Durability Of Concrete Structures Research Articles

Numerical Analysis of the Thermodynamic Response of a Hollow Concrete Cylinder

The stability and durability of concrete materials are essential factors in the construction industry. Environmental conditions, such as temperature affect the tensile strength and durability of concrete structures. This work investigates the thermodynamic behaviour of hollow cylindrical concrete using the finite element method (FEM). By deploying ANSYS®, the element mesh was created, and the temperature distribution inside the hollow cylinder was calculated. The effect of the hollowness of the concrete on its heat absorption is determined. The findings demonstrate that the temperature profiles changed radially throughout the concrete thickness. Moreover, it was discovered that the temperature distribution was impacted by the airflow into the cylinder. The numerical experiment in this study was essential in providing a comprehensive understanding of the behaviour of the concrete, particularly when exposed to higher heating rates. This study contributes to the knowledge of the performance and stability of concrete materials. It also demonstrates that the hollowness of the concrete enhances its heat-shielding performance. Furthermore, the inflow of air into the cylinder affects the temperature distribution, with a higher influx of air resulting in lower temperatures. These findings can be utilised to develop appropriate measures to enhance the performance and durability of concrete structures.

Effect of a Crystalline Admixture on the Permeability Properties of Concrete and the Resistance to Corrosion of Embedded Steel

Reinforced concrete structure durability hinges on concrete permeability, which relies on the characteristics of the inner porous network. Harmful ions and gases can accelerate steel corrosion. Permeability-reducing admixtures (PRA), including crystalline admixtures (CA), are commonly used to mitigate this. This study examines a commercial CA’s impact on durability-related aspects in concrete specimens. Two concrete mixtures with matching proportions were prepared: a reference mix and another mix with a commercial crystalline admixture. Several properties were studied, such as compressive strength, density, porosity, electrical resistivity, water absorption capacity, chloride diffusion, air permeability, and corrosion resistance. The studied admixture in concrete yields several positive outcomes such as a slight reduction in mixing water, a potential 6% increase in concrete’s compressive strength and the development of a denser and less permeable structure with 3% lower porosity and water absorption than the reference mix. Electrical resistivity improves by 10%. Unidirectional chloride diffusion tests show no differences. Air permeability decreases by from 36% to 55%, and the water absorption rate diminishes by 23%. The admixture potentially reduces the scatter in corrosion initiation periods for steel reinforcements, delaying corrosion onset by around 60 days, although more extensive experiments are needed for definitive conclusions.

The Impact of Climate Change and Carbonation on the Durability of Concrete Structures in Afghanistan

Infrastructure plays an important role in human settlements, offering essential facilities such as buildings, transportation and other necessary systems. However, the impacts of climate change, whether direct or indirect, create various challenges for human settlements and ecosystems. This study investigates the dual impact of climate change and carbonation on the durability of concrete structures in Afghanistan. The durability of reinforced concrete is significantly affected by the corrosion of steel reinforcement, and carbonation is the main factor causing corrosion of steel bars in concrete. With shifting climate patterns influencing environmental conditions, this study aims to analyze how these changes contribute to the carbonation process in concrete and the results will contribute to a deeper understanding of the challenges posed by climate-driven changes and carbonation, thereby providing the basis for necessary measures to minimize the environmental impacts. To facilitate this investigation, (75x75x75mm) concrete cubes were prepared and after 28 days of curing in laboratory conditions, the specimens were exposed in four different regions: Afghanistan, Japan, Indonesia and Malaysia. The carbonation depths were measured at the ages of 6 months and one year. Considering the environmental and climatic conditions of all mentioned regions, despite Kabul's lower humidity and temperature, the carbonation was still significant compared to the other regions. This substantial carbonation poses a threat to structures, emphasizing the need for special attention in the design phase to ensure resilience against climate-induced challenges.

