Self-compacting geopolymer concrete (SCGPC) is an ecofriendly substitute to traditional Portland cement concrete, known for its lower carbon footprint. This study compares two different types of SCGPC made from fly ash, ground granulated blast furnace slag (GGBFS), and waste ceramic powder (WCP), which are subjected to ambient and oven curing at 60 degrees C and 80 degrees C for durations of 24 and 48 hours. The focus has been on the use of WCP in SCGPC, which is essentially industrial waste that can be used in the construction industry. Two batches of SCGPC are prepared: one with 60 % fly ash, 30 % GGBFS, and 10 % WCP (F60G30W10) and another with 70 % fly ash, 30 % GGBFS, and 0 % WCP (F70G30W0). The study investigates the effect of different curing conditions on the fresh state properties, mechanical properties, as well as microstructural characteristics. The results reveal that curing plays a very significant role in enhancing the strength of the SCGPC. In the oven-cured at 80 degrees C, the compressive strength (CS) of the SCGPC mix F60G30W10 is 33.7MPa at 28 days, which was 3.37 % higher than that of the oven-cured mix F60G30W0 under similar curing conditions. Scanning electron microscopy (SEM) analyses confirm that the SCGPC microstructure improves with oven curing. X-ray diffraction (XRD) analysis shows that increased curing temperature and WCP content led to higher intensities of mullite, quartzite, CSH gel, and calcite peaks compared to those observed in composite F70G30W0.

The development of non-destructive testing methods for assessing the homogeneity of concrete is an emerging area of research. Despite advancements in the field, traditional techniques for structural condition assessment often face challenges in evaluating inaccessible locations, such as specific structural elements of bridges and flyovers. This research proposes a novel test setup based on the principle of the Impact Echo (IE) Test Method for structural condition assessment, with the potential to be integrated with drones. This innovative approach is designed to effectively detection of defects in structural members at inaccessible locations. Additionally, the method aims to provide a portable and efficient solution for assessing the condition of such elements while also evaluating the effectiveness of various repair techniques.

Beam-column joints play a critical role in the structural integrity of reinforced concrete frame constructions, as they facilitate the transfer of moments and forces between beams and columns in different bays and storeys. Beam-column joints significantly impact the overall behaviour of the structure under gravity and lateral loads. While several strengthening approaches for beam-column joints have been investigated in previous studies, limited attention has been given to their monotonic load performance when joints are externally reinforced with steel plates, especially considering variations in plate placement and thickness within the joint region. In this study, a total of 15 beam-column joints with different topologies, with and without transverse reinforcement, are modelled using ANSYS APDL 2024 R1 (ANSYS Parametric Design Language) software to analyse their behaviour under increasing load until failure. Additionally, beam-column joints with steel plates 50 mm and 25 mm thick applied externally to the column, beam, and entire joint are also analysed to assess their strengthening effect and corresponding ductility index. The test results reveal that the application of externally applied 50 mm and 25 mm thick steel plates on the joint without transverse reinforcement leads to an increase in load-carrying capacity by 26.5

Geopolymer concrete (GC) is a promising alternative to conventional cement concrete owing to its environmental benefits. However, water penetration, which is a common concern, significantly affects the performance of GC, thus causing efflorescence, reinforcement corrosion, and scaling, among other durability issues, which affect its longevity. The present study attempts to clarify the efficacy of incorporating an integral crystalline waterproofing admixture in enhancing the durability of GC by reducing the penetration of water into the concrete matrix. The samples are subjected to compressive-strength and split-tensile-strength tests to evaluate the material’s strength properties. Additionally, water absorption, chloride penetrability, water contact angle, and acid-resistance tests are performed to ascertain the durability of the modified GC. The results show that GC samples with a 3 % crystalline waterproofing content performs the best, i.e., it reduced water absorption by 42,85 %, 40,90 %, and 45,26 % after 7; 28; and 56 days of curing. In addition to improving water absorption, the admixture significantly enhances the mechanical strength of GC, with increases in compressive strength by 15,74 %, 15,65 %, and 15,86 % at 7, 28, and 56 days, respectively. Additionally, scanning electron microscopy analysis is performed on the GC samples to understand the changes in the microstructure of GC mixes with various dosages of the crystalline waterproofing agent added to them.

