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Bujang B. K. Huat - One of the best experts on this subject based on the ideXlab platform.
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Precast stabilized Peat columns to reinforce Peat Soil deposits.
2020Co-Authors: Behzad Kalantari, Bujang B. K. HuatAbstract:This article describes laboratory research on precast columns made of Peat Soil and ordinary Portland cement, with and without polypropylene fibers. The columns used in this study unlike the usual in situ or in place columns used previously, that are formed inside prepared holes in the ground, are formed outside the hole, and then inserted into the ground holes. The process of making precast stabilized Peat columns includes mixing Peat Soil with a specified amount of cement, (with or without polypropylene fibers) at their optimum moisture (found from compaction tests) contents. The mixture is then compacted into molds and left to dry. As the stabilized columns dry out, they gain strength. When drying is complete, they are taken out of their molds and inserted in the pre-drilled holes. In this laboratory study, long precast columns (L/D > 4) were used to reinforce undisturbed Peat Soil samples. The strength evaluation for the precast stabilized columns was done through consolidated undrained triaxial tests. The undisturbed Peat Soil in the study has been used as control sample. The results of the study obtained from shear strength parameters, stress-strain curves and undrained modulus prove that precast stabilized Peat columns can be used to reinforce and strengthen weak deposits of Peat Soil. Their production requires relatively small amounts of cement compared with the usual in situ columns but provides higher strength values, and therefore provides more load-bearing capacity. Since the production process does not waste much of the materials involved and does not use any fill materials the columns can also be considered environmentally friendly.
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Stabilising Peat Soil with cement and silica fume
Proceedings of the Institution of Civil Engineers - Geotechnical Engineering, 2011Co-Authors: Behzad Kalantari, Arun Prasad, Bujang B. K. HuatAbstract:Stabilising soft, wet and unconsolidated Peat Soil by using cement as binders and silica fume as additive is often cost-effective compared with other ground improvement methods. This study was carried out by adding 5–50% (by weight) cement to Peat Soil, and silica fume was added at the rate of 5–10% (by weight) of cement. An air-curing technique was used to cure the samples, as it was found that the water content of the untreated Peat Soil was very high. The air-cured Peat samples were tested for unconfined compressive strength (UCS) and California bearing ratio (CBR) for two conditions: soaked and unsoaked. For the soaked condition the samples were submerged in water for a period of 96 h; the samples after 90 days of air curing were considered as being in the unsoaked condition. From the test results, it was observed that the UCS and CBR increased by a factor as high as 11 and 25 respectively as compared with untreated Peat Soil. The optimum dose of cement and silica fume was also evaluated. It was obser...
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Experimental study of engineering behavior of fibrous Peat Soil reinforced by cement column
Geotechnical Society of Singapore - International Symposium on Ground Improvement Technologies and Case Histories ISGI'09, 2010Co-Authors: Siavash Kazemian, V Ghiasi, A Prasad, Bujang B. K. HuatAbstract:Peat Soils are extremely soft and unconsolidated surficial deposits constituting the subsurface of wetland systems. Due to high compressibility and low shear strength, these Soils are geotechnically problematic Soils. One of the most common methods for improving these Soils is cement columns. This paper presents test results of the shear strength and compressibility characteristics of fibrous Peat Soil and cement column reinforced Peat Soil. The shear strength and compressibility characteristics of the samples were obtained by a triaxial test under consolidated-undrained condition and Rowe cell respectively. The results indicated that, installing cement columns and increasing cement ratio could improve dramatically the compressibility and shear strength of Peat Soils. Copyright 2009 by Geotechnical Society of Singapore (GeoSS).
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Effect of polypropylene fibers on the California bearing ratio of air cured stabilized tropical Peat Soil
American Journal of Engineering and Applied Sciences, 2010Co-Authors: Behzad Kalantari, Bujang B. K. Huat, Arun PrasadAbstract:Problem statement: Peat Soil is well known to deform and fail under a light surcharge load and is characterized with low shear strength, high compressibility and high water content. With the rising demand from the construction industry, utilization of these Soils is required and suitable technique needs to be found out for stabilizing them. Approach: Model study had been carried to stabilize Peat Soil using cement as binding agent and polypropylene fibers as additive. Due to high natural water content of the Peat Soil, the stabilized Peat Soil samples were kept at normal room temperature and relative humidity for air curing for 90 days. The improvement in the mechanical strength of the stabilized samples was studied by California Bearing Ratio (CBR) test for both, unsoaked and soaked samples. The water-cement ratio of the samples was measured for 180 days to study the improvement in strength over time. Results: The results of CBR tests showed an increase by a factor over 22 for unsoaked condition and 15 for the soaked condition of the stabilized samples. With the addition of the polypropylene fibers to the stabilized Peat Soil with cement not only improved the strength of the stabilized Peat Soil but also contributed to considerable amount of uniformity and intactness to the stabilized Peat Soil samples. It was also observed that as the curing time for the stabilized Peat Soil continued through 180 days the moisture content continued to decrease as well. Thus the water-cement (w/c) ratio reduced and as a result of cement hydration, the strength stabilized Peat Soil samples increased in hardness and gained strength through the curing period. Conclusion/Recommendations: Cement and polypropylene fibers can be used to improve the mechanical strength of the soft Peat Soil by adopting air curing technique.
