Evaluation of Contributing Factors on Strength Development of Lime Stabilized Artificial Organic Soils Using Statistical Design of Experiment Approach

2014 ◽  
Vol 905 ◽  
pp. 362-368 ◽  
Author(s):  
Felix N.L. Ling ◽  
Khairul Anuar Kassim ◽  
Ahmad Tarmizi Abdul Karim ◽  
S.C. Ho
Keyword(s):  
Organic Matter ◽  
Statistical Design ◽  
Organic Soil ◽  
Curing Temperature ◽  
Organic Soils ◽  
Strength Development ◽  
Test Results ◽  
Contributing Factors ◽  
Strength Enhancement ◽  
Factor Interactions

Lime is widely used as chemical stabilizer in soft soil stabilization. However, lime is reported to be less effective when dealing with organic soil. It is believed that the organic matter in the soil will retard the pozzolanic reaction which is responsible for strength enhancement. The heterogeneity nature of the organic matter in the soil makes the study complicated and reduced the repeatability of the test results. Hence, artificial organic soil with known organic matter and content are preferred by researchers when repeatability of the test results are required in determining the influential effect of each contribution factor. Various factors such as additive contents, effect of aging (curing periods), curing temperature, density of materials and moisture content are reported by previous researchers as the potential contributing factors towards the strength development. It is believed that the interaction of the factors also will contribute to the strength enhancement. Hence, this study is carried out to evaluate the contributing factors and its interactions on strength development of artificial organic soils with known type and contents of organic matter. Statistical design of experiment (DOE) approach was utilized to evaluate the factors and its interaction on the strength development of lime stabilized artificial organic soils by using commercial statistics package. Three main factors were investigated: effect of organic content, effect of curing periods, and effect of additive, while other factors namely curing temperature, molding water content, types of compaction and compactive effort were keep constant through controlled experiments. Processed kaolin (inorganic material) is mixed with humic acid (organic matter) to simulate the organic soil which comprised of inorganic soil and organic matter. The density of the soil specimen and its moisture content were recorded before and after the curing process. General Linear Model (GLM) was utilized to determine the significance of the main factors, two-factor interactions, and three factor interactions. The significance factors and interactions were utilized in multiple regression analysis to develop the strength prediction model which can be utilized to predict the strength of stabilized materials within the inference space defined by the experiment.

HUMIC-FULVIC ACID RELATIONSHIPS IN ORGANIC SOILS AND HUMIFICATION OF THE ORGANIC MATTER IN THESE SOILS

1967 ◽  
Vol 47 (3) ◽  
pp. 245-250 ◽  
Author(s):  
M. Schnitzer
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Humic Acid ◽  
Fulvic Acid ◽  
Oxidative Degradation ◽  
Fulvic Acids ◽  
Organic Soil ◽  
Organic Soils ◽  
Salting Out ◽  
Naoh Solution

Twenty organic-soil samples of widely differing degrees of decomposition were extracted with 0.5 N NaOH solution under N2. Amounts of humic and of fulvic acids in the acidified extracts did not correlate significantly with pyrophosphate solubilities. This was thought to be due to interference in the separation scheme by relatively large amounts of ash constituents in the extracts. Since the "classical" fractionation of soil organic matter appears to involve essentially the "salting out" of higher molecular-weight humic from lower molecular-weight fulvic acids, an excessively high salt concentration during the separation should be avoided.To lower the concentration of inorganic constituents in the extracts, the samples were first pretreated with dilute HCl–HF solution and then extracted with 0.1 N NaOH rather than with 0.5 N NaOH. Under these conditions, amounts of fulvic acids in the acidified extracts showed a significant positive correlation (r = 0.52) with pyrophosphate solubilities of untreated extracts, whereas amounts of humic acids in the extracts exhibited a highly negative correlation (r = −0.57) with pyrophosphate solubilities. In the soils examined, increased humification was associated with increases in fulvic-acid but decreases in humic-acid concentrations.From the results of this and of earlier investigations done in this laboratory it appeared that the main mechanism governing humification in these soils was oxidative degradation, resulting ultimately in the formation of fulvic from humic acid.

