materials; 2) evaluate the effect of soil stabilization on water vapor movement in freezing base materials; 3) determine if the corresponding changes in water content are sufficient to cause frost heave during winter; 4) determine if the corresponding changes in water content are sufficient to cause reductions in stiffness during spring; 5) evaluate relationships between selected material properties, freezing conditions, and the occurrence and impact of water vapor movement; and 6) numerically simulate heat and water movement in selected pavement design scenarios. The research involved extensive laboratory and field testing, statistical analyses, and numerical modeling. The results of the laboratory testing, which included gradations, Atterberg limits, soil classifications, specific gravity and absorption values, electrical conductivity values, moisture-density relationships, soil-water characteristic curves, moisture-stiffness curves, hydraulic conductivity values, and frost susceptibility assessments, were used to characterize each material and enable subsequent statistical analyses. Testing of both treated and untreated materials enabled investigation of a wide variety of material properties. The results of the field testing, which included temperature, moisture content, water potential, elevation, and stiffness data over time, provided the basis for comparing pavement sections with and without capillary barriers and established the framework for numerical modeling. In a pavement section with a capillary barrier underlying the base layer, water vapor movement from the subgrade through the capillary barrier may be expected to increase the water content of the base layer by 1 to 3 percent during a typical winter season in northern Utah for base materials similar to those studied in this research. During winter, cold temperatures create an ideal environment for water vapor to travel upward from the warm subgrade soil below the frost line, through the capillary barrier, and into the base material. Soil stabilization can lead to increased or decreased amounts of water vapor movement in freezing base materials depending on the properties of the stabilized soil, which may be affected by gradation, mineralogy, and stabilizer type and concentration. Accumulation of water from long-term water vapor movement into frost-susceptible base materials underlain by a capillary barrier can lead to frost heave of the base layer as it approaches saturation, as water available in the layer can be redistributed upwards to create ice lenses upon freezing. However, the incremental increase in total water content that may occur exclusively from water vapor movement during a single winter season in northern Utah would not be expected to cause measurable increases in thaw weakening of the base layer during spring. Because water in a base layer overlying a capillary barrier cannot drain until nearly reaching positive pore pressures, the base layer will remain indefinitely saturated or nearly saturated as demonstrated in this research. For materials similar to those studied in this research, potentially important material properties related to the occurrence of water vapor movement during freezing include dry density, percent of material finer than the No. 200 sieve, percent of material finer than 0.02 mm, apparent specific gravity, absorption, initial water content, porosity, degree of saturation, hydraulic conductivity, and electrical conductivity. The rate at which water vapor movement occurs is also dependent on the thermal gradient within the given material, where higher thermal gradients are associated with higher amounts of water vapor movement. The numerical modeling supported the field observations that the capillary barrier effectively trapped moisture in the overlying base material, causing it to remain saturated or nearly saturated throughout the monitoring period. Only non-frost-susceptible aggregate base materials should be specified for use in cold climates in conjunction with capillary barriers, and the base material in this case should be assumed to remain in a saturated or nearly saturated condition during the entire service life of the pavement. Further study is recommended on water vapor movement in freezing aggregate base materials.

