Mass movements are one of the main causes of loss of people and environmental assets. Several fac... more Mass movements are one of the main causes of loss of people and environmental assets. Several factors contribute to mass movements, such as terrain morphology, rainfall regime, soil properties, land use and occupation. Studies showed that in the Northeast region of Brazil, between the years of 1991 and 2012, 38 events related to mass movements were recorded, resulting in 55,963,164 people affected by these events. Based on this information, the aim of this study was to build a systematic review of mass movement and erosion events that occurred in the northeast region of Brazil and were reported in Brazilian academic sources. The research was based on the articles published by the Soils and Rocks Journal and the proceedings of the Brazilian academic events: Brazilian Congress of Soil Mechanics and Geotechnical Engineering, the Brazilian Conference on Slope Stability and the Brazilian Congress of Engineering and Environmental Geology. A survey of all the articles involving the subject...
Revista Principia - Divulgação Científica e Tecnológica do IFPB
Solos de baixa resistência necessitam do uso de técnicas de consolidação, melhoramento e reforço ... more Solos de baixa resistência necessitam do uso de técnicas de consolidação, melhoramento e reforço no intuito de gerar uma redistribuição global das tensões e deformações. Entre elas, podem-se mencionar as técnicas de melhoramento com inserção de agentes cimentantes e de geossintéticos. A presente pesquisa teve por objetivo realizar um estudo da resistência ao cisalhamento de um solo de baixa capacidade de suporte no seu estado natural e após o emprego da técnica de estabilização química e de inserção de materiais de reforço (geotêxtil não-tecido e geogrelha). A avaliação do comportamento mecânico do solo foi realizada por meio do ensaio triaxial do tipo não adensado e não drenado. A técnica de estabilização química do solo, comparada às técnicas de reforço com geossintéticos, proporcionou melhor comportamento resistente, visto que a inserção do cimento ao solo promoveu resultados superiores de resistência ao cisalhamento do solo pesquisado. Entretanto, a presente pesquisa não conside...
A utilizacao de residuos e subprodutos industriais na construcao civil apresenta-se como uma alte... more A utilizacao de residuos e subprodutos industriais na construcao civil apresenta-se como uma alternativa efetiva para diminuicao do impacto ambiental deste setor. O presente trabalho tem como principal objetivo avaliar a viabilidade do emprego de solo-cimento e residuo de beneficiamento de pedras preciosas em estacas escavadas (SCR) para utilizacao em habitacao unifamiliar. Inicialmente foi definida uma mistura otima com os materiais que constituiriam as estacas. A mistura que melhor atendeu as caracteristicas de resistencia e trabalhabilidade foi aquela composta por 50% de residuo de beneficiamento de pedras preciosas e 50% de solo, com 10% de teor de cimento Portland, em relacao a massa seca dos materiais. Para os ensaios de campo foram executadas tres estacas escavadas de 0,23m de diâmetro e 3 metros de profundidade. Os resultados obtidos atraves das provas de carga estatica foram comparados a resultados de estacas escavadas com mesmas caracteristicas geometricas e compostas por ...
Revista Principia - Divulgação Científica e Tecnológica do IFPB
Solos que sofrem alterações volumétricas quando sua umidade varia são chamados de expansivos e po... more Solos que sofrem alterações volumétricas quando sua umidade varia são chamados de expansivos e podem ser encontrados com facilidade em regiões áridas e semiáridas, como o nordeste brasileiro. Visando aumentar a resistência do solo e diminuir sua variação volumétrica, pode-se utilizar aglomerantes químicos como o cimento. O objetivo desse trabalho foi analisar a aplicabilidade de uma nova metodologia de dosagem para prever a resistência à compressão simples do solo expansivo do nordeste brasileiro com o uso de cimento como aglomerante. Foram feitos ensaios de resistência à compressão simples em corpos de prova com diferentes teores de cimento e pesos específicos secos (4, 6, 8%, e 14,15,16 kN/m³, respectivamente) e teor de umidade de 19%. Os resultados mostraram que a resistência aumenta com o acréscimo do teor de cimento e com o decréscimo da porosidade. Observou-se, também, que a variação da resistência em função da razão porosidade/teor volumétrico de cimento ajustado com um expoe...
