The purpose of this study is to investigate effects of sedimentary environment (freshwater and ma... more The purpose of this study is to investigate effects of sedimentary environment (freshwater and marine deposits) on geotechnical properties for Kanto lowland clays. Freshwater and marine sediments were used to perform standard consolidation tests, undrained triaxial compression tests, and unconfined compression test. Pore-water compositions were also measured for the sediments. As results, higher compression index, higher sensitivity, and lower shear strength ratio were observed for the marine sediments as compared to those for the freshwater sediments. In addition, the measurements of pore-water compositions revealed that the sensitivity values were well related to the proportion of monovalent cations, especially for the sediments with plastic index of less than 30.
In Sri Lanka, solid waste management is mainly focused on waste collection and dump into open dum... more In Sri Lanka, solid waste management is mainly focused on waste collection and dump into open dumpsites. The leachate produced from these dumpsites often pollutes surface water and groundwater. Identification of temporal variation for leachate and groundwater quality is an important factor when installing leachate treatment systems, since water quality depends on many factors. In this study, an open dumpsite was selected from wet zone, Sri Lanka, and its perched water inside waste layer and groundwater quality were monitored for two years (March 2013 to March 2015). Perched water and groundwater samples were collected with one month interval and samples were analyzed for 14 parameters. Leachate pollution index (LPI) and piper diagrams were used to analyze the temporal variation of water quality. Overall and sub-indices of LPI were calculated to identify temporal variation of risk for groundwater contamination. Groundwater samples showed constant and low LPI values except for the ini...
The investigation of greenhouse gas emission from a waste dumping site in Sri Lanka was conducted... more The investigation of greenhouse gas emission from a waste dumping site in Sri Lanka was conducted. The investigated site in this study is an abandoned waste dump site located at a hilly river bank in the Central Province of Sri Lanka (N 7o 09', E 80o 35'), consisting of two different sections with waste ages of around 0.5 year (New-section) and 7 years (Old-section). A simplified method for determination of methane gas flux using laser methane detector was considered to be effective to grasp the magnitude of methane flux. It was shown that the points those exhibited high value of methane gas flux also showed low EC-value compared with those of the other surround points. Furthermore, the low hardness of these points indicated that large amount of methane gas flux was caused by high permeability of surface as some stumps had been grown or as boundary between buried waste and ground line had been loosened. Measured fluxes for methane, carbon dioxide, and nitrous oxide in New-se...
Compressibility characteristics of landfilling and buried waste samples are highly heterogeneous,... more Compressibility characteristics of landfilling and buried waste samples are highly heterogeneous, depending on various waste compositions, degree of organic matters, decomposition, and so on. Measured data presented in this paper are the results from laboratory tests for different types of landfilling and buried waste such as incineration ash, industrial waste (plastics, rubbers, etc.) and unburnable domestic waste (glasses, ceramics, etc.) and buried industrial solid waste fully mixed with soil from an industrial waste landfill at Saitama Prefecture in Japan, respectively. Prior to the compaction and consolidation tests, each sample was dried and the waste composition and particle size distribution were determined. Standard proctor compaction tests were carried out to discuss the compaction properties. For the buried industrial solid waste fully mixed with soil (two sample fractions: < 2 mm and < 9.5 mm) and incineration ash samples, optimized water contents (w opt) which gave the maximum dry bulk densities can be measured similar to typical soil samples. On the other hand, for the industrial and domestic waste samples mainly composed of plastics and glasses, the values of w opt could not be clearly observed and measured dry bulk densities were not controlled by the initial water content of samples. Consolidation tests for compacted samples at different compaction levels were carried out by using a specially designed oedometer in the laboratory. Based on the results from consolidation tests, the compressibility characteristics will be discussed based on the consolidation indices such as compression and consolidation coefficient, and their dependency of waste composition and fraction and surrounding environment (e.g., temperature).