Existen estudios sobre las mejoras mecánicas que le brinda la adición de cal y Ceniza de Cáscara de Arroz (CCA) a los suelos arcillosos -naturalmente plásticos- con más de 70% de material fino en su composición. Sin embargo, para el comportamiento de arcillas arenosas, cuyo porcentaje de granos gruesos en su estructura superan el 40%, hacen falta más referencias. En la investigación se evalúa la influencia de la adición de CCA a esta clase de suelo, estabilizado con 3% de cal. El suelo estabilizado (sin CCA) incrementó 11.2 veces su valor de CBR natural; al agregarle la adición, el CBR incrementó solo en 1.56%. Al adicionarle 28% de CCA se observó un decrecimiento en su resistencia. Por otro lado, según la clasificación AASHTO, la trabajabilidad del suelo estabilizado fue mejorando a medida que se incrementó la adición de CCA, llegando a valores de IG=0. La mejor performance del suelo estabilizado se obtuvo con 16% de CCA, alcanzando 51.3% de CBR, 1.65g/cm3 de MDS y 15.8% de OCH. El CBR de este suelo estabilizado con cal y con la adición de CCA no proyecta mejoras mecánicas sustanciales, por más que demuestre una mejor trabajabilidad, la estabilización con cal de este tipo de suelos resulta suficiente para una buena performance. / There are many studies about how the addition of lime and Rice Husk Ash (RHA) gives the soil a better mechanical behavior, particularly on clayey soils, where usually fine particles reach more than 75%. However, the soils with a small presence of fine particles (59-60%) do not have much research. This investigation evaluates the influence that RHA has on this kind of soil previously stabilized with 3% of lime. After the initial mix of soil-lime, the CBR increased 11.2 times its initial value; within the addition of the ash, the CBR maxed out its value increasing just 1.56%. When 28% of RHA was added, a decay in the value of CBR was noticed. Otherwise, soil workability improved and following the AASHTO standards, the specimens with more ash resulted in a more granular material, with a group index value of 0. The greatest CBR record was obtained when the stabilized soil was added a 16% RHA, reaching a 51.3% CBR, 1.58g/cm3 of MDD and 16.5% of OMC. The CBR of the soil stabilized with lime and the addition of RHA, does not shows substantial improvement, and beyond that the workability seems better, the addition of lime by itself should be enough for an adequate performance for silica-rich clayey soils. / Tesis

Concrete, the second most consumed material on earth after water, is a source of environmental problems due to global urbanization. The production of this construction material requires a large amount of natural resources, and portland cement (PC) is responsible for around 8 % of planet-warming CO2 emissions. Producing 1 ton of PC will release roughly 1 ton of CO2 into the atmosphere. In 2021, around 92 million metric tons of PC were produced in the U.S., and a total of 4.4 billion tons were manufactured worldwide. While there was a yearly increase of around 1.5 % in the direct CO2 intensity of cement production from 2015 to 2021, urgent annual declines of 3 % until 2030 are necessary to be in line with the Net Zero Emissions by 2050 Scenario. This dissertation presents different approaches and technologies to offset the CO2 footprint of the production of cement clinker, concrete, and cementitious materials in general. First, this dissertation investigated the possibility of using end-of-life tire (ELT) rubber powder and its zinc-recovered residual (treated ELT rubber) to partially replace fine aggregates of different construction and infrastructure materials including stabilized soft soil (0 %, 10 %, 30 %, and 50 % ELT rubber added by clay volume), portland cement concrete (0 %, 10 %, 20 %, and 30 % ELT rubber added by sand volume), and asphalt concrete (20 % ELT rubber added by sand volume). This work was discussed through aspects of engineering properties and environmental impacts. The results reveal that the ELT rubber had both negative and positive effects on the engineering properties of the three materials while this waste posed a huge leachability of zinc and total organic carbon (TOC) content when being subjected to aqueous environments. However, the findings indicate that all three materials' matrices could effectively immobilize most leachable zinc from the ELT rubber by more than 90 %. Meanwhile, only stabilized soft soil and asphalt concrete could effectively deal with leachable TOC content from ELT rubber, and portland cement concrete needed the addition of silica fume to reduce TOC concentration in its leachate. Second, while previous studies have shown that steel furnace slag (SFS) can stabilize clay soils, the evidence is not clear if the stabilization mechanism is chemical and/or mechanical. This dissertation used isothermal calorimetry (IC) to quantify the heat of hydration of the mixture to assess the chemical aspects of the stabilization. Specifically, kaolin and bentonite clays were each blended with 40 % SFS by mass at water-to-binder ratios ranging from 1.0 to 1.5. The hydration properties of stabilized mixtures using lime or PC were also tested for comparison at the same experimental conditions. The obtained thermal power and total heat curves of stabilized mixtures confirmed that, for the specific SFS in this study, there is a hydration process taking place in clay stabilized by SFS. Relative to lime and PC, the SFS performed similarly in terms of heat of hydration behavior. When blended into clays, SFS provided a more