Study on the monitoring method of debonding between concrete beams and reinforced steel plates based on piezoelectric smart materials

Concrete reinforcement is essential for ensuring the safety and durability of concrete structures. Bonding steel plates to reinforce concrete is widely used to renovate or strengthen concrete beam structures. Due to construction quality and the influence of factors such as environment and fatigue, debonding often occurs between the steel plate and concrete, making monitoring and early warning after concrete structure reinforcement challenging. This paper proposes a novel approach to monitor the degree of debonding between the steel plate and concrete beam using active sensing technology. The method uses lead zirconate titanate (PZT) as an actuator to generate stress waves. It prepares strip sensors with polyvinylidene fluoride as the sensing element to monitor stress waves passing through the steel plate and concrete beam. The monitoring system detects the degree of debonding between the steel plate and the concrete beam by monitoring the change in surface voltage of the sensor. Experiments show that the degree of debonding significantly correlates with the received voltage signal; the higher the debonding, the larger the received voltage signal. It is also observed that, at the same degree of debonding, the actuator and sensor attachment position have a particular impact on the received voltage signal. Through experiments and numerical simulation analysis, it is found that when the sensor is attached to the left side of the steel plate, that is, the bonded section of the steel plate, the amplitude of the voltage signal collected by the dynamic information acquisition system is the smallest, i.e., V_debonded section > V_middle > V_bonded section. Based on the above research, the active sensing technology proposed in this paper has good sensitivity to the degree of debonding between the steel plate and concrete. It is expected to become an effective monitoring and evaluation method for the degree of debonding between steel plates and concrete.

Preparation and Performance Study of High-Strength and Corrosion-Resistant Cement-Based Materials Applied in Coastal Acid Rain Areas.

Investigations regarding the preparation and durability of cement-based materials applied in specific coastal acid rain environments are scarce, particularly those involving the addition of four auxiliary cementitious materials (ACMs) to cement for modification. To improve the durability of concrete structures in coastal acid rain areas, a systematic study was conducted regarding the preparation of high-strength and corrosion-resistant cement-based materials using ACM systems composed of fly ash (FA), granulated blast furnace slag (GBFS), silica fume (SF), and desulfurization gypsum (DG) instead of partial cement. Through an orthogonal experimental design, the effect of the water-binder ratio, cementitious ratio, and replacement cement ratio on the compressive strength, corrosion resistance coefficient, and chloride ion permeability coefficient of the materials were analyzed and the mix proportions of the materials were evaluated and optimized using the comprehensive scoring method. The results show that implementing a FA:GBFS:SF:DG ratio of 2:6:1:1 to replace 60% of cement allows the consumption of calcium hydroxide crystals generated through cement hydration, promotes the formation of ettringite, optimizes the pore structures of cementitious materials, and improves the compressive strength, acid corrosion resistance, and chloride ion permeability of the materials. This study provides a reference for selecting concrete materials for buildings in coastal acid rain environments.

Impact of Fracture–Seepage–Stress Coupling on the Sustainability and Durability of Concrete: A Triaxial Seepage and Mechanical Strength Analysis

As an indispensable material in construction and engineering, concrete’s mechanical properties and permeability are crucial for structures’ stability and durability. In order to reasonably assess and improve the durability of fracture-containing concrete structures and to enhance the sustainable working life of concrete structures, this research investigated the seepage characteristics of fracture-containing concrete and its mechanical property deterioration under fracture–seepage coupling by testing the permeability and strength of concrete samples before and after water penetration using triaxial seepage test and mechanical strength test. The results show that the fracture–seepage coupling action significantly affects the permeability characteristics and mechanical strength of fracture-containing concrete. In particular, the strength of concrete samples containing a single fracture decreased with increased fracture angle, with a maximum decrease of 32.8%. The fracture–seepage–stress coupling significantly reduced the strength of the fracture-containing concrete samples, which was about twice as much as the strength of the no-fracture concrete samples. Different fracture angles affect the mode of fracture expansion and damage (The fracture angle varies from small to large, and the damage form of concrete changes from tensile damage to tensile–shear composite damage). Moreover, the coupling effect of fracture–seepage–stress will further increase fracture-containing concrete’s fragmentation in the damage process. Therefore, improving the seepage and fracture resistance of concrete plays a vital role in improving the sustainable working life of concrete structures.

