Hydraulic conductivity and volumetric shrinkage properties review on gradation effect of compacted laterite soil liner

This paper reviews the effects of gradation on hydraulic conductivity and volumetric shrinkage properties of compacted laterite soil liner. The distribution of different grain sizes affects the engineering properties of soil such as compressibility, swelling and shrinkage, shear strength, and hydraulic conductivity. It is observed that there are dissimilarities of values in laterite soils from various researches around tropical countries of the world in terms of hydraulic conductivity and volumetric shrinkage. Hydraulic conductivity varies from 4.36×10-3 m/s to 4.7×10-11 m/s and volumetric shrinkage of ≤ 4%relative to fine contents ranging from 1.3% to 69% and coarse contents ranging from 31% to 98.7%.Generally, there is no clear trend established for effects of gradation on hydraulic conductivity and volumetric shrinkage properties of compacted laterite soil liners. This is because laterite soils with less than 50% fines content might not be used as liner or hydraulic barriers because their hydraulic conductivities are less than the minimum requirement of 1 × 10-9 m/s. At times researchers usually left out volumetric shrinkage in their study, but field studies have shown that desiccation can induce severe cracking of unprotected soil barriers. When fine grained soils lose moisture they tend to shrink, which result to cracking that can adversely affect the engineering properties and performance of the soils. The adversative influence includes reduced strength of the cracked soils and increased hydraulic conductivity. It is expected that with logical understanding of the effects of gradation on hydraulic conductivity and volumetric shrinkage properties of compacted laterite soil it will serve as a guide in the design of hydraulic barriers for engineered sanitary landfills in tropical countries around the world

Volumetric shrinkage of compacted soil liner for sustainable waste landfill

One of the main principal sources that contributes to the release of leachates in the environment is the municipal solid waste in landfill facilities. To mitigate the negative effects of leachate, landfill liner is constructed to provide a protective barrier that will not allow the leachate to pass through the compacted soil, which may cause groundwater contamination. Due to seasonal variation in tropical regions, compacted or natural soil liners tend to lose moisture when dry. This result to volumetric shrinkage, which causes cracks that affect the engineering properties and performance of the soils. Groundwater can easily be affected by leachate permeating through these cracks in soils because of desiccation induced by volume change. This paper aims to evaluate the effect of fines content at various gradation and moulding water content on volumetric shrinkage property of compacted laterite soil; and to compare the results with the regulatory standard for compliance to mitigate the negative effects of leachate on the environment. The technique used in this study was to vary the gradation of laterite soil at different moisture contents to achieve a sustainable result. It is observed that the volumetric shrinkage increase as the percentage of fines content increase with corresponding water content. The changes in volumetric shrinkage with time shows a sharp increase within the first five to ten d of drying and then become constant. The soil needs to be compacted on the dry side of optimum moisture content or at the optimum moisture content in order to meet the regulatory criteria of ≤ 4 %

Effect of Chemicals on Compressive Strength of Plastic-Laterite Interlock Paving Blocks

This research centres on the need to develop a simple but sustainable material for the utilization of the quantum of plastic wastes that litter our environment. The research uses waste plastics and laterite soil and converts them into construction materials (interlock blocks) with the help of the densifier, thereby reducing the plastic waste, which is a key contributor to environmental pollution. Literature has shown that concrete structure is prone to chemical actions; the durability of conventional concrete bricks gets affected by chemical effects. The chemicals may cause cracking of concrete, rutting, and deterioration of the structure. In the same vein, the plastic-laterite interlock bricks might not be free from such defects due to chemical action. Therefore, this research looks into the effects of different chemical curing conditions on the compressive strength of plastic-laterite paving blocks. Varying proportions of plastic wastes and laterite soil were mixed and processed into composite bricks and subjected to different chemical treatments; in acid, base, oil, and water for 3, 14, and 28 days relative to a concrete brick control. It was observed that samples cured in acid solution gave the lowest compressive strength, while those in base solution gave the highest. The paving interlock blocks made from polyethylene/laterite composite registered relative performance compared to concrete interlock bricks control. If made and put into use, these blocks will reduce construction costs, assist in environmental sustainability and improve circular economic growth. Therefore, using this innovative approach will bolster infrastructural projects and checkmate plastic pollution within our environment

Effects of gradation on hydraulic conductivity properties of compacted laterite soil liner: a review

This paper presents the recent review on the effects of gradation on hydraulic conductivity properties of compacted laterite soil liner. The distribution of different grain sizes affects the engineering properties of soil such as compressibility, shear strength, and hydraulic conductivity . It is observed that there are variations in hydraulic conductivity values in laterite soils from various researches around tropical countries of the world . Hydraulic conductivity varies from 4.36×10 -3 m/s to 4.7×10 -11 m/s relative to fine contents ranging from 1.3% to 69% and coarse contents ranging from 31% to 98.7%. Generally, there is no clear trend established for effects of gradation on hydraulic conduc- tivity properties of compacted laterite soil liners. This is because laterite soils with less than 50 fines content cannot be used as liner or hydra ulic barriers because their hydraulic conductivities are less than the minimum requirement of 1 × 10 -9 m/s. It is anticipated that with logical understanding of the effects of gradation on hydraulic conductivity properties of compacted laterite soil it wil l serve as a guide in the design of hydraulic barriers for engineered sanitary landfills in tropical countries around the world