significant heat of hydration behavior than cement, but that was much milder than lime. X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were also employed to qualitatively analyze the mineralogy of the stabilized mixtures. Finally, this dissertation adopted a Digestion-Titration Method (DTM) for the determination of CO2 content in cementitious materials that has been mineralized in the form of calcium carbonate (CaCO3). This method was modified based on tests that were originally developed in the early 1900s. The method uses hydrochloric acid to digest CaCO3 under vacuum conditions. The CO2 released is captured by a barium hydroxide solution, which is then titrated to quantify the amount of CO2 absorbed. A design of experiments approach was used to optimize the experimental conditions. Samples of known CaCO3 content were first evaluated to establish the baseline test performance, and additional tests were performed on portland cement and various rock samples. The results were also compared to TGA, including a discussion to compare the two test methods. The data suggest that the new test method is feasibly applicable to chemically determine the CO2 captured in cementitious materials, and it can be an alternative method for TGA with lower experimental cost and easier access. Overall, it is evident that cement, concrete, and construction materials are essential to the functionality of civilization. Dealing with CO2 emissions and natural resource depletion induced by the production of these construction materials is urgent for sustainable development. Attempts toward construction materials with lower embodied CO2 by using low-carbon aggregates (e.g., waste aggregates, recycled aggregates) and alternative cementitious binders while controlling the environmental effects of the utilized waste materials are currently viable sustainable approaches. In addition, tools or new test methods that can support measuring the effectiveness of these reduced carbon cementitious materials are necessary. This dissertation investigates the feasibility of the use of ELT rubber waste in construction materials to reduce the exploitation of natural resources considering engineering properties and environmental impacts. It also provides a deeper understanding of the hydration behavior of stabilized soil using SFS which is expected to partially or fully replace PC in the material. Experimentally, it develops a chemical test model as an alternative method for TGA with lower experimental cost, less interference, and easier access to determine the CO2 captured in cementitious materials. / Doctor of Philosophy / Concrete, the second most consumed material on earth after water, is a source of environmental problems due to global urbanization. The production of this construction material requires a large amount of natural resources, and portland cement (PC) is responsible for around 8 % of planet-warming CO2 emissions. This dissertation presents different approaches and technologies to offset the CO2 footprint of the production of construction materials (i.e., cement clinker, concrete, and general cementitious materials). First, this dissertation investigated the possibility of using end-of-life tire (ELT) rubber powder in different construction materials including stabilized soft soil, portland cement concrete, and asphalt concrete. This work was discussed through aspects of engineering properties and environmental impacts. The results reveal that the ELT rubber had both negative and positive effects on the engineering properties of the three materials. In return, all three materials' matrices could effectively immobilize most leachable zinc and total organic carbon (TOC) from the ELT rubber, which are detrimental to aquatic animals, plants, and humans. Second, this dissertation used isothermal calorimetry (IC) for the first time to study the heat of hydration of soil stabilized by steel furnace slag (SFS) to assess the chemical aspects of the stabilization. The work compared the hydration behavior of SFS in clayey soil with traditional stabilizers such as lime or portland cement. The results demonstrated that there were chemical reactions taking place during the hydration of stabilized soil using SFS, explaining the improvement in engineering properties of the stabilized soil. Moreover, this dissertation adopted a Digestion-Titration Method (DTM) for the determination of mineralized CO2 content in cementitious materials. The method uses hydrochloric acid to digest CaCO3 under vacuum conditions. The CO2 released is captured by a barium hydroxide solution, which is then titrated to quantify the amount of CO2 absorbed. The data suggest that the new test method is feasibly applicable to chemically determine the CO2 mineralized in cementitious materials, and it can be an alternative method for thermogravimetric analysis with lower experimental cost and easier access. Overall, it is evident that cement, concrete, and construction materials are essential to the functionality of civilization. Dealing with CO2 emissions and natural resource depletion induced by the production of these construction materials is urgent for sustainable development. This dissertation is expected to fill the knowledge gap in carbon neutral construction materials research, including increasing the use of low-carbon aggregates (e.g., waste aggregates, recycled aggregates) and alternative cementitious binders as well as developing new test methods that can support measuring the effectiveness of these reduced carbon cementitious materials.

