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Industrial waste locks are used as raw materials to reduce harmful effects on the environment and improve environmental performance. Marble clay powder can be used as a filling aid and can fill voids in concrete structures. This article will show you how to use a maximum natural sand alternative in concrete with marble powder and quarry dust. The challenge of the 21st century is to change to a new form that can support the natural system. This necessitates a radical rethinking of how to give the community infrastructure and housing. Making a concerted effort to develop novel, innovative, and alternative construction materials may be necessary. Jungles of concrete around cause's impact on the Environment and it would result in climate change. Mankind must avoid the use of things that are detrimental to the environment. So in this paper, it is decided to address the issue by adopting the use of the green concrete concept which is environmentally friendly. Green concrete is concrete made up using industrial wastes such as marble powder, quarry dust, wood ash, paper pulp, etc. Green concrete, which is capable of sustainable development, helps to reduce the consumption of natural resources, energy use, and environmental pollution. Green concrete is more cost‐effective than ordinary concrete and reduces the cost of resultant concrete by 14%–20%. It is also observed that the alkali‐aggregate reaction and sulfate attack resistance of concrete are both significantly improved. Green concrete is a useful tool for lowering environmental pollution and enhancing concrete's resistance to harsh conditions. All stages of infrastructure construction and rehabilitation will follow this trend of using new cement and techniques. Green concrete's adaptability and its performance derivatives will meet a variety of future needs. [ABSTRACT FROM AUTHOR]

This study evaluates the potential use of discarded plasterboard paper as fibers from buildings to reinforce concrete. Various concentrations of wastepaper fibers (0.5%, 1%, 1.5%, 2%, and 2.5% by weight of the binder) were investigated in this research. To mitigate the water absorption effect of the paper fibers, metakaolin was employed as a partial cement replacement. The results demonstrate that the inclusion of the wastepaper fiber enhances the mechanical and durability performance of the concrete. The optimal fiber proportion was identified as 1%, leading to a 29% increase in the compressive strength, a 38% increase in the splitting tensile strength, a 12% decrease in the water absorption, and a 23% decrease in the drying shrinkage with respect to the concrete containing 20% metakaolin. However, exceeding this optimal fiber content results in decreased mechanical and durability properties due to the fiber agglomeration and non-uniform fiber distribution within the concrete matrix. Based on the microstructural analysis, the improved performance of the concrete is ascribed to decreased porosity, more refined pore structure, and reduced propagation of microcracks within the concrete matrix in the presence of wastepaper fiber. According to the results, concrete containing 20% metakaolin and 1% wastepaper fiber exhibits durability and mechanical properties comparable to those of the traditional concrete. This finding highlights the significant promise of reducing dependency on conventional cement and incorporating suitable recycled materials, such as discarded plasterboard, and secondary by-products like metakaolin. Such a strategy encourages the preservation of resources, reduction in carbon dioxide emissions, and a decrease in the ecological footprint resulting from concrete production. [ABSTRACT FROM AUTHOR]

This Special Issue covers the latest research on fatigue, performance, and damage assessments of concrete. Concrete fatigue is known as a phenomenon characterized by the repetition of loads. The fatigue-based performance of concrete may be affected by a combination of diverse loads, mechanical strength properties, and environmental changes. These factors eventually lead to poor concrete performance. In this Special Issue, nine papers were accepted, divided into three subgroups: two papers on fatigue, two papers on performance, and five papers on damage assessment. Unlike articles published in past Special Issues, our Special Issue contains papers that address concrete performance in concrete pavement applications. In particular, six of the articles contained in this issue concentrate on pavement performance and damage assessments, especially in terms of the Pavement Condition Index. Together with a brief introduction, the keywords, research significance and potential impacts of each article are summarized in this Editorial. [ABSTRACT FROM AUTHOR]