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UCS Evaluaton Tests for Cement Treated Peat Soil with Polypropylene Fibers
Ground Improvement Technologies and Case Histories, 2009Co-Authors: Behzad Kalantari, Bujang B. K. HuatAbstract:Peat Soil is one of the softest types of Soil. Various methods have been used in the past to strengthen Peat Soil deposits. In this research, unconfined compressive strength (UCS) of Peat Soil was studied while the Peat Soil was in its undisturbed state, stabilized with ordinary Portland cement, and mixed with polypropylene fibers. Unconfined compressive strength for either stabilized Peat with polypropylene fibers or Peat without polypropylene fibers was studied at different curing ages from immediately after molding (zero day) to 7, 28, 90, and 180 days. All samples were cured in air, and the procedure includes leaving the stabilized Peat Soil in normal room temperature and in air throughout the curing period. The curing procedure used to strengthen the Peat Soils shows that UCS values of stabilized Peat Soil were considerably increased through the curing process. As the curing time for the stabilized Peat Soil continues, the moisture contents of the UCS samples are reduced (through evaporation), and therefore the weight of water divided by the weight of cement (W/C) of stabilized samples is reduced. As W/C for samples reduces, the stabilized samples gain strength throughout the curing time. The strength gain continues beyond 28 days which is usual for concrete mixes. The UCS values for the stabilized Peat Soil show that the strength increases continues through six months of curing period. Addition of polypropylene fibers to the mixture of Peat and ordinary Portland cement as a non-reactive additive not only increases the UCS values of stabilized Peat Soil, but also contributes a considerable amount of uniformity and intactness to the stabilized Peat Soil samples as well. Copyright © 2009 by Geotechnical Society of Singapore (GeoSS).
L C Lundin - One of the best experts on this subject based on the ideXlab platform.
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Calibration of time domain reflectometry for water content in Peat Soil
Nordic Hydrology, 2001Co-Authors: Erik Kellner, L C LundinAbstract:Since Peat Soil differs from mineral Soil in several respects, mineral-Soil calibration functions for time domain reflectometry (TDR) are not necessarily applicable. This paper evaluates a number of calibration functions, both empirical polynomial and theoretical mixing models, on the basis of laboratory measurements on undisturbed Sphagnum Peat samples. Deviations between different samples within this study indicate dissimilarities in dielectric properties between Peats with different degrees of humification. Connections to physical properties such as amount of bound water and structural orientation are likely to exist. There is, however, a lack of methods to measure and quantify parameters expressing these properties. Therefore, until further studies on physical properties are accomplished, empirical or semi-empirical calibration curves are preferred. The best fit was obtained by an empirical, third order polynomial model. This model also gave a better fit than the mixing models when data were grouped into humification classes. However, all models reproduced pooled data with an r(2) better than 0.93.
Maria Perla Colombini - One of the best experts on this subject based on the ideXlab platform.