Analysis of Multi-Criteria Evaluation Method of Landfill Site Selection for Municipal Solid Waste Management

Landfilling remains the most common systematic technique of solid waste disposal in most of the developed and developing countries. Finding a suitable site for landfill is a very challenging task. Landfill site selection process aims to provide suitable areas that will protect the environment and public health from pollution and hazards. Therefore, various factors such as environmental, physical, socio-economic, and geological criteria must be considered before siting any landfill. This makes the site selection process vigorous and tedious because it involves the processing of large amount of spatial data, rules and regulations from different agencies and also policy from decision makers. This allows the incorporation of conflicting objectives and decision maker preferences into spatial decision models. This paper particularly analyzes the multi-criteria evaluation (MCE) method of landfill site selection for solid waste management by means of literature reviews and surveys. The study will help the decision makers and waste management authorities to choose the most effective method when considering landfill site selection

Analysis of Multi-Criteria Evaluation Method of Landfill Site Selection for Municipal Solid Waste Management

Landfilling remains the most common systematic technique of solid waste disposal in most of the developed and developing countries. Finding a suitable site for landfill is a very challenging task. Landfill site selection process aims to provide suitable areas that will protect the environment and public health from pollution and hazards. Therefore, various factors such as environmental, physical, socio-economic, and geological criteria must be considered before siting any landfill. This makes the site selection process vigorous and tedious because it involves the processing of large amount of spatial data, rules and regulations from different agencies and also policy from decision makers. This allows the incorporation of conflicting objectives and decision maker preferences into spatial decision models. This paper particularly analyzes the multi-criteria evaluation (MCE) method of landfill site selection for solid waste management by means of literature reviews and surveys. The study will help the decision makers and waste management authorities to choose the most effective method when considering landfill site selection

Using soil water characteristic curve in computing unsaturated hydraulic conductivity of compacted tropical soil

Contaminants flow through compacted soil liners and coversare usually considered under saturated conditions during design stage. Whereas, the compacted soil barriers in reality are neither completely saturated nor completely dry, rather they are in an unsaturated state. Thus, unsaturated flow principles need to be properly simulated to determine the contaminant flow through compacted soil barriers in order to protect groundwater. Soil water characteristic curve (SWCC) which is the relationship between soil suction and water content is the main modeling parameter of unsaturated soil. This paper evaluates the SWCC data of a tropical laterite soil used as a liner material in sanitary landfill. The effect of gradation with respect to fines content on the dry of optimum, optimum and wet of optimum moisture contents on SWCC were investigated. Laboratory tests using pressure plate apparatus were conducted to determine the variation of volumetric water content with soil suction for a pressure range of 1 kPa to 1000 kPa. The experimental SWCC data were fit to the Brooks and Corey parametric equation to compute the unsaturated hydraulic conductivity. Based on the SWCC data, greater air entry suctions were obtained for specimens with higher fines contents when compacted wet of optimum moisture content and the water retention capacity increased with increase in fines content. Using the SWCC, the unsaturated hydraulic conductivities of the soil liner used in simulating leachate migration were computed

Computer Modeling Approach of Leachate Flow in Compacted Laterite Soil Liner

The use of hydraulic barriers in sanitary landfills has become an impeccable means of protecting the groundwater system from leachate. A question to be asked is, can these barriers continue to impede the migration of leachate over a long period? This paper investigates the phenomenon of leachate migration in compacted laterite soil used as liner in sanitary landfills. An experiment was carried out using laterite soil compacted at optimum moisture content using Standard Proctor energy. Leachate was poured on the compacted soil in an acrylic column and its migration was monitored using Digital Image Technique (DIT). The DIT capture photographic images at successive intervals of time which were fed through an image processing code to convert them to hue-saturation-intensity (HSI) format with the help of Surfer and Matlab computer softwares. Subsequently, PetraSim computer software was applied to predict the velocity behavior. The predicted velocity value shows that the laterite soil is compatible with the leachate and can be used as soil liner. The outcome of this study would enable designers to use non-destructive method to monitor and predict leachate migration in compacted soil liners to simulates leachate migration in waste containment applications

Computer Modeling Approach of Leachate Flow in Compacted Laterite Soil Liner

The use of hydraulic barriers in sanitary landfills has become an impeccable means of protecting the groundwater system from leachate. A question to be asked is, can these barriers continue to impede the migration of leachate over a long period? This paper investigates the phenomenon of leachate migration in compacted laterite soil used as liner in sanitary landfills. An experiment was carried out using laterite soil compacted at optimum moisture content using Standard Proctor energy. Leachate was poured on the compacted soil in an acrylic column and its migration was monitored using Digital Image Technique (DIT). The DIT capture photographic images at successive intervals of time which were fed through an image processing code to convert them to hue-saturation-intensity (HSI) format with the help of Surfer and Matlab computer softwares. Subsequently, PetraSim computer software was applied to predict the velocity behavior. The predicted velocity value shows that the laterite soil is compatible with the leachate and can be used as soil liner. The outcome of this study would enable designers to use non-destructive method to monitor and predict leachate migration in compacted soil liners to simulates leachate migration in waste containment applications