Performance Of Concrete Structures Research Articles

Dynamic increase factor of concrete compressive strength in confined split hopkinson pressure bar tests

This study presented a methodology to evaluate the pure strain-rate effect on concrete compressive strength and developed a pure rate dynamic increase factor (DIF) model through numerical and experimental investigations into confined split Hopkinson pressure bar (SHPB) tests. The numerical investigation proposed the methodology to determine the pure rate DIF through confined SHPB tests. Subsequently, the confined SHPB tests were conducted on concrete specimens, and a pure rate DIF model was developed based on this methodology. Additionally, conventional SHPB tests were performed to obtain an apparent DIF, which was then compared to the developed pure rate DIF. The results indicated that the apparent DIF exceeded the pure rate DIF, thus confirming its tendency to overestimate the strain-rate effect on concrete. Therefore, the proposed methodology using confined SHPB tests provides an alternative approach to overcome the limitations of the apparent DIF determined from conventional SHPB tests. Lastly, the developed pure rate DIF model was validated through numerical analyses on conventional SHPB tests and drop-weight impact tests of reinforced concrete beams. This validation demonstrated that the proposed pure rate DIF model effectively considers the strain-rate effect on concrete structures, thereby enabling assessment of the performance of concrete structures under extreme loading conditions.

Modeling of Concrete Deterioration under External Sulfate Attack and Drying-Wetting Cycles: A Review.

This paper comprehensively summarizes moisture transport, ion transport, and mechanical damage models applied to concrete under sulfate attack and drying-wetting cycles. It highlights the essential aspects and principles of each model, emphasizing their significance in understanding the movement of moisture and ions, as well as the resulting mechanical damage within the concrete during these degradation processes. The paper critically analyzes the assumptions made in each model, shedding light on their limitations and implications for prediction accuracy. Two primary challenges faced by current models under sulfate attack and drying-wetting cycles are identified: the limited consideration of the coupled effects of chemical and physical attacks from sulfate, and the unclear mechanism of the sulfate attacks. Future research directions are proposed, focusing on exploring the transport mechanism of sulfate ions under various driving forces and further clarifying the crystallization process and expansion damage mechanism in concrete pores. Addressing these research directions will advance our understanding of sulfate attack under drying-wetting cycles, leading to improved models and mitigation strategies for enhancing the durability and performance of concrete structures.

Effects of Waste Glass Powder as Partial Replacement of Cement on the Structural Performance of Concrete

Effects of Waste Glass Powder as Partial Replacement of Cement on the Structural Performance of Concrete

Structural Performance of Concrete: Exploring the Limits of Steel Fiber Reinforcement

Structural Performance of Concrete: Exploring the Limits of Steel Fiber Reinforcement

Učinak uzoraka utora na čvrstoću prionljivosti u betonu ojačanom bambusom

The use of bamboo as a reinforcement material in concrete has garnered attention in recent years due to its low cost, renewability, and high strength-to-weight ratio. However, the bond strength between bamboo and concrete is a crucial factor affecting the overall performance of bamboo-reinforced concrete structures. In this study, the bond between bamboo and concrete is investigated through pull-out tests. Three different groove patterns - rectangular, semi-circular, and V-notch - are examined for their bond strength. Various chemical treatments are also being explored to reduce the water absorption capacity of bamboo splints. The highest bond strengths achieved after using Bond Tite adhesive and bituminous paint are 1.94 MPa and 1.41 MPa, respectively. The findings of this study can be valuable in optimizing the design and construction of bamboo-reinforced concrete structures.

Effects of multi-layer Ti3C2Tx nanosheets on compression strength and abrasion resistance of concrete