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the short term degradation of cellulosic pulp in lake water and Peat Soil a multi analytical study from the micro to the molecular level
International Biodeterioration & Biodegradation, 2017Co-Authors: Diego Tamburini, Jeannette Jacqueline łucejko, M Zborowska, Francesca Modugno, Emma Cantisani, Miroslava Mamoňova, Maria Perla ColombiniAbstract:Abstract Cellulosic pulp was analysed after two and five years of natural ageing in two different burial environments - lake water and Peat Soil - in order to investigate the chemical and structural changes undergone by the material. This research is part of a monitoring program developed in the archaeological site of Biskupin, whose final aim is to estimate the best re-burial conditions for an in situ conservation of archaeological wood. We applied SEM, FT-IR, XRD and Py-GC/MS with thermally assisted silylation using hexamethyldisilazane (HMDS) to obtain broad information on cellulosic pulp degradation. SEM provided information on the structural changes undergone by the fibres and on the microbial activity. FT-IR highlighted a depletion of the carbohydrates in the most degraded samples. Py(HMDS)-GC/MS confirmed these observations and provided detailed molecular information on cellulose alteration. The crystallinity index (CI) of cellulose was estimated by XRD, showing that the degradation began in amorphous regions. The correlation between the CI and the relative abundance of anhydrosugars detected by Py(HMDS)-GC/MS demonstrated that pyrolytic reactions are also influenced by the degree of crystallinity of cellulose. A mechanism of cellulose degradation in these natural environments was formulated: the degradation of cellulose in these natural environments proceeds through a depolymerisation step, initially involving the amorphous regions of cellulose, until the size of oligomers becomes sufficiently small to allow metabolisation by microorganisms or solubilisation by water. Secondly, a loss of carbohydrates was detected after five years of ageing and the loss reached 25% and 55% for the dark areas of samples aged in Peat Soil and lake water, respectively. Peat Soil was found to be more suitable than lake water in terms of preservation of carbohydrates.
Behzad Kalantari - One of the best experts on this subject based on the ideXlab platform.
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Precast stabilized Peat columns to reinforce Peat Soil deposits.
2020Co-Authors: Behzad Kalantari, Bujang B. K. HuatAbstract:This article describes laboratory research on precast columns made of Peat Soil and ordinary Portland cement, with and without polypropylene fibers. The columns used in this study unlike the usual in situ or in place columns used previously, that are formed inside prepared holes in the ground, are formed outside the hole, and then inserted into the ground holes. The process of making precast stabilized Peat columns includes mixing Peat Soil with a specified amount of cement, (with or without polypropylene fibers) at their optimum moisture (found from compaction tests) contents. The mixture is then compacted into molds and left to dry. As the stabilized columns dry out, they gain strength. When drying is complete, they are taken out of their molds and inserted in the pre-drilled holes. In this laboratory study, long precast columns (L/D > 4) were used to reinforce undisturbed Peat Soil samples. The strength evaluation for the precast stabilized columns was done through consolidated undrained triaxial tests. The undisturbed Peat Soil in the study has been used as control sample. The results of the study obtained from shear strength parameters, stress-strain curves and undrained modulus prove that precast stabilized Peat columns can be used to reinforce and strengthen weak deposits of Peat Soil. Their production requires relatively small amounts of cement compared with the usual in situ columns but provides higher strength values, and therefore provides more load-bearing capacity. Since the production process does not waste much of the materials involved and does not use any fill materials the columns can also be considered environmentally friendly.
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Stabilising Peat Soil with cement and silica fume
Proceedings of the Institution of Civil Engineers - Geotechnical Engineering, 2011Co-Authors: Behzad Kalantari, Arun Prasad, Bujang B. K. HuatAbstract:Stabilising soft, wet and unconsolidated Peat Soil by using cement as binders and silica fume as additive is often cost-effective compared with other ground improvement methods. This study was carried out by adding 5–50% (by weight) cement to Peat Soil, and silica fume was added at the rate of 5–10% (by weight) of cement. An air-curing technique was used to cure the samples, as it was found that the water content of the untreated Peat Soil was very high. The air-cured Peat samples were tested for unconfined compressive strength (UCS) and California bearing ratio (CBR) for two conditions: soaked and unsoaked. For the soaked condition the samples were submerged in water for a period of 96 h; the samples after 90 days of air curing were considered as being in the unsoaked condition. From the test results, it was observed that the UCS and CBR increased by a factor as high as 11 and 25 respectively as compared with untreated Peat Soil. The optimum dose of cement and silica fume was also evaluated. It was obser...
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Effect of polypropylene fibers on the California bearing ratio of air cured stabilized tropical Peat Soil
American Journal of Engineering and Applied Sciences, 2010Co-Authors: Behzad Kalantari, Bujang B. K. Huat, Arun PrasadAbstract:Problem statement: Peat Soil is well known to deform and fail under a light surcharge load and is characterized with low shear strength, high compressibility and high water content. With the rising demand from the construction industry, utilization of these Soils is required and suitable technique needs to be found out for stabilizing them. Approach: Model study had been carried to stabilize Peat Soil using cement as binding agent and polypropylene fibers as additive. Due to high natural water content of the Peat Soil, the stabilized Peat Soil samples were kept at normal room temperature and relative humidity for air curing for 90 days. The improvement in the mechanical strength of the stabilized samples was studied by California Bearing Ratio (CBR) test for both, unsoaked and soaked samples. The water-cement ratio of the samples was measured for 180 days to study the improvement in strength over time. Results: The results of CBR tests showed an increase by a factor over 22 for unsoaked condition and 15 for the soaked condition of the stabilized samples. With the addition of the polypropylene fibers to the stabilized Peat Soil with cement not only improved the strength of the stabilized Peat Soil but also contributed to considerable amount of uniformity and intactness to the stabilized Peat Soil samples. It was also observed that as the curing time for the stabilized Peat Soil continued through 180 days the moisture content continued to decrease as well. Thus the water-cement (w/c) ratio reduced and as a result of cement hydration, the strength stabilized Peat Soil samples increased in hardness and gained strength through the curing period. Conclusion/Recommendations: Cement and polypropylene fibers can be used to improve the mechanical strength of the soft Peat Soil by adopting air curing technique.
