Water Retention Behaviour Research Articles

Experimental and modeling study of water-retention behavior of fine-grained soils with dual-porosity structures

Experimental and modeling study of water-retention behavior of fine-grained soils with dual-porosity structures

Qualitative Rating System for Drainability of Roadway Base Materials

Poor drainage of roadway base/subbase materials can lead to increased pore water pressure, reduction of strength and stiffness, and freeze-thaw damage. Base course drainability is dependent on physical properties of the material that affect its water flow and retention behavior including particle size distribution, fines content, density or porosity, the geometric and boundary conditions of the pavement system, and site-specific environmental conditions. Objectives of this project are to quantitatively assess permeability and water retention characteristics of representative roadway base materials, to derive predictive equations for indirect estimation of material properties that control drainability, and to develop and recommend rating systems for assessing more general base materials. Laboratory tests were conducted on 16 samples of materials used in or considered for use in roadway applications to determine grain size distribution, hydraulic conductivity, and soil-water characteristic curves. Results are correlated to grain size characteristics including percent gravel, percent fines, grain size indices (e.g., D10, D30), and unit weight. Procedures are provided to qualitatively assess drainability as “excellent,”“marginal,” or “poor,” from grain size, thereby offering a rationale to reduce pavement life cycle costs, improve safety, realize material cost savings, and reduce environmental impacts.

Water Retention Behaviour and Fracture Toughness of Coir/Pineapple Leaf Fibre with Addition of Al2O3 Hybrid Composites under Ambient Conditions

Due to their high mechanical and physical properties, natural fibre-based composite materials have been important in many fields of application for four to five years. The chief intention of the current study is to determine the mechanical and water retention features of composite materials under ambient conditions. Coir and pineapple leaf fibre were used as a reinforcement, aluminium oxide as additives, and polyester as a matrix. The hybrid resources were laminated by the manual hand lay-up method. The mechanical characteristics like tensile, flexural, and fracture toughness properties were tested as per the ASTM standard. Nanoparticle weight ratio and its size variation significantly impact mechanical qualities. The hybrid composite’s water retention behaviour was tested for two types of water levels: ordinary tab water and nanofluid. The moisture uptake of the composites rose as the fibre volume increased, and after 640 hours, all of the composites had reached equilibrium. According to the results, the following combinations have the maximum mechanical strength: 15% wt.% coir, 15% wt.% pineapple, 10% wt.% nanofiller, and 60% wt.% polyester resin. The combinations mentioned above withstand the most load during the tests. Compared to 20% filler, 10% Al2O3 filler produces good interfacial adhesion in the current study. The fractured specimens were analyzed using scanning electron microscopic (SEM) pictures to recognize better the failure process of composites during mechanical testing.

Interlaminar Shear, Bending, and Water Retention Behavior of Nano-SiO2 Filler-Incorporated Dharbai/Glass Fiber-Based Hybrid Composites under Cryogenic Environment

In current history, adding nanoscale and micron-sized filler materials to composite materials for fabrication has been a popular approach for improving the composite’s mechanical characteristics. Due to their lower friction coefficient, excellent mechanical strength modulus, and low moisture uptake, filler-based hybrid composite materials are replacing metallic materials. Glass/Dharbai hybrid composites with nano-SiO2 fillers have been created in this study. After manufacture, the composite materials were treated with liquid nitrogen at 177 K for various durations. Every sample material was cut according to ASTM standards to investigate mechanical features such as ILSS, impact test, and flexural strength. The broken composite specimen was studied using a scanning electron microscope. Water retention studies have been conducted under two distinct liquid solutions: tab or regular water and seawater. ILSS, flexural strength, and water retention were all greater in 4 wt.% of nanofiller-rich composites than in ordinary composites. Compared to 30 minutes, the 15-minute cryo-treated specimens provide the highest mechanical strength. On the other hand, the automobile, aviation, and shipbuilding sectors would benefit from a nanofiller-based composite.

