Narala Gangadhara Reddy | Fiji National University (original) (raw)

Journal Papers by Narala Gangadhara Reddy

Discover Civil Engineering, 2024

The Topical Collection (TC) aims at advances happening in the construction and building materials... more The Topical Collection (TC) aims at advances happening in the construction and building materials for the development of sustainable composites with particular interest in Life Cycle Assessment (LCA) and Artificial Intelligence (AI). The TC also seeks to highlight the development, assessment, and optimization of composite materials to promote sustainability and resilience in civil engineering. It further includes the aspect of microstructural and phase composition characteristics defining the long-term stability of new composite materials, together with environmental impacts including the leaching of potentially toxic elements and carbon calculations. Overall, the goal is to develop sustainable composite materials using marginal and recycled materials with a special emphasis on using LCA and AI in construction and building materials.

Civil Engineering Journal, 2023

This research paper focuses on conducting a steady state seepage analysis along with the downstre... more This research paper focuses on conducting a steady state seepage analysis along with the downstream slope factor of safety using the Modified Bishops method in a poorly compacted earthen embankment and optimizing the same reservoir earthen embankment in a case study located near Sadiyavav village in Junagadh district in Gujarat, India. The study site, situated at 21°32'06.5"N and 70°37'26.7"E, is renowned for its Asiatic lions. The analysis and optimization were performed with a double-textured High-Density Polyethylene (HDPE) Geo-membrane barrier. Previously, designs and numerical solutions proposed homogenous embankments and too poorly compacted with no drainage arrangements, which led to anisotropic conditions within the section and water seeping out, cutting the phreatic line. The paper presents the documented improvements in the factor of safety achieved through the seepage analysis and the optimization of the HDPE Geomembrane barrier. Two improvement techniques were studied using the "Limiting Equilibrium-Finite Element Method" (LS-FEM). The first using (HDPE) Geo-membrane stabilized with gabions, and the second alternative using HDPE Geomembrane with gabions in addition to rock toe. The study results showed improvements in the downstream slope stability for the two alternatives by 3% and 10%, respectively.

City and Built Environment , 2023

The utilization of expansive soils for the construction of landfill liners and subgrade facilitie... more The utilization of expansive soils for the construction of landfill liners and subgrade facilities without stabilization leads to volume changes due to seasonal change between wet and dry. This necessitated the industrial- and agro-industrial-based waste materials reconstitution of expansive soils to fulfil sustainability requirements for the builtenvironment. In this research paper, multiple datasets were collected from mixes of bagasse ash (BA) and lime (Lm) blend reconstituted expensive soil and deployed in the training and validation interface of advanced machine learning (AML) techniques to predict the unconfined compressive strength (UCS) of the treated soil for their usein landfill liner and subgrade application. The relative importance values for each input parameter were evaluated, such as compaction parameters (MDD and OMC), plastic limit (PL), LL, Lm, and BA. The results of all developed models were observed and collected. The relations between calculated and predicted values show that the GP produced a parametric line of fit expression of y = 0.999 × with performance indices as MAE 14.80 kPa, MSE 400.7 kPa, RMSE 20.00 kPa, and R2 of 0.950, EPR produced a parametric line of fit expression of y = 0.992 × with performance indices as MAE 11.6 kPa, MSE 270.9 kPa, RMSE 16.50 kPa, and R2 of 0.963, and ANN produced a parametric line of fit expression of y = 0.997 × with performance indices as MAE 4.26 kPa, MSE 30.8 kPa, RMSE 5.55 kPa, and R2 of 0.996. The results show that the ANN outperforms the GP and the EPR having produced the least error values, the highest coefficient of determination (R2) and zero outliers beyond the ± 25% performance fit envelop and can be concluded that BA has a remarkable influence in the stabilization of expansive soils and its utilization.

Cleaner Materials, 2023

In this research, an attempt is made to partially replace ground granulated blast furnace Slag (G... more In this research, an attempt is made to partially replace ground granulated blast furnace Slag (GGBS) with a binder rich in SiO2 and CaO in alkali activated slag concrete (AASC) to increase workability and setting time. GGBS is replaced with bagasse ash powder (BAP) in 5%, 10%, and 15% of the binary mix, and subsequently with marble powder (MP) in 5% and 10% of the binary mix. After establishing the best mix for both binder replacements, a ternary mix with 5% BAP and 10% MP is created. The fine aggregates used in the comparison are 100 % river sand and slag sand. 10 M sodium hydroxide and the alkaline to binder ratio is 0.4, were used. Mechanical properties such as compressive strength, split tensile strength, and flexural strength are performed cured at 1, 3, 7, and 28 days samples. To further understand the intrinsic mechanism of strength development, microstructure, morphology and mineralogy on AASC are investigated. Based on the findings, it can be inferred that AASC mixes have a higher strength than OPC mixes. The mechanical strengths of the AASC binary mix with 10% MP and 5% BAP are higher. The microstructural analysis reveals the mixes developed with BAP and 100 % GGBS, had a denser microstructure than the normal mixes. The mechanical properties obtained for most of the AASC mixes are significantly higher than the IRC SP:62-2014 recommendations for rigid pavements for low volume roads.

Journal of Hazardous, Toxic, and Radioactive Waste, 2023

In bauxite residue (BR), the abatement and rebound of pH when ameliorated with different amendmen... more In bauxite residue (BR), the abatement and rebound of pH when ameliorated with different amendments have been reported as prime concerns. In addition, to the best of the authors' knowledge, no research has focused on the characterization of BR during the decrease and rebound in pH, which happens over an extended period. This characterization is essential to convert posttreated residue into green construction materials and to affirm that it does not pose a threat to the environment. This study aimed to investigate two important points. The evaluation of the efficacy of commonly and widely employed conventional additives and mineral acids while mitigating the pH of the residue and its characterization included sedimentation and leaching with a change in pH. The uniqueness of this study lay in the exploration of the latter point and pH rebound for ≤180 days. Cement, gypsum (G), fly ash (FA), and ground granulated blast furnace slag (GGBS) as conventional additives, and nitric (HNO 3) and hydrochloric acids (HCl) as mineral acids were selected to ameliorate BR. A significant pH rebound with time occurred from 6.59 to 9.51 and 7.54 to 9.78 when treated with 1M HCl and HNO 3 , which indicated the influence of the curing period and ameliorant on the alkalinity. Conventional additives, except for G, and their combinations proved ineffective when mitigating and maintaining pH within acceptable limits (i.e., 8.5). Settling analysis revealed accelerated particle settling at pH 4.5-7.0, which indicated implications for the safe disposal, washing, or slurry thickening of BR. The extensive leaching studies for potentially toxic elements (PTEs), which were further endorsed with a field case study, demonstrated that the amended residue was environmentally safe to be used as a construction material.

Journal of Hazardous, Toxic, and Radioactive Waste, 2022

The world is being burdened with excessive usage and indiscriminate dumping of plastic waste. The... more The world is being burdened with excessive usage and indiscriminate dumping of plastic waste. The world presently produces nearly 400 million tons of plastic every year: less than 10% is recycled, 8% is incinerated, and the rest is dumped in landfills. The reduction of plastic has become a significant challenge due to the lower degradation rate. A substantial amount of this waste turns out to be litter in the oceans or landfills due to limited recycling or reuse in an environmentally friendly way. Compared with incineration and landfilling processes, recycling plastic waste is more productive. Hence, the utilization of plastic waste in civil engineering applications is found to have the maximum potential for consumption in bulk quantities, which can also help in minimizing disposal issues. This article reviews the characteristic properties of waste plastic and its utilization in civil engineering applications, specifically in bricks, blocks, road embankment, pavement layers, plastic aggregates, and voided slabs, which are systematically comprehended with various international standards. The use of waste plastic either retained or slightly improved the properties of the materials to which it is added. The paper also discusses the leaching properties of different kinds of plastic waste; their limitations along with probable opportunities associated with plastic waste utilization.

Environmental Geotechnics, 2022

The capillary barrier effect of soil is the delayed water flow process inside soil pores due to i... more The capillary barrier effect of soil is the delayed water flow process inside soil pores due to intermolecular forces between liquid and solid particles. In this study, the capability of the fiber optic sensing technology to quantify water infiltration in soil with a capillary barrier system is explored by measuring spatio-temporal distributions of water contents. An actively heated fiber Bragg grating (AH-FBG) sensing tube was used to monitor rainfall infiltration in a one-dimensional soil column test. Frequency domain reflectometry (FDR) probes were used to perform in-situ calibration of the AH-FBG sensors. The fiber optic monitoring results indicate that the AH-FBG technology enables high-sensitivity detection of the capillary barrier effect. The empirical relationships between temperature changes and soil water contents can be well fitted by exponential or linear functions. The capillary barrier system has shown an apparent capability to store water after rainfall, which exerted a significant effect on the vertical infiltration process. Compared with the features of FDR and image acquisition, the proposed method can effectively reflect the whole process of wetting front movement and is more suitable for field monitoring due to its flexibility in large-scale and automatic measurement.