Actualmente, el tramo de Av. Venezuela desde Próceres hasta España, presenta un suelo de baja capacidad de soporte, con un grado plástico entre medio a alto y con indicios de ser expansivo, siendo este el responsable de generar problemas de transitabilidad en épocas de lluvias, asentamientos a nivel de vereda y hundimientos en la vía con ausencia de pavimento. Debido a la problemática anterior, la presente tesis busca mejorar las propiedades físicomecánicas del suelo mediante la incorporación de agregados de carpetas asfálticas recicladas (CAR) más cenizas de aserrín (CDA), evaluándose las siguientes combinaciones: 50%CAR+4CDA+46%S, 50%CAR+8%CDA+42%S, 60%CAR+4%CDA+36%S, 60%CAR+8%CDA+32%S, 70%CAR+4%CDA+26%S y 70%CAR+8%CDA+22%S, estos porcentajes fueron ensayados en cada muestra de subrasante arcillosa: ML(C-01), CL(C-02) y CH(C-03). En base a los ensayos de laboratorio desarrollados, se obtuvo el 70%CAR+4%CDA como porcentajes óptimos de los estabilizantes, ocasionando en las tres subrasantes arcillosas los siguientes cambios: el IP, varió entre 0.55 a 1.00 veces su valor natural, determinándose 17.00%, 18.00% y 17.00% según sea la muestra, así mismo, la MDS, incrementó entre 2.23 a 3.24 veces su valor original, obteniéndose 1.907, 1.930 y 1.922 g/cm3 correspondientemente, en tanto, el CBR(95%), aumentó entre 2.23 a 3.24 veces su valor inicial, alcanzando 9.50%, 6.70% y 9.40% respectivamente, recalcándose que, las tres muestras pasaron de ser una subrasante inadecuada a una regular. Finalmente, para la ejecución de pavimento flexible cuya subrasante esté mejorada con 70%CAR+4%CDA se necesitará S/893,764.88 soles por cada 500m, no obstante, esta propuesta disminuye al 42.11% los impactos que tradicionalmente se generarán. / Due to the above problems, this thesis seeks to improve the physical-mechanical properties of the soil by incorporating aggregates of recycled asphalt pavement (RAP) plus sawdust ashes (SDA), evaluating the following combinations: 50%RAP+4%SDA+46%S, 50%RAP+8%SDA+42%S, 60%RAP+4%SDA+36%S, 60%RAP+8%SDA+32%S, 70%RAP+4%SDA+26%S y 70%RAP+8%SDA+22%S, these percentages were tested in each sample of clayey subgrade: ML(C-01), CL(C-02) and CH(C-03). Based on the developed laboratory tests, 70%RAP+4%SDA was obtained as optimal percentages of the stabilizers, causing the following changes in the three clayey subgrades: the IP varied between 0.55 to 1.00 times its natural value, determining 17.00%, 18.00% and 17.00% depending on the sample, likewise, the MDD increased between 2.23 to 3.24 times its original value, obtaining 1.907, 1.930 and 1.922 g/cm3 correspondingly, while the CBR(95%), increased between 2.23 to 3.24 times its initial value, reaching 9.50%, 6.70% and 9.40% respectively, emphasizing that the three samples went from being an inadequate subgrade to a regular one. Finally, for the execution of flexible pavement whose subgrade is improved with 70%RAP+4%SDA, it will cost a total of S/893,764.88 per 500m, however, this proposal reduces the impacts that will traditionally be generated to 42.11%.