Abstract Compaction of layers of soil–fly ash–lime blends is often used to improve soil condition... more Abstract Compaction of layers of soil–fly ash–lime blends is often used to improve soil conditions for infrastructure projects. As system failures usually start up under tensile stresses at the base of such layers, splitting tensile strength can be used as a direct measure of the mechanical strength. In spite of that, there is not yet an understanding of the effect of distinct variables on the splitting tensile strength. Such understanding is the starting point to develop more rational dosages that allow for a more efficient use of resources (i.e. energy and raw materials). A series of splitting tensile tests were carried out. An equation linking the effect of porosity and lime content to the tensile strength was found for each curing temperature studied (20 °C, 27.5 °C, 35 °C and 50 °C). For all equations, it was found that a unique ratio between porosity and volumetric lime content controls the tensile strength. These equations could be further generalized into a single equation (linking the effect of curing temperature, porosity, and volumetric lime content to the tensile strength) that is valid for the studied blends and curing temperatures between 20 °C and 35 °C. An example showing how the proposed equations can be used to devise more rational dosages is also presented and highlights the practical application of this study.
Journal of Geotechnical and Geoenvironmental Engineering
AbstractFine-grained soils that expand when in contact with water can be a major issue in some ge... more AbstractFine-grained soils that expand when in contact with water can be a major issue in some geotechnical situations, but the soil can be stabilized through chemical means by hydrated lime incorp...
The pozzolanic reactions, responsible for the resistance of soil-lime blends, are endothermic. As... more The pozzolanic reactions, responsible for the resistance of soil-lime blends, are endothermic. As such, increasing the curing temperature in turn increases the strength of lime-stabilized soil. Recent research has shown that there is a maximum limit to the resistance of a specimen, based on its curing time. This study aims to predict the maximum tensile strength of sand-coal fly ash-lime blends for several curing times. To achieve that, a series of splitting tensile tests were carried out using cylindrical specimens with diameter and length equal to 50 mm and 100 mm, respectively. Lime content varied from 3% to 7%, dry unit weight ranged from 14 kN/m 3 to 16 kN/m 3 , curing temperatures were 20, 35, 50, 65, 80 and 90°C, curing periods were 1, 3 and 7 days and fly ash content was established as 25%. Results show that the increase in curing temperature boosts the tensile strength of sand-coal fly ash-lime blends up to a limit that varies with curing time. The porosity/lime index, defined as the ratio of the compacted mixture's porosity and volumetric lime content adjusted by an exponent, proves to be an appropriate parameter to estimate the splitting tensile strength of the soil-coal fly ash-lime studied for all curing times and temperatures studied. Using this index, curves were obtained for the calculation of the maximum temperature that influences the resistance of the studied mixture for each curing time. An equation capable of determining the maximum resistance that can be reached in each curing time, independent of curing temperature, was also obtained through the index.
Abstract Compaction of layers of soil–fly ash–lime blends is often used to improve soil condition... more Abstract Compaction of layers of soil–fly ash–lime blends is often used to improve soil conditions for infrastructure projects. Such understanding is the starting point to develop more rational dosages that allow for a more efficient use of resources. To achieve this objective the present research aims to quantify the influence of curing temperature (T), amount of lime (L), porosity (η), and porosity/lime ratio (η/L iv ) on the assessment of splitting tensile strength (q t ) and unconfined compressive strength (q u ) of sand–coal fly ash–lime blends. A series of splitting tensile and unconfined compression tests were carried out in the present work. The results show a linear function fits well the relation between q t and qu with L, and a power function fits well as the relation between q t and q u with η for all curing temperatures of the specimens. It was also shown that the porosity/lime ratio (η/L iv ) is a good parameter in the evaluation of q t and q u of the studied blends for the whole range of lime, porosities and temperature studied, at specific amount of coal fly ash (25%) and curing time period (28 days). The volumetric cementitious material content (L iv ) is adjusted by an exponent (0.30 for all curing temperatures blends) to end in unique correlations for each temperature. For the sand, coal fly ash, lime, curing time period and curing temperatures, a unique relationship was achieved linking q t as well q u to η; L iv and T. For a given curing time period (28 days), the relations q t -η/L iv and q u -η/L iv versus T are shown to vary linearly up to a threshold, when asymptotes occur. Finally, the relation between q t /q u is a constant and equal to 0.19 for the whole range of L, η and T studied.