Around the globe, cement production and its usage in developmental projects has increased carbon dioxide emissions, necessitating the development and adoption of eco-friendly substitute materials and technologies. Geopolymer concrete is a sustainable and effective alternative to traditional cement-based concrete that can be produced using different industrial waste products. A ternary blended Self-Compacting Geopolymer Concrete (SCGPC) made using 60

In this study, an attempt is made to analyse the reinforced concrete bridge by applying IRC Class AA-tracked moving load in longitudinal and transverse directions of the bridge. The Finite element model is formulated in ANSYS software. The variation in resultant parameters namely, total deformation, equivalent stress and equivalent strain produced in the bridge are analysed for moving load passing from different positions across the cross-section of the bridge. Also, for each case, the position of the moving load at which it gives the maximum values for the resultant parameters in the bridge is determined. The result shows that values for total deformation, equivalent stress, and equivalent strain in the bridge decrease by 13.76%, 9.48% and 9.48%, respectively, with an increasing eccentricity of 1200 mm to 2300 mm load position from the kerb. This shows that with the increase in the eccentricity of load from the kerb to the symmetric loading concerning the centerline of the bridge, there is a decrease in deformation, stress and strain. This implies that when a vehicle moves closer to the centerline of bridge, there is better distribution of load in the bridge than when vehicle moves closer to the kerb. This study also helps the way of creating baseline data for Structural Health Monitoring (SHM) of the structure by knowing the stress, strain and deformation existed in the bridge using Finite Element (FE) modelling.

Geopolymer Concrete (GC) is an innovative, environmentally friendly alternative to conventional concrete. The use of geopolymer as binder compared to Portland Cement has the potential to greatly reduce the carbon dioxide emissions and save natural resources being used in the production of building materials. GC, despite its many benefits, is susceptible to water penetration giving rise to durability and longevity issues in structures. Water can carry hostile ions like chlorides and sulphates among other deleterious substances which have the potential to undermine the structural integrity of the material. Therefore, it becomes imperative to address the vulnerability of GC to water penetration induced deterioration to guarantee long-term durability and dependability. The primary focus of this study is to investigate the impact of hydrophobic modification on the fresh state, mechanical, wettability and microstructure properties of GC. The microstructure was studied using Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-Ray Spectroscopy (EDS) analysis. The hydrophobic modification in GC is carried out by making use of polydimethylsiloxane (PDMS) as a hydrophobic additive to produce integral hydrophobic GC. The findings indicate that as the PDMS content increases, the Water Contact Angle (WCA) on the GC initially increases rapidly and then shows a gradually decreasing trend. PDMS inclusion in into GC showed a reduction in the compressive strength as well as the split tensile strength. Based on the experimental results and considering hydrophobicity as well as the mechanical properties, a PDMS content of 4 % is suggested as the most suitable, yielding a WCA of 132.18 & ring;.

Wind energy is a renewable energy source with a significant impact on the date for harnessing it. Different types of wind turbines (WTs) are being built to generate affordable, dependable, and eco-friendly renewable wind energy. Over time, cracks are found to be developed in the blades of the WTs, which is considered the most common type of damage that ultimately causes the catastrophic failure of the structures. This study aims to develop a structural health monitoring (SHM) framework for localizing cracks of a WT blade using a convolutional neural network (CNN)–based deep learning algorithm. With that objective, the NACA (National Advisory Committee for Aeronautics) 63-412 profile (WT blade) of length 29 m was modelled in finite element analysis (FEA) ANSYS 2022 R2. A crack is introduced to the model by making a groove at different blade locations. The mode shape and natural frequencies are obtained and validated with those reported in the literature. Further, the blade is excited by an impact load applied at the tip of the blade, and acceleration time histories are collected. The acceleration time history data are converted to scalogram images and fed into the CNN algorithm for damage classification and localization. In this study, the concept of class activation maps is also utilized for visual representations of the input images’ areas that significantly influence a class’s classification score. The classified results show that using CNN can successfully localize the region of the cracks and motivate us to examine it on a laboratory-based model.