Abstract Soil water repellency (SWR) of soils is a property with significant consequences for agr... more Abstract Soil water repellency (SWR) of soils is a property with significant consequences for agricultural water management, water infiltration, contaminant transport, and for soil erosion. It is caused by the presence of hydrophobic agents on mineral grain surfaces. Soils were samples in different depths at three forest sites in Japan and three pasture sites in New Zealand, covering soil organic carbon (SOC) contents between 1 and 26%. The SWR was measured over a range of water contents by three common methods; the water drop penetration time (WDPT) test, the molarity of an ethanol droplet (MED) method, and the sessile drop method (SDM). The aim to (i) compare the methods, (ii) characterize the soil-water repellency characteristic curves (SWRCC) being SWR as a function of the volumetric soil-water content ( θ ) or matric potential ( ψ ), and (iii) find relationships between SWRCC parameters and SOC content. The WDPT, MED, and SDM generally agreed well in predicting the θ range where SWR occurred, and there was close agreement between SWR results determined by average MED and SDM at similar θ . Generally, SWR was only found within the top 20 cm of the soil profiles. Six SWR parameters were introduced: (i) the area under the curve ( S WR ( θ ) ); (ii) θ at the maximum SWR ( θ WR-max ), (iii) θ where SWR ceased ( θ non-WR ), (iv) the maximum SWR ( CA i -max ), (v) pF at the maximum SWR ( pF WR-max ) and (vi) pF where SWR ceased ( pF non-WR ). The relationship between the first three parameters and SOC content were best described with Langmuir type equations (r 2 of 0.5–0.7), while the other three parameters changed linearly with SOC contents.
Low-Voltage Mineral Deposition technology (LVMD), widely known as Biorock, has previously been su... more Low-Voltage Mineral Deposition technology (LVMD), widely known as Biorock, has previously been suggested as support for coral reef restoration, as hypothesized high porosity, wide pore-size distribution and connectivity, and good strength properties may facilitate biological functions (for example larvae settlement) and durability. In this technology, very low voltage induces an electrical current that initiates precipitation and accretion of hard minerals (aragonite and calcite) on a metal in seawater. This technology has been discussed mainly for its biological value, while this paper wants to highlight also its engineering value as artificial reef material. Indeed, some of the properties that makes it valuable in one domain are also supporting its use in the other. Because the metal on which the precipitation takes place can be of any shape and size, so can the artificial reef and its mechanical strength characteristics are above the ones of corals and similar to concrete, indica...
Knowledge of heat and gas transport properties of the peat soils is important to simulate greenho... more Knowledge of heat and gas transport properties of the peat soils is important to simulate greenhouse gas behaviour and changes of soil(temperature in the wetlands. In this study, the heat and gas transport properties for differently(decomposed and variably saturated peat soils were measured in order to investigate the general analogies and differences between transport properties of the peat soils. As results, changes in liquid(phase tortuosity under different moisture conditions and volume shrinkage under dry conditions did not significantly affect the thermal conductivity, showing linear increase of thermal conductivity with moisture content. On the other hand, marked effects of soil(water blockage and volume shrinkage on the soil(gas diffusion coefficient under wet and dry conditions, respectively, were observed.
Due to rapid urbanization, generation of municipal solid waste is increasing in developing countr... more Due to rapid urbanization, generation of municipal solid waste is increasing in developing countries. However, most of the waste disposal site in developing countries is an unsanitary open dumping causing serious social and environmental problems such as subsidence and collapse of waste slopes at disposal sites. Sri Lanka is one of countries facing the waste disposal problems (Sato, et al,. 2012), and most of collected waste is dumped at the disposal sites without any engineering consideration such as ground settlement and slope stability. Several studies have been done to investigate geotechnical properties for municipal solid waste samples (e.g., Chen et al., 2009; Reddy et al., 2009), however effects of climate condition and age of waste on geotechnical properties are not well understood. In this study, to investigate effects of climatic conditions and age of waste fill on compaction properties of buried municipal solid waste. Boring core and box samples of buried municipal solid...
The final cover soil on a solid waste landfill consists of many layers of materials and is highly... more The final cover soil on a solid waste landfill consists of many layers of materials and is highly compacted. It is used to prevent rain/surface water infiltration in to the waste layer. On the otherhand, the landfill site has a significant emission source of greenhouse gases. Gas and mass transport in soils occurs through the soil pore network, which is highly affected by soil physical properties including compaction, particle size, moisture content and total porosity. However, there are a limited number of studies on visualization and quantification of soil pore network for highly compacted soil like final cover soil. The objectives of this study were setting of microfocus X-ray Computed tomography (CT) for scanning landfill final cover soils in conjunction with 3-D image analysis techniques and analyzing the soil pore structure parameters. In this study, soil samples were collected from landfill site in Saitama prefecture, Japan. Soil pore structure was analyzed using micro focus ...