[pt] A gestão dos Resíduos Sólidos Urbanos (RSU) e seu consequente reaproveitamento ou não é um problema existente no Brasil e no mundo. No Brasil, a produção de energia mediante incineração de RSU ainda está na sua etapa inicial, como por exemplo, com a implantação da Usina Verde no campus da UFRJ, com a consequente produção de subprodutos, como as cinzas volante e de fundo. Este estudo apresenta o comportamento de um solo coluvionar argiloso estabilizado com cinzas de RSU sob carregamento estático, tendo como principal objetivo avaliar a influência destas cinzas misturadas com o solo para possíveis aplicações em obras geotécnicas. Para isso foram realizados ensaios de caracterização física, química e mecânica, como ensaios de compactação Proctor Normal e ensaios triaxiais consolidados isotropicamente drenados (CID), para o solo puro e misturas solo-cinza. Foram avaliadas as influências do teor de cinzas (20 por cento, 30 por cento e 40 por cento de cinza volante e de cinza de fundo), bem como do tempo de cura (30 e 60 dias). Os resultados mostram que todas as misturas solo-cinza apresentam melhores parâmetros de resistência, em comparação do solo puro, onde as misturas solo-cinza volante apresentaram melhores resultados quando comparadas às misturas solo-cinza de fundo. A variação de teor de cinza adicionado ao solo, sem cura, mostra que para maiores teores de cinza volante a coesão diminui e ocorre o contrário com a cinza de fundo. Com relação ao tempo de cura, na maioria dos casos houve melhora do comportamento das misturas solo-cinza em comparação ao obtido sem cura. O teor de cinza (volante ou de fundo), tempo de cura e a tensão de confinamento influenciam na deformação volumétrica das misturas solo-cinza, apresentando menores deformações volumétricas para maiores teores de cinza e maiores tempos de cura. As misturas com 40 por cento de cinza volante e 30 por cento de cinza de fundo apresentaram as melhores características de resistência e poderiam ser utilizadas como estabilizante no solo estudado, cumprindo exigências geotécnicas e ambientais, além de rebaixar os custos de obra e dar um destino mais nobre para as cinzas de RSU. / [en] Management of Municipal Solid Waste (MSW) and its subsequent reuse or not is an existing problem in Brazil and the world. In Brazil, the production of energy through incineration of MSW is still in its initial stage, for example, with the implementation of Usina Verde on campus at UFRJ, with the consequent production of byproducts, such as fly and bottom ashes. This study presents the behavior of a colluvial clayey soil stabilized with ashes from MSW under static load, with the main objective to evaluate the influence of these ashes mixed with the soil for possible applications in geotechnical works. For this characterization were performed physical, chemical and mechanical tests, as Proctor compaction tests Normal isotropically consolidated and drained triaxial (CID) for the pure and soil-ash mixtures. Were evaluated the influence of the ash content (20 per cent, 30 per cent and 40 per cent fly ash and botton ash) and of curing time (30 and 60 days). The results show that all mixtures soil-ash have better shear strength compared to the pure soil, where the soil- fly ash mixtures showed better results compared to mixtures of soil- bottom ash. The variation of the ash content added to the soil, without curing, shows that higher levels of ash the cohesion decrease and the opposite occurs with the bottom ash. Respect to the curing time, in most cases there was as improvement of the behavior of mixtures soil-ash compared to that obtained without curing. The ash content (fly or bottom), curing time and confinement stress influence the volumetric deformation to soil-ash mixtures, showed lower volumetric deformations to higher concentrations of ash and longer curing times. The mixtures with 40 per cent fly ash and 30 per cent bottom ash, showed the best characteristics of strength and could be used as stabilizer in the studied soil, compliance requirements geotechnical and environmental, in addition to lower labor costs and give a nobler destiny for the ashes of MSW.

