Civil Engineering Applications Research Articles

Intelligent railroad inspection and monitoring

Railways are essential to the global transportation infrastructure, providing eco-friendly and economical solutions for the movement of freight and passengers. Inspecting and maintaining extensive rail networks timely poses significant challenges. My group and collaborators have focused on automated railroad inspection technologies, emphasizing the use of deep learning and computer vision to overcome the limitations of traditional manual inspections. Our research introduces groundbreaking real-time inspection methods, leveraging a specialized dataset of railroad components for enhanced instance segmentation models, achieving unprecedented accuracy and inference speeds. The developed computer vision systems efficiently detect track components and their changes over time, and also quantify rail surface defects. Additionally, our work extends to improving railroad crossing safety, utilizing deep learning frameworks for the detection of unusual pedestrian behaviors and object identification, aimed at reducing crossing incidents and improving emergency response times. Our future research directions aim to further refine the cost-effectiveness and autonomy of railroad inspection systems. Through these innovations, we hope to aid in the inspection and maintenance of railroads, offering practical solutions for railroad and other civil engineering applications.

Multi-objective optimization of sustainable cement-zeolite improved sand based on life cycle assessment and artificial intelligence

Background Cement-zeolite improved sand can be used in diverse civil engineering applications. However, earlier research has not duly optimized its production process to attain best mechanical strength, lowest cost, and least environmental impact. This study proposes a multi-objective optimization approach using back-propagation neural network (BPNN) to predict the mechanical strength, along with an adaptive geometry estimation-based multi-objective evolutionary algorithm (AGE-MOEA) to identify the best parameters for cement-zeolite-improved sand, filling a long-lasting research gap. Methods A collection of unconfined compression tests was used to evaluate cemented sand specimens treated with stabilizers including portland cement (at dosages of 2, 4, 6, 8, and 10%) and six dosages of natural zeolite as partial replacement for cement (0, 10, 30, 50, 70, and 90%) at different curing times of 7, 28, and 90 days. The study further conducts a detailed analysis of life cycle assessment (LCA) to show how partial zeolite replacement for cement impacts the environment. Through a tuning process, the BPNN model found the optimal architecture and accurately predicted the unconfined compressive strength of cement-zeolite improved sand systems. This allowed the AGE-MOEA to optimize zeolite and cement dosages, density, curing time, and environmental impact. Results The results of this study reveal that the optimal range of zeolite was between 30-45%, which not only increased cemented sand strength, but also reduced the cost and environmental impact. It is also shown that increasing the zeolite replacement to 25-30% can increase the ultimate strength of cemented sand, yet exceeding this limit can cause the strength to decrease. Conclusions Zeolite has the potential to serve as an alternative for cement in applications that involve cemented sand, while still achieving mechanical strength performance, which is comparable or even superior. From an LCA standpoint, using zeolite as partial cement replacement in soil improvement projects is a promising alternative.

Synthesis and characterization of bentonite-based lightweight ceramic aggregates using coal combustion residue and kerosene bloating agent

Coal combustion residue (CCR) is an industrial by-product that has been widely adopted in civil engineering applications. However, a significant portion of CCR is still left unused around the world. This study investigates the feasibility of incorporating CCR into ceramic aggregates to enhance their engineering properties. Through a combination of kerosene as a bloating agent and CCR addition, the study demonstrates significant improvements in ceramic aggregate properties. Particle strength ranged from 0.33 to 8.53 MPa, with density variations between 0.39 and 0.95 g/cm³. Additionally, the additives also promoted the crystallization process, as shown by the increase in crystallinity from 40.67% to 61.87%. This was confirmed by the X-ray diffraction analysis, which revealed the changes in the mineral composition and crystallinity due to the additives. Furthermore, the micro and macro pores of bentonite profoundly influence the bloating process of aggregate, contributing to the formation of a well-distributed porous structure in ceramic pellets. The resulting ceramic aggregate exhibited favorable strength-to-density ratios suitable for both structural and non-structural concrete applications. This research highlights the potential of CCR utilization in ceramic aggregates, offering sustainable solutions for the construction industry while mitigating waste disposal concerns.

Fine-Grained Permeable Surface Mapping through Parallel U-Net.

