Durable hydrophobic multifunctional nanocoating for long-term protection of stone built heritage
Article, Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2026, DOI Link
View abstract ⏷
Preserving stone-built cultural heritage from environmental degradation poses significant challenges, as moisture ingress and extreme weather accelerate weathering, leading to structural damage and escalating maintenance costs worldwide. While hydrophobic coatings show promise for protection, achieving long-term durability under harsh conditions remains elusive. The present research demonstrates a robust hydrophobic nanocomposite coating based on silica nanoparticles (SiNPs) functionalized with 1 H,1 H,2 H,2H-perfluorodecyltriethoxysilane (PFDTS), synthesized via alkaline hydrolysis of tetraethylorthosilicate (TEOS) and applied by spray coating to diverse heritage stones including sandstone, granite, and marble. The coatings achieve water contact angles of 130°–137° and sliding angles of 9°–10°, conferring exceptional self-cleaning properties that endure after saline exposure, wet-dry cycles, and marine simulations. Additionally, various water absorption tests, including the Karsten tube, ASTM D6489 surface uptake, ASTM C642 immersion tests, and droplet impact tests, showed a significant decrease in water absorption compared to uncoated stones. The overall results suggest that the water penetration at the coated surface was reduced by a factor of about 80–100 for the stone samples. This research study offers a scalable, cost-effective approach to enhance the longevity of cultural monuments, minimising preservation expenses and safeguarding irreplaceable historical assets for future generations.
Enhancing access to rainwater harvesting in regions with saline groundwater
Article, Discover Sustainability, 2025, DOI Link
View abstract ⏷
Rooftop Rainwater Harvesting (RRWH) offers a viable solution to the pressing issue of saline groundwater in regions like Ainavolu, a village in Andhra Pradesh, India. This study examines the potential of RRWH systems to provide a sustainable alternative water source in rural settings faced with water scarcity due to saline groundwater. Firstly, in view of the limitation in terms of spatial resolution associated with satellite imagery, a UAV-based survey is conducted to create a high-resolution orthomosaic of the study region, enabling precise delineation and classification of rooftop materials to estimate harvestable rainwater. Findings of this study suggest that RRWH could significantly alleviate water shortages by potentially collecting approximately 20.16 million litres of rainwater annually. However, despite this substantial capacity, the adoption of RRWH remains limited due to financial, technical, behavioural, and institutional factors. Through comprehensive fieldwork, including focus group discussions and one-on-one interactions, we identified 17 critical factors hindering RRWH adoption. Based on these insights, we propose a tailored roadmap to promote RRWH implementation, incorporating strategies such as partnerships with local vendors, specialized training programs, subsidies, and targeted awareness campaigns. This study not only underscores the practicality of RRWH in offsetting the challenges posed by unsuitable groundwater but also provides a scalable model for enhancing water security through community-based initiatives and technological integration. Since the scenario of water scarcity and responses of residents change with the cultural and economic characteristics, it is suggested to update the factors while adopting the proposed framework.
Bio-enzyme Application for Enhancement of Pavement Subgrade Performance
Chaduvula U., Parmar K., Bhagat J., Patel G., Rami Z., Peddinti P.
Conference paper, Lecture Notes in Civil Engineering, 2025, DOI Link
View abstract ⏷
Subgrade soil is a critical component of highway construction. In general, a subgrade soil can be made using locally available materials. The performance parameters of soils must be modified to ensure the long-term sustainability of structures built on them. In the field of geotechnical engineering, the bio-enzymes can be used for the stabilization of weak soil produces positive results. Most countries have recently begun to produce and utilize bio-enzymes as additives to improve soil stability and usefulness in soil stabilization. Bio-enzymes can lower the cost of construction while also providing the best output from the stabilization process. It is simple to make bio-enzymes utilizing local resources with a little research and experience. Bio-enzymes can be used in ground improvement projects such as pavements and embankments by performing some laboratory tests and field experiments. The efficiency of soil stabilizer and the need for adequate soil grading as per project requirements are explained by the combination of laboratory tests and field execution. The purpose of this research is to find out what engineering properties soil has after treating the soil with bio-enzyme and investigate the effect of changing the bio-enzyme dosage on the different properties of soil, and several strength parameters like California Bearing Ratio and unconfined compressive strength (UCS) were calculated using standard sized samples at curing periods of 0, 7, 14, 21, 28 days. Then to discover the properties of modified (stabilized) soil. Here, we will obtain the optimum measure of bio-enzyme at which soil will acquire maximum strength.