This study explores the fresh state properties, as well as the mechanical and microstructural properties, of self-compacting geopolymer concrete (SCGPC) using class F-fly ash, ground granulated blast furnace slag (GGBFS), and waste ceramic powder (WCP) as binders. Due to their high silica and alumina content, fly ash and GGBFS are predominantly used as raw materials in geopolymer concrete (GPC) production. In this study, we developed a new SCGPC using waste ceramic powder under ambient curing as a new construction material. Three factors were considered: binder content, including three combinations of GGFBS and WCP, dosage of molarity, and dosage of superplasticizer with different proportions. A mix containing 60

Strength monitoring is a crucial aspect in determining the durability and serviceability of concrete based structures. Strength monitoring can be done using two main approaches which are broadly termed as destructive testing and non-destructive testing. This study focusses on the applicability of non-destructive techniques (NDT) for concrete testing such as acoustic emission technique (AET) and ultrasonic guided wave (UGW) method in order to monitor early age setting properties of concrete which is modified by flyash addition. Experimental investigation was carried out on concrete mixes containing varying amounts of flyash which went up from 0

In the past two decades, thin lead zirconate titanate (PZT) sensors have been widely used in the electro-mechanical impedance (EMI) technique for sensing applications, particularly for monitoring civil structures. They are typically surface bonded using an industrial adhesive to the monitored structure. The bond between a PZT sensor and structure must be sufficiently strong to transmit the response of the structure to the sensor. In this study, acrylic cubes bonded with PZT patches are subjected to high compressive strains above 2000 με to develop a better understanding of bonding conditions when structures undergo such high strains. Acrylic can undergo such high strains without developing fissures or cracks. Thus, the recorded EMI response only reflects changes in the bonding condition due to the development of strains. The experiments are also numerically supplemented by simulating various debonding conditions. At higher strains, it was observed that the admittance signatures tend to behave similarly to a freely vibrating PZT patch, indicating debonding around the periphery. Even after the complete unloading of the structure, the signatures did not return to their initial state, indicating a permanent partial debonding. The strains developed on a loaded structure are not uniform and can be localized due to structural imperfections, resulting in higher strains in the region where a sensor is bonded. The insights from this study will aid in expanding the scope of the application of PZT sensors for monitoring civil structures through better comprehension of the PZT-structure bond under high compressive strains.

The long-term durability of geopolymer concrete is one of the main problems that needs to be overcome before it can be universally acknowledged as a viable alternative to conventional concrete. The main cause of the durability issue is the migration and transport of water in the hydrophilic porous structure of geopolymer materials. To increase the long-term durability of geopolymer concrete, hydrophobic modification of geopolymers has recently garnered the interest of the researchers, and there is a lack of comprehensive summarization of the literature on hydrophobic geopolymer concrete composites, their preparation strategies, characterization methods, and properties, which has been the inspiration behind this literature review. This paper discusses the recent developments in the field of hydrophobic modification of geopolymer concrete, the different modification approaches, surface classification based on wettability, materials used, and the properties affected due to hydrophobic alternation. Properties studied include Water Contact Angle (WCA), surface energy, physical, mechanical, durability, and microstructural properties of the modified composites. Based on the literature reviewed, a pilot study was also carried out using an organosilane-based material to induce hydrophobicity in geopolymer concrete. Integral hydrophobic modification yielded a WCA of 66.083whereas surface modification yielded a WCA as high as 106.038, which indicates successful modification of a hydrophilic surface to a hydrophobic one. Although the work on hydrophobic geopolymer concrete is limited, this paper is anticipated to serve as a roadmap for future investigations into the creation, processing, and characterization of hydrophobic geopolymer concrete.