This paper explores the creation, development, and dissemination of prefabricated concrete rural houses in Jiangsu Province in East China from 1961 to the 1980s, an example of the technological transition provoked by the depletion of forest and timber in China. Through archival research, fieldwork and interviews, the paper examines the two waves of design and dissemination of prefabricated concrete rural houses between 1961 and 1965 and their subsequent 'vernacularisation' in the 1970s and the 1980s. This research provides a twofold insight into the current scholarly debates surrounding built heritage and global climate change. On one hand, it addresses a historical context of concrete overuse in contemporary China, a matter of critical importance in relation to carbon emissions and global climate change. On the other hand, it offers a counter-argument to today's call for reintroducing timber structures in many places, as evidenced by the case of East China, where the widespread use of materials like concrete was primarily a consequence of the ecological crisis following decades of deforestation and timber resource depletion. In addition, the 'vernacularisation' of concrete structures manifested by this case still provides lessons for today's efforts to popularise more eco-friendly construction materials and technologies, especially in rural areas, and the prefabricated concrete houses possess potential heritage values as trackers of ecological changes. [ABSTRACT FROM AUTHOR]

The mitigation of sewage sludge is quite challenging, as the general method of disposal of sludge after being treated at the waste water treatment plant is landfilling, which makes land unfit for either agricultural or commercial growth. The disposal of sewage sludge in India presents significant environmental challenges due to increasing urbanization and limited land availability. Understanding the potential use of sewage sludge as a construction material has been verified to be the best method of recycling and environmental protection. The possible use of sewage sludge in civil engineering firms is discussed in this paper, along with the various testing methods. Carefully treated sewage sludge is proven to be an effective material, either as a replacement for cement or aggregates in construction. This paper indicates that sewage sludge can be effectively utilized as a raw material in concrete, contributing to resource conservation and environmental sustainability. It supports the feasibility of using sewage sludge in various construction applications, such as eco-cement, bricks, and lightweight aggregates, offering an eco-friendly solution to sewage sludge disposal. [ABSTRACT FROM AUTHOR]

The construction industry is looking for sustainable and cost-effective alternatives to conventional building materials. As the world faces increasing environmental challenges, the need for greener construction practices has become more urgent. Cement production is known for its high energy consumption and significant carbon dioxide emissions. Therefore, it is essential to find ways to reduce the environmental impact of cement production and use. One promising area of research is the use of industrial byproducts such as steel slag to partially replace cement in concrete. The use of these by-products not only solves the problem of waste disposal but also provides a sustainable solution to improve the properties of building materials. When mixed with cement, steel slag participates in pozzolanic reactions, in which reactive silica from the slag reacts with calcium hydroxide, produced during the hydration of cement, to form calcium silicate hydrate gel (CSH). This CSH gel is responsible for the strength and durability of concrete. Incorporating steel slag can improve the mechanical properties of concrete, including compressive, flexural, and tensile strength. In addition, steel slag can improve the durability properties of concrete, such as resistance to chemical attack, reduced permeability, and increased resistance to physical and chemical degradation over time. This paper investigates the durability properties of cement when partially replaced by steel slag, focusing on various aspects of durability, including resistance to chemical attack, mechanical strength, and long-term performance under various environmental conditions. The study includes a comprehensive experimental program designed to evaluate the impact of steel slag on the durability of concrete through a series of tests and analyses. [ABSTRACT FROM AUTHOR]

In recent years, the development of high‐speed railways in China has been rapid. High‐speed railway bridges play an essential role whenever the railway intersects with existing facilities in three dimensions. With the increasing speed of high‐speed railways and increasingly complex geographical locations, the span of bridges is constantly increasing. Based on their advantages, steel structures in large‐span bridges are beginning to replace traditional concrete structures. Taking the steel cover beam technology applied in the Fuqiangbao Tremendous Bridge as a starting point, this paper uses Rhino parameterized modeling and Abaqus software to conduct finite element analysis on the stress of steel cover beams. It compares and analyzes stress under different conditions. The results show that the steel cover beam's most unfavorable and unstable position in this paper is at the support on the stress side. This provides a reference for monitoring the steel cover beam after its application in the Fuqiangbao Tremendous Bridge and technical accumulation for the application of steel cover beam technology. [ABSTRACT FROM AUTHOR]