Phenotypic Trait Monitoring of Victoria amazonica Plants Using Unmanned Aerial Vehicles
Rai A., Peddinti P.R.T., Kim B., Han S.S., Park S.J.
Article, Journal of the Indian Society of Remote Sensing, 2025, DOI Link
View abstract ⏷
The study investigates the potential of unmanned aerial vehicles (UAVs) for acquiring phenotypic trait parameters of Victoria amazonica in an open pond environment. Sequential 2D images using UAVs were acquired from multiple views on a weekly basis. The structure from motion (SfM) technique was then used to build high-resolution orthomosaic and 3D models of the mapping area. Measurements corresponding to typical leaf, petiole, and flower growth were made using digital models. It was observed that the digital models could represent the actual ground truth values for all the traits with a ground sample distance ranging between 0.25 and 0.4 cm/pixel. A comparison of digital and manually measured phenotypic trait data revealed that the UAV-based measurements could predict on par with the conventional manual measurements. Additionally, linear regression fits generated for digital and manual trait data resulted in adjusted coefficients of determination (Adj. R2) of atleast 0.98 for all parameters. The trait data were also statistically analyzed to assess the growth rates of various parameters during the monitoring period. It is observed that the leaf rim height and petiole parameters are the highly sensitive and varying traits (COV range: 53–78%) for Victoria amazonica species. Besides addressing the problems with manual phenotyping, the proposed methodology provides an easy, flexible, frequent, accurate, contactless, non-destructive and cost-effective solution for aquatic plant research.
Thermographic inspections of solar photovoltaic plants in India using Unmanned Aerial Vehicles: Analysing the gap between theory and practice
Article, Renewable Energy, 2024, DOI Link
View abstract ⏷
Aerial inspection of solar PV plants using Unmanned Aerial Vehicles (UAVs) is gaining traction due to benefits such as no downtime and cost-effectiveness. This technology is proven to be the low-cost alternative to conventional approaches involving visual inspection and I-V curve tracing to identify physical damages and underperforming strings, respectively. Though the use of UAVs for thermographic solar PV inspection is a popular alternative in developed countries, its use in developing economies experience various challenges. Studies emphasizing these challenges especially in the context of rapid evolution of drones are limited. To overcome this limitation, literature scoping, a one-on-one survey, focus group discussion, and a flight campaign using a UAV with a thermal payload is conducted in India to identify the limitations. These are further categorized into Technical, Behavioural, Implementation, Pre-deployment, Deployment, and Post-deployment categories. The relevance and significance of each challenge are analysed using a hybrid multi-criteria framework developed in this study. Findings of this study highlight the importance of drone regulations, technology readiness, and workshops for drone pilots, industry professionals, and solar developers in India. This study aid developing economies in devising strategies that can promote the use of UAVs for solar PV plant commissioning activities.
Leveraging ChatGPT and Bard: What does it convey for water treatment/desalination and harvesting sectors?
Article, Desalination, 2024, DOI Link
View abstract ⏷
Artificial intelligence (AI) has emerged as a prominent tool in the modern day. The utilization of AI and advanced language models such as chat generative pre-trained transformer (ChatGPT) and Bard is not only innovative but also crucial for handling challenges related to water research. ChatGPT is an AI chatbot that uses natural language processing to create humanlike conversations. ChatGPT has recently gained considerable public interest, owing to its unique ability to simplify tasks from various backgrounds. Similarly, Google introduced Bard, an AI-powered chatbot to simulate human conversations. Herein, we investigated how ChatGPT and Bard (AI powdered chatbots) tools can impact water research through interactive sessions. Typically, ChatGPT and Bard offer significant benefits to various fields, including research, education, scientific publications, and outreach. ChatGPT and Bard simplify complex and challenging tasks. For instance, 50 important questions about water treatment/desalination techniques and 50 questions about water harvesting techniques were provided to both chatbots. Time analytics was performed by ChatGPT 3.5, and Bard was used to generate full responses. In particular, the effectiveness of this emerging tool for research purposes in the field of conventional water treatment techniques, advanced water treatment techniques, membrane technology and seawater desalination has been thoroughly demonstrated. Moreover, potential pitfalls and challenges were also highlighted. Thus, sharing these experiences may encourage the effective and responsible use of Bard and ChatGPT in research purposes. Finally, the responses were compared from the perspective of an expert. Although ChatGPT and Bard possess huge benefits, there are several issues, which are discussed in this study. Based on this study, we can compare the abilities of artificial intelligence and human intelligence in water sector research.