Soil water repellency (SWR)is a phenomenon that exhibits soil hydrophobicity mainly related to th... more Soil water repellency (SWR)is a phenomenon that exhibits soil hydrophobicity mainly related to the presence of organic matter coating in soil grains. Agricultural farm manure, organic fertilizer, different vegetation type as well as microbial activity in the soil could be the reasons to develop hydrophobicity of soil. Importance of SWR studies is to understand the nonuniformed infiltration, surface run-off and soil erosion etc. The objectives of this study are (i) to investigate the difference of SWR measurement in the field and laboratory condition and (ii) to identify the relationship between the SWR and soil physical and chemical properties. Two sites were selected; greenhouse vegetable farm at Mizuho-farm, Miki city, Hyogo prefecture in Japan and pasture land at Tihoi farm, Waikato in New Zealand. Field measurement and soil sampling in Mizuho-farm were carried out on December 2013 and October 2014. Sampling in Tihoi farm was carried out on February 2014 and December 2014. At the...
As a developing country in the context of globalization, Vietnam is experiencing a boom in its ec... more As a developing country in the context of globalization, Vietnam is experiencing a boom in its economy, characterized by a rapid rate of urbanization nationwide. Together with its benefits, this process also puts pressure on the environment, among which the increasing generation of construction and demolition waste (CDW) is an urgent issue. In this study, the authors conducted an in-depth investigation of various aspects in the generation and management of CDW in Vietnam. Firstly, part of the overall picture of CDW management in Vietnam was revealed in detail from the perspective of demolition contractors, one of the important stakeholders in the field. Their insights provide valuable information on current situation, practice, and attitude towards CDW recycling. Secondly, this paper reports the generation rate of different categories of materials from demolition sites of building structures in Hanoi, Vietnam, with the main focus on crushed concrete and crushed brick (CC–CB) and ste...
Japanese Geotechnical Society Special Publication, 2016
Due to formation of shrinkage cracks in landfill clay liners in dry zone of Sri Lanka leads to in... more Due to formation of shrinkage cracks in landfill clay liners in dry zone of Sri Lanka leads to infiltration of leachate into ground during the rainy season. Therefore, in this research study, shrinkage behaviour of expansive soil available in dry zone of Sri Lanka, which is used to develop compacted clay liners, were evaluated using laboratory desiccation plate tests. Circular desiccation plates with different thicknesses were used for the experiments. A series of tests have been carried out with unamended soil and soil amended with different percentages of bentonite. Further, shrinkage behaviour was studied by amending oleic acid and coconut coir fibers into the soil. Digital image processing technique has been used to determine the Crack Intensity Factor (CIF). Crack initiation time under different configuration was recorded. Based on visual observations, it can be seen that all samples produce predominantly orthogonal crack patterns leading to sub division of crack area in to smaller cells. Higher desiccation rate was observed for smaller thickness of soil specimen. In addition, higher CIF was recorded for the bentonite amended soil. It was noted that shrinkage cracks can be controlled by amending soil with coconut coir fibers.
Along with economic development, urbanization will generate a large amount of solid waste and put... more Along with economic development, urbanization will generate a large amount of solid waste and put pressure on the waste management systems in developing countries. Face-to-face interview methods were used to investigate the current status of construction and demolition waste (CDW) management (collection, transportation, treatment, and storage) as well as reveal attitudes of governmental agencies and enterprises towards CDW recycling and recycled material products in Hai Phong City, Vietnam. Waste generation rates (WGRs) of the works were also determined by site surveys and as-built drawings method of typical old buildings to be demolished and two licensed new construction works. WGRs of 34.5 kg/m2 and 758 kg/m2 were identified during the construction and demolition of small private houses, respectively, while WGRs at public house demolition sites were 1053 kg/m2. To effectively manage the CDW, the gross floor area of new construction work was estimated by a multiple regression equat...