Influence of Nanosilica Particle Addition on Mechanical and Water Retention Properties of Natural Flax- and Sisal-Based Hybrid Nanocomposites under NaOH Conditions

Organic filament-based lightweight materials are increasingly being used because of their high strength-to-weight ratio, recyclability, and low cost. The application of nanofillers in addition to natural fibres is a fascinating one. The main purpose of the current experimental investigation is to manufacture and estimate the mechanical material of nanocomposites. Natural fibres like flax and sisal are used as reinforcement; nanosilica particles act as fillers, and epoxy resin as a matrix. The composites were created using the Taguchi L9 orthogonal array and a hand lay-up technique. The mechanical and water retention behaviour of the hybrid composites is based on the following three parameters, each with three different levels: (i) adding different weight ratios of nanofiller (1.5, 3, and 4.5 wt%), (ii) weight ratio of reinforcements (20, 30, and 40 wt%), and (iii) duration of NaOCl conditions (2, 4, and 6 hours). Mechanical possessions like tension, bending, and impact were tested as per the ASTM standard. The tested composites show that 30 wt% reinforcement, 3 wt% nanosilica, and 4 hours of alkaline processing provide the best materials and aquatic preoccupation belongings. When compared to nanofiller composites, nanoparticle-filled composites have 17% evolution in tension, 22% upsurge in flexural strength, 13% in impact strength, and 36% increase in impact strength hygroscopic behaviour. Scanning electron microscopes were used to analyze the fractured structure of hybrid composites. Compared to 1.5 and 4.5 wt% of nanofiller, the 3 wt% of filler provides high interfacial adhesion to the hybrid composites. It helps the reinforcement and matrix to contact each other.

Coupling cyclic and water retention response of a clayey sand subjected to traffic and environmental cycles

Compacted soils used as formation layers of railways and roads continuously undergo water content and suction changes due to seasonal variations. Such variations, together with the impact of cyclic traffic-induced loads, can alter the hydro-mechanical behaviour of the soil, which in turn affects the performance of the superstructure. This study investigates the impact of hydraulic cycles on the coupled water retention and cyclic response of a compacted soil. Suction-monitored cyclic triaxial tests were performed on a compacted clayey sand. The cyclic response of the soil obtained after applying drying and wetting paths was different to that obtained immediately after compaction. The results showed that both suction and degree of saturation are required to interpret the cyclic behaviour. A new approach was developed using (a) a hysteretic water retention model to predict suction variations during cyclic loading and (b) Bishop's stress together with a bonding parameter to predict accumulated permanent strain and resilient modulus. The proposed formulations were able to predict the water retention behaviour, accumulated permanent strains and resilient modulus well, indicating the potential capability of using the fundamentals of unsaturated soils for predicting the effects of drying and wetting cycles on the coupled soil water retention and cyclic response.

Water retention and compression behavior of MX80 bentonite pellet

Water retention and compression behavior of MX80 bentonite pellet

Soil Shrinkage Characterization of Low Plasticity Soil Using Digital Image Analysis Process

The goal of this paper is to better understand the shrinkage behavior of low plasticity (CL) soil, which is common in Warangal, India. Understanding the tensile strength and hydro-mechanical response of soil requires an understanding of the contraction behavior of soil caused by drying during wet-dry moisture cycles. With the use of simple and reliable experimental approaches, the shrinkage mechanism and behavior with suction variation are characterized and described in this study. The findings are related to the change in suction, water content, and void ratio of soil that has been air-dried from complete saturation to dryness. The proposed framework uses two simple approaches to understand soil water retention during the drying phase: one to quantify the suction potential and the other to characterize the shrinkage mechanism. In addition, the use of digital image processing (DIP) to capture sample shrinkage using a simple experimental setup is thoroughly discussed. ImageJ software has been found to be feasible for DIP and to quantify the volume change of laboratory samples. The absence of well-structured soil phases or macropores is attributable to the presence of only normal shrinkage and zero shrinkage phases in the tested soil. In terms of water–retention behavior, the shrinkage curve, and the suction curve are very similar. The effects of capillary suction on the shrinkage response of low plastic soil have been observed, emphasizing the importance of characterizing soil shrinkage behavior using suction as a stress-state variable in volume change studies.