Zinc slag utilization as a sustainable material in pavement construction: a comprehensive review and future prospective
Bodhanam S P., Baadiga R., P. S. P., Peddinti P.R.T.
Book chapter, Sustainable Materials in Civil Infrastructure, 2024, DOI Link
View abstract ⏷
As global concerns over sustainable infrastructure continue to rise, there is an increasing interest in looking into alternative materials for pavement construction. Zinc slag (ZS) has attracted interest because it has the potential to be a more affordable alternative to conventional pavement materials. This paper delves into the physical, mechanical, and chemical properties of ZS, discussing its composition and grain size distribution relevant to pavement applications. Previous studies and case studies that have utilized ZS in pavement applications were discussed. It then highlights the potential of ZS as a viable alternative by providing the opportunity for waste diversion. The utilization of ZS as a sustainable pavement material offers the potential for waste reduction, resource conservation, carbon footprint reduction and energy savings. The illustrations made in this manuscript would aid the transportation industry's efforts toward sustainable and economical construction of roads across the globe.
Geotechnical Assessment of Highly Saline Soil Stabilized with Fly Ash–Cement Admixtures
Parmar J., Prasad P.S., Pandya S., Peddinti P.R.T.
Conference paper, Lecture Notes in Civil Engineering, 2024, DOI Link
View abstract ⏷
Coastal cities are in desperate need of suitable land to meet the ever-increasing demand for urban infrastructure to support commercial, residential, tourism, and off-shore activities. Countries with a lengthy coastal line, such as India, possess significant areas of widespread highly saline soils subjected to periodic seawater intrusion. One such soil stratum was encountered in the Gulf of Cambay, Bhavnagar district, Gujarat, India. Due to the high volume of river runoff, the Gulf has a positive water balance. The relative humidity ranges from 65 to 86%, making the climate semi-arid to sub-humid. The high salinity, mineral content, basaltic origin, and deeper water table offered the impetus to investigate the applicability of various soil treatment options for such saline soils. Admixture stabilization techniques have been shown to help with problematic soil features. The Current study aims to determine the effectiveness of the addition of locally available lignite fly ash (10–30% by weight) and cement (6–9% by weight) to Bhavnagar saline soil in respect of strength, electrical conductivity, and CBR. In this assessment, a comparison of stabilized and unstabilized saline soil mixtures is expected to highlight the need of understanding the influence of treatment on the instinctive performance of stabilized saline soils, as well as assist practitioners in efficacious treatment of extreme saline soils for diverse geotechnical and construction applications.
Experimental study on the use of lightweight expanded clay aggregate as coarse aggregate for light traffic, medium traffic, and light weight concrete application
Book chapter, Sustainable Materials in Civil Infrastructure, 2024, DOI Link
View abstract ⏷
The commencement of the green revolution has carved the path toward more sustainable approaches in the construction industry. Extraction of conventional coarse aggregates disrupts the ecological and environmental balance from production, transportation, and disposal point of view. In this experimental investigation, an attempt has been made to evaluate lightweight expanded clay aggregates (LECAs) as a coarse aggregate substitute. The study has been conducted in two sections. The first portion investigates the influence of partial and full replacement of conventional coarse aggregates by LECA on the mechanical properties of concrete paver blocks for light and medium traffic conditions. Compressive strength, flexural strength, and abrasion resistance of M35 grade paver block of 60mm thickness and M40 grade paver block of 80mm thickness have been evaluated and examined at varying percentages of LECA (0%, 20%, 40%, 60%, 80%, and 100%). The selected grade met with light and medium traffic conditions as per IS-15658 (2006). Partial and full replacement of conventional coarse aggregate by LECA exhibited considerable alteration in the mechanical behavior of the paver blocks for both light traffic and medium traffic applications. The second portion of the study assesses the mechanical response of lightweight concrete of M25 grade produced by full replacement of LECA as a coarse aggregate and partial replacement of cement by fly ash. Performance parameters such as compressive strength, flexural strength, and abrasion resistance of the lightweight concrete were determined and analyzed. Cost analysis was also carried out to evaluate the economic repercussions asserted due to the use of LECA in concrete production. Henceforth, further investigations on interactions at the microlevel, formation of long-term secondary cementations compound and use of superplasticizers were recommended to prepare sustainable concrete.