Geotechnical Testing Journal, 2022

Understanding the mechanical characteristics of clayey soil is critical to estimate the stability... more Understanding the mechanical characteristics of clayey soil is critical to estimate the stability of clay-related geotechnical engineering works. However, the distributed information of the internal deformation of clay is hard to capture through traditional methods. In this paper, a set of four-point bending tests were performed on a compacted clay beam instrumented with fiber optic strain sensors to investigate the flexure and cracking behaviors. The optical frequency domain reflectometry technique with high spatial resolution and precision was employed to establish a distributed strain sensing (DSS) system in this study. The results show that the DSS system exhibits a high accuracy in the collection of the clay deformation in terms of compression, tension, and cracking. The comparison of the internal strain profiles with the observation of particle image velocimetry analysis system verifies the feasibility of fiber optic sensing technology in the quantitative assessment of clay deformation. The performance of fiber optic sensors in the rebound deformation and creep deformation monitoring was preliminarily issued in the study. In addition, the progressive failure on the fiber-soil interface was analytically studied to evaluate the deformation compatibility between the fiber and surrounding clayed soil. The conclusions drawn in this paper can help to guide the state interpretation of clayey soil instrumented with fiber optic sensors.

Scientific reports, 2021

Recent studies on water retention behaviour of biochar amended soil rarely considers the effect o... more 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.

Journal of Rock Mechanics and Geotechnical Engineering, 2021

Biochar has been used as an environment-friendly enhancer to improve the hydraulic properties (e.... more Biochar has been used as an environment-friendly enhancer to improve the hydraulic properties (e.g. suction and water retention) of soil. However, variations in densities alter the properties of the soil–biochar mix. Such density variations are observed in agriculture (loosely compacted) and engineering (densely compacted) applications. The influence of biochar amendment on gas permeability of soil has been barely investigated, especially for soil with different densities. The major objective of this study is to investigate the water retention capacity, and gas permeability of biochar-amended soil (BAS) with different biochar contents under varying degree of compaction (DOC) conditions. In-house produced novel biochar was mixed with the soil at different amendment rates (i.e. biochar contents of 0%, 5% and 10%). All BAS samples were compacted at three DOCs (65%, 80% and 95%) in polyvinyl chloride (PVC) tubes. Each soil column was subjected to drying–wetting cycles, during which soil suction, water content, and gas permeability were measured. A simplified theoretical framework for estimating the void ratio of BAS was proposed. The experimental results reveal that the addition of biochar significantly decreased gas permeability kg as compared with that of bare soil (BS). However, the addition of 5% biochar is found to be optimum in decreasing kg with an increase of DOC (i.e. kg,65% > kg,80% > kg,95%) at a relatively low suction range (< 200 kPa) because both biochar and compaction treatment reduce the connected pores.

Journal of Hazardous, Toxic, and Radioactive Waste, 2021

The application of industrial waste in construction reduces the dependency on natural resources. ... more The application of industrial waste in construction reduces the dependency on natural resources. The materials, including red mud (RM) and fly ash (FA), proved to be favorable materials. However, the materials potential together as a geopolymer composite for road applications has rarely been explored. This study will examine the possibility of the replacement of natural materials in subgrade applications. To achieve this, the geopolymer compositions will be prepared by replacing RM with FA at replacement rates of 10%, 20%, and 30% by dry weight basis. The alkaline activator solution of 8 M will be prepared using sodium hydroxide (NaOH) and sodium silicate to develop geo-polymer composites. The strength properties will be studied using the California Bearing Ratio (CBR) and unconfined compression strength (UCS) and validated with microstructural analysis using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). The results reveal that geopolymer composites could achieve a maximum CBR value of 12% and UCS of 2,700 kPa. The microstructural analysis revealed that the formation of dense calcium aluminate hydrate (C-A-H) and calcium silicate hydrate (C-S-H) are the reason for strength improvement. The leaching studies show that the toxic elements were within the permissible limits. Overall , the test results confirmed that the geopolymer composites meet the required strength and could be used as a subgrade material in road construction.

Journal of Hazardous, Toxic, and Radioactive Waste, 2020

In this paper, citric acid (CA) is chosen as an additive for the treatment of bauxite residue, a ... more In this paper, citric acid (CA) is chosen as an additive for the treatment of bauxite residue, a by-product generated by the aluminum industry. The potential of CA to improve geotechnical (e.g., compaction, strength, consolidation, and collapse potential) and geoenvironmental (e.g., pH and leaching) properties are explored by conducting elaborate laboratory experimental investigations on the treated bauxite residue samples. CA concentrations of 0.1, 0.5, 1, 2, 4, and 6 M are considered in this paper. The emphasis, in particular, is on the quantification of pH change in terms of rebound rate of pH (RRP) and rebound termination period (trt). It has been found from various results that 1 M CA successfully heightened the desirable properties and overcame the limitations of the treated bauxite residue simultaneously. The mineralogical analysis revealed minuscule changes in mineral phases, the formation of cementitious compounds (C-S-H), and fast crystallization of hydroxy sodalite, which is further confirmed by morphological studies. The leachability of potentially toxic elements (PTEs) is observed to be within the regulatory permissible limits of the USEPA and the Resource Conservation and Recovery Act (RCRA), demonstrating that the posttreated bauxite residue is environmentally benign and is safe to be used as a geomaterial. It is concluded based on the results that CA is a very good additive to convert the highly alkaline bauxite residue into a usable green geomaterial.

Journal of Hazardous, Toxic, and Radioactive Waste, 2020

Assessment of cracks are essential for attaining better performance of landfill liner system. Thi... more Assessment of cracks are essential for attaining better performance of landfill liner system. This study provides a new vision toward crack prevention in clayey soils. A comparative study of using various geomaterials, biomaterials, and synthetic materials to prevent the desiccation cracks formation in landfill clay liners has been performed. Small-scale materials-amended soil specimens have been subjected to extreme conditions (i.e., soil saturation to drought) for 25 days and crack-influencing parameters, such as crack intensity factor, water content, and shear strength of soil, have been obtained. The results show that addition of wood biochar (WB), pig manure biochar (PMB), and gypsum (GY) can significantly assist the soil to retain more water compared with other amendments. Furthermore, WB, PMB, and GY reduce the development of desiccation cracks in landfill liners. Altogether, this study provides useful insight toward the selection of suitable amendments for various landfill applications.

Nature Scientific Reports, 2020

Generated hazardous or toxic waste posses a serious threat if dumped into ponds or low lying area... more Generated hazardous or toxic waste posses a serious threat if dumped into ponds or low lying areas which leads to contamination, this necessitates the effective landfill liner system. Mainly compacted clayey soils are used as an engineered barrier. Recently, composite materials have gained popularity as landfill liner materials, including the use of waste materials amended with low permeable soils. Though, studies on the composite optimum mix and its corresponding thickness are very scarce. Here, we evaluated the unconfined compressive strength and hydraulic conductivity of fly ash-bentonite composites. Efforts were also made to determine the thickness of landfill liner composite using a finite difference method (i.e. MATLAB). The results reveal that composite consists of 30% bentonite and 70% fly ash is suitable for landfill liner, which meets strength and permeability criteria. Numerical simulation for five major contaminants shows that the composite plays a crucial role in reducing the leaching of heavy metals and suggests an optimum thickness in the range of 126-154 cm. Overall, the findings of the study indicate that fly ash-bentonite composite can be used to solve real-life challenges in a sustainable way.

International Journal of Geosynthetics and Ground Engineering, 2020

In recent years, biochar has been widely used in environmental and geotechnical engineering appli... more In recent years, biochar has been widely used in environmental and geotechnical engineering applications, but minimal studies have been done on its influence on soil engineering properties. In this study, the effect of biochar on the compression and swelling characteristics of two clayey soils, namely PKE and XS, was studied by conducting standard consolidation tests and no-load swelling tests. The compression curves and swelling parameters of modified clays with different biochar content (0, 0.5, 1, 2%, w/w) and biochar particle sizes (<0.15, 1–2 mm) were obtained. The microstructure of the biochar-clay mixture was analyzed by scanning electron microscopy (SEM) test. The results showed that: (1) the compressibility of clayey soils can be effectively reduced by adding biochar, and this effect is more significant with the increase biochar percentage; (2) the effect of reducing soil compressibility by fine biochar was better than coarse biochar; (3) under the same pressure, the settlement rate of soil increased with the increase of biochar content; (4) the incorporation of biochar had no obvious influence on the no-load swelling behaviour of PKE while it has significantly increased the swelling of XS (low expansive soil). Additionally, the fine-grained biochar has a significant effect than the coarse-grained biochar on clayey soils.