Permeable surface mapping, which mainly is the identification of surface materials that will percolate, is essential for various environmental and civil engineering applications, such as urban planning, stormwater management, and groundwater modeling. Traditionally, this task involves labor-intensive manual classification, but deep learning offers an efficient alternative. Although several studies have tackled aerial image segmentation, the challenges in permeable surface mapping arid environments remain largely unexplored because of the difficulties in distinguishing pixel values of the input data and due to the unbalanced distribution of its classes. To address these issues, this research introduces a novel approach using a parallel U-Net model for the fine-grained semantic segmentation of permeable surfaces. The process involves binary classification to distinguish between entirely and partially permeable surfaces, followed by fine-grained classification into four distinct permeability levels. Results show that this novel method enhances accuracy, particularly when working with small, unbalanced datasets dominated by a single category. Furthermore, the proposed model is capable of generalizing across different geographical domains. Domain adaptation is explored to transfer knowledge from one location to another, addressing the challenges posed by varying environmental characteristics. Experiments demonstrate that the parallel U-Net model outperforms the baseline methods when applied across domains. To support this research and inspire future research, a novel permeable surface dataset is introduced, with pixel-wise fine-grained labeling for five distinct permeable surface classes. In summary, in this work, we offer a novel solution to permeable surface mapping, extend the boundaries of arid environment mapping, introduce a large-scale permeable surface dataset, and explore cross-area applications of the proposed model. The three contributions are enhancing the efficiency and accuracy of permeable surface mapping while progressing in this field.

Mathematical Modeling of a Corrugated Geogrid and Geocell Reinforced Flexible Pavement Base with Interlayer Shear Performance Analysis

To combat permanent deformation in flexible road pavements and extend lifespan while reducing maintenance costs, an investigated solution "Corrugated Geogrid and Geocell Reinforced Flexible Pavement Base Design" is proposed. It enhances durability by improving inter-layer bonding and increasing the friction coefficient with a Corrugated Imminent Hexagonal Composite Geogrid, boosting pavement bearing capacity. The necessity of this research is the integration of corrugated geogrids and geocells into the design of flexible pavement, in conjunction with a comprehensive evaluation of interlayer shear performance, effectively tackles a range of engineering obstacles and enhances the pavement system's durability, stability, and affordability. Geogrid's corrugated structure resists shoving, offers stabilization, and, combined with Fusion Geoblanket and Perforated Geocell, prevents potholes. Typically, geocellular brace parts are utilized in civil engineering and technical applications, and they are frequently connected to geocellular systems or geocells. These systems are frequently employed in the building of retaining walls, slope protection, erosion control, and soil stabilization. The intended use and product design influence the installation procedures and specific functioning approach. The proposed model prevents permanent pavement failures, ensuring durability, low maintenance, and improved lifespan, assessed through Finite Element Analysis. Thus, the proposed method develops a layout for flexible pavement that's going to prolong its life expectancy and prevent long-term deformation failure.

Design and in field validation of a modular metamaterial for mitigation of railway induced vibrations

Metamaterials are artificial structures exhibiting wave control properties that can be exploited in civil engineering applications. Among them, locally resonant metamaterials are able to control and manipulate wave propagation at wavelengths several times larger than the unit cell size, and can therefore be useful for low-frequency vibration suppression. This paper presents the design, installation and validation of a 0.4 m thick metamaterial-based panel for mitigation of railway-induced vibrations. The barrier comprises a cubic locally resonating unit made of four concrete pyramids connected together by external slender steel rebars. The unit cell is characterized from the dynamic point of view both numerically and experimentally, and a full-scale field test is then performed on the barrier at the railway station in Elze (Germany). This test validates the effectiveness of the metamaterial-based panel in providing a low-frequency mitigation of 10 dB at the resonance frequency around 30 Hz, in good agreement with the numerical and laboratory tests.