scholarly journals Organic Matter Causes Chemical Pollutant Dissipation Along With Adsorption and Microbial Degradation

2021 ◽  
Vol 9 ◽  
Author(s):  
A. Vilhelmiina Harju ◽  
Ilkka Närhi ◽  
Marja Mattsson ◽  
Kaisa Kerminen ◽  
Merja H. Kontro
Keyword(s):  
Organic Matter ◽  
Microbial Degradation ◽  
Mineral Soil ◽  
Organic Soil ◽  
Organic Soils ◽  
First Response ◽  
Chemical Pollutant ◽  
Mineral Soils ◽  
Soil And Sediment

Views on the entry of organic pollutants into the organic matter (OM) decaying process are divergent, and in part poorly understood. To clarify these interactions, pesticide dissipation was monitored in organic and mineral soils not adapted to contaminants for 241 days; in groundwater sediment slurries adapted to pesticides for 399 days; and in their sterilized counterparts with and without peat (5%) or compost-peat-sand (CPS, 15%) mixture addition. The results showed that simazine, atrazine and terbuthylazine (not sediment slurries) were chemically dissipated in the organic soil, and peat or CPS-amended soils and sediment slurries, but not in the mineral soil or sediment slurries. Hexazinone was chemically dissipated best in the peat amended mineral soil and sediment slurries. In contrast, dichlobenil chemically dissipated in the mineral soil and sediment slurries. The dissipation product 2,6-dichlorobenzamide (BAM) concentrations were lowest in the mineral soil, while dissipation was generally poor regardless of plant-derived OM, only algal agar enhanced its chemical dissipation. Based on sterilized counterparts, only terbutryn appeared to be microbially degraded in the organic soil, i.e., chemical dissipation of pesticides would appear to be utmost important, and could be the first response in the natural cleansing capacity of the environment, during which microbial degradation evolves. Consistent with compound-specific dissipation in the mineral or organic environments, long-term concentrations of pentachloroaniline and hexachlorobenzene were lowest in the mineral-rich soils, while concentrations of dichlorodiphenyltrichloroethane (DTT) and metabolites were lowest in the organic soils of old market gardens. OM amendments changed pesticide dissipation in the mineral soil towards that observed in the organic soil; that is OM accelerated, slowed down or stopped dissipation.

scholarly journals Strength characteristics of artificial organic soils stabilized with copolymer stabilizer

2018 ◽  
Vol 169 ◽  
pp. 01010 ◽  
Author(s):  
Chia-Wen Law ◽  
Felix Ngee-Leh Ling ◽  
Boon-Khiang Ng
Keyword(s):  
Organic Matter ◽  
Organic Soil ◽  
Organic Soils ◽  
Chemical Stabilization ◽  
Test Device ◽  
Compressive Test ◽  
Acid Ratio ◽  
Strength Material ◽  
Strength Increment ◽  
Effective Stabilization

Organic soil is known as low strength material, and chemical stabilization is widely used to increase its bearing capacity. However, the use of traditional stabilizer has some limitations. Therefore, stabilization was carried out by using non-traditional stabilizer - Vinyl acetate-ethylene (VAE) copolymer emulsion in this study with the aim to determine its suitability to stabilize soil mixed with organic matter. Two types of artificial organic soil with kaolin: organic acid ratio of 5:5 (K5HA5) and 7:3 (K7HA3) were utilized. Control specimens were tested using pure kaolin. Different percentages of VAE (5%, 7.5%, 10%) were added in order to determine the minimum amount of stabilizer required to achieve a minimum strength increment of a 345 kPa. The strength of samples was determined with automated unconfined compressive test device. Specimens were air cured for 7 days prior to testing. Both K7HA3 with 7.5% VAE and K5HA5 with 10% VAE had achieved the minimum strength increment to be considered as effective stabilization. The strength of the artificial organic soil was found to be increasing with the increment of percentages of VAE used. Hence, it can be concluded that stabilizing mechanism of the artificial organic soils with VAE is not affected by organic matter.