Japanese Geotechnical Society Special Publication, 2021
Untreated oil-contaminated water discharge from domestic and industrial sources has led to seriou... more Untreated oil-contaminated water discharge from domestic and industrial sources has led to serious environmental pollution, especially in developing countries. Many technologies (e.g., floatation and coagulation, biological treatment, membrane separation, and so on) have been developed to treat effluents. Among them, the oil-water separation utilizing hydrophobized filtration beds can be expected to be a cost-effective and quick treatment technology. Previously, hydrophobized solid grains have been preliminary tested but applicability of hydrophobized porous grains have not been fully examined in oil-water separation system. This study aimed to characterize the hydrophobicity for artificially hydrophobized porous grains of autoclave aerated concrete (AAC) grains. The AAC grains (0.106 to 0.250 mm) were coated with two hydrophobic agent (HA) such as oleic acid (OA) and stearic acid (SA) at different concentrations (5 to 750 g of HA / kg of AAC grains). The OA-coated grains exhibited high hydrophobicity with HA 50 g/kg while for SA-coated grains, hydrophobicity became significant from HA 5 g/kg. Both OA-and SA-coated grains gave a rapid increase with increasing HA concentration and maximum contact angles reached 140-145 o , suggesting that they had a high potential to apply in the filtration beds in oil-water separation system.
Many domestic sources and industries, such as foods, textiles, metal industries, petrochemicals, ... more Many domestic sources and industries, such as foods, textiles, metal industries, petrochemicals, and mining, produce massive volumes of oily wastewater all over the world. The insufficient treatment of oily wastewater in developing countries leads to serious environmental pollution and so on. In this review, we summarize many oil/water separation techniques to treat oily wastewater that have been developed such as flotation, chemical coagulation, biological treatment, filtration and membrane separation, and adsorption. Among them, oil/water separation techniques based on adsorption and filtration utilizing naturally hydrophilic sands and hydrophobized/oleophilized grains are worth attention due to their ease of application and cost effectiveness. In this review, we summarize recent studies on adsorption-and filtration-based oil/water separation techniques utilizing naturally hydrophilic sands and grains coated/modified with hydrophobic/oleophilic substances and compare the treatment performance, categorizing types of grains, coating substances, oil used, and testing methods. Prospects and challenges of oil/water separation studies are also given.
The purpose of this study is to investigate effects of sedimentary environment (freshwater and ma... more The purpose of this study is to investigate effects of sedimentary environment (freshwater and marine deposits) on geotechnical properties for Kanto lowland clays. Freshwater and marine sediments were used to perform standard consolidation tests, undrained triaxial compression tests, and unconfined compression test. Pore-water compositions were also measured for the sediments. As results, higher compression index, higher sensitivity, and lower shear strength ratio were observed for the marine sediments as compared to those for the freshwater sediments. In addition, the measurements of pore-water compositions revealed that the sensitivity values were well related to the proportion of monovalent cations, especially for the sediments with plastic index of less than 30.
In Sri Lanka, solid waste management is mainly focused on waste collection and dump into open dum... more In Sri Lanka, solid waste management is mainly focused on waste collection and dump into open dumpsites. The leachate produced from these dumpsites often pollutes surface water and groundwater. Identification of temporal variation for leachate and groundwater quality is an important factor when installing leachate treatment systems, since water quality depends on many factors. In this study, an open dumpsite was selected from wet zone, Sri Lanka, and its perched water inside waste layer and groundwater quality were monitored for two years (March 2013 to March 2015). Perched water and groundwater samples were collected with one month interval and samples were analyzed for 14 parameters. Leachate pollution index (LPI) and piper diagrams were used to analyze the temporal variation of water quality. Overall and sub-indices of LPI were calculated to identify temporal variation of risk for groundwater contamination. Groundwater samples showed constant and low LPI values except for the ini...
The investigation of greenhouse gas emission from a waste dumping site in Sri Lanka was conducted... more The investigation of greenhouse gas emission from a waste dumping site in Sri Lanka was conducted. The investigated site in this study is an abandoned waste dump site located at a hilly river bank in the Central Province of Sri Lanka (N 7o 09', E 80o 35'), consisting of two different sections with waste ages of around 0.5 year (New-section) and 7 years (Old-section). A simplified method for determination of methane gas flux using laser methane detector was considered to be effective to grasp the magnitude of methane flux. It was shown that the points those exhibited high value of methane gas flux also showed low EC-value compared with those of the other surround points. Furthermore, the low hardness of these points indicated that large amount of methane gas flux was caused by high permeability of surface as some stumps had been grown or as boundary between buried waste and ground line had been loosened. Measured fluxes for methane, carbon dioxide, and nitrous oxide in New-se...