The grid plays a prominent role in architecture, aiding in space organization and influencing all aspects of planning, ranging from urban design to intricate building details. This paper posits that the grid receives heightened emphasis in Brutalism, particularly in constructivist Brutalism, where materials and construction are intentionally exposed. A question arises regarding the grid's characteristics—despite its subtle appearance, the grid can sometimes be deceptive, ambiguous, and manipulative. The paper analyzes the merits and drawbacks of employing the grid in architecture, shedding light on its contributions to both structural and perceptual comprehensibility, as well as its role in increasing usefulness. To illustrate the application and perception of the grid, the paper examines two primary planning levels: urban planning and building design. The case studies focus on examples from New York City housing developments, specifically those constructed between the 1950s and the 1970s, and projects by architect I. M. Pei, which offer valuable insights into practical implementation. The paper concludes that while the grid can establish order, it may also engender an "uncanny" feeling. [ABSTRACT FROM AUTHOR]

Large-span, post-tensioned (PT) beams play a crucial role in maximizing the benefits of post-tensioning techniques. Bonded and unbonded systems are prevalent, with the latter being more widespread in the United States. While bonded systems are advantageous for creating long spans when multiple tendons are grouped in ducts, limited studies in the literature exist on their demolition. With a case study, this paper addresses the unique challenge of demolishing large-span-bonded, post-tensioned beams that occurs due to a building's functional change. Emphasizing insights for engineers, it explores the use of cutting and dismantling methods, thereby considering the presence of prestressed cables. The demolition process is distinctive due to the presence of numerous prestressed cables along the beams, necessitating a specialized and cautious cutting approach. This is accomplished through the use of a drilling technique that selectively distresses the tendons, ensuring they are not all affected simultaneously. An intriguing observation discussed in this paper pertains to the occurrence of horizontal cracks accompanied by loud sounds following the drilling process, thereby offering insights from the design perspective of PT systems. This paper details an innovative method for safely demolishing large-span, bonded PT beams using ground-penetrating radar and computer models to navigate structural complexities and ensure nearby structures' safety. [ABSTRACT FROM AUTHOR]

Sensitivity analysis of influencing factors on frost resistance is carried out in this paper, and a two-stage neural network model based on grey theory and Back Propagation Neural Networks (BPNNs) is established for the sake of predicting the frost resistance of active-admixture recycled concrete quickly and accurately. Firstly, the influence degree of cement, water, sand, natural aggregate, recycled aggregate, mineral powder, fly ash, fiber and air-entraining agent on the frost resistance of active-admixture recycled-aggregate concrete was analyzed based on the grey system theory, and the primary and secondary relationships of various factors were effectively distinguished. Then, the input layer of the model was determined as cement, water, sand, recycled aggregate and air-entraining agent, and the output layer was the relative dynamic elastic modulus. A total of 120 datasets were collected from the experimental data of another author, and the relative dynamic elastic modulus was predicted using the two-stage BPNN prediction model proposed in this paper and compared with the BPNN prediction results. The results show that the proposed two-stage BPNN model, after removing less-sensitive parameters from the input layer, has better prediction accuracy and shorter run time than the BPNN model. [ABSTRACT FROM AUTHOR]

Phosphogypsum (PG) is a solid waste generated by phosphate fertilizer industries that is currently used in concrete materials. However, adding PG to concrete usually results in reducing its water resistance and corrosion resistance. This paper presents a new method of applying PG to concrete to improve its water resistance. In this paper, a green superhydrophobic PG (SPG) coating was prepared using modified PG as a hydrophobic medium and cement as the bonding material. The contact angle between the superhydrophobic phosphogypsum coating (SPG coating) and water was 156°, and the coating reached a superhydrophobic state with good self-cleaning ability. Even when sandpaper was used to polish the coating, the water contact angle of the coating was still greater than 150°, indicating that the coating had good wear resistance. In addition, the results of water absorption and electrochemical experiments indicated that mortar coated with SPG had better water resistance and corrosion resistance than ordinary mortar. The SPG coatings with water resistance, wear resistance, and self-cleaning properties have potential applications in building exterior walls. [ABSTRACT FROM AUTHOR]