Challenges of using microbial explicit models for evaluating organic matter decomposition in predominantly organic soils 

2021 ◽  
Author(s):  
Debjani Sihi ◽  
Stefan Gerber
Keyword(s):  
Organic Matter ◽  
Soil Carbon ◽  
Organic Soil ◽  
Organic Soils ◽  
Mineral Matter ◽  
Carbon Limitation ◽  
Classical Models ◽  
Mineral Soils ◽  
Set Up ◽  
Som Decomposition

<p class="rolelistitem">Models of soil organic matter (SOM) decomposition are critical for predicting the fate of soil carbon (and nutrient) under changing climate. Traditionally, models have used a simple set-up where the substrate is divided into conceptual pools to represent their resistance to microbial degradation, and decomposition rates are often proportional to the amount of substrate in each pool. Emerging models now consider explicit microbial dynamics and show that SOM loss under warming may be fundamentally different from the classical models. Microbial explicit models use reaction kinetics, represented on a concentration basis. However, when the substrate makes up most of the volume of soils (e.g., the organic horizon in forest soils or peat), an increase or decrease in SOM does not, or only very little, affect concentrations of microbes and substrate. Consequently, reduction in SOM does not reduce the amount of substrate the microbial biomass encounters. This problem does not occur in classical models like CENTURY. We incorporated the effect of organic matter on soil volume in several microbial models. If microbes are solely limited by enzymes, organic soils or peats are decomposed very quickly as there is no mechanism that stops the positive feedback between microbial growth and SOM concentration until the substrate is gone. Alternative formulations that account for carbon limitation or microbial ‘cannibalism’ display a sweet spot of soil carbon concentration. Interestingly, a response to warming will depend on the amount of organic vs. mineral materials. Apparent Q<sub>10</sub> was higher in fully organic soil than in mineral soils, which was pronounced when small to moderate amounts of the mineral matter was present that diluted the substrate for microbes. We suggest that model formulations need to be clear about the assumption in key processes, as each of the steps in the cascade of biogeochemical reaction can produce surprising results.</p>

scholarly journals Vertical and horizontal permeability measurements in organic soils

2015 ◽  
Vol 47 (2) ◽  
pp. 153-161 ◽  
Author(s):  
Edyta E. Malinowska ◽  
Alojzy Szymański
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Flow Characteristics ◽  
Vertical Direction ◽  
Organic Soil ◽  
Organic Soils ◽  
Test Results ◽  
Consolidation Process ◽  
Consolidation Model ◽  
Horizontal Permeability

Abstract The paper is referring to vertical and horizontal laboratory permeability measurements in soft organic soils. The estimation of anisotropic permeability in soft organic soils, as peats, requires to use a special apparatus and the knowledge of proper analysis of the test results. During loading the void ratio decreases substantially that causes the changeability of the permeability. The change of permeability during the compression is very important because of the influence of the consolidation co-efficient. Initial strain in soft organic soils appears very quickly, just after loading, and brings immediately the decrease of permeability. In most of the estimations, it is assumed that during the consolidation process the water flows just in the vertical direction. In soft organic soils, like peats, the consolidation theory should consider the changes of mechanical and physical properties in consolidation period, in both directions. The direct measurement of vertical and horizontal permeability of organic soil and the non-Darcian flow theory may be of considerable importance in estimating pore water pressure dissipation, and settlement rates in the consolidation model. In the paper, the method of investigation and the test results of the vertical and horizontal permeability are presented. The Modified Rowe Cell Set for obtaining consolidation and flow characteristics in different directions is used.