Compressibility characteristics of landfilling and buried waste samples are highly heterogeneous,... more Compressibility characteristics of landfilling and buried waste samples are highly heterogeneous, depending on various waste compositions, degree of organic matters, decomposition, and so on. Measured data presented in this paper are the results from laboratory tests for different types of landfilling and buried waste such as incineration ash, industrial waste (plastics, rubbers, etc.) and unburnable domestic waste (glasses, ceramics, etc.) and buried industrial solid waste fully mixed with soil from an industrial waste landfill at Saitama Prefecture in Japan, respectively. Prior to the compaction and consolidation tests, each sample was dried and the waste composition and particle size distribution were determined. Standard proctor compaction tests were carried out to discuss the compaction properties. For the buried industrial solid waste fully mixed with soil (two sample fractions: < 2 mm and < 9.5 mm) and incineration ash samples, optimized water contents (w opt) which gave the maximum dry bulk densities can be measured similar to typical soil samples. On the other hand, for the industrial and domestic waste samples mainly composed of plastics and glasses, the values of w opt could not be clearly observed and measured dry bulk densities were not controlled by the initial water content of samples. Consolidation tests for compacted samples at different compaction levels were carried out by using a specially designed oedometer in the laboratory. Based on the results from consolidation tests, the compressibility characteristics will be discussed based on the consolidation indices such as compression and consolidation coefficient, and their dependency of waste composition and fraction and surrounding environment (e.g., temperature).
Abstract Soil water repellency (SWR) of soils is a property with significant consequences for agr... more Abstract Soil water repellency (SWR) of soils is a property with significant consequences for agricultural water management, water infiltration, contaminant transport, and for soil erosion. It is caused by the presence of hydrophobic agents on mineral grain surfaces. Soils were samples in different depths at three forest sites in Japan and three pasture sites in New Zealand, covering soil organic carbon (SOC) contents between 1 and 26%. The SWR was measured over a range of water contents by three common methods; the water drop penetration time (WDPT) test, the molarity of an ethanol droplet (MED) method, and the sessile drop method (SDM). The aim to (i) compare the methods, (ii) characterize the soil-water repellency characteristic curves (SWRCC) being SWR as a function of the volumetric soil-water content ( θ ) or matric potential ( ψ ), and (iii) find relationships between SWRCC parameters and SOC content. The WDPT, MED, and SDM generally agreed well in predicting the θ range where SWR occurred, and there was close agreement between SWR results determined by average MED and SDM at similar θ . Generally, SWR was only found within the top 20 cm of the soil profiles. Six SWR parameters were introduced: (i) the area under the curve ( S WR ( θ ) ); (ii) θ at the maximum SWR ( θ WR-max ), (iii) θ where SWR ceased ( θ non-WR ), (iv) the maximum SWR ( CA i -max ), (v) pF at the maximum SWR ( pF WR-max ) and (vi) pF where SWR ceased ( pF non-WR ). The relationship between the first three parameters and SOC content were best described with Langmuir type equations (r 2 of 0.5–0.7), while the other three parameters changed linearly with SOC contents.
Low-Voltage Mineral Deposition technology (LVMD), widely known as Biorock, has previously been su... more Low-Voltage Mineral Deposition technology (LVMD), widely known as Biorock, has previously been suggested as support for coral reef restoration, as hypothesized high porosity, wide pore-size distribution and connectivity, and good strength properties may facilitate biological functions (for example larvae settlement) and durability. In this technology, very low voltage induces an electrical current that initiates precipitation and accretion of hard minerals (aragonite and calcite) on a metal in seawater. This technology has been discussed mainly for its biological value, while this paper wants to highlight also its engineering value as artificial reef material. Indeed, some of the properties that makes it valuable in one domain are also supporting its use in the other. Because the metal on which the precipitation takes place can be of any shape and size, so can the artificial reef and its mechanical strength characteristics are above the ones of corals and similar to concrete, indica...