Waste and Biomass Valorization, 2021

In order to conserve natural resources and prevent waste generation, effective utilization of ind... more In order to conserve natural resources and prevent waste generation, effective utilization of industrial wastes and/or by-products for beneficial engineering applications becomes inevitable. In order to accomplish this, extensive research studies, exploring properties and new applications of waste materials in a sustainable and environmentally friendly manner, have been initiated worldwide. Red mud (RM, also known as bauxite residue) is one of the wastes generated by the aluminium industry and its disposal and utilization have been traditionally hindered due to the extreme alkalinity (pH about 10.5–13.5). To date, no comprehensive review on various properties of RM of different origin and associated challenges in using it as a beneficial engineering material has been performed. The objective of this study is first to critically appraise the current understanding of properties of RM through a comprehensive literature review and detailed laboratory investigations conducted on Indian RM by the authors, to assess and identify the potential engineering applications, and to finally discuss associated challenges in using it in practical applications. Physical, chemical, mineralogical and geotechnical properties of RMs of different origin and production processes are reviewed. Mechanisms behind the pozzolanic reaction of RM under different chemical and mineralogical compositional conditions are discussed. Environmental concerns associated with the use of RM are also raised. Studies relevant to leachability characteristics reveal that most of the measured chemical concentrations are within the permissible regulatory limits. Overall, the review shows that RM disposal and reuse is complicated by its extreme alkalinity, which is also noticed to be influencing multiple engineering properties. But with selected pH amendments, the treated RM is found to have significant potential to be used as an effective and sustainable geomaterial. The assessment is majorly based on the characteristics of Indian RMs; hence the adaptation of the findings to other RMs should be assessed on a case-by-case basis. Moreover, field studies demonstrating the performance of RM in various engineering applications are warranted.

Waste and Biomass Valorization, 2021

Greenhouse gasses generated from the degradation of solid waste pass through landfill covers and ... more Greenhouse gasses generated from the degradation of solid waste pass through landfill covers and participate in climate change. The formation of desiccation cracks in surface soil leads to direct interaction of greenhouse gasses into the atmosphere. In current study, attempts were made to reduce crack damage and water evaporation of a sandy soil amended with intrusive aquatic biomass derived carbon (water hyacinth and dry algae) also known as biochar. The results show that, the addition of water hyacinth biochar (WHB) and algae biochar (AB) reduced the evaporation rate of densely compacted soil and increases the water retention capacity of soil at 5% and 10% application rate. Furthermore, WHB produced at high temperature has more potential in reducing cracks than that produced at lower temperature. WHB showed better performance than AB at any temperature (i.e. 300 °C, 400 °C and 700 °C) due to its highly porous structure. The current study concludes that biochars from aquatic weeds can be utilized for soil remediation (i.e., minimizing cracking and evaporation rate), which is useful in both waste management and agricultural applications.

Journal of Hazardous, Toxic, and Radioactive Waste, 2019

Excessive pH (>11) and inconsistent engineering properties because of the chemicomineralogical co... more Excessive pH (>11) and inconsistent engineering properties because of the chemicomineralogical composition of red mud warrant devising an alternate approach to render it more environmentally benign. In this study, the performance of lime stabilization coupled with oxalic acid, which acts as a neutralizing agent, was explored systematically to improve the long-term strength and to reduce the alkalinity of red mud. The mechanisms governing the behavior of additives along with their effects were investigated by examining the mineralogical, elemental, and morphological characteristics. The results suggest an effect of sodalite and alumina on the inconsistency in dry unit weight and claylike behavior of red mud. A reduction in pH was found to be instrumental during early phases of lime stabilization and in precipitation of cementitious hydration products, leading to strength gain in the long term in red mud. Moreover, the addition of lime and oxalic acid was found to yield more encouraging results than lime treatment alone, and hence this is recommended to be used for red mud stabilization. The obtained results were substantiated by comparison with code provisions.

Environmental Geotechnics, 2022

In this study, the usefulness of two biopolymers (guar gum and xanthan gum) in improving the stre... more In this study, the usefulness of two biopolymers (guar gum and xanthan gum) in improving the strength properties of two types of red muds was explored. Experiments were performed to determine the unconfined compressive strength and to establish morphological and mineralogical compositions of stabilised samples cured for 7, 28, 45, and 90 days. The obtained results were interpreted to understand the red mud-biopolymer interactions. Considerable improvement in compressive strength of stabilised samples, by 4 to 5 times, vis-à-vis the untreated samples was observed. Based on the results obtained on different admixture contents (i.e. 0.5, 1, 2 and 3%), the optimum dosage of biopolymers was found as 0.5%. The morphological analysis revealed the formation of gels and their role in aggregation of particles by the combined action of binding and pore filling. However, no changes in mineralogical compositions were identified from diffraction patterns of stabilised samples. Both biopolymers proved to be effective in improving the strength characteristics, but the efficacy of xanthan gum was found to be superior over the guar gum. Despite extreme alkalinity in the media, biopolymers were still able to impart reasonably good strength to the treated samples, demonstrating their usefulness and applicability.

Previous studies reveal that the geotechnical properties of red mud waste (RMW) closely resemble ... more Previous studies reveal that the geotechnical properties of red mud waste (RMW) closely resemble that of conventional soils. Due to the predominant presence of exchangeable sodium, the red mud waste tends to exhibit high dispersion behaviour. In this study, mitigation of the dispersion characteristics of RMW using eco-friendly biopolymers was investigated. Two types of biopolymers, namely guar gum (GG) and xanthan gum (XG), in 0.5, 1.0, 2.0, 3.0, and 4% (by weight), were selected for the study. The untreated and polymer amended red mud waste samples were subjected to cylindrical dispersion crumb tests for examining the dispersion phenomenon, and the hardened samples were further analyzed for microstructure, mineralogical, and elemental compositions. Turbidity and pH of water in the crumb tests as well as consistency limits of untreated and polymer amended RMW were also tested. The microstructural analysis revealed an increase in particles aggregations with an increase in the biopolymer content, while elemental compositions showed gel formation by GG cross-linking with calcium. As such, GG proved to be more effective over XG in mitigating the dispersion characteristics of the RMW. Overall, this study shows that GG biopolymer has potential to be used for mitigating dispersion and controlling dusting in field applications.

Discover Civil Engineering, 2024

The Topical Collection (TC) aims at advances happening in the construction and building materials... more The Topical Collection (TC) aims at advances happening in the construction and building materials for the development of sustainable composites with particular interest in Life Cycle Assessment (LCA) and Artificial Intelligence (AI). The TC also seeks to highlight the development, assessment, and optimization of composite materials to promote sustainability and resilience in civil engineering. It further includes the aspect of microstructural and phase composition characteristics defining the long-term stability of new composite materials, together with environmental impacts including the leaching of potentially toxic elements and carbon calculations. Overall, the goal is to develop sustainable composite materials using marginal and recycled materials with a special emphasis on using LCA and AI in construction and building materials.

Civil Engineering Journal, 2023

This research paper focuses on conducting a steady state seepage analysis along with the downstre... more This research paper focuses on conducting a steady state seepage analysis along with the downstream slope factor of safety using the Modified Bishops method in a poorly compacted earthen embankment and optimizing the same reservoir earthen embankment in a case study located near Sadiyavav village in Junagadh district in Gujarat, India. The study site, situated at 21°32'06.5"N and 70°37'26.7"E, is renowned for its Asiatic lions. The analysis and optimization were performed with a double-textured High-Density Polyethylene (HDPE) Geo-membrane barrier. Previously, designs and numerical solutions proposed homogenous embankments and too poorly compacted with no drainage arrangements, which led to anisotropic conditions within the section and water seeping out, cutting the phreatic line. The paper presents the documented improvements in the factor of safety achieved through the seepage analysis and the optimization of the HDPE Geomembrane barrier. Two improvement techniques were studied using the "Limiting Equilibrium-Finite Element Method" (LS-FEM). The first using (HDPE) Geo-membrane stabilized with gabions, and the second alternative using HDPE Geomembrane with gabions in addition to rock toe. The study results showed improvements in the downstream slope stability for the two alternatives by 3% and 10%, respectively.

City and Built Environment , 2023

The utilization of expansive soils for the construction of landfill liners and subgrade facilitie... more The utilization of expansive soils for the construction of landfill liners and subgrade facilities without stabilization leads to volume changes due to seasonal change between wet and dry. This necessitated the industrial- and agro-industrial-based waste materials reconstitution of expansive soils to fulfil sustainability requirements for the builtenvironment. In this research paper, multiple datasets were collected from mixes of bagasse ash (BA) and lime (Lm) blend reconstituted expensive soil and deployed in the training and validation interface of advanced machine learning (AML) techniques to predict the unconfined compressive strength (UCS) of the treated soil for their usein landfill liner and subgrade application. The relative importance values for each input parameter were evaluated, such as compaction parameters (MDD and OMC), plastic limit (PL), LL, Lm, and BA. The results of all developed models were observed and collected. The relations between calculated and predicted values show that the GP produced a parametric line of fit expression of y = 0.999 × with performance indices as MAE 14.80 kPa, MSE 400.7 kPa, RMSE 20.00 kPa, and R2 of 0.950, EPR produced a parametric line of fit expression of y = 0.992 × with performance indices as MAE 11.6 kPa, MSE 270.9 kPa, RMSE 16.50 kPa, and R2 of 0.963, and ANN produced a parametric line of fit expression of y = 0.997 × with performance indices as MAE 4.26 kPa, MSE 30.8 kPa, RMSE 5.55 kPa, and R2 of 0.996. The results show that the ANN outperforms the GP and the EPR having produced the least error values, the highest coefficient of determination (R2) and zero outliers beyond the ± 25% performance fit envelop and can be concluded that BA has a remarkable influence in the stabilization of expansive soils and its utilization.