Concrete is a leader composite material for structural use in buildings, adaptable to all locations and circumstances in view of its properties such as versatility, durability, and performance. MXenes are new two-dimensional (2D) materials that are very promising for applications in many fields due to their layered structure and physicochemical characteristics. Focused on increasing the performance of concrete structures, this work proposed the reinforcement of concrete with the addition of very small amounts (0.02 wt-%) of MXenes consisting of multi-layer Ti3C2Tx nanosheets to improve compression and abrasion resistance. The reinforced concrete specimens were tested by uniaxial compression tests and rubber-wheel abrasion tests. The results obtained were compared with reference concrete prepared without any added nanosheets. The concrete with MXenes presented higher compression strength (15% higher) in relation to the reference samples after 3 days of molding. After 28 days, the average compression strength was 20.5% higher with Mxenes, but the difference at 28 days was not statistically significant. The rubber-wheel abrasion tests showed a tendency for reduced wear rates with Mxenes, but the difference was statistically significant only for the tests with larger abrasives. Differences in macroporosity of the concretes were not found to justify the improved performance with Mxenes. The main differences due to the Mxenes reinforcement were due a smoother microtopography. It was proposed that the mechanism responsible for obtaining smoother topography with MXenes was related to the lubricious nature of the Ti3C2Tx nanosheets, that can reduce interparticle friction when a transition of the paste flow to the thickening regime occurs, which is governed by boundary lubrication.

A review on retrofitting concrete members with near‐surface mounted‐fiber reinforced polymer composites

AbstractIn an era flooded with a multitude of studies investigating the performance of concrete structures retrofitted using fiber‐reinforced polymer (FRP) materials, this review addresses the critical need for a comprehensive overview of the retrofitting of concrete members using near‐surface mounted (NSM)‐FRP composites, aiming to save time and effort while providing engineers and research community with valuable resources relevant to the field. This review focuses on the key factors influencing both the flexural and shear retrofitting processes of reinforced concrete (RC) beams, such as the percentage, type, size and geometry of NSM‐FRP reinforcement, as well as groove design, groove‐filling materials and beam depth. Moreover, the paper explores the failure modes associated with each retrofitting type, for example, debonding failures, shear/flexural failure and rupture of steel or NSM‐FRP reinforcement, to name a few. The review also delves into the bond behavior of NSM‐FRP‐bonded joints, examining factors, such as the bonded length, surface texture of NSM‐FRP reinforcement and type of bonding agent, which would affect the bond behavior and strength of the joints. The failure mechanisms associated with the bonded joints, such as interfacial bond failure, FRP rupture and splitting of the adhesive cover, are also highlighted. Finally, this compilation aims to guide engineers and researchers by offering a critical and comprehensive database for optimal designs, further development and suggesting future research directions.

The failure evolution of hydraulic asphalt concrete under different tensile fatigue loading

The fracture and damage evolution patterns of hydraulic asphalt concrete (HAC) under cyclic tensile loading determine the performance of asphalt concrete impermeable structures in embankment dams under seismic loading. Therefore, in this study, the whole fatigue tensile damage process of HAC under different loading conditions was studied with the help of acoustic emission (AE) technique. The results indicated that the fatigue behaviors of the HAC and AE signals follow the same evolutionary pattern, experiencing the initial deformation stage, the stability stage, the acceleration stage, and the failure stage. The b value, obtained from the least square fit between AE event number and magnitude, decreases to its lowest point upon specimen failure, and this decrease corresponds to a sudden increase in the peak frequency of the AE. The parametric analysis of relative amplitude-average frequency values classified for different cracking modes revealed that the tensile cracking dominates during the fatigue damage process, while the proportion of shear cracking events increases during the failure stage. Moreover, the peak value of the proportion of shear cracking events appears within the range near the point of failure, making it a useful indicator for providing critical warnings of HAC fatigue damage.

Combined Impact of PolypropyleneFibers and Silica Fume on M30 Concrete Grade

This research project investigates the combined influence of silica fume and polypropylene fibers on the mechanical properties of M30 grade concrete. Silica fume, known for its ability to enhance concretestrength and durability, is introduced at varying percentages (0%, 10%, and 20%), while polypropylene fibers, chosen for preventing cracks and improving strength, are added at different levels (0%, 0.5%, and 1%). The project employs systematic experimentation, testing concrete mixes with different proportions of silica fume and polypropylene fibers at various curing periods for 7 days and 28 days to assess their impact on mechanical properties. The research seeks to identify the most effective mix design for achieving desired strength outcomes in M30 grade concrete. Silica fume is recognized for its ability to enhance concrete impermeability and strength, while polypropylene fibers offer benefits such as controlling shrinkage cracking and improving impact resistance. This research contributes to advancing construction materials by optimizing the utilization of silica fume and polypropylene fibers in concrete mixes. The findings aim to provide valuable insights for industry professionals seeking to improve the quality and performance of high-grade concrete structures. The search results indicate that the inclusion of silica fume helps the dispersion of fibers and increases the specimens' strength more than the addition of silica fume alone. Polypropylene fibers are also added to improve mechanical qualities.