Effect of structural parameters on compression performance of autoclaved aerated concrete: Simulation and machine learning

Autoclaved aerated concrete (AAC) has broad applications in civil engineering due to its lightweight, thermal and sound insulation. However, the relation between the complex random porous structures and the compression performances of AAC is complex, limiting the optimization and application of AAC. In this study, finite element simulation was implemented and validated based on the experimental results. The simulation results showed that the compressive strength of AAC increased by 31.7, 45.8, and 134% with the porosity decreasing from 70% to 40%, the average pore diameter decreasing from 1.5 to 0.5 mm, and the pore connectivity decreasing from 50% to 0, respectively. Then, based on the numerical dataset, integrated machine learning methods were implemented to rapidly predict the compressive properties of AAC and analyze the main factors affecting the compressive properties. The ML results showed that the CatBoost model had the best predictive performance based on the small dataset of simulation results, with an average relative error of 18% and 7% for compressive strength and modulus of AAC, respectively. The component modulus was the most important feature for predicting the compressive strength and modulus of AAC.

Mechanical properties of a novel high nitrogen and low nickel stainless steel S35657

Stainless steel exhibits excellent ductility and corrosion resistance, making it highly promising for applications in civil engineering. In order to investigate the mechanical properties of a novel stainless steel S35657, a total of 150 coupons including 125 plates and 25 rods were tested. The failure modes, stress-strain curves, and mechanical parameters of coupons were obtained. Fractographic analysis using scanning electron microscopy was also performed to investigate the failure mechanisms. It was found that all coupons exhibited ductile failure mode with elongation up to 52.08%. The nominal yield strength standard value reached 370.50 MPa, while the ultimate tensile strength standard value reached 736.07 MPa. The various existing typical constitutive models were assessed, indicating that these models provide a good fit in the elastic stage but are not applicable in the hardening stage. Based on the Ramberg-Osgood model and test results, a new constitutive model applicable to stainless steel S35657 was proposed. Moreover, a design reliability analysis was carried out using the Equivalent Normalization Method (JC method), and partial factors for resistance of stainless steel S35657 were calibrated, which were 1.05 under windless load combinations and 1.15 under windy combinations.

Experimental study on flexural performance of prestressed concrete beams strengthened by Fe-SMA plates

Shape memory alloy (SMA) is an innovative intelligent material, capable of restoring its shape before deformation upon reaching the critical activation temperature. This property promotes its promising applications in civil engineering. This paper proposes a novel reinforcement method and aims to investigate the reinforcing effect of iron-based shape memory alloy (Fe-SMA) plates on prestressed concrete (PC) beams through four-point bending tests on one reference beam without reinforcement and three Fe-SMA reinforced beams, as well as with three beams reinforced by carbon fiber-reinforced polymer (CFRP). The results show that Fe-SMA can effectively reduce concrete cracks, and improve stiffness and characteristic loads of beams without negative effects. Under the same loading conditions, new cracks of Fe-SMA reinforced beams were relatively fewer than those of CFRP reinforced beams. Besides, Fe-SMA exhibited superior performance when utilizing the same cross-sectional reinforcement material to enhance the bending capacity of beam, and proved more advantageous for improving stiffness and characteristic loads of beam under the identical initial tensile force. Furthermore, the reinforcing effectiveness of Fe-SMA positively correlates with the cross-sectional area (thickness) and recovery stress (pre-stretch level and activation temperature) of Fe-SMA. Increasing the thickness of Fe-SMA plates by 100%, while maintaining other parameters constant, resulted in a 33% increase in cracking load. Similarly, elevating the recovery stress from 314 MPa to 340 MPa led to a 12.5% rise in cracking load. This paper investigates the reinforcement effect of Fe-SMA plates on PC beams, and provides a reference for the application of Fe-SMA in PC beam reinforcement, laying a foundation for promoting the utilization of Fe-SMA in civil engineering.

Size effect on compressive behavior of GFRP bars

In the last three decades, studies investigating the use of Glass Fiber Reinforced Polymer (GFRP) bars as an alternative to conventional steel rebars have increased due to their corrosive resistance. In addition to corrosion resistance, GFRP bars utilize high specific tensile strength, which makes them highly desirable in civil engineering applications. However, major design guidelines for GFRP-reinforced concrete structures currently do not consider their compressive contribution. Nevertheless, there is a growing trend in utilizing GFRP bars as compressive elements, driven by various studies demonstrating their ability to bear compressive loads effectively. This increasing demand underscores the need to comprehend the mechanical properties of GFRP bars, particularly in terms of their compressive behavior. Furthermore, a standardized test method to evaluate their compressive properties has not yet been developed. Addressing these gaps, this research paper focuses on investigating the influence of specimen size on the compressive strength of GFRP bars, specifically emphasizing on the compressive properties of GFRP bars. Compressive tests were conducted on GFRP specimens with varying diameters while maintaining a constant slenderness ratio. The findings from these compression tests shed light on the critical role of size in the compressive behavior of GFRP. This research emphasizes the importance of considering size as a significant parameter in designing mechanical properties for GFRP reinforcements.