Cleaner Materials, 2023

In this research, an attempt is made to partially replace ground granulated blast furnace Slag (G... more In this research, an attempt is made to partially replace ground granulated blast furnace Slag (GGBS) with a binder rich in SiO2 and CaO in alkali activated slag concrete (AASC) to increase workability and setting time. GGBS is replaced with bagasse ash powder (BAP) in 5%, 10%, and 15% of the binary mix, and subsequently with marble powder (MP) in 5% and 10% of the binary mix. After establishing the best mix for both binder replacements, a ternary mix with 5% BAP and 10% MP is created. The fine aggregates used in the comparison are 100 % river sand and slag sand. 10 M sodium hydroxide and the alkaline to binder ratio is 0.4, were used. Mechanical properties such as compressive strength, split tensile strength, and flexural strength are performed cured at 1, 3, 7, and 28 days samples. To further understand the intrinsic mechanism of strength development, microstructure, morphology and mineralogy on AASC are investigated. Based on the findings, it can be inferred that AASC mixes have a higher strength than OPC mixes. The mechanical strengths of the AASC binary mix with 10% MP and 5% BAP are higher. The microstructural analysis reveals the mixes developed with BAP and 100 % GGBS, had a denser microstructure than the normal mixes. The mechanical properties obtained for most of the AASC mixes are significantly higher than the IRC SP:62-2014 recommendations for rigid pavements for low volume roads.

Journal of Hazardous, Toxic, and Radioactive Waste, 2023

In bauxite residue (BR), the abatement and rebound of pH when ameliorated with different amendmen... more In bauxite residue (BR), the abatement and rebound of pH when ameliorated with different amendments have been reported as prime concerns. In addition, to the best of the authors' knowledge, no research has focused on the characterization of BR during the decrease and rebound in pH, which happens over an extended period. This characterization is essential to convert posttreated residue into green construction materials and to affirm that it does not pose a threat to the environment. This study aimed to investigate two important points. The evaluation of the efficacy of commonly and widely employed conventional additives and mineral acids while mitigating the pH of the residue and its characterization included sedimentation and leaching with a change in pH. The uniqueness of this study lay in the exploration of the latter point and pH rebound for ≤180 days. Cement, gypsum (G), fly ash (FA), and ground granulated blast furnace slag (GGBS) as conventional additives, and nitric (HNO 3) and hydrochloric acids (HCl) as mineral acids were selected to ameliorate BR. A significant pH rebound with time occurred from 6.59 to 9.51 and 7.54 to 9.78 when treated with 1M HCl and HNO 3 , which indicated the influence of the curing period and ameliorant on the alkalinity. Conventional additives, except for G, and their combinations proved ineffective when mitigating and maintaining pH within acceptable limits (i.e., 8.5). Settling analysis revealed accelerated particle settling at pH 4.5-7.0, which indicated implications for the safe disposal, washing, or slurry thickening of BR. The extensive leaching studies for potentially toxic elements (PTEs), which were further endorsed with a field case study, demonstrated that the amended residue was environmentally safe to be used as a construction material.

Journal of Hazardous, Toxic, and Radioactive Waste, 2022

The world is being burdened with excessive usage and indiscriminate dumping of plastic waste. The... more The world is being burdened with excessive usage and indiscriminate dumping of plastic waste. The world presently produces nearly 400 million tons of plastic every year: less than 10% is recycled, 8% is incinerated, and the rest is dumped in landfills. The reduction of plastic has become a significant challenge due to the lower degradation rate. A substantial amount of this waste turns out to be litter in the oceans or landfills due to limited recycling or reuse in an environmentally friendly way. Compared with incineration and landfilling processes, recycling plastic waste is more productive. Hence, the utilization of plastic waste in civil engineering applications is found to have the maximum potential for consumption in bulk quantities, which can also help in minimizing disposal issues. This article reviews the characteristic properties of waste plastic and its utilization in civil engineering applications, specifically in bricks, blocks, road embankment, pavement layers, plastic aggregates, and voided slabs, which are systematically comprehended with various international standards. The use of waste plastic either retained or slightly improved the properties of the materials to which it is added. The paper also discusses the leaching properties of different kinds of plastic waste; their limitations along with probable opportunities associated with plastic waste utilization.

Environmental Geotechnics, 2022

The capillary barrier effect of soil is the delayed water flow process inside soil pores due to i... more The capillary barrier effect of soil is the delayed water flow process inside soil pores due to intermolecular forces between liquid and solid particles. In this study, the capability of the fiber optic sensing technology to quantify water infiltration in soil with a capillary barrier system is explored by measuring spatio-temporal distributions of water contents. An actively heated fiber Bragg grating (AH-FBG) sensing tube was used to monitor rainfall infiltration in a one-dimensional soil column test. Frequency domain reflectometry (FDR) probes were used to perform in-situ calibration of the AH-FBG sensors. The fiber optic monitoring results indicate that the AH-FBG technology enables high-sensitivity detection of the capillary barrier effect. The empirical relationships between temperature changes and soil water contents can be well fitted by exponential or linear functions. The capillary barrier system has shown an apparent capability to store water after rainfall, which exerted a significant effect on the vertical infiltration process. Compared with the features of FDR and image acquisition, the proposed method can effectively reflect the whole process of wetting front movement and is more suitable for field monitoring due to its flexibility in large-scale and automatic measurement.

Geotechnical Testing Journal, 2022

Understanding the mechanical characteristics of clayey soil is critical to estimate the stability... more Understanding the mechanical characteristics of clayey soil is critical to estimate the stability of clay-related geotechnical engineering works. However, the distributed information of the internal deformation of clay is hard to capture through traditional methods. In this paper, a set of four-point bending tests were performed on a compacted clay beam instrumented with fiber optic strain sensors to investigate the flexure and cracking behaviors. The optical frequency domain reflectometry technique with high spatial resolution and precision was employed to establish a distributed strain sensing (DSS) system in this study. The results show that the DSS system exhibits a high accuracy in the collection of the clay deformation in terms of compression, tension, and cracking. The comparison of the internal strain profiles with the observation of particle image velocimetry analysis system verifies the feasibility of fiber optic sensing technology in the quantitative assessment of clay deformation. The performance of fiber optic sensors in the rebound deformation and creep deformation monitoring was preliminarily issued in the study. In addition, the progressive failure on the fiber-soil interface was analytically studied to evaluate the deformation compatibility between the fiber and surrounding clayed soil. The conclusions drawn in this paper can help to guide the state interpretation of clayey soil instrumented with fiber optic sensors.

Scientific reports, 2021

Recent studies on water retention behaviour of biochar amended soil rarely considers the effect o... more 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.

Journal of Rock Mechanics and Geotechnical Engineering, 2021

Biochar has been used as an environment-friendly enhancer to improve the hydraulic properties (e.... more Biochar has been used as an environment-friendly enhancer to improve the hydraulic properties (e.g. suction and water retention) of soil. However, variations in densities alter the properties of the soil–biochar mix. Such density variations are observed in agriculture (loosely compacted) and engineering (densely compacted) applications. The influence of biochar amendment on gas permeability of soil has been barely investigated, especially for soil with different densities. The major objective of this study is to investigate the water retention capacity, and gas permeability of biochar-amended soil (BAS) with different biochar contents under varying degree of compaction (DOC) conditions. In-house produced novel biochar was mixed with the soil at different amendment rates (i.e. biochar contents of 0%, 5% and 10%). All BAS samples were compacted at three DOCs (65%, 80% and 95%) in polyvinyl chloride (PVC) tubes. Each soil column was subjected to drying–wetting cycles, during which soil suction, water content, and gas permeability were measured. A simplified theoretical framework for estimating the void ratio of BAS was proposed. The experimental results reveal that the addition of biochar significantly decreased gas permeability kg as compared with that of bare soil (BS). However, the addition of 5% biochar is found to be optimum in decreasing kg with an increase of DOC (i.e. kg,65% > kg,80% > kg,95%) at a relatively low suction range (< 200 kPa) because both biochar and compaction treatment reduce the connected pores.

Journal of Hazardous, Toxic, and Radioactive Waste, 2021

The application of industrial waste in construction reduces the dependency on natural resources. ... more The application of industrial waste in construction reduces the dependency on natural resources. The materials, including red mud (RM) and fly ash (FA), proved to be favorable materials. However, the materials potential together as a geopolymer composite for road applications has rarely been explored. This study will examine the possibility of the replacement of natural materials in subgrade applications. To achieve this, the geopolymer compositions will be prepared by replacing RM with FA at replacement rates of 10%, 20%, and 30% by dry weight basis. The alkaline activator solution of 8 M will be prepared using sodium hydroxide (NaOH) and sodium silicate to develop geo-polymer composites. The strength properties will be studied using the California Bearing Ratio (CBR) and unconfined compression strength (UCS) and validated with microstructural analysis using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). The results reveal that geopolymer composites could achieve a maximum CBR value of 12% and UCS of 2,700 kPa. The microstructural analysis revealed that the formation of dense calcium aluminate hydrate (C-A-H) and calcium silicate hydrate (C-S-H) are the reason for strength improvement. The leaching studies show that the toxic elements were within the permissible limits. Overall , the test results confirmed that the geopolymer composites meet the required strength and could be used as a subgrade material in road construction.