EFFECT OF DUNE SAND AND FLY ASH ON THE MICROSTRUCTURE OF FIBER REINFORCED CONCRETE

The current study investigates the effect of dune sand (DS) and fly ash (FA) on the microstructure of fiber-reinforced concrete (FRC). Concrete is a widely used construction material, and understanding its behavior under different conditions is important for optimizing its performance. The use of alternative materials, like FA and DS, in concrete production has gained attention due to their abundance and potential environmental benefits. The research methodology involved the preparation of FRC mixes with different combinations of FA and DS, along with varying fiber content. The microstructural analysis of the samples was conducted through scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The findings revealed that the addition of FA and DS influenced the microstructure of the FRC. Furthermore, the inclusion of FA contributed to improved pore structure and enhanced the pozzolanic reaction, resulting in a denser microstructure. The incorporation of steel and basalt fibers demonstrated significant effects on the microstructure of the concrete. The results provide valuable insights for optimizing the design and performance of concrete structures in arid regions while considering sustainable materials.

Prediction models for creep and creep recovery of fly ash concrete

In order to clarify the deformation effect of fly ash concrete members after loading and unloading subsequently, experiments on creep and creep recovery of fly ash concrete were carried out on consideration of three fly ash contents and two concrete loading ages. After comparing the available prediction models for concrete creep, the B4 model was modified by multiplying the influence coefficient and creep terms, and the fly ash concrete creep prediction model was established correspondingly. The comparison shows that the modified B4 model is in good agreement with the experimental data. Furthermore, based on the experimental phenomena and the development law of creep recovery of fly ash concrete, the prediction model for creep recovery of fly ash concrete was proposed in combination with the factors affecting creep recovery which include loading age, fly ash content, etc. Finally, the calculated values of the proposed creep recovery model were compared with the experimental results and the applicability of the model was discussed. The creep and creep recovery model of fly ash concrete proposed is of great significance for revealing the time-varying law of fly ash concrete and improving the performance of concrete structures.

Comprehensive analytical study on seismic performance of concrete structures equipped with self-centered hybrid wall system in moderate to high seismic hazard zones

Comprehensive analytical study on seismic performance of concrete structures equipped with self-centered hybrid wall system in moderate to high seismic hazard zones

Compressive and Bonding Performance of GFRP-Reinforced Concrete Columns

The use of glass-fiber-reinforced polymer (GFRP) bars as an alternative to steel bars for reinforcing concrete (RC) structures has gained increasing attention in recent years. GFRP bars offer several advantages over steel bars, such as corrosion resistance, lightweight, high tensile strength, and non-magnetic properties. However, there are also some challenges and uncertainties associated with the behavior and performance of GFRP-reinforced concrete (GFRP-RC) structures, especially under compression and bonding behavior. Therefore, there is a need for comprehensive experimental investigations to validate the effectiveness of GFRP bars in concrete columns. This paper presents a study that aims to address these issues by conducting experimental tests on GFRP-RC columns. The experimental tests examine the mechanical properties of GFRP bars and their bond behavior with concrete, as well as the axial compressive behavior of GFRP-RC columns with different reinforcement configurations, tie spacing, and bar sizes. The findings reveal that GFRP bars demonstrate a comparable, if not superior, compressive capacity to traditional steel bars, significantly contributing to the load-bearing capacity of concrete columns. The study concludes with a set of recommendations for further exploration, underscoring the potential of GFRP bars in revolutionizing the construction industry.

Enhancing concrete durability with polymer impregnation: A comparative study of corrosion and freeze-thaw resistance