Conjugate heat transfer of aqueous hybrid nanoliquid between coaxial cylinders subjected to magnetic field
Article, International Journal of Thermofluids, 2023, DOI Link
View abstract ⏷
The current numerical investigation deals with the conjugate (conduction–convection) magnetohydrodynamic (MHD) incompressible flow and thermal dissipation processes of Multi-wall carbon nanotube - silver (MWCNT - Ag) water hybrid Newtonian nanoliquid filled in an annular enclosure. The inner cylinder having finite thickness is subjected to uniform/non-uniform thermal profiles whereas the exterior cylinder is kept at low temperature. However, the horizontal surfaces are retained adiabatic. An in-house FORTRAN code has been developed to solve the two dimensional, axisymmetric and unsteady governing equations by employing time-splitting technique. Detailed numerical simulations have been carried out for control parameters such as Rayleigh number, thermal conductivity ratio, wall thickness, Hartmann number, nanoparticle concentration and for a clear visualization of the impact of various range of these parameters, the obtained numerical results are represented by the streamlines, isotherms and plot of average Nusselt number values. From detailed numerical computations, greater heat transport rate is achieved with minimum wall thickness and maximum thermal conductivity ratio irrespective of thermal boundary condition. The results also reveal that hybrid nanoliquid with equal proportion of MWCNT and silver (Ag) nanoparticles dispersed in the water helps in dissipating maximum amount of thermal energy from the solid–fluid interface of annulus. In addition, uniform heating condition helps in extracting greater amount of heat dissipation compared to linear heating.
Unmanned aerial vehicles for planning rooftop rainwater harvesting systems: a case study from Gurgaon, India
Article, Water Supply, 2023, DOI Link
View abstract ⏷
Rooftop rainwater harvesting systems (RRWHS) effectively provide water access by storing precipitated water. The amount of water harvestable using these systems is proportional to the availability of rooftop areas in the region. The use of satellite imagery has gained traction in recent times considering the challenges in conducting a manual survey to determine the rooftop area. However, the limitations on spatial resolution impaired stakeholders from conducting similar assessments in areas with small residential units. In this regard, the use of unmanned aerial vehicles (UAVs) providing high-resolution spatial imagery for the delineation of rooftops of all scales has become popular. The present study is an attempt to utilize UAV-generated orthomosaics to estimate the harvestable quantity of rainwater for setting up an RRWHS. A study area in the Gurgaon district, India, is selected, and the steps involved in estimating the quantity of water harvestable using UAVs are demonstrated. In addition to these computations, a suitable site for constructing the storage unit is identified with the aid of a weighted overlay technique implemented using a Geographic Information System. The results from the study show that nearly 11,229 m3 of water can be harvested per year in the study site using the RRWHS.
Barriers to the adoption of new technologies in rural areas: The case of unmanned aerial vehicles for precision agriculture in India
Article, Technology in Society, 2023, DOI Link
View abstract ⏷
Technological advances can significantly transform agrarian rural areas by increasing productivity and efficiency while reducing labour intensive processes. For instance, the usage of Unmanned Aerial Vehicles (UAVs) can offer flexibility collecting real-time information of the crops enabling farmers to take timely decisions. However, little is known about the barriers to the adoption of such technologies by rural farmers in emerging economies like India. Building on an extensive literature review, focussed group discussions, and field visits, the barriers impacting the adoption are identified and classified into technical, social, behavioural, operational, economic, and implementation categories. The relevance of each barrier and its importance is evaluated using a hybrid multi-criteria framework built on the theory of Fuzzy Delphi and Fuzzy Analytical Hierarchy Process to identify the most crucial barriers to the adoption of UAVs to implement precision agriculture in rural India. The paper suggests new avenues for accelerating technology adoption in rural areas of emerging economies.
Pavement Monitoring Using Unmanned Aerial Vehicles: An Overview
Review, Journal of Transportation Engineering Part B: Pavements, 2023, DOI Link
View abstract ⏷
Pavement monitoring involves periodic damage detection and condition assessment of pavements for efficient pavement management. Unmanned aerial vehicle (UAV)-based pavement monitoring requires multidisciplinary knowledge of pavement distress, drone type, payload, flight parameters, drone deployment, and image processing. Owing to the availability of various UAVs, data sensing devices, operating ecosystems, and post-processing tools, selecting an appropriate combination of these systems is crucial. Therefore, the primary objective of this study is to provide essential knowledge on the prevalent challenges of existing monitoring techniques and discuss the potential advantages of UAVs over conventional pavement monitoring practice. A state-of-the-art review emphasizing UAV technicalities in the context of image-based pavement monitoring is presented. A detailed workflow and checklist for drone deployment is drafted for novice users to ensure safe and high-quality data acquisition. Finally, the present challenges and future scope of UAV-based pavement monitoring is discussed. Overall, this study aims to provide inclusive and comprehensive information on UAV-based pavement monitoring to beginner researchers.