Journal of Hazardous, Toxic, and Radioactive Waste, 2020

In this paper, citric acid (CA) is chosen as an additive for the treatment of bauxite residue, a ... more In this paper, citric acid (CA) is chosen as an additive for the treatment of bauxite residue, a by-product generated by the aluminum industry. The potential of CA to improve geotechnical (e.g., compaction, strength, consolidation, and collapse potential) and geoenvironmental (e.g., pH and leaching) properties are explored by conducting elaborate laboratory experimental investigations on the treated bauxite residue samples. CA concentrations of 0.1, 0.5, 1, 2, 4, and 6 M are considered in this paper. The emphasis, in particular, is on the quantification of pH change in terms of rebound rate of pH (RRP) and rebound termination period (trt). It has been found from various results that 1 M CA successfully heightened the desirable properties and overcame the limitations of the treated bauxite residue simultaneously. The mineralogical analysis revealed minuscule changes in mineral phases, the formation of cementitious compounds (C-S-H), and fast crystallization of hydroxy sodalite, which is further confirmed by morphological studies. The leachability of potentially toxic elements (PTEs) is observed to be within the regulatory permissible limits of the USEPA and the Resource Conservation and Recovery Act (RCRA), demonstrating that the posttreated bauxite residue is environmentally benign and is safe to be used as a geomaterial. It is concluded based on the results that CA is a very good additive to convert the highly alkaline bauxite residue into a usable green geomaterial.

Journal of Hazardous, Toxic, and Radioactive Waste, 2020

Assessment of cracks are essential for attaining better performance of landfill liner system. Thi... more Assessment of cracks are essential for attaining better performance of landfill liner system. This study provides a new vision toward crack prevention in clayey soils. A comparative study of using various geomaterials, biomaterials, and synthetic materials to prevent the desiccation cracks formation in landfill clay liners has been performed. Small-scale materials-amended soil specimens have been subjected to extreme conditions (i.e., soil saturation to drought) for 25 days and crack-influencing parameters, such as crack intensity factor, water content, and shear strength of soil, have been obtained. The results show that addition of wood biochar (WB), pig manure biochar (PMB), and gypsum (GY) can significantly assist the soil to retain more water compared with other amendments. Furthermore, WB, PMB, and GY reduce the development of desiccation cracks in landfill liners. Altogether, this study provides useful insight toward the selection of suitable amendments for various landfill applications.

Nature Scientific Reports, 2020

Generated hazardous or toxic waste posses a serious threat if dumped into ponds or low lying area... more Generated hazardous or toxic waste posses a serious threat if dumped into ponds or low lying areas which leads to contamination, this necessitates the effective landfill liner system. Mainly compacted clayey soils are used as an engineered barrier. Recently, composite materials have gained popularity as landfill liner materials, including the use of waste materials amended with low permeable soils. Though, studies on the composite optimum mix and its corresponding thickness are very scarce. Here, we evaluated the unconfined compressive strength and hydraulic conductivity of fly ash-bentonite composites. Efforts were also made to determine the thickness of landfill liner composite using a finite difference method (i.e. MATLAB). The results reveal that composite consists of 30% bentonite and 70% fly ash is suitable for landfill liner, which meets strength and permeability criteria. Numerical simulation for five major contaminants shows that the composite plays a crucial role in reducing the leaching of heavy metals and suggests an optimum thickness in the range of 126-154 cm. Overall, the findings of the study indicate that fly ash-bentonite composite can be used to solve real-life challenges in a sustainable way.

International Journal of Geosynthetics and Ground Engineering, 2020

In recent years, biochar has been widely used in environmental and geotechnical engineering appli... more In recent years, biochar has been widely used in environmental and geotechnical engineering applications, but minimal studies have been done on its influence on soil engineering properties. In this study, the effect of biochar on the compression and swelling characteristics of two clayey soils, namely PKE and XS, was studied by conducting standard consolidation tests and no-load swelling tests. The compression curves and swelling parameters of modified clays with different biochar content (0, 0.5, 1, 2%, w/w) and biochar particle sizes (<0.15, 1–2 mm) were obtained. The microstructure of the biochar-clay mixture was analyzed by scanning electron microscopy (SEM) test. The results showed that: (1) the compressibility of clayey soils can be effectively reduced by adding biochar, and this effect is more significant with the increase biochar percentage; (2) the effect of reducing soil compressibility by fine biochar was better than coarse biochar; (3) under the same pressure, the settlement rate of soil increased with the increase of biochar content; (4) the incorporation of biochar had no obvious influence on the no-load swelling behaviour of PKE while it has significantly increased the swelling of XS (low expansive soil). Additionally, the fine-grained biochar has a significant effect than the coarse-grained biochar on clayey soils.

Waste and Biomass Valorization, 2021

In order to conserve natural resources and prevent waste generation, effective utilization of ind... more In order to conserve natural resources and prevent waste generation, effective utilization of industrial wastes and/or by-products for beneficial engineering applications becomes inevitable. In order to accomplish this, extensive research studies, exploring properties and new applications of waste materials in a sustainable and environmentally friendly manner, have been initiated worldwide. Red mud (RM, also known as bauxite residue) is one of the wastes generated by the aluminium industry and its disposal and utilization have been traditionally hindered due to the extreme alkalinity (pH about 10.5–13.5). To date, no comprehensive review on various properties of RM of different origin and associated challenges in using it as a beneficial engineering material has been performed. The objective of this study is first to critically appraise the current understanding of properties of RM through a comprehensive literature review and detailed laboratory investigations conducted on Indian RM by the authors, to assess and identify the potential engineering applications, and to finally discuss associated challenges in using it in practical applications. Physical, chemical, mineralogical and geotechnical properties of RMs of different origin and production processes are reviewed. Mechanisms behind the pozzolanic reaction of RM under different chemical and mineralogical compositional conditions are discussed. Environmental concerns associated with the use of RM are also raised. Studies relevant to leachability characteristics reveal that most of the measured chemical concentrations are within the permissible regulatory limits. Overall, the review shows that RM disposal and reuse is complicated by its extreme alkalinity, which is also noticed to be influencing multiple engineering properties. But with selected pH amendments, the treated RM is found to have significant potential to be used as an effective and sustainable geomaterial. The assessment is majorly based on the characteristics of Indian RMs; hence the adaptation of the findings to other RMs should be assessed on a case-by-case basis. Moreover, field studies demonstrating the performance of RM in various engineering applications are warranted.

Waste and Biomass Valorization, 2021

Greenhouse gasses generated from the degradation of solid waste pass through landfill covers and ... more Greenhouse gasses generated from the degradation of solid waste pass through landfill covers and participate in climate change. The formation of desiccation cracks in surface soil leads to direct interaction of greenhouse gasses into the atmosphere. In current study, attempts were made to reduce crack damage and water evaporation of a sandy soil amended with intrusive aquatic biomass derived carbon (water hyacinth and dry algae) also known as biochar. The results show that, the addition of water hyacinth biochar (WHB) and algae biochar (AB) reduced the evaporation rate of densely compacted soil and increases the water retention capacity of soil at 5% and 10% application rate. Furthermore, WHB produced at high temperature has more potential in reducing cracks than that produced at lower temperature. WHB showed better performance than AB at any temperature (i.e. 300 °C, 400 °C and 700 °C) due to its highly porous structure. The current study concludes that biochars from aquatic weeds can be utilized for soil remediation (i.e., minimizing cracking and evaporation rate), which is useful in both waste management and agricultural applications.

Journal of Hazardous, Toxic, and Radioactive Waste, 2019

Excessive pH (>11) and inconsistent engineering properties because of the chemicomineralogical co... more Excessive pH (>11) and inconsistent engineering properties because of the chemicomineralogical composition of red mud warrant devising an alternate approach to render it more environmentally benign. In this study, the performance of lime stabilization coupled with oxalic acid, which acts as a neutralizing agent, was explored systematically to improve the long-term strength and to reduce the alkalinity of red mud. The mechanisms governing the behavior of additives along with their effects were investigated by examining the mineralogical, elemental, and morphological characteristics. The results suggest an effect of sodalite and alumina on the inconsistency in dry unit weight and claylike behavior of red mud. A reduction in pH was found to be instrumental during early phases of lime stabilization and in precipitation of cementitious hydration products, leading to strength gain in the long term in red mud. Moreover, the addition of lime and oxalic acid was found to yield more encouraging results than lime treatment alone, and hence this is recommended to be used for red mud stabilization. The obtained results were substantiated by comparison with code provisions.