Effects of Periodic Materials on Distance Attenuation in Wall–Slab Structures: An Experiment

This research examines the application of periodic materials in wall–slab structures to mitigate impact noise and vibration propagation, a prevalent issue in multifamily housing. Traditional methods, such as floating floors, have proven insufficient in addressing low-frequency impact noises and in facilitating the identification of noise origins, leading to increased resident annoyance. Periodic materials, known for their effectiveness in controlling plane waves in civil engineering, were applied to the intermediate slab of a wall–slab experimental setup. The research involved assessing the attenuation of noise and vibration over distance before and after the application of periodic materials by measuring indoor sound pressure levels and the natural vibration amplitude of the structure’s members upon impact. The results showed that periodic materials not only facilitated distance attenuation but also significantly diminished noise and vibration throughout the structure, without the side effects of vibration amplification seen in prior civil engineering applications. This indicates a practical advancement in using these materials, offering a novel approach to sound insulation and enabling more precise impact source localization. Ultimately, this study contributes to improving urban living by suggesting a method to enhance acoustic comfort in multifamily housing, underlining the importance of further exploration in architectural applications of periodic materials.

Lattice concrete: 3D printed periodic cellular structures through selective cement hydration

3D printing of concrete allows fabrication of complex shapes and structures. Among various 3D printing approaches, the particle bed 3D printing technique has gained attention in recent years, especially for its ability to generate complex topologies that are otherwise impossible to make using cement-paste extrusion-based techniques. In this work, we present our trials on 3D printing cellular lattice concrete structures using a powder bed technique by employing selective cement hydration. Specifically, we print two-types of cellular concrete blocks (i) with interconnected spherical voids and (ii) with gyroid structures, each block with uniform edge lengths of 15 cm. We use Ordinary Portland Cement, fine-grained sand, and normal water, without the use of any admixtures or additives. The printing technology used was custom-made and is quite simple and inexpensive involving a syringe based water jetting on to a powder bed of cement and sand mixture. We discuss the quality of the printed specimens obtained as well as their strength characteristics. An inadvertent observation was made, where a compressive strength gain by a factor of more than 2 was obtained in specimens that were exposed to open atmosphere for a long duration after a 28 day curing period compared to those that were tested immediately after curing. The current study demonstrates the feasibility of fabricating cellular lattice concrete structures that can potentially be useful as programmable metamaterials for civil engineering applications.

A COMBINED ULTRASONIC PROCEDURE TO EVALUATE DAMAGE IN CONCRETE BEAMS SUBJECTED TO STATIC LOAD

Concrete is utilized in a wide range of civil engineering applications specifically in infrastructure projects. In general, as with any construction material, it may be subjected to deterioration over time because of various reasons such as excessive loading and so on. In this research, two reinforced concrete beams on a large scale (length 2400 mm, depth 350 mm, and width 250 mm) are cast and tested under static load using the ultrasonic pulse velocity (UPV) technique consisting of three pairs of transducers (54 kHz, 150 kHz, and 250 kHz). During the loading, the signals are sent and captured through the used transducers at selected loading steps. Two new proposed procedures based on signal peaks in time and frequency domains are used to monitor the crack progress induced in concrete beams under concentrated load. The findings of this study revealed the suitability of the proposed two approaches to detect the propagation of cracks to evaluate damage induced in concrete beams.