New technology adoption in rural areas of emerging economies: The case of rainwater harvesting systems in India
Article, Technological Forecasting and Social Change, 2023, DOI Link
View abstract ⏷
Technological advancements can accelerate the attainment of Sustainable Development Goals (SDGs). However, technology adoption is associated with complex, interrelated factors, even more so in the context of rural areas in emerging economies. We examine the adoption of one technology that can be crucial for resolving water scarcity issues facing countries around the world–the Rainwater Harvesting (RWH) technology and the critical success factors (CSFs) that promote its adoption in rural India. Building on an extensive literature review, focus group discussions, and field visits, this paper identifies a list of factors that promote its adoption. To derive the CSFs, the relevance of each factor is analysed using Fuzzy-Delphi, and the significance is determined using D-DEMATEL technique. The novel results presented here suggest that awareness about RWH technologies, their perceived usefulness, ease of use, and tax incentives for companies are some crucial factors that can increase RWH technology adoption. Furthermore, community-based workshops explaining the architecture and operational aspects of the RWH System as well as simplifying the RWH system architecture can accelerate its usage in rural areas. Based on these results, the paper presents a new roadmap for leveraging technology to attain SDGs in rural areas of developing countries.
An Experimental Study on the Strength Behaviour of Black Cotton Soil Stabilized with Industrial Waste Material (Zinc Slag) for Pavement Construction
Patel M., Prasad P.S., Peddinti P.R.T., Kanaujia V.K.
Conference paper, Lecture Notes in Civil Engineering, 2023, DOI Link
View abstract ⏷
Depletion of natural resources for construction material, abundant generation of industrial wastes, disposal problems and their environmental impact have resulted in a continuous research scope for reuse of industrial wastes for sustainable engineering practice. Among these practices, the utilization of industrial wastes from metal processing industry for pavement subgrade stabilization has gained significant global importance. Present research aims at investigating the potential of one such material zinc slag (ZS) in altering and enhancing the strength properties of black cotton soils (BCS) for possible pavement applications. Different dosages of ZS (25, 50 and 75%) and cement (3, 6 and 9%) are administered to the black cotton soil. The mechanistic performance of these stabilized soil–slag mixtures in the form of CBR and unconfined compressive strength (UCS) values has been observed and used as an indicator to investigate the suitability of these mixes as pavement subgrade and subbase roads having traffic intensity up to 5 msa. The proposed layer thicknesses due to the increased CBR/UCS values is calculated to meet the IRC: 372018 guidelines. The IITPAVE analysis is used to quantify the fatigue and rutting strains at perilous locations in the pavement during the desired service life.
Effectiveness of nanoparticles-based ultrahydrophobic coating for concrete materials
Ray S.S., Peddinti P.R.T., Soni R., Kim B., Park Y.-I., Kim I.-C., Lee C.Y., Kwon Y.-N.
Article, Journal of Building Engineering, 2023, DOI Link
View abstract ⏷
Moisture interaction and extreme weather may complicate the service life and increase the maintenance cost of various building materials. This paper investigates the performance of protective surface coatings applied to the most common building material, concrete. A novel synthesis route for producing ultrahydrophobic surface coatings is demonstrated to enhance the impermeability of concrete. The concrete specimens were chemically modified with silica sol, which was synthesized by hydrolysis of tetraethoxysilane (TEOS) under alkaline conditions, followed by treatment with hexadecyltrimethoxysilane (HDTMS) solution. The concrete specimens coated with proposed micro-composite coating were tested for hydrophobicity and self-cleaning characteristics in terms of contact angle and sliding angle at various water exposure conditions and periods of exposure. The permanency and efficiency of proposed coatings was further tested after exposure to alternate wet-dry cycles and highly saline environment. The modified specimens exhibited a contact angle of 121° – 135° and a sliding angle of 9° – 22° at various exposure conditions, depicting superior hydrophobicity. The overall findings of this study could aid in maintaining the intended longevity and performance of various concrete materials.