A fully-coupled water-vapor flow and rock deformation/damage model for shale and coal: Its application for mine stability evaluation

Roof instability is a pervasive hazard that may cause injuries and fatalities in underground coal mines. Variations in air humidity and the duration of roof exposure are known to significantly influence the stability of shale roof strata. Moisture-sensitive shales progressively deteriorate over time due to humidity-interaction and matrix swelling which can trigger skin failure and roof falls. Quantifying the evolution of dynamic mechanical and petrophysical properties of the shale roof requires a comprehensive understanding of the retention behavior of multiphase fluids in the shale and of the induced alterations associated with air-water-shale/coal interactions. This study presents a mechanism-based framework for modeling the integrative deformation and failure behaviors of the rock structure, shale roof and coal pillar—and integrates the coupled effects of water vapor flow, elastic deformation, and damage. A Time-Dependent Rock-Fluid-Geomechanics Model (TD-RFG Model) was developed to evaluate the time-dependent rock structure dynamics. The interactions across the elastic deformation field, the transient fluid transport field and the discontinuous damage field are analyzed and modeled using TD-RFG. The established TD-RFG platform provides a pathway for multi-field and time-dependent rock structure stability assessment. A case study of shaly roof stability in an Illinois Basin coal mine and an analysis of it are presented. In the analysis we investigate the time- and location-dependent propagation of rock fractures that create connected channels that allow for rapid water penetration. The analysis indicates that, because of damage-induced increases in permeabilities, moisture transport is facilitated and so seasonal relative humidity variations at the mine opening are quickly reflected at interior locations in the shale roof, coal pillars and ground floor. The results of the modeling can ultimately provide the approach and data for quantifying and evaluating the water retention behavior and suction potential in an unsaturated air-water-shale/coal system and define strategies for ground control.

Synthesis of cellulose modified material from waste straw and the growth-promotion effects on wheat

This study aimed to synthesize the cellulose-modified material [potassium carboxymethylcellulose (CMC-K)] based on wheat straw from straw cellulose by alkalization and etherification so as to enhance the use of waste straw and improve water and fertilizer efficiency. Potassium was introduced through the carboxymethylation of cellulose to supply nutrients to crops. Moreover, the order of influential factors on the water absorption property was determined by an orthogonal experiment. The results showed that the highest water absorbency of 196.2 g/g was achieved for the conditions of 1.5:1 potassium hydroxide to cellulose, 1.5:1 chloroacetic acid to cellulose, 50% potassium hydroxide, and 80% chloroacetic acid. The CMC-K was characterized by Fourier-transform infrared, x-ray diffraction, and scanning electron microscopy techniques, and the results indicated that the product exhibited excellent water-retention ability in the soil and reduced infiltration. The agricultural application of CMC-K promoted the growth indexes of wheat, which improved wheat yields. Moreover, it also increased total nitrogen, ammonium nitrogen, total potassium, and available potassium. The fertilizer efficiency and water-retention behavior of CMC-K encouraged its use as a safe water- and fertilizer-retaining agent and as a soil conditioner in agricultural applications.

Coupled hydro-mechanical analysis of compacted bentonite behaviour during hydration

This study analyses the response of compacted bentonites upon hydration based on a coupled hydro-mechanical elasto-plastic framework. As an alternative to multi-porosity interpretation, the framework was selected based on the experimental evidence of adsorbed water behaviour in bentonites and the volumetric response at saturated states, apparently independent of its initial state. Based on these premises, a water retention model was formulated using an explicit distinction between adsorbed water and free water, enabling the postulation of the water properties and behaviour depending on its state. In order to effectively account for the transition between unsaturated to saturated state, that can occur in a wide range of suctions, the stress–strain constitutive equations are written in terms of an effective stress and degree of saturation framework. The mathematical formulation was implemented in a finite element code and used to simulate and interpret the behaviour of MX-80 bentonite compacted in different forms during hydration for several stress paths, including loading and unloading cycles after saturation. A good agreement of the model with experimental results was obtained using a consistent set of parameters describing the saturated state behaviour. The typical non-linear swelling pressure development was interpreted through the two-way coupling between the water retention behaviour and elasto-plastic compressibility. The possible high suctions at saturated states explain the swelling potential after full hydration. Overall, this study offers new perspectives on the role of hydro-mechanical interactions in bentonite behaviour upon hydration.