Wind responses on a twin box girder bridge can be observed by a wind tunnel experiment or by having a full-scale setup if possible. Another possible approach is to go through a numerical approach, which is the CFD simulation of the atmospheric boundary layer surrounding the twin box girder bridge deck. A virtual wind tunnel CFD modelling simulation was carried out on the bridge deck using the Ansys Fluent FSI technique to find out the displacement of the bridge deck. The steady-state simulations were computed. The turbulence model was used to calculate the mean force coefficients as K-ω SST. It has been seen that steady simulation is needed to get the static aerodynamic coefficients right when modelling. Ansys ICEM CFD is used for meshing the bridge deck. In this study, the wind flow behaviour around the structure is analysed at different wind incident angles of − 10°, − 5°, 0°, 5°, and 10°. The pressure variations at different wind directions are mapped in the present work. Responses across and along the wind are also depicted. It was found that the drag coefficient was higher at low angles of attack, whereas the moment and the lift coefficients showed fewer values at large angles.

The inherent nature of concrete is porous, hydrophilic, and microcracked, making it susceptible to water penetration into its matrix. This is the primary source of durability concerns. Furthermore, this type of penetration leads to considerable issues for concrete structures, resulting in significant financial burdens due to regular repairs and maintenance and a reduction in the structure's lifespan. In this study, the properties, uses, and advancements of hydrophobic concrete are investigated, focusing on durability, corrosion resistance, and sustainability. The various types and techniques for producing hydrophobic concrete are explored. Additionally, the paper presents the impacts of hydrophobic treatment on concrete properties such as compressive strength, water absorption, and permeability. Potential applications of hydrophobic concrete, including use in bridges, tunnels, and marine structures, are also discussed. The review concludes by examining the benefits, challenges and limitations of hydrophobic concrete technology, including aspects like cost-effectiveness, compatibility with other construction materials, and potential environmental repercussions. In summary, this review highlights the potential of hydrophobic concrete to transform the construction industry by offering enduring and sustainable solutions to water-related issues.

Skewed bridges are commonly used to cross those roadways, waterways, or railways which are not perpendicular to the bridge at the intersection. In the last few years, several cases of distresses in the skew bridges have been reported to CSIR-Central Road Research Institute for their investigation. From the investigations, it is experienced that there is lack of understanding amongst the bridge designers regarding the flexural behaviour of skew bridges especially with high skew angle (> 30°). This paper presents the case study of highly skewed three-cell reinforced cement concrete bridge, in which distresses in the form of diagonal cracks connecting the acute-angled corners in the soffit of the deck slabs were seen immediately after opening the bridge for the traffic. The aim of this study was to investigate the reasons for the distress observed in the bridge and to suggest suitable strengthening measures. To identify the reason of distress in the bridge, structural design of this bridge was reviewed and the non-destructive tests as well as core tests on the concrete were undertaken besides detailed visual inspection. Based upon the result of this study, it was concluded that insufficient longitudinal reinforcement in the direction of principal bending and the lower grade of concrete than designed, may be attributed as the one of the reasons for the development of diagonal cracks connecting the acute-angled corners in the soffit of the deck slab. Based on the present strength of the concrete and provided steel reinforcement, resisting bending moment capacity of the bridge was calculated. Repair and rehabilitation scheme was recommended for the shortfall capacity. This paper highlights the importance of understanding the structural behaviour of the skew bridges amongst the bridge designers especially when they are dealing with highly skewed bridges (skew angle > 30°). This will enable them to be cautious whilst designing, detailing and constructing skewed bridges to avoid the kind of distresses observed in this case study.

In this study, acrylic cubes bonded with PZT patches are subjected to high compressive strains above 2000 με to develop a better understanding of bonding conditions. Acrylic can undergo such high strains without developing fissures or cracks, thus the recorded EMI response only reflects changes in the bonding condition due to the development of strains. The experiments are also numerically supplemented by simulating various debonding conditions. At higher strains, it was observed that the admittance signatures tend to behave similarly to a freely vibrating PZT patch, indicating debonding around the periphery. Even after complete unloading of the structure, the signatures did not return to their initial state, indicating a permanent partial debonding. The insights from this study will aid in expanding the scope of application of PZT sensors for monitoring civil structures through better comprehension of the PZT-structure bond under high compressive strains.