This paper presents the mathematical derivation and numerical implementation of a novel regularized density-driven damage mechanics (D3M) model for simulating failure in concrete members. The novel idea behind the derivation of the approach is that damage is described as a function of the local change in material density. This choice is justified by the fact that the development of local damage directly corresponds to a reduction in local density since undamaged cementitious composites inherently have a higher density than the fluid or gas that occupies damaged regions. For this reason, devising numerical approaches that can predict the material behavior as a function of density could open up new possibilities for the prediction of the nonlinear behavior of concrete structures, as well as the derivation of novel testing procedures for the evaluation of strength by means of direct and indirect measures of density. In this context, a three-phase mesoscopic representation of concrete material is used, where coarse aggregate, mortar, and the interfacial transition zone are explicitly modeled to obtain a realistic representation of the material internal structure. The manuscript first presents the mathematical derivation of the model, with emphasis devoted to the regularization of the computational implementation. This paper then proceeds to demonstrate that the novel regularized D3M is insensitive to the mesh size chosen to represent the three material phases while also predicting realistic compression-to-tension strength ratios and damage patterns at failure. In addition, a parametric study is carried out to illustrate the effect of the relevant mechanical parameters on the observed response. Finally, the proposed model is validated by comparison with experimental results of 3-point bending tests on plain concrete beams of various sizes, also demonstrating that the regularized D3M is capable of predicting size effect in concrete members. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the effects of using palm leaves ash, when it partially replaces the concrete cement content, to treat the effects of using seawater as a mixing water and curing water on concrete. The paper also explores the suitable replacement percentage of cement with palm ash to give the concrete more strength and suitable workability. A slump test was used to assess the fresh concrete's workability, as well as concrete strength testing after 7, 28, and 60 days. It was found that 5% of the cement replacement with palm leaves ash in conjunction with the full replacement of the mixing of pure water with seawater achieves an 84.188% increase in the ultimate compressive strength after 28 days of curing in tap water compared with that gained by normal concrete with mixing in seawater. Also, a reasonable workability was obtained. In the case of curing with seawater for 28 days, the partial replacement of 2.5% of cement with palm leaves ash achieves a 70.75% increase in the compressive strength when compared to normal concrete with mixing in seawater. [ABSTRACT FROM AUTHOR]

Segmental tunnel linings have a complex structural behavior that is difficult to predict. Full-scale in situ structural monitoring allows us to gain access to these structures, observe the acting mechanisms, and better understand the actual structural behavior under realistic boundary conditions. In a recent structural monitoring project in Frankfurt, Germany, strains, deformations, and temperatures were measured at the segmental lining of a twin-tube tunnel boring machine (TBM) tunnel. Hereby, internal forces were back-calculated from the strain measurements. The results of the monitoring are presented and discussed in this paper. The measurements began immediately after the assembly of the segments and have been performed continuously over several years. Because of that, it was possible to observe that the internal forces differ significantly between the construction stage and the final state. During the construction stage, the internal forces develop quickly within hours after ring assembly, showing a distribution along the lining's circumference that is hard to predict. Almost all radial deformations occur during this period and remain unchanged afterward. After this first early phase, a period of stress redistribution follows, including significant changes in the internal forces. At its end, the stable, final state is reached. In this state, the internal forces match better with expectations. In the monitored areas, the stresses during the construction stage slightly exceeded those of the final state, which should be avoided for economic reasons. Additional investigations regard the temperature development within the lining, the influence of the second tube construction on the already built tube, and the development of longitudinal ring interaction over time. The latter significantly influences the structural behavior, but its development is often subject to uncertainties. In this case, it was observed that the longitudinal interaction decreases considerably over time. Practical Applications: In the structural design of segmental tunnel linings, structural or geotechnical engineers have various options regarding the available calculation methods and modeling strategies. All of these options are part of the state of the art, and the selection is up to the engineer. However, the results can be quite different depending on the chosen option. Consequently, uncertainties remain regarding the real linings' internal forces and structural reliability. The actual mechanisms can be identified by investigating the real structural behavior of segmental tunnel linings with in situ structural monitoring. Then, with back-analyses, on the one hand, it can be tested to determine how well different calculation methods and modeling strategies correspond to reality. On the other hand, the monitoring data can contribute to improving existing calculation methods, developing new modeling approaches, and establishing more detailed recommendations or optimizations regarding the design and construction of segmental tunnel linings. This paper presents findings derived from a structural monitoring project on a segmental lining. Different mechanisms and aspects, sometimes uncertain or debatable in tunnel design, are discussed regarding their real in situ appearance. The gained data will also be used for further back-analyses and investigations. [ABSTRACT FROM AUTHOR]