Knowledge of heat and gas transport properties of the peat soils is important to simulate greenho... more Knowledge of heat and gas transport properties of the peat soils is important to simulate greenhouse gas behaviour and changes of soil(temperature in the wetlands. In this study, the heat and gas transport properties for differently(decomposed and variably saturated peat soils were measured in order to investigate the general analogies and differences between transport properties of the peat soils. As results, changes in liquid(phase tortuosity under different moisture conditions and volume shrinkage under dry conditions did not significantly affect the thermal conductivity, showing linear increase of thermal conductivity with moisture content. On the other hand, marked effects of soil(water blockage and volume shrinkage on the soil(gas diffusion coefficient under wet and dry conditions, respectively, were observed.
Due to rapid urbanization, generation of municipal solid waste is increasing in developing countr... more Due to rapid urbanization, generation of municipal solid waste is increasing in developing countries. However, most of the waste disposal site in developing countries is an unsanitary open dumping causing serious social and environmental problems such as subsidence and collapse of waste slopes at disposal sites. Sri Lanka is one of countries facing the waste disposal problems (Sato, et al,. 2012), and most of collected waste is dumped at the disposal sites without any engineering consideration such as ground settlement and slope stability. Several studies have been done to investigate geotechnical properties for municipal solid waste samples (e.g., Chen et al., 2009; Reddy et al., 2009), however effects of climate condition and age of waste on geotechnical properties are not well understood. In this study, to investigate effects of climatic conditions and age of waste fill on compaction properties of buried municipal solid waste. Boring core and box samples of buried municipal solid...
The final cover soil on a solid waste landfill consists of many layers of materials and is highly... more The final cover soil on a solid waste landfill consists of many layers of materials and is highly compacted. It is used to prevent rain/surface water infiltration in to the waste layer. On the otherhand, the landfill site has a significant emission source of greenhouse gases. Gas and mass transport in soils occurs through the soil pore network, which is highly affected by soil physical properties including compaction, particle size, moisture content and total porosity. However, there are a limited number of studies on visualization and quantification of soil pore network for highly compacted soil like final cover soil. The objectives of this study were setting of microfocus X-ray Computed tomography (CT) for scanning landfill final cover soils in conjunction with 3-D image analysis techniques and analyzing the soil pore structure parameters. In this study, soil samples were collected from landfill site in Saitama prefecture, Japan. Soil pore structure was analyzed using micro focus ...
Soil water repellency (SWR)is a phenomenon that exhibits soil hydrophobicity mainly related to th... more Soil water repellency (SWR)is a phenomenon that exhibits soil hydrophobicity mainly related to the presence of organic matter coating in soil grains. Agricultural farm manure, organic fertilizer, different vegetation type as well as microbial activity in the soil could be the reasons to develop hydrophobicity of soil. Importance of SWR studies is to understand the nonuniformed infiltration, surface run-off and soil erosion etc. The objectives of this study are (i) to investigate the difference of SWR measurement in the field and laboratory condition and (ii) to identify the relationship between the SWR and soil physical and chemical properties. Two sites were selected; greenhouse vegetable farm at Mizuho-farm, Miki city, Hyogo prefecture in Japan and pasture land at Tihoi farm, Waikato in New Zealand. Field measurement and soil sampling in Mizuho-farm were carried out on December 2013 and October 2014. Sampling in Tihoi farm was carried out on February 2014 and December 2014. At the...
As a developing country in the context of globalization, Vietnam is experiencing a boom in its ec... more As a developing country in the context of globalization, Vietnam is experiencing a boom in its economy, characterized by a rapid rate of urbanization nationwide. Together with its benefits, this process also puts pressure on the environment, among which the increasing generation of construction and demolition waste (CDW) is an urgent issue. In this study, the authors conducted an in-depth investigation of various aspects in the generation and management of CDW in Vietnam. Firstly, part of the overall picture of CDW management in Vietnam was revealed in detail from the perspective of demolition contractors, one of the important stakeholders in the field. Their insights provide valuable information on current situation, practice, and attitude towards CDW recycling. Secondly, this paper reports the generation rate of different categories of materials from demolition sites of building structures in Hanoi, Vietnam, with the main focus on crushed concrete and crushed brick (CC–CB) and ste...