Environmental Geotechnics, 2022

In this study, the usefulness of two biopolymers (guar gum and xanthan gum) in improving the stre... more In this study, the usefulness of two biopolymers (guar gum and xanthan gum) in improving the strength properties of two types of red muds was explored. Experiments were performed to determine the unconfined compressive strength and to establish morphological and mineralogical compositions of stabilised samples cured for 7, 28, 45, and 90 days. The obtained results were interpreted to understand the red mud-biopolymer interactions. Considerable improvement in compressive strength of stabilised samples, by 4 to 5 times, vis-à-vis the untreated samples was observed. Based on the results obtained on different admixture contents (i.e. 0.5, 1, 2 and 3%), the optimum dosage of biopolymers was found as 0.5%. The morphological analysis revealed the formation of gels and their role in aggregation of particles by the combined action of binding and pore filling. However, no changes in mineralogical compositions were identified from diffraction patterns of stabilised samples. Both biopolymers proved to be effective in improving the strength characteristics, but the efficacy of xanthan gum was found to be superior over the guar gum. Despite extreme alkalinity in the media, biopolymers were still able to impart reasonably good strength to the treated samples, demonstrating their usefulness and applicability.

Previous studies reveal that the geotechnical properties of red mud waste (RMW) closely resemble ... more Previous studies reveal that the geotechnical properties of red mud waste (RMW) closely resemble that of conventional soils. Due to the predominant presence of exchangeable sodium, the red mud waste tends to exhibit high dispersion behaviour. In this study, mitigation of the dispersion characteristics of RMW using eco-friendly biopolymers was investigated. Two types of biopolymers, namely guar gum (GG) and xanthan gum (XG), in 0.5, 1.0, 2.0, 3.0, and 4% (by weight), were selected for the study. The untreated and polymer amended red mud waste samples were subjected to cylindrical dispersion crumb tests for examining the dispersion phenomenon, and the hardened samples were further analyzed for microstructure, mineralogical, and elemental compositions. Turbidity and pH of water in the crumb tests as well as consistency limits of untreated and polymer amended RMW were also tested. The microstructural analysis revealed an increase in particles aggregations with an increase in the biopolymer content, while elemental compositions showed gel formation by GG cross-linking with calcium. As such, GG proved to be more effective over XG in mitigating the dispersion characteristics of the RMW. Overall, this study shows that GG biopolymer has potential to be used for mitigating dispersion and controlling dusting in field applications.

Geoenvironmental and Geotechnical Issues of Coal Mine Overburden and Mine Tailings, 2023

Bauxite residue (also known as red mud) is a by-product obtained during the production of alumina... more Bauxite residue (also known as red mud) is a by-product obtained during the production of alumina. The landfill liners are widely known as hydraulic barriers which attenuate the flow of leachate/contaminant migration into the groundwater. It is imperative to study the geotechnical engineering properties of the landfill liner and needs to be examined. This chapter reviews the use and application of bauxite residue as a landfill liner material. The geotechnical and environmental engineering properties of bauxite residue have been studied from the literature and its suitability has been assessed based on the criterion limits suggested by the United States Environmental Protection Agency (USEPA). The engineering properties such as particle size distribution, compaction properties, hydraulic conductivity, strength, adsorption characteristics and leaching characteristics have been presented. Further, the suitability of bauxite residue to be used as a landfill liner with different additives and research needs also have been discussed. This review study suggests that bauxite residue could be a potential landfill liner material as it satisfies the criterion limits. However, the use of any bauxite residue should be evaluated individually on a case-by-case basis.

Site inspection for quality checking, work progress, material unloading, etc., has to be done by ... more Site inspection for quality checking, work progress, material unloading, etc., has to be done by site owners, architects, structural designers, waterproofing agencies, etc. In order to do this task, each of these parties has to do a large number of site visits, which adds to the site's cost. Moreover, due to so many people visiting the site, there are often management and construction issues. To avoid this, a novel drone-based site monitoring and management system has been proposed in this paper. This work uses machine learning algorithms to identify inconsistencies in material unloading, construction quality, site progress, worker activities, etc. The underlying technique is flexible and can be adopted to add multiple event types for better site quality maintenance. Upon statistical analysis at over five different-sized sites, it is observed that the drone-based machine learning model can reduce site construction costs by over 10% and improve site construction quality by 15%, thereby improving the overall efficiency of construction sites and development.

Urban Mining for Waste Management and Resource Recovery, 2021

More than 90% of the pavements constructed all over the world have bituminous surface, binder, an... more More than 90% of the pavements constructed all over the world have bituminous surface, binder, and base courses. In India, there are numerous new projects as well as widening and rehabilitation projects going on that require huge quantities of both road quality aggregates and binders. The material removed by scarifying the bituminous layers consists of good quality materials, which provides a viable alternative through reuse of the material. Due to the depletion of aggregates and binder sources, utilization of higher percentages of reclaimed asphalt pavement (RAP) has become a way to attain a better approach in the pavement construction. Use of RAP material in bituminous mixes poses the challenges in terms of performance of the mixes prepared. Superior mechanical and fatigue properties are important in usage of recycled materials without compromising on the overall performance. This chapter presents the challenges of using RAP material as a part of bituminous mixes. Use of RAP material for the preparation of bituminous mixes by choosing appropriate virgin binder poses a challenge in terms of the RAP binder brittleness which in turn affects the fatigue resistance of the mix. To overcome the deterioration of fatigue properties, different technologies like use of rejuvenators and warm mix additives for the preparation of RAP mixes are presented in the chapter. Relation between chemical makeup and the mechanical properties and its effect on the performance is also discussed. The techniques used to overcome the variability in the RAP material is also discussed toward the end.

Advances in Sustainable Construction Materials, 2021

Most of the soils and waste materials are proven to be problematic in geotechnical engineering du... more Most of the soils and waste materials are proven to be problematic in geotechnical engineering due to shrinkage, collapse, swelling, dispersion, excessive settlement, and low strength; such characteristic behavior of materials hinders their utilization in engineering applications. Stabilization of materials using cement and lime is a widespread practice for the improvement of engineering properties. Due to the negative impacts of these additives on the environment, there is an increasing focus on the use of sustainable and eco-friendly additives for improving the strength or engineering properties. In this study, an attempt is made to review the application of biopolymers on enhancing the engineering properties of problematic soil and waste materials. The study highlights the applicability of biopolymers, future challenges, and research needs. This review shows that biopolymers are promising in strength improvement, reduces permeability, and alleviation of problematic soil and waste material challenges in an environmental and sustainable manner.

Sustainable Environmental Geotechnics, 2020

The chemico-mineralogical compositions of red mud lead to its abnormal pH (>11), rendering it unu... more The chemico-mineralogical compositions of red mud lead to its abnormal pH (>11), rendering it unusable as a resource material for civil engineering applications. Such extreme alkalinity accentuates the dearth of contriving a solution to ensure the acceptability and reutilization of the waste. Curing period has considerable significance in the context that the previous studies reported reversal of pH of the red mud after neutralization. Thus, efforts are made in the present study to evaluate the usefulness and applicability of a variety of additives for neutralizing the red mud waste. Additives such as lime, ground granulated blast furnace slag, fly ash, gypsum in different proportions, and acids such as nitric acid and hydrochloric acid of varying strengths were employed, aiming at investigating the alkalinity mitigation capacity in the red mud. The results demonstrated a substantial reduction in the alkalinity levels of the red mud immediately after treatment, but the post-neutralization pH results exhibited noteworthy reversal with time. It has also been found that the type of neutralizing additives has considerable influence on the chemistry which in turn might have affected alkalinity levels in the red mud.

The present study deals with evaluating the dispersion characteristics of red mud by adapting to ... more The present study deals with evaluating the dispersion characteristics of red mud by adapting to chemical analysis methods. For this purpose, the leached aqueous solution has been extracted by suitably diluting the red mud particles with distilled water. The parameters like sodium absorption ratio (SAR) and exchangeable sodium percentage (ESP), which are strong indicators of flocculation or dispersion stability, pH, zeta potential and electrical conductivity, have been measured and employed to assess the dispersive nature of the red mud. The values of SAR and ESP are measured as 54.9% and 98.3%, respectively. The very high values of SAR and ESP demonstrate that the red mud tends to exhibit moderate to high dispersive behaviour. Usually, dispersive soils are not selected as a source material for the construction of earth structures, without adequately stabilizing or treating with chemical additives. As such, the results emphasize that there is a need for treating the red mud with additives like gypsum or alum for mitigating the dispersion behaviour, before its intended use.

Environmental Science and Engineering, Springer, Singapore, 2019

Knowledge of consistency limits is considered important in predicting the engineering properties ... more Knowledge of consistency limits is considered important in predicting the engineering properties (viz., swelling, shrinkage, strength, etc.) as well as for identifying and classifying the geomaterials. Determination of these consistency indices becomes even more imperative when selecting geomaterials (soil or waste) as a resource material for constructing earthen structures. This paper focuses on evaluating the consistency limits (or Atterberg's limits such as liquid limit, plastic limit, and plasticity index) of red mud waste admixed with oxalic acid, gypsum, sodium silicate, and the combination of fly ash and gypsum additives in different proportions, in a comprehensive way. The results show significant variations in the value of Atterberg's limits of ameliorated red mud waste vis-à-vis with that of raw waste. It has been inferred that the results reported in the study are of great help in asserting the suitability of the red mud waste in geotechnical engineering applications.