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UCS Evaluaton Tests for Cement Treated Peat Soil with Polypropylene Fibers
Ground Improvement Technologies and Case Histories, 2009Co-Authors: Behzad Kalantari, Bujang B. K. HuatAbstract:Peat Soil is one of the softest types of Soil. Various methods have been used in the past to strengthen Peat Soil deposits. In this research, unconfined compressive strength (UCS) of Peat Soil was studied while the Peat Soil was in its undisturbed state, stabilized with ordinary Portland cement, and mixed with polypropylene fibers. Unconfined compressive strength for either stabilized Peat with polypropylene fibers or Peat without polypropylene fibers was studied at different curing ages from immediately after molding (zero day) to 7, 28, 90, and 180 days. All samples were cured in air, and the procedure includes leaving the stabilized Peat Soil in normal room temperature and in air throughout the curing period. The curing procedure used to strengthen the Peat Soils shows that UCS values of stabilized Peat Soil were considerably increased through the curing process. As the curing time for the stabilized Peat Soil continues, the moisture contents of the UCS samples are reduced (through evaporation), and therefore the weight of water divided by the weight of cement (W/C) of stabilized samples is reduced. As W/C for samples reduces, the stabilized samples gain strength throughout the curing time. The strength gain continues beyond 28 days which is usual for concrete mixes. The UCS values for the stabilized Peat Soil show that the strength increases continues through six months of curing period. Addition of polypropylene fibers to the mixture of Peat and ordinary Portland cement as a non-reactive additive not only increases the UCS values of stabilized Peat Soil, but also contributes a considerable amount of uniformity and intactness to the stabilized Peat Soil samples as well. Copyright © 2009 by Geotechnical Society of Singapore (GeoSS).
Calen Maytobin - One of the best experts on this subject based on the ideXlab platform.
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modeling relationships between water table depth and Peat Soil carbon loss in southeast asian plantations
Environmental Research Letters, 2015Co-Authors: Kimberly M Carlson, Lael K Goodman, Calen MaytobinAbstract:Plantation-associated drainage of Southeast Asian Peatlands has accelerated in recent years. Draining exposes the upper Peat layer to oxygen, leading to elevated decomposition rates and net Soil carbon losses. Empirical studies indicate positive relationships between long-term water table (WT) depth and Soil carbon loss rate in Peatlands. These correlations potentially enable using WT depth as a proxy for Soil carbon losses from Peatland plantations. Here, we compile data from published research assessing WT depth and carbon balance in tropical plantations on Peat. We model net carbon loss from subsidence studies, as well as Soil respiration (heterotrophic and total) from closed chamber studies, as a function of WT depth. WT depth across all 12 studies and 59 sites is 67 ± 20 cm (mean ± standard deviation). Mean WT depth is positively related to net carbon loss, as well as Soil respiration rate. Our models explain 45% of net carbon loss variation and 45–63% of Soil respiration variation. At a 70 cm WT depth, the subsidence model suggests net carbon loss of 20 tC ha−1 yr−1 (95% confidence interval (CI) 18–22 tC ha−1 yr−1) for plantations drained for >2 yr. Closed chamber-measured total Soil respiration at this depth is 20 tC-CO2 ha−1 yr−1 (CI 17–24 tC-CO2 ha−1 yr−1) while heterotrophic respiration is 17 tC-CO2 ha−1 yr−1 (CI 14–20 tC-CO2 ha−1 yr−1), ~82% of total respiration. While land use is not a significant predictor of Soil respiration, WT depths are greater at acacia (75 ± 16 cm) than oil palm (59 ± 15 cm) sample sites. Improved spatio-temporal sampling of the full suite of Peat Soil carbon fluxes—including fluvial carbon export and organic fertilizer inputs—will clarify multiple mechanisms leading to carbon loss and gain, supporting refined assessments of the global warming potential of Peatland drainage.