AbstractThe present research aims to quantify the influence of curing temperature (T), amount of ... more AbstractThe present research aims to quantify the influence of curing temperature (T), amount of lime (L), porosity (η), and porosity/lime ratio (η/Liv) on the assessment of splitting tensile strength (qt) and unconfined compressive strength (qu) of sand–coal fly ash–lime blends. A series of splitting tensile and unconfined compression tests were carried out in the present work. The results show that increasing curing temperature in the blend, for the whole range of lime studied, increases qt and qu. A power function fits well as the relation between qt and qu with η, and a linear function fits well the relation between qt and qu with L for all curing temperatures of the specimens. It was also shown that the porosity/lime ratio (η/Liv) is a good parameter in the evaluation of qt and qu of the studied blends for the whole range of lime, porosities and temperature studied, at specific amount of coal fly ash (25%) and curing time period (28 days). The volumetric cementitious material content (Liv) is adjuste...
Revista Principia - Divulgação Científica e Tecnológica do IFPB
Solos que sofrem alterações volumétricas quando sua umidade varia são chamados de expansivos e po... more Solos que sofrem alterações volumétricas quando sua umidade varia são chamados de expansivos e podem ser encontrados com facilidade em regiões áridas e semiáridas, como o nordeste brasileiro. Visando aumentar a resistência do solo e diminuir sua variação volumétrica, pode-se utilizar aglomerantes químicos como o cimento. O objetivo desse trabalho foi analisar a aplicabilidade de uma nova metodologia de dosagem para prever a resistência à compressão simples do solo expansivo do nordeste brasileiro com o uso de cimento como aglomerante. Foram feitos ensaios de resistência à compressão simples em corpos de prova com diferentes teores de cimento e pesos específicos secos (4, 6, 8%, e 14,15,16 kN/m³, respectivamente) e teor de umidade de 19%. Os resultados mostraram que a resistência aumenta com o acréscimo do teor de cimento e com o decréscimo da porosidade. Observou-se, também, que a variação da resistência em função da razão porosidade/teor volumétrico de cimento ajustado com um expoe...
Mass movements are one of the main causes of loss of people and environmental assets. Several fac... more Mass movements are one of the main causes of loss of people and environmental assets. Several factors contribute to mass movements, such as terrain morphology, rainfall regime, soil properties, land use and occupation. Studies showed that in the Northeast region of Brazil, between the years of 1991 and 2012, 38 events related to mass movements were recorded, resulting in 55,963,164 people affected by these events. Based on this information, the aim of this study was to build a systematic review of mass movement and erosion events that occurred in the northeast region of Brazil and were reported in Brazilian academic sources. The research was based on the articles published by the Soils and Rocks Journal and the proceedings of the Brazilian academic events: Brazilian Congress of Soil Mechanics and Geotechnical Engineering, the Brazilian Conference on Slope Stability and the Brazilian Congress of Engineering and Environmental Geology. A survey of all the articles involving the subject...
Revista Principia - Divulgação Científica e Tecnológica do IFPB
Solos de baixa resistência necessitam do uso de técnicas de consolidação, melhoramento e reforço ... more Solos de baixa resistência necessitam do uso de técnicas de consolidação, melhoramento e reforço no intuito de gerar uma redistribuição global das tensões e deformações. Entre elas, podem-se mencionar as técnicas de melhoramento com inserção de agentes cimentantes e de geossintéticos. A presente pesquisa teve por objetivo realizar um estudo da resistência ao cisalhamento de um solo de baixa capacidade de suporte no seu estado natural e após o emprego da técnica de estabilização química e de inserção de materiais de reforço (geotêxtil não-tecido e geogrelha). A avaliação do comportamento mecânico do solo foi realizada por meio do ensaio triaxial do tipo não adensado e não drenado. A técnica de estabilização química do solo, comparada às técnicas de reforço com geossintéticos, proporcionou melhor comportamento resistente, visto que a inserção do cimento ao solo promoveu resultados superiores de resistência ao cisalhamento do solo pesquisado. Entretanto, a presente pesquisa não conside...