scholarly journals Prediction on Compressive and Split Tensile Strengths of GGBFS/FA Based GPC

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4198
Author(s):  
Songhee Lee ◽  
Sangmin Shin
Keyword(s):  
Curing Temperature ◽  
Test Results ◽  
Portland Cement Concrete ◽  
Contributing Factors ◽  
Split Tensile Strength ◽  
Equivalent Age ◽  
Granulated Blast Furnace Slag ◽  
Model Predictions ◽  
Taguchi Orthogonal Arrays ◽  
Cylindrical Test

Based on rate constant concept, empirical models were presented for the predictions of age-dependent development of compressive and split tensile strengths of geopolymer concrete composite (GPCC) with fly ash (FA) blended with ground granulated blast furnace slag (GGBFS). The models were empirically developed based on a total of 180 cylindrical test results of GPCC. Six different independent factors comprising of curing temperature, the weight ratios of GGBFS/binder, the aggregate/binder, the alkali solution/binder, the Na2SiO3/NaOH, and the NaOH concentration were considered as the variables. The ANOVA analyses performed on Taguchi orthogonal arrays with six factors in three levels showed that the curing temperature and ratio of GGBFS to binder were the main contributing factors to the development of compressive strength. The models, functionalized with these contributing factors and equivalent age, reflect the level of activation energy of GPCC similar to that of ordinary Portland cement concrete (OPC) and a higher frequency of molecular collisions during the curing period at elevated temperature. The model predictions for compressive and split tensile strength showed good agreements with tested results.

scholarly journals Method for determining the degree of influence of the heating temperature on the strength set of concrete based on isotherms

2021 ◽  
Vol 79 (1) ◽  
pp. 283-288
Author(s):  
E.B. Utepov ◽  
◽  
A.S. Tulebekova ◽  
D.A. Akhmetov ◽  
E.N. Root ◽  
...  
Keyword(s):  
Heating Temperature ◽  
Concrete Strength ◽  
Curing Temperature ◽  
Strength Development ◽  
Numerical Comparison ◽  
Test Results ◽  
Strength Gain ◽  
Sample Heating ◽  
Temperature Regimes ◽  
Alternative Approach

The article presents the development of an alternative approach to determining the degree of influence of the curing temperature on the concrete strength gain, based on the construction of isotherms. Based on the test results, isotherms were plotted, representing the graphs of strength gain for each of the temperature regimes. Visual and numerical comparison of the concrete strength values obtained from isotherms gave an understanding of the degree of influence of sample heating on strength development.

scholarly journals Solutions for subsidence in the California Delta, USA, an extreme example of organic-soil drainage gone awry

2020 ◽  
Vol 382 ◽  
pp. 837-842
Author(s):  
Steven J. Deverel ◽  
Sabina Dore ◽  
Curtis Schmutte
Keyword(s):  
Organic Matter ◽  
Water Supply ◽  
Greenhouse Gas ◽  
Greenhouse Gas Emission ◽  
Animal Feed ◽  
Organic Matter Content ◽  
Organic Soil ◽  
Organic Soils ◽  
Human Consumption ◽  
Land Uses