This study explores the efficacy of Polymer Concrete (PC) in bolstering the durability and performance of concrete structures under diverse environmental conditions. Three variants of PC were examined: Polymer Impregnated Concrete (PIC), Polymer Portland Cement Concrete (PPCC), and Polymer Concrete (PC). The study focused on their resistance to corrosion and freeze-thaw cycles. The research also delved into the protective influence of various polymers, including silicone and epoxy, on both concrete and steel. The findings revealed that PIC surpassed other PC types in terms of corrosion and freeze-thaw resistance, while PC and PPCC necessitate further improvements. Silicone emerged as the most potent polymer for enhancing the durability of concrete and steel. PIC, exhibiting superior compressive strength and durability compared to control samples, was proposed as an apt material for construction projects in cold and corrosive environments. The PIC samples, composed of polymer, silicone, and polyvinyl acetate, displayed a significant improvement in their corrosion potential. Over a 90-day period, these samples showed a reduction of approximately 70 units, resulting in a value of 560 mV. When juxtaposed with other PC variants tested in the study, the PIC samples demonstrated superior corrosion resistance. The PIC samples also exhibited a higher average compressive strength and improved frost resistance compared to the PPCC and PC samples. The strength of PIC samples was 16.7% and 14.3% higher than control before and after cycles, respectively. Conversely, PPCC and PC samples displayed lower strengths than control, with PC samples recording the lowest. The strength reduction due to freeze-thaw cycles was least in PIC samples. In conclusion, PIC holds promise as a material for enhancing the durability and performance of concrete structures. Further research is recommended to assess its cost-effectiveness and environmental impact.

Unraveling the Effects of Compound Additives on the Strength of Cast Concrete

Purpose: The aim of this study is to examine the influence of a complex additive on the fundamental physico-mechanical properties of cast concrete. Methods: The research involves the introduction of a complex additive, comprised of plasti-cizers such as "ACF," "SAFA," and "SOAPSTONE," into the concrete mixture. This leads to structural changes in the cast concrete, impacting its physico-mechanical properties, including strength, uniformity, deformability, durability, and cement utilization coefficient. The significance of each component of the additive is thoroughly examined to identify optimal dosages and meth-ods of introduction for achieving desired results. Results and Conclusion: The conducted analysis reveals insights into the impact of the complex additive on the final characteristics of the concrete. Optimal dosages and incorporation methods are identified, contributing to enhanced performance and durability of cast concrete structures. Research Implications: The practical aspects of utilizing the complex additive in real con-struction conditions are elucidated, with examples provided to optimize construction processes, increase efficiency, and reduce environmental burden. Furthermore, the study underscores the im-portance of further research in developing more effective and sustainable construction materials and technologies. Originality/Value: The research contributes to the advancement of knowledge in the field of construction materials by highlighting the influence of complex additives on the physico-mechanical properties of cast concrete. The obtained results have implications for improving the quality and durability of concrete structures across various construction sectors.

Advancing ultimate bond stress–slip model of UHPC structures through a novel hybrid machine learning approach

The significance of Ultimate Bond Stress-Slip (UBS-S) in reinforced Ultra-High Performance Concrete (UHPC) structures cannot be overstated, as it directly affects their load-carrying capacity, structural integrity, and long-term performance. A comprehensive analysis of the UHPC-Parallel Micro Element System (UHPC-PMES), including 144 specimens, evaluated the computational efficiency of the proposed UBS-S model. To this end, the most critical settings of steel bar diameter, concrete cover, bond length, and UHPC compressive strength (db,c,lb,fUHPC′) were directed to create this parametric research. Applying the hybrid approach of three different optimization techniques, namely Physics-Informed Neural Networks (PINN), Genetic Algorithms (GA), and Multiple Linear Regression (MLR), this study predicted the UBS-S at the interface of UHPC and steel bars. It formulated the hyper-parameters effect values (a,m,β,G). The presented research used these algorithms to solve an inverse problem in structural engineering. Comparing the results obtained from PINN, GA, and MLR demonstrated that machine learning techniques and the proposed PMES model could effectively and accurately investigate the ultimate bond stress-slip for reinforced UHPC structures.

Mechanical performance analysis of prestressed socket assembled concrete frame structure relying on computer simulation analysis

In order to improve the mechanical performance analysis of assembled concrete frame structure, this paper combines with computer simulation technology to analyze the mechanical performance of concrete frame structure, and uses the concrete damage plastic constitutive model provided by ABAQUS to define the nonlinear constitutive behavior of concrete. Based on the elastic-plastic model, the damage variables are added to the model, which can better reflect the performance of concrete under cyclic loading, such as stiffness degradation. In addition, this paper uses ABAQUS finite element analysis software to further analyze the structural parameters of this form of joints, and design related prestressed socket assembled concrete frame to study the seismic performance of prestressed socket assembled frame structure. Finally, the effectiveness of this model is verified by computer simulation.