A utilizacao de residuos e subprodutos industriais na construcao civil apresenta-se como uma alte... more A utilizacao de residuos e subprodutos industriais na construcao civil apresenta-se como uma alternativa efetiva para diminuicao do impacto ambiental deste setor. O presente trabalho tem como principal objetivo avaliar a viabilidade do emprego de solo-cimento e residuo de beneficiamento de pedras preciosas em estacas escavadas (SCR) para utilizacao em habitacao unifamiliar. Inicialmente foi definida uma mistura otima com os materiais que constituiriam as estacas. A mistura que melhor atendeu as caracteristicas de resistencia e trabalhabilidade foi aquela composta por 50% de residuo de beneficiamento de pedras preciosas e 50% de solo, com 10% de teor de cimento Portland, em relacao a massa seca dos materiais. Para os ensaios de campo foram executadas tres estacas escavadas de 0,23m de diâmetro e 3 metros de profundidade. Os resultados obtidos atraves das provas de carga estatica foram comparados a resultados de estacas escavadas com mesmas caracteristicas geometricas e compostas por ...
Revista Principia - Divulgação Científica e Tecnológica do IFPB
Solos que sofrem alterações volumétricas quando sua umidade varia são chamados de expansivos e po... more Solos que sofrem alterações volumétricas quando sua umidade varia são chamados de expansivos e podem ser encontrados com facilidade em regiões áridas e semiáridas, como o nordeste brasileiro. Visando aumentar a resistência do solo e diminuir sua variação volumétrica, pode-se utilizar aglomerantes químicos como o cimento. O objetivo desse trabalho foi analisar a aplicabilidade de uma nova metodologia de dosagem para prever a resistência à compressão simples do solo expansivo do nordeste brasileiro com o uso de cimento como aglomerante. Foram feitos ensaios de resistência à compressão simples em corpos de prova com diferentes teores de cimento e pesos específicos secos (4, 6, 8%, e 14,15,16 kN/m³, respectivamente) e teor de umidade de 19%. Os resultados mostraram que a resistência aumenta com o acréscimo do teor de cimento e com o decréscimo da porosidade. Observou-se, também, que a variação da resistência em função da razão porosidade/teor volumétrico de cimento ajustado com um expoe...
Abstract Compaction of layers of soil–fly ash–lime blends is often used to improve soil condition... more Abstract Compaction of layers of soil–fly ash–lime blends is often used to improve soil conditions for infrastructure projects. As system failures usually start up under tensile stresses at the base of such layers, splitting tensile strength can be used as a direct measure of the mechanical strength. In spite of that, there is not yet an understanding of the effect of distinct variables on the splitting tensile strength. Such understanding is the starting point to develop more rational dosages that allow for a more efficient use of resources (i.e. energy and raw materials). A series of splitting tensile tests were carried out. An equation linking the effect of porosity and lime content to the tensile strength was found for each curing temperature studied (20 °C, 27.5 °C, 35 °C and 50 °C). For all equations, it was found that a unique ratio between porosity and volumetric lime content controls the tensile strength. These equations could be further generalized into a single equation (linking the effect of curing temperature, porosity, and volumetric lime content to the tensile strength) that is valid for the studied blends and curing temperatures between 20 °C and 35 °C. An example showing how the proposed equations can be used to devise more rational dosages is also presented and highlights the practical application of this study.
Journal of Geotechnical and Geoenvironmental Engineering
AbstractFine-grained soils that expand when in contact with water can be a major issue in some ge... more AbstractFine-grained soils that expand when in contact with water can be a major issue in some geotechnical situations, but the soil can be stabilized through chemical means by hydrated lime incorp...
The pozzolanic reactions, responsible for the resistance of soil-lime blends, are endothermic. As... more The pozzolanic reactions, responsible for the resistance of soil-lime blends, are endothermic. As such, increasing the curing temperature in turn increases the strength of lime-stabilized soil. Recent research has shown that there is a maximum limit to the resistance of a specimen, based on its curing time. This study aims to predict the maximum tensile strength of sand-coal fly ash-lime blends for several curing times. To achieve that, a series of splitting tensile tests were carried out using cylindrical specimens with diameter and length equal to 50 mm and 100 mm, respectively. Lime content varied from 3% to 7%, dry unit weight ranged from 14 kN/m 3 to 16 kN/m 3 , curing temperatures were 20, 35, 50, 65, 80 and 90°C, curing periods were 1, 3 and 7 days and fly ash content was established as 25%. Results show that the increase in curing temperature boosts the tensile strength of sand-coal fly ash-lime blends up to a limit that varies with curing time. The porosity/lime index, defined as the ratio of the compacted mixture's porosity and volumetric lime content adjusted by an exponent, proves to be an appropriate parameter to estimate the splitting tensile strength of the soil-coal fly ash-lime studied for all curing times and temperatures studied. Using this index, curves were obtained for the calculation of the maximum temperature that influences the resistance of the studied mixture for each curing time. An equation capable of determining the maximum resistance that can be reached in each curing time, independent of curing temperature, was also obtained through the index.