Fly Ash Stabilized Saline Soils as Subgrade for Low Volume Roads
Conference paper, AIP Conference Proceedings, 2023, DOI Link
View abstract ⏷
Coastal areas are ideal settings for both individual and commercial real estate projects, as well as the infrastructure that supports them. Coastal and offshore structures, on the other hand, are sensitive to the effects of seawater on their foundations. Seawater contains a variety of salts that can harm civil engineering structures. The majority of India's highways are flexible pavements, which carry the majority of the country's passenger traffic. As a result, predicting the appropriate thickness of pavement layers (bituminous and granular layer) are necessary to safeguard the pavement from rutting and cracking for weak and strong subgrades for low and high-volume roads. This paper describes the use of locally available self-cementing Class C fly ash at a concentration of 20% to stabilize saline soil in the Bhavnagar area of Gujarat and broaden the scope of pavement design and analyze them with the IITPAVE software. Unconfined Compressive Strength and durability was performed to see the efficacy of fly ash on saline soil.
Enhanced green view index
Article, MethodsX, 2022, DOI Link
View abstract ⏷
Quantifying street-level greenery has been the subject of interest for researchers as it has several implications for community residents. Green View Index (GVI) is a widely used parameter to compute the greenery along the streets. However, it does not account for the health of the greenery. The new Enhanced Green View Index (EGVI) that we propose computes the amount of greenery along the streets along with the health of the greenery. • The new indicator computes street-level greenery; • Considers the health of vegetation while calculating greenery; and • Helps to study the impact of street-level greenery on community residents precisely.
Sustainable Pavement Subgrades for Unsaturated Saline Bhavnagar Coast
Parmar J., Pandya S., Peddinti P.R.T., Prasad P.S.
Conference paper, International Conference on Transportation and Development 2022: Application of Emerging Technologies - Selected Papers from the Proceedings of the International Conference on Transportation and Development 2022, 2022, DOI Link
View abstract ⏷
The present case study discusses the subgrade enhancement strategies for highly saline marine soils located at Bhavnagar District, Gujarat, India. In addition to the presence of various salts, the saturation levels of these soils were observed to vary throughout the year due to several climatic and geographical factors. Initially, the unsaturated behaviour is evaluated using the standard filter paper method. Due to the low in situ California bearing ratio (CBR) value (1.62%), locally available fly ash (10%-30% by weight) was used to improve the strength and stiffness of the soil. Addition of fly ash resulted in the considerable reduction of salinity and suction levels at all dosages of fly ash. The unconfined compressive strength (UCS) and CBR have increased until 20% fly ash and reduced from thereof. The maximum CBR obtained was about 9%, which can withstand low to medium volumes of traffic. However, the UCS developed at seven days was observed to reduce at 28 days. This may be due to the secondary reactions and change of form of salts present in the matrix. Henceforth, further investigations on interactions at micro-level, formation of secondary compounds, and suction levels were recommended to prepare a sustainable subgrade in this terrain.
Efficient Pavement Monitoring for South Korea Using Unmanned Aerial Vehicles
Conference paper, International Conference on Transportation and Development 2022: Application of Emerging Technologies - Selected Papers from the Proceedings of the International Conference on Transportation and Development 2022, 2022, DOI Link
View abstract ⏷
The present study is aimed at using unmanned aerial vehicles (UAVs) for pavement monitoring. It was taken up as an initial pilot study to develop a network level asset management framework for South Korean conditions. A varying pavement stretch containing a bridge, culvert, streams, and merging traffic junctions was selected for the study. Using a quadcopter UAV, 139 overlapping images were acquired and processed using a structure from motion (SfM) program to develop a digital twin of the pavement. The generated orthomosaic and 3D digital twin were used to identify pavement damage and other infrastructural assets. UAV-based image acquisition was found to provide sufficient resolution, exposure, and key point matches, enabling an accurate 3D model generation with detailed feature extraction. Geometric measurements of various features depicted the potential and efficiency of UAV surveys. The research work is expected to aid in effective contactless pavement monitoring and asset management during regular surveys as well as disasters.
Application of data handling techniques to predict pavement performance
Book chapter, Handbook of Statistics, 2021, DOI Link
View abstract ⏷
The present study discusses the design of pavements and the importance of big data handling in improving their performance. A comprehensive framework based on a simple natural language processing technique is presented to reduce the computational time and error in data handling for pavement applications. The application of the proposed method to automate a graphical user interface (UI) adopted in pavement design is demonstrated. The proposed method was found to reduce the run-time by about 83% as compared to the conventional procedures. The proposed framework is highly flexible and can be adapted to extract data from various file formats and automate UIs at ease. To present the potential of this framework, about 0.2 million data sets representing pavement geometry and material properties were generated using language processing algorithms. Further, robust non-linear regression equations for calculating pavement damage in terms of fatigue and rutting strains were developed by using automated data processing through the pavement design interface.