Springer Singapore, Jun 2017

Neutralization is essential for high alkaline wastes like red mud for its effective utilization. ... more Neutralization is essential for high alkaline wastes like red mud for its effective utilization. As such, the process of neutralization involves treating the red mud with either chemicals or other waste materials. Among several factors that affect the efficiency of the treatment, surface charge characteristics and particles diameter parameters predominantly influence the performance of the neutralization. The present study focuses on examining the surface charge properties include flocculation and dispersion, and determining the particle size characteristics includes mean particle diameter, under variable pH conditions. Surface charge properties are interpreted from zeta potential, , measurements made on suspensions prepared with red mud waste at different pH values. The average particles diameter is obtained from the grain size analysis established on the same suspensions using the zeta potential analyzer. Results indicate that the zeta potential increases with pH up to a certain pH value of 4 and then begin to fall with the further increase in pH. The zeta potential turned into negative (up to a maximum value of -48 mV) at pH value of 6.6, which denotes the point of zero charge for the red mud, from the initial positive (from a maximum of +41.8 mV) value. However, the value becomes stabilized when the pH is 10 and above. An average particles diameter of (a) 65 nm to 150 nm at pH of 3.96 and above 9.00, indicating a complete dispersed state of the grains, and (b) 1660 nm, 2176 nm and 1080 nm at pH of 1.15, PZC (i.e. pH of 6.6) & pH of 7.48, respectively, indicating likely agglomeration of the grains, was recorded with the change in pH of the suspension. The study finds that the waste possesses surface charge characteristics, which appear to be greatly influenced by the pH.

Lecture Notes in Civil Engineering, 2023

Red mud is also known as bauxite residue, an industrial by-product obtained during the processing... more Red mud is also known as bauxite residue, an industrial by-product obtained during the processing of bauxite into alumina. The produced red mud is usually disposed of on land and water bodies, leading to various environmental issues. Red mud is composed of fine particles, various chemical constituents and minerals. It cannot be utilized mainly due to its high alkalinity and the possible presence of heavy metals. Moreover, low hydraulic conductivity, extreme corrosive in nature, high water holding capacity, low shear strength, longer consolidation time, high salinity, lack of plant nutrients, and very low organic content are the other major concerns with red mud. Hence, red mud is to be utilized as an amendment or adsorbent in various engineering applications. There is a serious emergency and a lot of scope to study various physiochemical, mineralogical, and geoenvironmental properties to pave a path to utilize red mud in various applications such as treatment of wastewater, acid mines, reducing swelling of soils and as an amendment for clay liner preparation. This paper aims to review and highlight the applications of red mud as an amendment, adsorbent, catalyst, and coagulant to remove pollutants/contaminants in soil or water.

International Conference on Recent Developments in Sustainable Infrastructure (ICRDSI -2020), KIIT University, India, 2020

International Conference on Recent Developments in Sustainable Infrastructure (ICRDSI -2020), 2020

The scarcity of conventional natural materials and the jeopardized environment have been compelli... more The scarcity of conventional natural materials and the jeopardized environment have been compelling the tendency towards evolution of new or alternate materials and resources to be incorporated in sustainable infrastructure development. The inclusion of such materials entails several secondary and tertiary materials. Indeed, there is a strong thrust to investigate the feasibility of locally available industrial waste materials to replace the conventional construction materials. In India, vast network of existing industries spread across length and breadth of the country and many more to come in the near future, are certainly going to generate millions of tonnes of variety of waste and by-product materials. The pollution and disposal problems can be minimised to greater extent by properly utilising these materials in civil engineering applications. Several types of waste/by-product materials have already been investigated, assessed, and evaluated for utilization and practice in the field. In this paper, assessment of different waste materials produced by various industries was reviewed for ascertaining their suitability in the construction of rural roads, embankments, and subgrade layers. Physical, chemical and geotechnical properties of these waste materials have been critically evaluated for this purpose. From the results, it has been observed that most of the materials have potential to be selected as source materials for embankment and as a construction material in roads. Materials like steel furnace slag and zinc slag found to have their useful in partial replacement of aggregate for the construction of sub-base and base layers.

In the present study, attempts are made to investigate the susceptibility to compaction of raw re... more In the present study, attempts are made to investigate the susceptibility to compaction of raw red mud and when it is admixed with lime & ground granulated blast-furnace slag (GGBS). Results show that the raw red mud exhibits a range of dry unit weight values for the same applied compaction energy. When it is treated with lime, a steady decrease in maximum dry unit weight and increase in optimum water content was noticed. Similarly, GGBS admixed red mud showed almost remained constant values of the maximum dry unit weight, however, with slight variation in optimum water content. The compaction properties are further critically evaluated vis-a-vis with that of fly ash and foundry sand, which are widely being utilized as a substitute to natural material, and also compared with various code provisions, in order to explore avenues of utilization. From the technical perspective, it is important that a material/waste to be selected for constructing an earthen structure must exhibit reproducible compaction curves. In this context, results reported in the paper gains significant importance.

International Conference on Environment and Energy (ICEE-2014)

Springer, Singapore , 2022

City and Built Environment

The utilization of expansive soils for the construction of landfill liners and subgrade facilitie... more The utilization of expansive soils for the construction of landfill liners and subgrade facilities without stabilization leads to volume changes due to seasonal change between wet and dry. This necessitated the industrial- and agro-industrial-based waste materials reconstitution of expansive soils to fulfil sustainability requirements for the builtenvironment. In this research paper, multiple datasets were collected from mixes of bagasse ash (BA) and lime (Lm) blend reconstituted expensive soil and deployed in the training and validation interface of advanced machine learning (AML) techniques to predict the unconfined compressive strength (UCS) of the treated soil for their usein landfill liner and subgrade application. The relative importance values for each input parameter were evaluated, such as compaction parameters (MDD and OMC), plastic limit (PL), LL, Lm, and BA. The results of all developed models were observed and collected. The relations between calculated and predicted va...

Springer eBooks, Oct 11, 2018

Journal of Hazardous, Toxic, and Radioactive Waste

In bauxite residue (BR), the abatement and rebound of pH when ameliorated with different amendmen... more In bauxite residue (BR), the abatement and rebound of pH when ameliorated with different amendments have been reported as prime concerns. In addition, to the best of the authors&#39; knowledge, no research has focused on the characterization of BR during the decrease and rebound in pH, which happens over an extended period. This characterization is essential to convert posttreated residue into green construction materials and to affirm that it does not pose a threat to the environment. This study aimed to investigate two important points. The evaluation of the efficacy of commonly and widely employed conventional additives and mineral acids while mitigating the pH of the residue and its characterization included sedimentation and leaching with a change in pH. The uniqueness of this study lay in the exploration of the latter point and pH rebound for ≤180 days. Cement, gypsum (G), fly ash (FA), and ground granulated blast furnace slag (GGBS) as conventional additives, and nitric (HNO 3) and hydrochloric acids (HCl) as mineral acids were selected to ameliorate BR. A significant pH rebound with time occurred from 6.59 to 9.51 and 7.54 to 9.78 when treated with 1M HCl and HNO 3 , which indicated the influence of the curing period and ameliorant on the alkalinity. Conventional additives, except for G, and their combinations proved ineffective when mitigating and maintaining pH within acceptable limits (i.e., 8.5). Settling analysis revealed accelerated particle settling at pH 4.5-7.0, which indicated implications for the safe disposal, washing, or slurry thickening of BR. The extensive leaching studies for potentially toxic elements (PTEs), which were further endorsed with a field case study, demonstrated that the amended residue was environmentally safe to be used as a construction material.

Lecture notes in civil engineering, 2022

Lecture notes in civil engineering, 2022

Lecture Notes in Civil Engineering, 2019

Geotechnical Research, 2018

This study deals with the evaluation of the compaction and consolidation characteristics of untre... more This study deals with the evaluation of the compaction and consolidation characteristics of untreated as well as hydrochloric acid (HCl)- and sodium chloride (NaCl)-treated red mud wastes. A series of standard and modified Proctor compaction and one-dimensional consolidation tests were conducted for the study purpose. Sodium chloride solutions of 1·71 and 3·42 M and hydrochloric acid solutions with pH of 1, 1·5, 2, 3 and 4 are selected to treat the waste. Results show that standard Proctor compaction tests yield inconsistent and low dry unit weight values with relatively high optimum water content. On the other hand, modified Proctor compaction test produced consistent dry unit weight values with low optimum water content. There is only a marginal improvement in dry unit weight and compression properties of hydrochloric acid- and sodium chloride-treated samples; however, the treatment proved effective in reducing pH of the waste. It has been noticed that the compressibility of both ...