Microstructural damage and durability of plateau concrete: Insights into freeze-thaw resistance and improvement strategies

Extreme environmental conditions and inferior building materials in plateau regions present significant challenges to the durability of concrete structures, particularly in resisting freeze-thaw cycles. This study employs an actual mix ratio from a concrete mixing station in the Qinghai-Tibet Plateau for a comparative analysis against conventional mixes in plain terrains. Utilizing a fast-freezing test with controlled variables, the study explores the microstructural evolution of plateau concrete. Results reveal that although the adapted mix ratio meets strength criteria, it falls short in frost resistance compared to standard concrete used in plain regions. Further, the plateau-specific curing conditions were shown to increase both the width and porosity of the interface transition zone (ITZ). High clay content in building materials for plateau construction also impacts the cement paste's microstructure. The study offers engineering recommendations aimed at enhancing the quality and performance of concrete in plateau conditions to address the unique challenges posed by extreme environmental factors.

Characteristics of non-steady-state chloride migration of self-compacting concrete containing recycled concrete aggregate made of fly ash and silica fume

Chloride migration poses a significant challenge to the long-term durability of concrete structures due to its potential to corrode reinforcement and deteriorate the structure. This study focuses on chloride migration in self-compacting concrete (SCC) made with pozzolans, namely silica fume (SF) and fly ash (FA), along with recycled concrete aggregate (RCA). Particularly, the effects of external electrical potential (power-on) duration and RCA content on the features of SCC were examined, alongside the influence of pozzolanic materials, focusing on the chloride migration coefficient and mechanical properties. Six groups of SCC mixtures were created with varying proportions of SF and FA, and different levels of RCA replaced the natural coarse aggregate. The findings reveal a multifaceted impact on SCC behaviour. The chloride migration coefficient exhibits a distinct pattern as the power-on duration increases from 12 to 36 h. Initially, the coefficient increases and then decreases, demonstrating a healing and sealing mechanism within the concrete matrix, which enhances resistance to chloride penetration. The chloride migration coefficient significantly decreased with adding SF and FA. With 15% SF and 30% FA, the coefficient decreased to 59.9% and 49.5%, respectively. Moreover, incorporating RCA in SCC mixtures significantly influences coefficient levels. RCA inclusion at 20% remarkably decreased the coefficient after 12 h by 16.17%. Subsequently, the levels decreased by 39.49% and 46.87% after 24 and 36 h, respectively, compared to the control mixture. This behaviour highlights the importance of RCA in enhancing the resistance of SCC to chloride ingress, a crucial factor for long-term durability. Additionally, mechanical properties such as splitting tensile strength, ultrasonic pulse velocity and surface hardness consistently improved with longer power-on durations and higher RCA and SF content. SCC with RCA and pozzolanic materials exhibits enhanced chloride resistance and superior mechanical performance, making it ideal for sustainable concrete production.

Flexural behavior of warp knitted textile reinforced concrete impregnated with cementitious binder

Textile reinforced concrete is a novel and high performance material which is gaining popularity in the recent days due to its high potential to effectively improve the strength and durability of concrete structures. Owing to absence of coarse aggregate and presence of high cement paste content, TRC has properties that are different from conventional concrete. In this paper, performance of three different types of binders ie., Organic binder, Inorganic Geopolymer binder and epoxy binders for compressive and split tensile strengths was presented and were compared to assess their effectiveness in enhancing properties by testing 12 mortar cubes of size 70.6 mm and 6 mortar cylinders of size 75 × 150 mm. The efficaciousness of weft insertion warp-knitted textile fabrics of ARG and Basalt on the Compressive strength, flexural strength, ductility, toughness, and failure modes were evaluated experimentally by investigations carried out on 4 RCC beams. The effect of the thickness of Textile reinforcement is also studied by using textile layers of thicknesses of 5, 10, and 15 mm. The results indicated that application of basalt textiles fabric using cementitious binder exhibit higher strength and ductility. Basalt textile is more preferable due to its eco-friendly properties. The experimental findings are validated through analytical equations, ensuring the reliability of the study.