System Reliability Framework for Design of Flexible Pavements
Article, Journal of Transportation Engineering Part B: Pavements, 2020, DOI Link
View abstract ⏷
The paper presents a methodology to carry out the series system reliability analysis of multilayered flexible pavements with respect to correlated fatigue and rutting failure modes. The importance of assessing the uncertainty associated with the random variables, which are the layer thicknesses and material properties, used in pavement designs was discussed. The variability associated with layer thicknesses and resilient moduli was incorporated into the design by performing component and system reliability analysis with correlated failure modes. Robust nonlinear regression equations which were proposed recently were used to relate the fatigue and rutting strains to the thickness and resilient moduli of the four layered flexible pavements. The first-order reliability method (FORM) was used to evaluate the component reliability indexes against fatigue and rutting failure modes. The overall performance of the pavement system was assessed using series system reliability analysis considering the simultaneous occurrence of both failure modes. A high variation in the degree of correlation between-0.02 and 0.90, was observed between fatigue and rutting modes. The sensitivity of layer thicknesses and corresponding resilient moduli on the performance of a pavement system was presented. The mean values of thicknesses and resilient moduli of bituminous, base, and subbase layers; resilient modulus of subgrade; and coefficients of variation of bituminous layer thickness (h1) and resilient modulus of subbase layer (Mr3) were found to predominantly influence the pavement system performance. The design values of resilient moduli and thicknesses of bituminous, base, and subbase layers to meet a desired system reliability level were presented in the form of design charts. A comparative study with existing design methods was presented, accounting the variability in pavement designs. The proposed system reliability-based design optimization (SRBDO) helps to improve the robustness and reliability of existing flexible pavement designs.
Evaluation of Flexible Pavement Distress Using Nonlinear Regression Analysis
Book chapter, Lecture Notes in Civil Engineering, 2019, DOI Link
View abstract ⏷
The current study aims at developing well-predicting regression equations for evaluating the fatigue and rutting strains at critical locations within the flexible pavement layers. With an objective to develop unified regression models, the practical on-field ranges for thickness and layer moduli of various pavement layers are used in the analysis. These design input combinations are fed into a multilayer elastic analysis program using an automation technique to reduce a lot of human effort and evaluation time. The output obtained from the program is used to develop equations for fatigue and rutting strains by nonlinear regression analysis. The outcomes of this study will aid the design engineers as well as researchers in multiple ways. In addition to the advantages in pavement design, the automation procedure combined with regression would also aid the researchers in simulation studies, reliability analysis, etc.
Reliability Perspective on Optimum Design of Flexible Pavements for Fatigue and Rutting Performance
Article, Journal of Transportation Engineering Part B: Pavements, 2019, DOI Link
View abstract ⏷
This study presents a reliability-based design optimization (RBDO) framework for evaluating a four-layered flexible pavement system. The major focus of the study is the optimum design of flexible pavements with respect to fatigue and rutting performance considering the variability associated with design variables. The influence of variability associated with thickness and resilient moduli of flexible pavement layers on fatigue and rutting failures is discussed. Initially, robust nonlinear regression equations were proposed to relate the fatigue and rutting strains to the thickness and resilient moduli of the pavement layers and were validated. Then, the reliability indexes against fatigue and rutting failures for the design of flexible pavements were evaluated using the first-order reliability method (FORM). Typical design charts were presented to estimate reliability indexes against fatigue and rutting based on a wide range of thicknesses and moduli values of pavement layers. The results from the reliability and sensitivity analyses show that the bituminous layer's thickness and resilient modulus of the base layer are the most influential parameters for the fatigue failure. Further, the reliability index against rutting failure is significantly influenced by all the random variables except the bituminous layer's resilient modulus. It is proposed that for pavement systems, a reliability of 95% against both fatigue and rutting failure criteria may be adopted. A reliability-based design example was presented and the results were compared with that of the traditional design method. For the selected mean and standard deviation of resilient moduli of pavement layers, it is noted that the traditional method overestimates the reliability levels by 10%-40% due to nonconsideration of variability associated with the independent layer moduli.
Probability density functions associated with the resilient modulus of virgin aggregate bases
Conference paper, Geotechnical Special Publication, 2017, DOI Link
View abstract ⏷
The accuracy of the reliability-based designs for pavements mostly depends on the probability density functions (PDF) associated with the resilient modulus of the pavement layer. The present study attempts to find out the appropriate PDF corresponding to the base resilient modulus (Mr) of different virgin aggregates that are used in the flexible pavements. Extensive literature study has been conducted and about 120 data points were collected from various global studies performed on virgin aggregate base materials for their use in flexible pavements. Histogram and statistical analyses are performed on the dataset. An accurate PDF is then proposed from the available distributions by using percentile (P-P) and quantile (Q-Q) fit assessment plots. The proposed mean, standard deviation and coefficient of variation associated with the best PDF are further useful for developing the reliability based design optimization methods for pavements.