Structural retrofitting and upgradation of existent structures is amongst one of the major challenges that modern civil engineers are currently facing. To this effect, self-compacting concrete (SCC) mixes can be used efficiently as a material for retrofitting of various structural members. In this study, the efficacy and applicability of SCC mixtures as retrofitting material for column specimens using jacketing techniques was investigated. It was found that retrofitting of damaged primary column samples making use of SCC jacket and reinforced with welded wire mesh restores and enhances the ultimate load carrying capacity of primary column specimen from 18 to 47% of the ultimate load carrying capability. It also enhanced the strain at ultimate load from 59 to 66% with respect to primary column specimens depending upon strength of concrete used in jacket and number of curing days. Two SCC mixes—OSCC1 and OSCC2—were used for retrofitting and it was reported that the use of OSCC1 as retrofitting material improved the load carrying capability of column specimens by 47%, whereas the use of OSCC2 as retrofitting material improved the load carrying capability of column specimens by 35% at 90 days of curing. Experimental results were then compared with analytical results revealing that out of the analytical models, Mander and Legeron model predict the ultimate load carried by the column specimens retrofitted with SCC more accurately. Saatcioglu model overestimated the strain, whereas Legeron model underestimated the axial strain at ultimate load. However, Mander model predicted the strains closer to experimental results.

Purpose This study aims to perform the experimental work on a laboratory-constructed steel truss bridge model on which hammer blows are applied for excitation. The vibration response signals of the bridge structure are collected using sensors placed at different nodes. The different damaged states such as no damage, single damage, double damage and triple damage are introduced by cutting members of the bridge. The masked noise with recorded vibration responses generates challenge to properly analyze the health of bridge structure. Design/methodology/approach The analytical modal properties are obtained from finite element model (FEM) developed using SAP2000 software. The response signals are analyzed in frequency domain by power spectrum and in time-frequency domain using spectrogram and Stockwell transform. Various low pass signal-filtering techniques such as variational filter, lowpass sparse banded (AB) filter and Savitzky–Golay (SG) differentiator filter are also applied to refine vibration signals. The proposed methodology further comprises application of Hilbert transform in combination with MUSIC and ESPRIT techniques. Findings The outcomes of SG filter provided the denoised signals using appropriate polynomial degree with proper selected window length. However, certain unwanted frequency peaks still appeared in the outcomes of SG filter. The SG-filtered signals are further analyzed using fused methodology of Hilbert transform-ESPRIT, which shows high accuracy in identifying modal frequencies at different states of the steel truss bridge. Originality/value The sequence of proposed methodology for denoising vibration response signals using SG filter with Hilbert transform-ESPRIT is a novel approach. The outcomes of proposed methodology are much refined and take less computational time.

Concrete is inherently micro-cracked, porous, and hydrophilic by nature making it prone to water ingress into its matrix which is the primary cause of all durability issues related to concrete. Water acts as a carrier of corrosive ion species which apart from weakening the matrix due to its reaction with cement paste, also causes reinforcement corrosion, carbonation, and efflorescence. In addition, in the regions subjected to subzero temperatures, water in the pores of concrete freezes and thaws on temperature fluctuations, causing cracking and spalling of concrete. The uncertainty in the quantification of above concrete characteristics poses serious durability problems in concrete structures causing heavy economic losses due to frequent repair and maintenance and also leading to a reduction in the service life of the structure. To mitigate these harmful effects related to water penetration in concrete, numerous studies focused on hydrophobicity of the concrete and mortar have been carried out. Concrete hydrophobicity can be accomplished by either surface protection systems or by integral hydrophobic modification. Properties such as rheological properties, mechanical properties like compressive and flexural strength, durability properties such as pore structure and permeability, air entrainment, water absorption, sorptivity, water contact angle and sliding angle, chloride ion penetration, corrosion resistance, carbonation and freeze-thaw resistance, and microstructure analysis have been reviewed in this paper for ordinary hydrophobic concrete as well as for hydrophobic geopolymer concrete. Studies conclude that hydrophobic treatment of concrete is an effective way of preventing water ingress into the concrete matrix, in turn enhancing the durability and service life of concrete structures.