Reverse-seepage and saturation action anti-corrosion tech (RS-AAT) for corrosion resistance and self-healing of cracked concrete in seawater immersion

Reverse-seepage and Saturation based Action Anti-corrosion Tech (RS-AAT) is a cutting-edge technology that saturates concrete materials and provides anti-hydraulic pressure to offer robust protection against chloride salt-induced corrosion. This study examined the crack repair capability and anti-chloride invasion effect of RS-AAT-treated concrete by experimental and numerical analyses. The results indicated that, under the effect of RS-AAT, the crack healing rate achieved the highest value of 12 % and the total chloride concentration dropped by the largest amount of 51.41 % after 120 days. Under 0.4 MPa water pressure, the surface chloride concentration decreased by the most of 69.42 % and the depth concentration curves of different crack widths approached a variance of 1. Moreover, the crack repair coefficients were introduced to improve the accuracy of numerically simulating the chloride ion migration process in cracked concrete. The findings unequivocally demonstrate that the use of RS-AAT could significantly inhibit chloride ion intrusion into the concrete's protective layer, of which effect was intensified with the increase of reverse osmosis water pressure. Such results provided invaluable insights into enhancing the durability and chloride ion resistance of marine-immersed concrete structures.

Data acquired on some old reinforced concrete structures to validate the threshold levels of the French performance‐based method for the durability of concrete structures

AbstractThe objective of this paper is to present the methodology used to validate the threshold levels of durability indicators from data acquired from existing reinforced concrete structures that may present corrosion problems resulting from carbonation or chloride ingress. This study was conducted in the framework of the French National Project PERFDUB in close collaboration with the MODEVIE ANR project. Durability tests form the basis of a performance‐based approach for the durability of concrete structures, and in order to set the threshold level for each of these durability indicators, it is important to take into account the experience feedback that can be obtained from the actual behavior of existing structures. This paper presents the investigations carried out on eight reinforced concrete structures, all of them having an age well in excess of 50 years, and the main data gathered on some relevant durability and lifetime indicators. Based on all these data, predictive models of carbonation and chloride penetration are applied in order to validate the threshold levels to be adopted for the durability indicators, and several other conclusions are drawn.

Effects of carbonation and chloride ingress on the durability of concrete structures

The durability of concrete structures, which are designed for long-term use is predominantly determined by the resistance to chemical influences, i.e., the concrete?s ability to protect the reinforcement steel. The carbonation and the chloride ingress into concrete are the most significant causes of steel corrosion and the potential failure of the structure. The primary goal is to ensure that any significant damage does not occur during the structure's service life, primarily achieved by selecting an adequate thickness of the concrete cover. The issue is approached through calculations based on performance analyses, and the use of appropriate models for these chemical phenomena. The paper provides a brief overview and the methodology for analysing the impact on the durability of concrete structures in accordance with the leading international normative documents. The emphasis is on the recent changes introduced in second generation of European Eurocode standards. The consequences of the analysed phenomena are presented through the results of field tests conducted at salt factories, coke industries, and thermal power plants, and through laboratory tests. The tests were performed in order to develop a rapid prediction method for the measure of chloride ingress into concrete without the stimulating chloride ion migration by electricity, as an alternative to standardized tests.

Effect of column dimension on the punching shear capacity of concrete slabs reinforced with GFRP bars

Traditional steel reinforcements are highly susceptible to corrosion affecting their durability and leading to structural weaknesses. The use of GFRP bars offers a corrosion-resistant alternative, potentially extending the lifespan and durability of concrete structures. With this in mind, the current research looks at the efficiency of GFRP bars towards the punching shear capacity of slabs. This study, in specific, explores the effect of column size on the punching shear capacity of glass fiber-reinforced polymer (GFRP) reinforced square concrete slabs. The research involves square concrete slabs (1500×1500 mm) reinforced with GFRP bars, which were centrally loaded until failure. Parameters like the ultimate load capacity, crack patterns, strain development in the GFRP bars and concrete, and critical punching shear area were assessed to evaluate the slabs’ behavior. The punching shear area measured at failure was notably larger than the distance specified by design codes.