Interfacial shear properties of geosynthetic interlayered asphalt overlays
Conference paper, Geotechnical Special Publication, 2017, DOI Link
View abstract ⏷
Hot mix asphalt (HMA) overlays are the most common and cost effective rehabilitation technique available to restore the serviceability of existing distressed pavement surfaces. It is often observed that within a short span of placing HMA overlays, the distress in the existing pavement surface reflect to the new overlay surface and this process is termed as reflective cracking. To reduce the effect of reflection cracks and to improve the performance of HMA overlays, the geosynthetic interlayers are placed at the interface of old and new pavement layers. The current study aims to understand the interfacial shear properties of geosynthetic interlayered HMA overlays placed on a distressed pavement surface. The interfacial shear properties are determined in the laboratory using a large scale interface shear test apparatus. The geosynthetic interlayers used in the current study are biaxial geogrids with varying material properties and aperture sizes and a geo-jute mat. The results indicate a reduction in the interfacial bond strength (shear) between the old and new pavement layers with the inclusion of geosynthetic interlayers at the interface zone. Among different types of geosynthetic interlayers used, the polymer modified polyester grid has shown least reduction (17%) in the interface bond strength. The maximum reduction of 46% in the interface bond strength was observed in the geo-jute mat interlayers.
Variability Associated with the Resilient Modulus of Reclaimed Asphalt Pavements
Conference paper, Geotechnical Special Publication, 2016, DOI Link
View abstract ⏷
Research on reclaimed asphalt pavement (RAP) material has been on its high all over the world since last three decades. Sustainability, cost effectiveness and eco-friendliness of RAP make it a potential secondary alternative in pavement applications. Often, to meet the strength and stiffness requirements, RAP is blended with virgin aggregates (VA) at various proportions. The resilient modulus (Mr) of base material plays a major role in deciding the pavement thickness. A considerable amount of variability in the Mr values of RAP is observed from laboratory and field studies all over the world. In view of the increased usage of RAP, there is a definite need to understand the statistical variability associated with the Mr of RAP. In this paper, the variability associated with Mr is quantified statistically. Based on the compilation of Mr values from several published studies, the average values of mean, standard deviation, coefficient of variation (COV), and the best fit probability density functions for Mr are computed. The appropriate distributions for RAP and VA mixes are discussed. The outcome of the study will be useful to quantify the performance of the flexible pavements using reliability based design optimization (RBDO) framework which is based on the probability theory.
Durability and long term performance of geopolymer stabilized reclaimed asphalt pavement base courses
Article, Construction and Building Materials, 2016, DOI Link
View abstract ⏷
Utilization of reclaimed asphalt pavement (RAP) materials in pavement base courses has proven to be a viable alternative not only to conserve the natural resources but also to reduce the environmental pollution and landfilling. Recent studies demonstrated that untreated RAP is inefficient to be used as a pavement material unless blended with virgin aggregates (VA) and/or stabilized with additives, because of their inferior gradation and bonding characteristics. Most of the design guidelines limit the amount of RAP in the base course up to 30% by weight of the virgin aggregates, in lieu of the aged bitumen coating present on the RAP aggregates and lack of understanding of the long term performance of the material. Hence, in this study it is proposed to promote a high percentage of RAP in the base course by stabilizing the RAP:VA mixes with a fly ash. However, the presence of the aged bitumen over the RAP aggregates may affect the long term strength and durability of the design mixes. Hence, to attain the desired design strength, the fly ash is activated in an alkali environment to form a geopolymer by triggering the unreacted polymeric compounds present in the fly ash. However, exposure of these mixes to the severe moisture and temperature variations may alter the cementation. This process may lead to strippage of the asphalt coating from the RAP aggregates and leach out the stabilizer from the mixes. Hence, the present study verifies the suitability of these mixes in terms of their initial compressive strength and the corresponding retained strength after exposure to the alternate wet/dry cycles in the severe laboratory environment. The permanency of the stabilizer/activator is also verified through leachate studies. Variation in the hydration products and oxide contents of the mixes are verified at every stage using X-ray diffraction (XRD) and X-ray florescence (XRF) studies. The comprehensive test results indicated that the strength loss of RAP:VA mixes is very minimal and are found suitable for the base course applications.