A Unified Approach for Establishing Soil Water Retention and Volume Change Behavior of Soft Soils

Abstract The assumption of treating the specimen volume as constant while experimentally determining the soil water retention curve (SWRC) of soils is valid only for nonplastic, granular soils. Fine-grained soils usually undergo significant volume change during dewatering and densification, and therefore such an assumption is misleading, even falsifying. The need for developing an easy-to-use lab-scale technique that can enable continuous monitoring of the evolutions in volume, suction, and moisture content of a progressively drying soft soil specimen is evident in the field of characterizing unsaturated soils. Such a method is relevant to establishing SWRC and soil shrinkage curve (SSC) of soft soils that exhibit an appreciable degree of deformation upon subjection to dewatering. To this end, a simple yet improvised method based on the balloon technique incorporating a commercially available high-capacity polymer tensiometer has been proposed to establish SWRC-SSC of soft soils. A comparison between the SWRC and SSC obtained through the proposed method and the conventional methods demonstrated a satisfactory degree of agreement. Densification of the materials realized under the influence of mechanical and hydraulic stresses has been discussed through a comparative analysis between the results from the proposed method and one-dimensional odometer test. For soft soils, the proposed method is particularly appropriate for establishing SWRC in terms of volumetric moisture content and degree of saturation through just a single test.

The Significance of Hydrophobicity for the Water Retention Properties of Sand and Coal

For mine wastes such as coal tailings, management of these materials requires complex geotechnical engineering that uses many soil properties, such as water retention. However, coal itself is chemically heterogeneous and often appears to be partially hydrophobic, which affects its water retention properties. This study aims to outline how hydrophobic soil particles and coal alter water retention curves compared to hydrophilic materials. The study involves four materials: sand, hydrophobized sand, crushed rock and crushed coal. Mixtures of sand with different proportions of hydrophobic particles had their water retention curves measured and compared, with the only variable being the particle surface characteristics. The rock and coal were separated into different particle size fractions and had their water retention curves measured and compared, with the only variable being particle hydrophobicity. A clear trend was observed for the sand mixtures: the degree of saturation at any suction was reduced when increasing the hydrophobicity of the material. This trend indicates the fundamental water retention behavior expected for soils more hydrophobic than is typical, which was not clearly demonstrated in previous studies. However, a similar trend was not seen when comparing the rock and otherwise identical hydrophobic coal samples, which actually appeared hydrophilic in terms of water retention. ESEM imaging shows a dual hydrophilic and hydrophobic behavior for coal which may explain the result. However, further research is required to understand the discrepancy, which appears to be caused by an unknown coal–water phenomena.

Insights into the water retention behaviour of GMZ bentonite pellet mixture

Insights into the water retention behaviour of GMZ bentonite pellet mixture

Influence of Swelling Media on the Crystallinity and Accessibility of Lyocell Fibers: An FTIR and 13C NMR Analysis

ABSTRACT Cellulose swelling using different protic, aprotic and alkaline solvents, which are capable of penetrating crystalline parts of cellulose is one of the important methods to enhance the accessibility and, as a result, the reactivity of cellulose in modification reactions. Here we discuss changes in the structure of cellulose II in never-dried Lyocell fibers upon swelling with different solvents and aqueous solutions using FTIR as well as solid-state 13C NMR spectroscopies and DSC thermal analysis. Changes in the water retention behavior and accessibility of fibers were correlated with solvent-related changes in the fiber structure and were in accordance with the results obtained by FTIR and 13C NMR spectroscopies.

Modelling the water retention behaviour of anisotropic soils

Water retention curve (WRC) is an important parameter for unsaturated soils. It is greatly affected by the anisotropy of pore structure, as supported by experimental results in the literature. So far, however, the mechanism and theoretical modelling of anisotropy effects have not been investigated. These two issues were explored in this study based on two-dimensional analysis of soil pores, while were approximated as a series of ellipses for simplicity. According to experimental results in the literature, the pores of anisotropic specimen are more elongated than those of isotropic specimen on average. The elongated pore has a higher water retention ability than the round pore when they have the same area. As a consequence, the water retention ability of anisotropic specimen is higher than that of isotropic specimen. On the basis of this mechanism, a new WRC model was proposed for isotropic and anisotropic soils . To verify the new model, it was applied to simulate the WRCs of three soils with isotropic and anisotropic pore structures. Measured and calculated results were well matched with the coefficient of determination (R2) in the range of 0.89 to 0.99 and the root-mean-square error (RMSE) ranging from 0.009 to 0.073. It is convincingly demonstrated that the new model is able to capture the influence of anisotropy on WRC.