Recycled gypsum powder from waste drywalls is a new alternative that has been recently introduced for partial cement replacement in concrete for construction applications. It has been shown that the recycled gypsum, alongside fly ash, can partially replace cement in concrete to some extent without hurting the required properties of concrete. In this paper, the impact of recycled gypsum content on the durability of concrete (hereafter called gypsum concrete) exposed to different environmental exposures is evaluated. A total of 153 concrete cylinders (100×200 mm) with different recycled gypsum contents (0%, 10%, and 20% of cement replacement) were considered. Each mix was exposed to air-dry, freshwater, seawater, freshwater–air dry cyclic, and seawater–air dry cyclic conditions. The specimens were tested in compression loading after 1,000, 3,000, and 6,000 h of exposure. Recycled gypsum used in this research was in two types of a powder with fine particles only (hereafter called fine gypsum) and in the form of mixed fine, coarse, and paper particles (hereafter called whole gypsum). Other mechanical and physical properties of concrete such as absorption, volume change, and ultrasonic pulse velocity were analyzed. It was observed that the compressive strength of the specimens with 10% and 20% fine gypsum content at Day 28 was about 36% and 40% lower than that of the control specimens, respectively. However, the strength gap was reduced to about 16% and 7% at the end of 6,000 h in the air-dry condition. The specimens submerged in freshwater and seawater showed a rate of strength gain higher than that of the control specimens, bringing the compressive strength of the gypsum concrete specimens slightly higher than that of the control specimens after 6,000 h exposure. Overall, recycled gypsum in combination with fly ash not only does not hurt the long-term strength of concrete but also can enhance the strength under certain conditions, mostly those exposures involving water exposure. [ABSTRACT FROM AUTHOR]

This paper re-examines common notions and conventions regarding the compressive strength of concrete in general and of the uniaxial compressive strength of concrete in particular. A distinction is introduced between the strength of the specimen and the strength of the concrete as a material, and the commonly measured and adopted strength is shown to be the specimen's strength, wrongly interpreted as the material's strength. the two major damage modes of concrete specimens (with the formation of either longitudinal cracks or shear bands) are discussed. Such failure modes are wrongly considered as features of concrete behavior in uniaxial compression, but this is not the case. Longitudinal cracking is due to lateral expansion (Poisson's effect) and occurs at a relatively low applied load in absence of friction at specimen's top and bottom boundaries. Shear failure (accompanied by the formation of an inclined shear band) is related to the shear envelope parameters that are related to the concrete mixture, but the applied ultimate pressure is not the concrete uniaxial compressive strength. Hence, though caused by applied compressive loading, these failure modes are little/hardly related to the concrete material intended as the ultimate uniaxial stress (strength) corresponding to a maximum value of the uniaxial compressive strain. Using the shear envelope parameters has been proven to yield a very good prediction of the applied compressive loading of the specimen in the limit state, as a demonstration that the applied pressure at specimen's failure resulting from the formation of inclined fracture bands is the specimen's failure strength, and not the material's compressive strength! Reasons are given against the existence of a uniaxial compressive strength failure for concrete, and a piece of evidence in this direction is provided by concrete specimens subjected to pure hydrostatic compression, that do not fail at all. The entire issue requires, therefore, a deep revisiting and re-thinking, to provide correct measures for representing concrete response under compression in analysis and design. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This study explores the feasibility of utilizing Waste Brick Powder (WBP) and fly ash as substitutes for cement in concrete, addressing growing environmental concerns and waste accumulation from demolition activities in India. The partial replacements of cement with 10%, 15%, and 12.5% fly ash, alongside 10%, 15%, and 12.5% WBP in M25-grade concrete, are investigated over a 7-day curing period. The compressive strength is evaluated as the primary parameter, while specific gravity tests are conducted to analyze material properties. The study aims to assess the sustainability and cost-effectiveness of incorporating fly ash and WBP in concrete production. The results reveal the influence of varying fly ash and WBP proportions on concrete strength, with the optimized mix of 12.5% fly ash and 12.5% waste brick powder demonstrating superior strength properties compared to conventional concrete. This blend demonstrates practical feasibility and potential for widespread adoption in construction applications. This study underscores the sustainable utilization of industrial by-products, aligning with eco-conscious construction practices and contributing to reduced carbon emissions. This paper provides insights for the construction industry in India, offering a solution to waste management challenges while enhancing the sustainability and cost-effectiveness of concrete production. [ABSTRACT FROM AUTHOR]