Abstract Compaction of layers of soil–fly ash–lime blends is often used to improve soil condition... more Abstract Compaction of layers of soil–fly ash–lime blends is often used to improve soil conditions for infrastructure projects. Such understanding is the starting point to develop more rational dosages that allow for a more efficient use of resources. To achieve this objective the present research aims to quantify the influence of curing temperature (T), amount of lime (L), porosity (η), and porosity/lime ratio (η/L iv ) on the assessment of splitting tensile strength (q t ) and unconfined compressive strength (q u ) of sand–coal fly ash–lime blends. A series of splitting tensile and unconfined compression tests were carried out in the present work. The results show a linear function fits well the relation between q t and qu with L, and a power function fits well as the relation between q t and q u with η for all curing temperatures of the specimens. It was also shown that the porosity/lime ratio (η/L iv ) is a good parameter in the evaluation of q t and q u of the studied blends for the whole range of lime, porosities and temperature studied, at specific amount of coal fly ash (25%) and curing time period (28 days). The volumetric cementitious material content (L iv ) is adjusted by an exponent (0.30 for all curing temperatures blends) to end in unique correlations for each temperature. For the sand, coal fly ash, lime, curing time period and curing temperatures, a unique relationship was achieved linking q t as well q u to η; L iv and T. For a given curing time period (28 days), the relations q t -η/L iv and q u -η/L iv versus T are shown to vary linearly up to a threshold, when asymptotes occur. Finally, the relation between q t /q u is a constant and equal to 0.19 for the whole range of L, η and T studied.
AbstractThe present research aims to quantify the influence of curing temperature (T), amount of ... more AbstractThe present research aims to quantify the influence of curing temperature (T), amount of lime (L), porosity (η), and porosity/lime ratio (η/Liv) on the assessment of splitting tensile strength (qt) and unconfined compressive strength (qu) of sand–coal fly ash–lime blends. A series of splitting tensile and unconfined compression tests were carried out in the present work. The results show that increasing curing temperature in the blend, for the whole range of lime studied, increases qt and qu. A power function fits well as the relation between qt and qu with η, and a linear function fits well the relation between qt and qu with L for all curing temperatures of the specimens. It was also shown that the porosity/lime ratio (η/Liv) is a good parameter in the evaluation of qt and qu of the studied blends for the whole range of lime, porosities and temperature studied, at specific amount of coal fly ash (25%) and curing time period (28 days). The volumetric cementitious material content (Liv) is adjuste...
Revista Principia - Divulgação Científica e Tecnológica do IFPB
Solos que sofrem alterações volumétricas quando sua umidade varia são chamados de expansivos e po... more Solos que sofrem alterações volumétricas quando sua umidade varia são chamados de expansivos e podem ser encontrados com facilidade em regiões áridas e semiáridas, como o nordeste brasileiro. Visando aumentar a resistência do solo e diminuir sua variação volumétrica, pode-se utilizar aglomerantes químicos como o cimento. O objetivo desse trabalho foi analisar a aplicabilidade de uma nova metodologia de dosagem para prever a resistência à compressão simples do solo expansivo do nordeste brasileiro com o uso de cimento como aglomerante. Foram feitos ensaios de resistência à compressão simples em corpos de prova com diferentes teores de cimento e pesos específicos secos (4, 6, 8%, e 14,15,16 kN/m³, respectivamente) e teor de umidade de 19%. Os resultados mostraram que a resistência aumenta com o acréscimo do teor de cimento e com o decréscimo da porosidade. Observou-se, também, que a variação da resistência em função da razão porosidade/teor volumétrico de cimento ajustado com um expoe...
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