Stress-strain behavior of square concrete columns confined with hybrid B-CSM composites and development of novel prediction models

This paper presents a comprehensive investigation into the behavior of concrete confined with hybrid Basalt and Chopped Strand Mat (B-CSM) fibers. The newly proposed B-CSM confinement technique substantially enhances the brittle compressive stress-strain behavior, leading to a noteworthy increase in peak strength (approximately 90%) and ultimate strain (approximately 461 %). The efficiency of B-CSM confinement is affected by the strength of plain concrete, with lower-strength specimens indicating a more pronounced enhancement. The performance of existing analytical models for FRP confinement in predicting ultimate strength and strain in B-CSM confined concrete is assessed, highlighting the need for tailored models. Regression-based equations are proposed for characteristic points along the stress-strain curve, enabling accurate prediction of material behavior. The predicted stress-strain curves exhibit a high level of agreement with experimental results. These findings provide valuable insights for the design and application of B-CSM confinement techniques in structural engineering, facilitating improved performance and ductility of concrete structures under compressive loading conditions.

Study of pathological manifestations in concrete structures in the municipality of Carlos Chagas: case study

Concrete is the main material used in the construction industry. However, even with technological advances in its production, many structures perform unsatisfactorily due to errors in design, implementation, maintenance, repairs, poor quality materials, lack of maintenance and other factors of a physical, chemical or mechanical nature that contribute to structural deterioration. Given this scenario, it is crucial to explore contemporary solutions to improve the durability and performance of concrete structures in construction. Therefore, greater knowledge of structures and materials is needed, through studies and analysis of pathological manifestations, as this makes it possible to evolve the quality of constructions, which allows for better habitability and durability. The main objective of this study is to investigate the main causes of pathological manifestations in reinforced concrete structural elements in a building in the municipality of Carlos Chagas-MG, as well as methods of preventing and repairing them. To this end, the work was divided into two stages: a literature review to provide a theoretical basis for finding out about published studies dealing with the proposed topic, as well as defining an appropriate analysis methodology, and a case study. In addition, on-site visits were made to assess the state of the building and record pathologies. The results showed various pathologies such as exposure to corrosion of the reinforcement, segregation of the concrete, cracks and fissures, and efflorescence. Thus, intervention proposals were made as described in the literature to provide safety, stability, aesthetics and comfort for residents.

Research on uniaxial mechanical performance of high-performance concrete after high temperature rapid cooling and damage mechanism analysis

High-performance concrete (HPC) is widely used in civil and hydraulic engineering, with durability as its main indicator. During the service life of high-performance concrete structures, there is a risk of extreme fire incidents. The fire department generally adopt water cooling to quickly control the fire after a fire occurred. Studying the mechanical property of high-performance concrete after high temperature and rapid cooling is of great significance for evaluating the safety performance of high-performance concrete structures after a fire. Therefore, three types of uniaxial loading modes (uniaxial compression, pure shear, uniaxial tension) and five temperatures (20OC, 200OC, 400OC, 600OC, 800OC) were considered in this study. Hydraulic servo machine was used to conduct experimental research on the uniaxial mechanical properties of high-performance concrete after high temperature and rapid cooling. In addition, digital image correlation (DIC) and acoustic emission technology (AE) were combined to analyze the external and internal damage evolution processes of concrete during loading process. The experimental results are as follows: as the temperature increases, the compression strength of high-performance concrete under uniaxial compression is initially increased and then decreased, with a maximum reduction of 62.02%; however, the strength of high-performance concrete under pure shear and uniaxial tension conditions are gradually decreased, with maximum reduction of 76.12% and 81.26% respectively; compared to room temperature cooling conditions, the strength of high-performance concrete under water cooling condition is decreased more greatly, but this difference gradually decreases with the increase of temperature; combined with the analysis of DIC and AE, under different stress states, the surface main cracks of HPC become more tortuous and accompanied by more micro-cracks under the influence of high temperature, and the evolution process of cracks inside HPC also changes significantly with the temperature. At the same time, the surface damage process of HPC under the influence of load has obvious lag compared with the internal damage process. Finally, based on the cumulative ringing count obtained by AE, the damage process of high-performance concrete under different loads is characterized, and the constitutive model of high-performance concrete after high temperature and rapid cooling under different loading modes is established. The research results provide a theoretical basis for the safety evaluation and calculation of high-performance concrete structures after fire.