Numerical Investigation of the Effect of Geocell-Reinforced Cushion on Load Distribution and Settlement Reduction in Unconnected Piled Raft Foundations

The effect of geocell-reinforced cushion on load distribution and settlement reduction in unconnected piled raft foundations was investigated. Modeling and analysis of various scenarios were carried out using Abaqus software. In this research, a total of nine models, including one connected, three unconnected and unreinforced, and five unconnected and reinforced with geocell, were analyzed. Cushions with thicknesses half of, equal to, and twice that of the foundation were used. The results have shown that optimal outcomes in terms of load distribution efficiency and settlement reduction are achieved when the cushion's stiffness is set at half that of the foundation. The obtained results demonstrate the positive effect of geocell reinforcement in enhancing the performance of unconnected piled raft foundations. The introduction of geocells into the models increases soil stiffness and pile load ratio, consequently enhancing the load-bearing capacity of the piled raft foundation compared to the unreinforced models. The study's findings pave the way for a more effective use of geocells in civil engineering applications, particularly in scenarios demanding high load-bearing capacity and minimal foundation settlement.

Clarisia racemosa: phytochemical characterization and biological activities a brief literature review

Clarisia racemosa is a valuable resource in the wood industry, commonly used as raw material for furniture, boat construction, civil engineering, and various other applications. However, this species is used in other sectors as well. Research has shown that this plant has therapeutic potential for medicinal purposes. This review aims to present the various biological activities of the Clarisia racemosa plant. This study was conducted by postgraduate students in the Morphotechnology program at the Federal University of Pernambuco, from September 1st to October 6th, 2023, as part of a course on scientific article and patent preparation. The research findings confirmed that the species has the ability to promote various beneficial activities, including antioxidant, antitumor, toxicological, insecticidal, antimicrobial, antiparasitic, and photoprotective effects. This review aims to increase the value of species found in the Brazilian flora by obtaining products with high added value.

Optimized systems of multi-layer perceptron predictive model for estimating pile-bearing capacity

The primary goal of this research is to leverage the advancements in machine learning techniques to forecast the bearing capacity of piles effectively. Accurately predicting load-bearing capability is an indispensable aspect in the field of substructure engineering. It is worth noting that determining load-bearing capability via in-place burden tests is a resource-intensive and labor-intensive process. This study presents a pragmatic soft computing methodology to tackle the aforementioned challenge, employing a multi-layer perceptron (MLP) for the estimation of load-bearing capacity. The dataset employed in this research encompasses a multitude of field-based pile load tests, with a meticulous selection of the most impactful factors influencing pile-bearing capacity as input variables. For a comprehensive comparative analysis, genetic algorithm-based optimizers (Crystal Structure Algorithm (CSA) and Fox Optimization (FOX)) were incorporated with MLP, leading to the development of hybrid models referred to as MLFO and MLSC, both structured with three layers. The performance of these models was rigorously evaluated using five key performance indices. The findings indicated a consistent superiority of MLFO over MLSC across all three layers. Remarkably, MLFO exhibited exceptional performance in the second layer (MLFO (2)), boasting an impressive R2 value of 0.992, an RMSE of 33.470, and a minimal SI value of 0.031. On the other hand, MLCS (1) registered the lowest accuracy in predicting the process with the least R2 value related to the validation phase of the model with 0.953. Taken together, these results affirm that the optimized MLP model stands as a valuable and practical tool for accurately estimating pile-bearing capacity in civil engineering applications.

Post-fire compressive behavior of CFRP stirrups reinforced CFST columns: Experimental investigation and calculation models

This paper investigates the post-fire compressive behavior of CFST columns reinforced with CFRP strip stirrups. CFRP materials possess higher tensile strength than steel, making them promising candidates to enhance the ductility of high strength concrete when properly confined. However, direct exposure to fire leads to burning and rapid loss of tensile capacity in CFRP materials. To mitigate this, the study explores embedding CFRP stirrups in concrete to provide additional confinement besides the steel tube which prevents fire penetration through concrete cracks and protects the CFRP stirrups. Through experimental tests and comparisons with steel stirrups reinforced counterparts, it was observed that the CFRP stirrups, even after heating, still provided confinement to the concrete core as the overlapping joints of the strips remained intact. The failure mode observed in the CFRP stirrups was the rupture of FRP, rather than debonding of overlapping joints. Additionally, the use of CFRP stirrups led to reduced concrete temperatures and significantly higher unit enhancement in residual load-bearing capacity for the CFST columns compared to steel stirrups. Practical calculation models were developed to estimate the historical maximum temperatures and residual load-bearing capacity of the CFRP stirrups reinforced CFST columns, regardless of whether high strength or normal strength concrete was used. The calculated values demonstrated good agreement with experimental results. This study provides valuable insights into the performance of CFRP stirrups reinforced CFST columns under post-fire conditions, highlighting their potential as effective fire-resistant and structurally efficient solutions in civil engineering applications.