Drawing on dialogues between Michael Ball and Ben Fine, this paper proposes provisioning approaches as a way of reintegrating theoretical and institutional work on rent. Recent debates on financialisation and rent theory overlook the potential contribution of provisioning approaches because urban studies typically take the work of Ball as reference point. By looking at provisioning approaches beyond Ball, the paper shows that such approaches are already making important contributions to financialisation research. It then proposes an interpretation of provisioning approaches as extending Marx's method of moving between abstract and concrete and thereby integrating agentic and theoretic understandings of rent. [ABSTRACT FROM AUTHOR]

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Inconsistencies in standards and codes result in confusion, increased costs, and do not promote the efficient use of concrete. In addition to inconsistencies, the lack of science-based approaches and data used for defining criteria in these standards and codes can limit the reliability and trust of these requirements. A review of industry documents indicates that inconsistencies and lack of science-based approaches exist across many documents, both throughout the industry and within ACI, relating to the corrosion of steel reinforcement embedded in concrete. This paper proposes to address five key issues to promote science-based standardization of requirements necessary for reinforced concrete systems exposed to corrosive conditions. These five issues include the need for: 1) standardization of chloride testing methods and requirements; 2) standardization of chloride reporting units; 3) standardization of terminology for specifying chlorides in cementitious systems; 4) standardization of exposure classifications for corrosive conditions; and 5) standardization of allowable chloride limits. This paper presents current inconsistencies in guide documents and codes for each of the items listed previously and then proposes an approach to standardize each using either available data and/ or a scientifically based approach. Recommendations for testing, reporting, definition of exposure classifications, and allowable chloride limits are then proposed. It is hoped that the systematic approach used herein will lead to standardization and consistency, less confusion, and will promote the efficient use of durable and economical concrete. [ABSTRACT FROM AUTHOR]

Failure in beams reinforced with a small amount of transverse reinforcement is brittle due to reinforcement rupture after critical shear cracking occurs. To eliminate this problem, standards recommend formulas to calculate the minimum amount of transverse reinforcement in reinforced concrete structures. Reinforcement can resist loads after the first crack's appearance, preventing beam rupture from being brittle but making it somewhat ductile. This paper presents a theoretical experimental analysis to determine the minimum transverse reinforcement ratio in beams of high-strength ordinary portland cement concrete (BHSOPCC), low-strength ordinary portland cement concrete (BLSOPCC), and low-strength geopolymeric concrete (BLSGC). The beam dimensions were 150 x 450 x 4500 mm. They were subjected to a four-point bending test to assess shear failure. The transverse reinforcement ρsw,minfyk ranged from 0 to 1.16 MPa, in the ranges provided by ACI 318-19, AASHTO LRFD, fib Model Code, and ABNT NBR 6118:2014. This paper investigates the minimum shear reinforcement ratio for various types of concretes with different strengths and attempts to reevaluate the associated standards that have already been established. The parameter τwy*/τwcr proposed in this paper to define whether or not a beam has minimum transverse reinforcement is more appropriate. [ABSTRACT FROM AUTHOR]

Mathematical physics equations are often utilized to describe physical phenomena in various fields of science and engineering. One such equation is the Fourier equation, which is a commonly used and effective method for evaluating the effectiveness of temperature control measures for mass concrete. One important measure for temperature control in mass concrete is the use of cooling water pipes. However, the mismatch of grids between large-scale concrete models and small-scale cooling pipe models can result in a significant waste of calculation time when using the finite element method. Moreover, the temperature of the water in the cooling pipe needs to be iteratively calculated during the thermal transfer process. The substructure method can effectively solve this problem, and it has been validated by scholars. The Abaqus/Python secondary development technology provides engineers with enough flexibility to combine the substructure method with an iteration algorithm, which enables the creation of a parametric modeling calculation for cooling water pipes. This paper proposes such a method, which involves iterating the water pipe boundary and establishing the water pipe unit substructure to numerically simulate the concrete temperature field that contains a cooling water pipe. To verify the feasibility and accuracy of the proposed method, two classic numerical examples were analyzed. The results showed that this method has good applicability in cooling pipe calculations. When the value of the iteration parameter a is 0.4, the boundary temperature of the cooling water pipes can meet the accuracy requirements after 4~5 iterations, effectively improving the computational efficiency. Overall, this approach provides a useful tool for engineers to analyze the temperature control measures accurately and efficiently for mass concrete, such as cooling water pipes, using Abaqus/Python secondary development. [ABSTRACT FROM AUTHOR]