Indian Geotechnical Journal, 2018

Géotechnique Letters, 2018

Previous studies revealed that the geotechnical properties of red mud waste (RMW) closely resembl... more Previous studies revealed that the geotechnical properties of red mud waste (RMW) closely resemble that of conventional soils. Due to the predominant presence of exchangeable sodium, the RMW tends to exhibit high-dispersion behaviour. In this study, mitigation of the dispersion characteristics of RMW using eco-friendly biopolymers was investigated. Two types of biopolymers, namely guar gum (GG) and xanthan gum (XG), in 0·5, 1, 2, 3 and 4% (by weight), were selected for the study. The untreated and polymer-amended RMW samples were subjected to cylindrical dispersion crumb tests for examining the dispersion phenomenon, and the hardened samples were further analysed for microstructure, mineralogical and elemental compositions. Turbidity and pH of water in the crumb tests as well as consistency limits of untreated and polymer-amended RMW were also tested. The microstructural analysis revealed an increase in particle aggregations with an increase in the biopolymer content, while elementa...

Geo-Chicago 2016, 2016

This paper focuses on evaluating the compaction characteristics of untreated and treated red mud ... more This paper focuses on evaluating the compaction characteristics of untreated and treated red mud waste in a comprehensive way. Chemical solutions such as NaCl and HCl were used to treat the red mud waste. A series of standard Proctor (SP) and modified Proctor (MP) compaction tests were conducted on identical samples of (a) untreated and (b) NaCl and HCl treated samples. It has been observed that among standard Proctor and modified Proctor test, the latter one yields reproducible compaction curves especially on untreated red mud waste. The results also showed significant variations in the value of maximum dry density and optimum water content between NaCl and HCl treated samples. Further, it has also been found that compaction energy can considerably influence the density characteristics of the red mud waste.

Lecture notes in civil engineering, Dec 11, 2022

Red mud is also known as bauxite residue, an industrial by-product obtained during the processing... more Red mud is also known as bauxite residue, an industrial by-product obtained during the processing of bauxite into alumina. The produced red mud is usually disposed of on land and water bodies, leading to various environmental issues. Red mud is composed of fine particles, various chemical constituents and minerals. It cannot be utilized mainly due to its high alkalinity and the possible presence of heavy metals. Moreover, low hydraulic conductivity, extreme corrosive in nature, high water holding capacity, low shear strength, longer consolidation time, high salinity, lack of plant nutrients, and very low organic content are the other major concerns with red mud. Hence, red mud is to be utilized as an amendment or adsorbent in various engineering applications. There is a serious emergency and a lot of scope to study various physiochemical, mineralogical, and geoenvironmental properties to pave a path to utilize red mud in various applications such as treatment of wastewater, acid mines, reducing swelling of soils and as an amendment for clay liner preparation. This paper aims to review and highlight the applications of red mud as an amendment, adsorbent, catalyst, and coagulant to remove pollutants/contaminants in soil or water.

Advances in Sustainable Materials and Resilient Infrastructure, 2022

Site inspection for quality checking, work progress, material unloading, etc., has to be done by ... more Site inspection for quality checking, work progress, material unloading, etc., has to be done by site owners, architects, structural designers, waterproofing agencies, etc. In order to do this task, each of these parties has to do a large number of site visits, which adds to the site&#39;s cost. Moreover, due to so many people visiting the site, there are often management and construction issues. To avoid this, a novel drone-based site monitoring and management system has been proposed in this paper. This work uses machine learning algorithms to identify inconsistencies in material unloading, construction quality, site progress, worker activities, etc. The underlying technique is flexible and can be adopted to add multiple event types for better site quality maintenance. Upon statistical analysis at over five different-sized sites, it is observed that the drone-based machine learning model can reduce site construction costs by over 10% and improve site construction quality by 15%, thereby improving the overall efficiency of construction sites and development.

Journal of Hazardous, Toxic, and Radioactive Waste

The world is being burdened with excessive usage and indiscriminate dumping of plastic waste. The... more The world is being burdened with excessive usage and indiscriminate dumping of plastic waste. The world presently produces nearly 400 million tons of plastic every year: less than 10% is recycled, 8% is incinerated, and the rest is dumped in landfills. The reduction of plastic has become a significant challenge due to the lower degradation rate. A substantial amount of this waste turns out to be litter in the oceans or landfills due to limited recycling or reuse in an environmentally friendly way. Compared with incineration and landfilling processes, recycling plastic waste is more productive. Hence, the utilization of plastic waste in civil engineering applications is found to have the maximum potential for consumption in bulk quantities, which can also help in minimizing disposal issues. This article reviews the characteristic properties of waste plastic and its utilization in civil engineering applications, specifically in bricks, blocks, road embankment, pavement layers, plastic aggregates, and voided slabs, which are systematically comprehended with various international standards. The use of waste plastic either retained or slightly improved the properties of the materials to which it is added. The paper also discusses the leaching properties of different kinds of plastic waste; their limitations along with probable opportunities associated with plastic waste utilization.

Lecture Notes in Civil Engineering, 2020

Springer Transactions in Civil and Environmental Engineering, 2022

Advances in Sustainable Construction Materials, 2021

Most of the soils and waste materials are proven to be problematic in geotechnical engineering du... more Most of the soils and waste materials are proven to be problematic in geotechnical engineering due to shrinkage, collapse, swelling, dispersion, excessive settlement, and low strength; such characteristic behavior of materials hinders their utilization in engineering applications. Stabilization of materials using cement and lime is a widespread practice for the improvement of engineering properties. Due to the negative impacts of these additives on the environment, there is an increasing focus on the use of sustainable and eco-friendly additives for improving the strength or engineering properties. In this study, an attempt is made to review the application of biopolymers on enhancing the engineering properties of problematic soil and waste materials. The study highlights the applicability of biopolymers, future challenges, and research needs. This review shows that biopolymers are promising in strength improvement, reduces permeability, and alleviation of problematic soil and waste material challenges in an environmental and sustainable manner.

Geotechnical Testing Journal, 2022

Understanding the mechanical characteristics of clayey soil is critical to estimate the stability... more Understanding the mechanical characteristics of clayey soil is critical to estimate the stability of clay-related geotechnical engineering works. However, the distributed information of the internal deformation of clay is hard to capture through traditional methods. In this paper, a set of four-point bending tests were performed on a compacted clay beam instrumented with fiber optic strain sensors to investigate the flexure and cracking behaviors. The optical frequency domain reflectometry technique with high spatial resolution and precision was employed to establish a distributed strain sensing (DSS) system in this study. The results show that the DSS system exhibits a high accuracy in the collection of the clay deformation in terms of compression, tension, and cracking. The comparison of the internal strain profiles with the observation of particle image velocimetry analysis system verifies the feasibility of fiber optic sensing technology in the quantitative assessment of clay deformation. The performance of fiber optic sensors in the rebound deformation and creep deformation monitoring was preliminarily issued in the study. In addition, the progressive failure on the fiber-soil interface was analytically studied to evaluate the deformation compatibility between the fiber and surrounding clayed soil. The conclusions drawn in this paper can help to guide the state interpretation of clayey soil instrumented with fiber optic sensors.

Environmental Geotechnics, 2022

The capillary barrier effect of soil is the delayed water flow process inside soil pores due to i... more The capillary barrier effect of soil is the delayed water flow process inside soil pores due to intermolecular forces between liquid and solid particles. In this study, the capability of the fiber optic sensing technology to quantify water infiltration in soil with a capillary barrier system is explored by measuring spatio-temporal distributions of water contents. An actively heated fiber Bragg grating (AH-FBG) sensing tube was used to monitor rainfall infiltration in a one-dimensional soil column test. Frequency domain reflectometry (FDR) probes were used to perform in-situ calibration of the AH-FBG sensors. The fiber optic monitoring results indicate that the AH-FBG technology enables high-sensitivity detection of the capillary barrier effect. The empirical relationships between temperature changes and soil water contents can be well fitted by exponential or linear functions. The capillary barrier system has shown an apparent capability to store water after rainfall, which exerted...

Waste and Biomass Valorization, 2020

Abstract Greenhouse gasses generated from the degradation of solid waste pass through landfill co... more Abstract Greenhouse gasses generated from the degradation of solid waste pass through landfill covers and participate in climate change. The formation of desiccation cracks in surface soil leads to direct interaction of greenhouse gasses into the atmosphere. In current study, attempts were made to reduce crack damage and water evaporation of a sandy soil amended with intrusive aquatic biomass derived carbon (water hyacinth and dry algae) also known as biochar. The results show that, the addition of water hyacinth biochar (WHB) and algae biochar (AB) reduced the evaporation rate of densely compacted soil and increases the water retention capacity of soil at 5% and 10% application rate. Furthermore, WHB produced at high temperature has more potential in reducing cracks than that produced at lower temperature. WHB showed better performance than AB at any temperature (i.e. 300 °C, 400 °C and 700 °C) due to its highly porous structure. The current study concludes that biochars from aquatic weeds can be utilized for soil remediation (i.e., minimizing cracking and evaporation rate), which is useful in both waste management and agricultural applications. Graphic Abstract