Hydration properties of magnesium phosphate cement paste mixed with metakaolin and silica fume

AbstractMagnesium phosphate cement (MPC) exhibits a faster setting time and higher early strength, making it suitable for crack repair. However, its application in civil engineering is hindered by its fast initial hydration rate and poor water resistance. To address these limitations, metakaolin (MK) and silica fume (SF) were utilized to enhance the properties of MPC. The effects of MK and SF on the setting time, compressive strength, water resistance, hydration process, and microstructure of MPC were investigated. The results demonstrate that both MK and SF significantly prolong the setting time of MPC and improve its water resistance. The main hydration products of MPC, after incorporating MK and SF, are k‐struvite (MgKPO4·6H2O) and unreacted MgO. The presence of MgSiO3 and AlPO4 also contributes to the enhancement of compressive strength and water resistance. The incorporation of MK and SF actively participates in the hydration reaction of the MPC system. Furthermore, MgSiO3 and AlPO4 intertwine with MKP, resulting in a denser internal structure of the cured MPC, thereby improving its water resistance.

Flexural behavior of LVL made from Australian radiata pine

As a commonly used engineering wood in modern timber constructions, laminated veneer lumber (LVL), produced from small-diameter wood, short-dimension wood, or fast-growing wood, significantly enhances material properties to meet the mechanical and physical requirements in structural engineering. This study aims to investigate the feasibility of utilizing fast-growing Australian radiata pine to produce structural LVL, providing essential theoretical support for its application in civil engineering. The investigation focuses specifically on Australian radiata pine LVL (RP-LVL) and involves a systematic experimental study to assess the bending performance of RP-LVL under various bending directions and specimen sizes. The findings reveal that the edgewise bending strength of RP-LVL is comparatively lower than its flatwise bending strength. Nevertheless, RP-LVL exhibits superior bending strength compared to conventional glulam and dimensional lumber, rendering it an attractive and suitable building material for achieving enhanced bending performance in flexure members. Moreover, the study identifies significant influences of height and width on the bending strength of RP-LVL. Consequently, prediction method is proposed to calculate the bending strength of RP-LVL, considering these size influences. Importantly, the size influences on bending strength are quantified to provide a comprehensive evaluation of the bending capacity of RP-LVL flexure members.

Synergistic effect of recycling waste coconut shell ash, metakaolin, and calcined clay as supplementary cementitious material on hardened properties and embodied carbon of high strength concrete

Researchers are investigating eco-friendly binders like coconut shell ash (CSA), metakaolin (MK), and calcined clay (CC) as supplementary cementitious materials (SCM) in high-strength concrete (HSC). Abundantly available as industrial or agricultural waste, these materials, when combined with Portland cement (PC), offer synergistic benefits. This not only improves concrete performance but also addresses waste disposal issues, presenting a sustainable and environmentally friendly solution for long-term use in HSC production. However, this study performed on fresh and mechanical characteristics of HSC blended with CSA, MK, and CCA alone and together as SCM after 28 days of curing. A total of 504 samples of standard concrete were cast and the cubical samples were tested to achieve the targeted compressive strength about 80 MPa after 28 days. The experimental results indicated that the rise in tensile, flexural and compressive strengths of 9.62%, 8.27%, and 10.71% at 9% of CSA, MK, and CC as SCM after 28 days of curing. As SCM content increases, the density, porosity and water absorption of concrete decrease. Moreover, the workability of fresh concrete is getting reduced when the concentration of SCMs increases in HSC. In addition, the concrete's sustainability assessment revealed that employing 18% MK, CC, and CSA as SCM reduced carbon emissions by approximately 11.78%. It is suggested that using 9% CC, MK and CSA together in HSC yields the best results for practical applications in civil engineering.