Influence of Water Content on Track Degradation at Transition Zones

This study aims to explore the role of water retention behaviour in the track degradation of the transition zone by examining the influence of water content variation. A model of railway bridge approach transition was built in the PLAXIS 3D to simulate the track degradation under diverse water content scenarios. A wedge-shaped backfill with unbound granular material (UGM) was simulated as a technical solution between the bridge abutment and open track. The most distinctive characteristic of the model is that the direct relationship between soil water content and soil displacement can be explored. To achieve this, the seasonal change in the soil moisture content of subsoil was simulated as the independent variable. The water content variation adopted mimicked the wet season (ω = 7.6%), as-compacted (ω = 5.6%) and dry season (ω = 3.6%) water content conditions. The results indicate that higher soil strains and displacements are obtained for high water contents. This indicates that there is a clear correlation between soil water retention and track displacements. In addition, the results suggest that a reduction in water content in the track substructure can be effective in mitigating in-service settlement as overall track stiffness increases as a result. However, this effect is more pronounced at the track level and becomes less important at higher depth in the formation layer. This study also shows that the bump from the bridge structure to backfill can be mitigated and smooth track geometry from the backfill and the open track can be achieved by manipulating the water content.

Modeling the WRC and volume change behavior of GCLs considering net stress and temperature

Geosynthetic clay liners (GCLs) are used in cover and bottom lining systems to mitigate contamination from landfills. During their service period, they are often subjected to varying net mean stress levels, temperature fluctuation, and water content, which could affect their water retention and volume change behavior severely. These changes under thermo-hydro-mechanical conditions can be evaluated through experimental methods or mathematical models. In the present study, the combined effect of net mean stress and temperature on water retention and volume change behavior of GCL in the unsaturated regime were studied. A theoretical thermo-hydro-mechanical framework for GCLs over a wide suction range is proposed based on experimental observations. The proposed framework was implemented in a simple water retention model and volumetric constitutive model to capture the thermo-hydro-mechanical behavior of GCL through several sets of experimental data available in the literature. The predicted results from the proposed method were in good agreement with the experimental results. Also, the proposed method required minimal input parameters to predict water retention and volume change behavior over a wide suction range. The proposed framework is therefore quite useful for engineering applications of GCLs under the combined effect of suction, net mean stress, and temperature.

Effects of pyrolysis temperature, feedstock type and compaction on water retention of biochar amended soil

Recent studies on water retention behaviour of biochar amended soil rarely considers the effect of pyrolysis temperature and also feedstock type into account. It is well known that pyrolysis temperature and feedstock type influences the physical and chemical properties of biochar due to stagewise decomposition of structure and chemical bonds. Further, soil density, which is in a loose state (in agricultural applications) and dense (in geo-environmental engineering applications) can also influence water retention behaviour of biochar amended soils. The major objective of this study is to investigate the water retention properties of soil amended with three different biochars in both loose and dense state. The biochars, i.e. water hyacinth biochar (WHB), chicken manure biochar (CMB) and wood biochar (WB) were produced in-house at different pyrolysis temperature. After then, biochars at 5% and 10% (w/w%) were amended to the soil. Water retention behaviour (soil suction and gravimetric water content) was studied under drying and wetting cycle simulated by varying relative humidity (RH, 50–90%). Results show that 10% WHB produced at 300 °C were found to possess highest water retention. CMB is found to possess higher water retention than WB for 10% amendment ratio. In general, the addition of three biochars (at both 300 °C and 600 °C) at 10% (w/w) significantly improved the water retention at all suction ranges in both loose and dense compaction state as compared to that of the bare soil. The adsorption (wetting) and desorption (drying) capacity of biochar amended soils is constant at corresponding RH.

Hysteresis of the water retention curves of geosynthetic clay liners in the high suction range

This paper examines two needle-punched geosynthetic clay liners' water retention behaviour at high suction ranges using the vapour equilibrium technique where super-saturated salt solutions controlled the relative humidity. This study shows that the bentonite form and its mineralogy affect the absorption/desorption of GCLs and their corresponding water retention curves. In particular, a granular bentonite-based GCL was found to absorb more and release less water than a powdered bentonite-based GCL due to its higher montmorillonite content and larger pores. The water retention curves of both GCLs exhibited very little hysteretic behaviour at high suction. Repeated wetting-drying cycles shifted the WRCs of both GCLs slightly downward with minimal impact on their degree of hysteresis.