Japanese Geotechnical Society Special Publication, 2016
Due to formation of shrinkage cracks in landfill clay liners in dry zone of Sri Lanka leads to in... more Due to formation of shrinkage cracks in landfill clay liners in dry zone of Sri Lanka leads to infiltration of leachate into ground during the rainy season. Therefore, in this research study, shrinkage behaviour of expansive soil available in dry zone of Sri Lanka, which is used to develop compacted clay liners, were evaluated using laboratory desiccation plate tests. Circular desiccation plates with different thicknesses were used for the experiments. A series of tests have been carried out with unamended soil and soil amended with different percentages of bentonite. Further, shrinkage behaviour was studied by amending oleic acid and coconut coir fibers into the soil. Digital image processing technique has been used to determine the Crack Intensity Factor (CIF). Crack initiation time under different configuration was recorded. Based on visual observations, it can be seen that all samples produce predominantly orthogonal crack patterns leading to sub division of crack area in to smaller cells. Higher desiccation rate was observed for smaller thickness of soil specimen. In addition, higher CIF was recorded for the bentonite amended soil. It was noted that shrinkage cracks can be controlled by amending soil with coconut coir fibers.
Along with economic development, urbanization will generate a large amount of solid waste and put... more Along with economic development, urbanization will generate a large amount of solid waste and put pressure on the waste management systems in developing countries. Face-to-face interview methods were used to investigate the current status of construction and demolition waste (CDW) management (collection, transportation, treatment, and storage) as well as reveal attitudes of governmental agencies and enterprises towards CDW recycling and recycled material products in Hai Phong City, Vietnam. Waste generation rates (WGRs) of the works were also determined by site surveys and as-built drawings method of typical old buildings to be demolished and two licensed new construction works. WGRs of 34.5 kg/m2 and 758 kg/m2 were identified during the construction and demolition of small private houses, respectively, while WGRs at public house demolition sites were 1053 kg/m2. To effectively manage the CDW, the gross floor area of new construction work was estimated by a multiple regression equat...
Japanese Geotechnical Society Special Publication, 2021
Untreated oil-contaminated water discharge from domestic and industrial sources has led to seriou... more Untreated oil-contaminated water discharge from domestic and industrial sources has led to serious environmental pollution, especially in developing countries. Many technologies (e.g., floatation and coagulation, biological treatment, membrane separation, and so on) have been developed to treat effluents. Among them, the oil-water separation utilizing hydrophobized filtration beds can be expected to be a cost-effective and quick treatment technology. Previously, hydrophobized solid grains have been preliminary tested but applicability of hydrophobized porous grains have not been fully examined in oil-water separation system. This study aimed to characterize the hydrophobicity for artificially hydrophobized porous grains of autoclave aerated concrete (AAC) grains. The AAC grains (0.106 to 0.250 mm) were coated with two hydrophobic agent (HA) such as oleic acid (OA) and stearic acid (SA) at different concentrations (5 to 750 g of HA / kg of AAC grains). The OA-coated grains exhibited high hydrophobicity with HA 50 g/kg while for SA-coated grains, hydrophobicity became significant from HA 5 g/kg. Both OA-and SA-coated grains gave a rapid increase with increasing HA concentration and maximum contact angles reached 140-145 o , suggesting that they had a high potential to apply in the filtration beds in oil-water separation system.
Many domestic sources and industries, such as foods, textiles, metal industries, petrochemicals, ... more Many domestic sources and industries, such as foods, textiles, metal industries, petrochemicals, and mining, produce massive volumes of oily wastewater all over the world. The insufficient treatment of oily wastewater in developing countries leads to serious environmental pollution and so on. In this review, we summarize many oil/water separation techniques to treat oily wastewater that have been developed such as flotation, chemical coagulation, biological treatment, filtration and membrane separation, and adsorption. Among them, oil/water separation techniques based on adsorption and filtration utilizing naturally hydrophilic sands and hydrophobized/oleophilized grains are worth attention due to their ease of application and cost effectiveness. In this review, we summarize recent studies on adsorption-and filtration-based oil/water separation techniques utilizing naturally hydrophilic sands and grains coated/modified with hydrophobic/oleophilic substances and compare the treatment performance, categorizing types of grains, coating substances, oil used, and testing methods. Prospects and challenges of oil/water separation studies are also given.
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Papers by Ken Kawamoto