Performance Study of Plain Cement Concrete Containing Quartz Powder and Eggshell Powder as Partial Replacement of Cement

Concrete remains a mainstay among construction materials despite ongoing improvements to enhance its environmental friendliness and effectiveness. This study explores the effects of adding quartz and eggshell powder to concrete. The experimental investigation measures concrete samples’ compressive strength, split tensile strength, and flexural strength at 7, 28, and 90 days. Concrete mixes with varying percentages of quartz powder and eggshell powder and their combinations were prepared and tested. The findings show that using quartz and eggshell powder improves the strength characteristics of concrete, with several mixtures performing better than conventional concrete. The examination of experimental data highlights the potential of these supplementary materials to enhance the sustainability and durability of concrete structures. It provides valuable insights into the mechanisms contributing to the strength improvement. These results advance the field of construction materials by contributing to ongoing efforts to create high-performance, environmentally friendly concrete compositions.

Real Time Quality Detection and Automatic Recognition of Concrete Structures: Image Processing Algorithm Based on Deep Learning

The safety and durability of concrete structure is an important issue in engineering quality management. In this paper, an image processing algorithm based on deep learning is proposed to realize real-time quality inspection and automatic defect identification of concrete structures. This algorithm uses the Convolutional Neural Network (CNN) to automatically extract the features of concrete surface quality images, and then identify the existence of defects, thus improving the detection efficiency and accuracy. In this paper, for this method, data samples with different specific structures are collected and manually labeled to the data set; then, a multi-layer CNN model with convolution layer, pool layer and full connection layer is designed to train the model, and then image enhancement technology is used to reduce information noise, and data enhancement technology is used to improve the problem-solving ability of the model. In addition, the strategy of Dropout is used to close some nodes to reduce parameters and prevent over-fitting, and the learning rate is adjusted to optimize the classification effect. In addition, this study constructs an all-weather real-time detection framework, including data acquisition, preprocessing, feature extraction, classification and identification and decision-making alarm system, to ensure the rapid positioning of the detection system. To sum up, the results of this study show that the deep learning image processing algorithm has good contrast performance in the field of real-time quality inspection of concrete structures. CNN model has better performance than GAN (Generative Adversarial Network) and LSTM (Long Short-Term Memory) models in detection time, defect identification resolution and detection accuracy. The maximum detection time is 366ms and the shortest is 213 ms. The successful development of this algorithm provides a new method for automatic detection of concrete structure quality, which has important application value in engineering practice. This research has a broad development prospect.

Design and Implementation of an Autonomous Wheelchair with Medical Kit Access Using Raspberry Pi

Concrete is a fundamental construction material that is continually evolving to enhance its performance and sustainability. This research explores the potential of incorporating natural pumice powder and polypropylene as partial substitutes for cement in M20-grade concrete. The aim is to assess how these alternative materials influence concrete properties and sustainability. Through a comprehensive evaluation, the study provides valuable insights into improving the characteristics and environmental impact of concrete structures. This experimental study examines properties such as split tensile strength, compressive strength, and flexural strength of concrete specimens after curing periods of 7, 14, and 28 days. Concrete mixes with varying proportions of pumice powder (5%, 10%) and polypropylene (5%, 10%), as well as their combinations, are meticulously prepared and tested. The results indicate that adding pumice powder and polypropylene positively affects the strength properties of concrete, with some mixtures performing better than conventional concrete. The analysis reveals the underlying mechanisms contributing to enhanced strength, emphasizing the potential of these materials to boost the durability and long-term sustainability of concrete structures. These findings contribute to ongoing efforts to develop eco-friendly and highly durable concrete, promoting advancements in construction engineering.

Impact of Ceramic Insulator Waste as Partial Replacement of Coarse Aggregate in Concrete: An Experimental Study and Evaluation of Mechanical Properties

This study investigates the use of ceramic insulator waste (CIW) as a partial replacement for coarse aggregate in concrete, along with the effects of curing conditions on the mechanical properties of the resulting concrete mixtures. Concrete specimens with varying percentages of CIW replacement (0%, 2%, 4%, 6%, 8%, and 10%) were subjected to compressive strength, flexural strength, and tensile strength tests at 7 days, 14 days, and 28 days. Additionally, the specimens were cured under both traditional water curing and acidic curing conditions to assess the impact of different curing environments on concrete performance. The results indicate a consistent increase in compressive strength, flexural strength, and tensile strength of concrete with increasing CIW replacement by up to 4%, regardless of the curing method. However, beyond the 4% replacement threshold, there is a slight decline in mechanical properties. Furthermore, the study highlights the necessity of optimizing mix proportions and implementing quality control measures to mitigate the negative effects of higher CIW replacement ratios. These steps are essential to ensure the durability and structural integrity of concrete structures. This research contributes to the growing body of knowledge on sustainable construction materials and provides valuable insights for engineers and researchers aiming to develop environmentally friendly and structurally sound concrete mixtures.