Externally bonded reinforcement on groove (EBROG) is a significant reinforcement technology proposed by researchers to enhance the bond properties of reinforced concrete structural members. To understand the influence of groove size on concrete specimens of different strength, a total of 60 concrete specimens with 4 different strengths were cast with the single shear test in this paper, among which 48 EBROG specimens and 12 specimens with externally bonded reinforcement method (EBR) were used as the control group. The failure modes and failure mechanisms of specimens with various sizes and reinforcement methods were analyzed. Additionally, the test results of ultimate load, load–displacement curves, and bond-slip curves for specimens with different groove sizes were compared. The effectiveness of EBROG method in enhancing the ultimate load capacity at the bond interface of the specimens is proved. Furthermore, in situations where the volume of the groove was kept constant, the specimens with lower concrete strength and deeper groove exhibited superior bond properties. Also, the influence of groove width on bond properties was better than that of groove depth. Finally, the test results in this paper were compared with the prediction of the existing EBR and EBROG models to evaluate the performance of different models, and based on the original model, a prediction model for EBROG method in the groove region with higher accuracy was proposed. [ABSTRACT FROM AUTHOR]

The establishment of many industries produces a large amount of by-products in solid, semi-solid, and liquid form because industrial waste can be toxic or non-toxic in nature, causing serious damage to the environment. India has a vast network of existing industries, and in the future, many more will produce millions of tons of various by-product materials. Pollution and disposal problems can be reduced by using these materials effectively in civil engineering projects. This paper examined the evaluation of red mud produced in the alumina processing industry to determine its suitability as a construction material based on physical, chemical, and other civil engineering properties. Red mud is the fine-grained residue that remains after alumina has been extracted from bauxite ore. About 10 million metric tons of red mud waste is generated every year in India, causing very serious and alarming environmental problems. Neutralizing this red mud would be very beneficial, as it would reduce pollution. In addition, the neutralized red mud could be reused in construction mixes and as a raw material. The physical, chemical, and geotechnical characteristics of these waste materials were critically evaluated for this purpose. It was found that red mud can be used as building material. [ABSTRACT FROM AUTHOR]

Vaults are among the oldest known engineering structures, and have escorted the history of architecture through thousands of years. Nowadays, construction industry rarely uses them, and doesn't consider them as a general option to be used for floorslab structures, although they offer several opportunities. The presentation aims to re-introduce vaults into everyday usage, emphasizing their efficient shape, building technology and aesthetic values. The following aspects are featured in the paper: -mathematical definition of vaults, -main technical terms considering vault constructions, -main features of the statics of vaults, -connection of the force-trajectory and the central core, -importance of shape for ideal material distribution, -a proposal for a contemporary floorslab structure featuring beams and narrow vaultzones, -pros and cons of the proposed floorslab structure [ABSTRACT FROM AUTHOR]

Waste ceramic is produced from different sources and, if not reused, is often disposed of in landfills, contributing to the pressure on landfill capacity and potentially releasing toxins into the surrounding environment as ceramics break down over time. The waste can easily be crushed to the required sizes, which has interested many researchers. It has been used as a replacement for concrete constituents, including cement and aggregates. This offers a promising avenue for reducing the environmental impact and promoting sustainable construction practices by reducing the amount of energy consumed and resources required for concrete production, as well as the amount of waste being sent to landfills. This paper aims to provide a review of the use of waste ceramic in concrete. In essence, the paper is divided into several sections. The first section highlights the current environmental issues associated with concrete production and waste disposal. The second section deals with ceramics, its raw materials, production steps, and the different types of waste ceramic used in concrete. A literature review of the use of waste ceramic in concrete was included in the third section. The study reports different research on the use of waste ceramic and its impacts on the mechanical and durability properties of concrete. [ABSTRACT FROM AUTHOR]