Abstract. The Sacramento-San Joaquin Delta is at the heart of California's water supply system that provides water for irrigation and human consumption. It is also home to subsiding organic soils, decreasing native aquatic species populations, water quality degradation, vulnerable levees (levees are equivalent to dikes) and decreasing agricultural viability. There has been substantial progress in the interdisciplinary understanding and quantification of the nature and effects of subsidence and its mitigation. Because of the need for a drained rootzone, farming of crops such as vegetables, trees, vines, corn and alfalfa, results in an ongoing unsustainable cycle of continuing peat oxidation and deepening of drainage ditches to compensate for elevation loss. Despite substantial evidence for the increasing risks to the State's economy and water supply, the unsustainability of the status quo, and evidence for the benefits of alternatives, there has been limited progress in converting to land uses that can reduce, stop and reverse subsidence. Our overall approach has been to measure land-surface elevation changes; understand, quantify and model subsidence and greenhouse gas emissions from drained organic soil, and evaluate alternate land uses. Subsidence rates vary from less than 0.5 to over 2 cm yr−1, depending primarily on depth to groundwater and soil organic matter content. The primary cause of subsidence is the oxidation of organic matter, which has resulted in elevations of −3 to −9 m on about 100 000 ha. Using the results from micrometeorological measurements and modelling, we estimate that organic-matter oxidation causes an annual emission of over 2×106 t of CO2-equivalent which represents about 21 % of the State's plant-based agricultural emissions. Rewetting of the peat soils is emerging as a viable solution. Rice and wetlands stop and (in the case of wetlands) reverse the effects of subsidence and result in a net greenhouse-gas emission reduction benefit. Wetlands accrete about 3 cm of soil per year, can break the unsustainable subsidence/drainage cycle, reverse the trajectory of increasing hydraulic pressures on levees, reduce the probability of levee failure and seepage onto islands (islands are equivalent to polders), and may provide material for biofuels and animal feed. The recent implementation of a methodology for quantification of the GHG benefit is facilitating land use conversion and participation in the carbon market.

scholarly journals Identification of local organic soils based on cone penetration test results

2014 ◽  
Vol 13 (2) ◽  
pp. 049-056
Author(s):  
Grzegorz Straż
Keyword(s):  
Organic Soil ◽  
Organic Soils ◽  
Test Results ◽  
Penetration Test ◽  
Cone Penetration ◽  
Penetration Testing ◽  
Cone Penetration Testing ◽  
In Situ Conditions

This paper presents the results of attempts to identify organic soils on the basis of test results performed under in situ conditions by cone penetration testing (CPT). The results of 439 selected tests were analysed which reflected the behaviour of local organic soils of organic matter ranging from 6,3 to 17,4%. Crucial to soil investigation were values measured of cone resistance (qc) and sleeve friction (fs) and the friction ratio (Rf) estimated according to those values. To identify organic soils, selected criteria were used, proposed among others by: Mayne, Marr, Bergmann, Schmertmann, Capanella and Robertson [2,5]. An analysis showed that an identification of organic soil types in terms of the present classification of standards, in view of the criteria used, is ambiguous and does not allow to identify them precisely by CPT.

scholarly journals Effects of Fly Ash on Mechanical Properties of Concrete

2018 ◽  
Vol 8 (2) ◽  
pp. 35-40 ◽  
Author(s):  
Masoud Zabihi-Samani ◽  
Seyed Payam Mokhtari ◽  
Farzaneh Raji
Keyword(s):  
Fly Ash ◽  
Transport Properties ◽  
Carbon Dioxide Emissions ◽  
Recycled Concrete ◽  
Curing Temperature ◽  
Strength Development ◽  
Concrete Aggregate ◽  
Test Results ◽  
Recycled Concrete Aggregate ◽  
Low Carbon

Abstract Cement is a common and widespread building material over the world. Similarly, carbon dioxide emissions have been significantly increased due to cement production. Alternative low-carbon binders rather than cement have been progressively sought in recent years. Fly ash was found as an available option, since it is being largely disposed annually as a waste material. In this research several studies have been reviewed and recent applications of fly ash on concrete specification, including strength and fracture toughness of green concrete have been perused. Furthermore, transport properties of high volume fly ash after exposure to high temperature and influence of curing temperature on strength development of fly ash-recycled concrete aggregate blends have been investigated. The investigated test results showed that the properties of composites incorporating fly ash depend on the age of the concrete. Test results also revealed that transport properties of concrete increased notably after exposure to 400cº and the results achieved on fly ash-recycled concrete aggregate led to the conclusion that 15% FA is the optimum blend for road stabilization applications.

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