Performance Study of Cement Concrete Containing Natural Zeolite Powder and Glass Powder as Partial Replacement of Cement

Concrete, as a fundamental construction material, is constantly evolving to enhance its performance and sustainability. This study explores the effects of incorporating natural zeolite powder and glass powder as partial replacements for cement in M50 grade concrete. The experimental investigation evaluates the compressive, split tensile, and flexural strengths of concrete specimens at 7, 14, and 28 days. Concrete mixtures containing various proportions of zeolite powder (10%, 20%, 30%) and glass powder (10%, 20%, 30%), both individually and in combination, were prepared and tested. Results indicate that the inclusion of zeolite and glass powders positively influences the strength properties of concrete, with certain mixes outperforming conventional concrete. The analysis of experimental data provides insights into the strength enhancement mechanisms and underscores the potential of these supplementary materials to improve the durability and sustainability of concrete structures. These findings contribute to the development of eco-friendly and high-performance concrete, advancing the field of construction materials engineering.

Data Analysis and Model Development for Chloride Attack Strength Loss Index in Chikoko Blended Concrete

This study investigates the resistance of Chikoko blended concrete to chloride attack, which is critical for ensuring the durability and longevity of concrete structures. Chloride attack is a major concern for concrete structures, as it can lead to corrosion of embedded steel reinforcement, undermining structural integrity. The study employs the chloride attack strength loss index (CASLI) to gauge performance, examining the influence of various factors, including Chikoko concentration, calcination temperature, and curing age. A comprehensive analysis demonstrates a quadratic relationship between these factors and compressive strength. The optimal outcome occurs at a 10% Chikoko concentration and calcination temperatures ranging from 400°C to 800°C. These conditions yield a concrete with high resistance to chloride attack and robust compressive strength. A quadratic model was developed using design Expert 13 in other to predict CASLI derived from the data, providing a reliable tool for forecasting the durability of Chikoko blended concrete under chloride exposure. The study also identifies key independent variables for further optimization, enabling concrete with both high chloride resistance and enhanced compressive strength. This approach shows considerable improvements over traditional concrete made with natural sand, suggesting Chikoko blended concrete as a viable alternative for high-performance applications. Overall, the results indicate that Chikoko blended concrete has significant potential for use in construction, combining durability with high strength. This makes it a promising material for a variety of construction projects, particularly where chloride exposure is a concern, such as in coastal environments or de-icing salt-exposed structures.

An Experimental Investigation on Partial Replacement of Oil Palm Shell as Coarse Aggregate and M Sand as Fine Aggregate with Elevated Temperature

Concrete plays a pivotal role in construction, and the quest to enhance its performance and sustainability is ongoing. Aggregates, comprising 70-80% of concrete, are traditionally made of crushed rocks as coarse aggregates and river sand as fine aggregates. However, increasing demand for these natural resources due to growing construction activities has escalated costs and raised environmental concerns. This study investigates the potential of using Oil Palm Shell (OPS) as a partial replacement for coarse aggregates and Manufactured Sand (M Sand) as a substitute for fine aggregates in M30 grade concrete. Furthermore, the study examines how these replacements affect the concrete’s properties when exposed to elevated temperatures. Various tests were conducted to evaluate slump, split tensile strength, compressive strength, and flexural strength of concrete specimens after 7, 14, and 28 days of curing. Concrete samples were prepared with varying proportions of OPS (5%, 10%, and 15%) and M Sand (10%, 20%, and 30%), along with combinations of both. The results indicated that the inclusion of OPS and M Sand improved the concrete’s strength properties, with certain mixtures outperforming conventional concrete. The analysis of these outcomes underscores the factors contributing to the enhanced strength, demonstrating the potential of OPS and M Sand in boosting the durability and sustainability of concrete structures. Adopting these materials not only reduces construction costs but also promotes environmentally sustainable practices within the construction industry.