[pt] Este estudo apresenta o comportamento de um solo arenoso estabilizado com cinzas obtidas através da incineração de Resíduo Sólido Urbano (RSU) e cal. Através de um estudo experimental, objetiva-se avaliar a aplicabilidade de misturas solo-cinza e solo-cinza volante-cal em obras geotécnicas como, por exemplo, camadas de aterros sanitários, aterros sobre solos moles e estabilização de taludes. Para isso, foram realizados ensaios de caracterização física, química e mecânica (ensaios triaxiais CID) para os materiais envolvidos. Para as misturas solo-cinza volante-cal, adicionou-se 3 porcento de cal em substituição ao peso seco das cinzas. Foram avaliadas as influências do teor de cinza (30 e 40 porcento) e tipo de cinza (volante - CV e fundo - CF), bem como o tempo de cura (0, 60 e 90 dias) para misturas com cinza volante e cal. Os resultados mostram que tanto as misturas com CV, como CF, apresentam resultados satisfatórios. Para ambas as cinzas, as porcentagens de 30 e 40 porcento apresentaram resultados similares, podendo-se adotar o valor de 40 porcento como teor ótimo, uma vez que proporciona a utilização de uma maior quantidade de resíduo. Comparando-se as cinzas, a CF apresentou resultados mais satisfatórios que a CV. Para as misturas com cura, observou-se que no tempo de 60 dias o material sofreu um maior ganho de resistência. Foram utilizados dois métodos de moldagem de corpo de prova para o ensaio com cura, obtendo-se melhor resultado para o método onde a cura era realizada em um corpo de prova pré-moldado. Portanto o uso das cinzas de RSU em mistura com este tipo de solo se mostra satisfatório, uma vez que apresentou um bom comportamento, contribui com o menor consumo de material natural e proporciona uma destinação ambientalmente correta deste resíduo. / [en] This study presents the behavior of a sandy soil stabilized with municipal solid waste ash, and lime. In order to evaluate the applicability of mixtures soil-ash and soil-fly ash-lime for using in geotechnical projects as layers of landfills, embankment on soft soils and slope stability, an experimental campaign is presented. Thus, physical, chemical and mechanical (isotropically consolidated-drained triaxial test) characterization tests were performed for each material and mixtures. It was used 3 percent of lime in the mixtures soil- fly ash-lime, being added in replacement to the dry weight of fly ash. Were evaluated the influence of ash content (30 and 40 percent), type of ash (fly ash and bottom ash) and curing time (0, 60 and 90 days) for mixtures containing fly ash and lime. The results have shown that mixtures with both kinds of ashes present a satisfactory behavior, increasing or maintaining the shear strength parameters similar to the pure material. For both kinds of ashes the variation of the content has not provided significant changes in the strength parameters, therefore, 40 percent can be considered as best content, once it provides a bigger destination of the residue. Comparing fly and bottom ash, the last has presented better results than fly ash. For mixtures with lime and cure, it has been observed better results for 60 days of cure, with greater gain of strength. Two molding methods have been used for preparing the mixture specimen, being obtained a better result with pre modeled specimen. Therefore, the use of municipal solid waste ash for stabilizing this kind of soil for using in the cited works, could minimize the current problems of waste disposal, contribute with the reduction of consumption of natural resources and give a noble use for this material.

Expansive clays undergo a large swell when they are subjected to water. Thus, expansive clay is one of the most abundant problems faced in geotechnical engineering applications. It causes heavy damages in structures, especially in water conveyance canals, lined reservoirs, highways, airport runways etc., unless appropriate measures are taken. In this thesis, Granulated Blast Furnace Slag (GBFS), GBFS - Lime combinations and GBFS Cement (GBFSC) were utilized to overcome or to limit the expansion of an artificially prepared expansive soil sample (Sample A). GBFS and GBFSC were added to Sample A in proportions of 5 to 25 percent. Different GBFS-Lime combinations were added to Sample A by keeping the total addition at 15 percent. Effect of stabilizers on grain size distribution, Atterberg limits, swelling percentage and rate of swell of soil samples were determined. Effect of curing on swelling percentage and rate of swell of soil samples were also determined. Leachate analysis of GBFS, GBFSC and samples stabilized by 25 percent GBFS and GBFSC was performed. Use of stabilizers successfully decreased the amount of swell while increasing the rate of swell. Curing samples for 7 and 28 days resulted in less swell percentages and higher rate of swell.