The paper investigates and refines the proportionalist solution to the causal exclusion problem developed by Menzies and List. First and foremost, it explores the implications of their inter-level compatibility result. It is highlighted that in theory the inter-level causal compatibility of realizer and realized properties allows for scenarios where the higher-level property is multiply realized. By developing concrete illustrations, the paper proves this to be an empirically plausible option. Further non-trivial implications of the framework are unpacked to show that the sensitivity of causal relations to background conditions is as important in deciding on the existence and the direction of exclusion as sensitivity to the realization of the cause. This insight also opens the way to further refinements: a richer reconceptualization of upwards exclusion and a plausible answer to a critic of the Menzies and List project. [ABSTRACT FROM AUTHOR]

Chloride corrosion is a key factor affecting the life of marine concrete, and surface chloride concentration is the main parameter for analyzing its durability. In this paper, we first introduce six erosion mechanism models for surface chloride ion concentration, reveal the convection effect in the diffusion behavior of chloride ions, and then introduce the corrosion mechanisms that occur in different marine exposure environments. On this basis, the analysis is carried out using empirical formulations and machine learning methods, which provides a clearer understanding of the research characteristics and differences between empirical formulas and emerging machine learning techniques. This paper summarizes the time-varying model and multifactor coupling model on the basis of empirical analysis. It is found that the exponential function and the reciprocal function are more consistent with the distribution law of chloride ion concentration, the multifactor model containing the time-varying law is the most effective, and the Chen model is the most reliable. Machine learning, as an emerging method, has been widely used in concrete durability research. It can make up for the shortcomings of the empirical formula method and solve the multifactor coupling problem of surface chloride ion concentration with strong prediction ability. In addition, the difficulty of data acquisition is also a major problem that restricts the development of machine learning and incorporating concrete maintenance conditions into machine learning is a future development direction. Through this study, researchers can systematically understand the characteristics and differences of different research methods and their respective models and choose appropriate techniques to explore the durability of concrete structures. Moreover, intelligent computing will certainly occupy an increasingly important position in marine concrete research. [ABSTRACT FROM AUTHOR]

Space truss analogy and collapse mechanisms are the theoretical methods which are available at present to predict the collapse loads of single-cell concrete box-girder bridges. It is observed that of the two formulations, the one based on a collapse mechanism is found to be more versatile and better suited to box sections. The eccentric load acting on the top flange of a box girder may be resolved to symmetric and antisymmetric components. The antisymmetric component may again be resolved as torsion component and distortion component. However, no researcher has extended this concept to determine an equation for the estimation of collapse load. The present study proposes a theory for calculating the collapse load of single-cell concrete box-girder bridges considering pure torsion and distortion mechanisms. The box girder is treated as a folded plate structure subjected to the vertical and horizontal components of the load in the plane of each plate. It is assumed that plastic hinges are developed at the four corners of the box girder for distortion mechanism and the cross section causes pure twisting without distortion for torsion mechanism. The proposed pure torsion and distortion mechanisms are incorporated in the existing collapse mechanism method and the modified method is validated with the experimental results available in the literature. Estimation of the ultimate load carrying capacity of existing concrete box-girder bridges is discussed in this paper. Among the various simplified theoretical models available to predict the collapse load of single-cell concrete box-girder bridges, the collapse mechanisms theory yields the most accurate results according to the existing literature. To the existing, pure bending and distortion-bending mechanisms, two more mechanisms (torsion and distortion mechanisms) are proposed in the current paper to make the collapse mechanisms theory more conclusive. With the introduction of these two new mechanisms, the collapse load of existing single-cell concrete box-girder bridges subjected to unsymmetrical loading can be predicted by taking the lowest value obtained from: (i) pure bending mechanism; (ii) distortion-bending mechanism; (iii) torsion mechanism; and (iv) distortion mechanism. This will help the bridge engineers to ascertain the functioning of existing as well as new concrete box-girder bridges. [ABSTRACT FROM AUTHOR]

This paper explores the new potential strategy of using fine recycled aggregates (fRA) derived from waste 3D printed concrete (3DPC) as a substitute for cement in additive manufacturing. This study hypothesizes that fRA can optimize mixture design, reduce cement content, and contribute to sustainable construction practices. Experimental programs were conducted to evaluate the fresh and hardened properties, printability window, and buildability of 3DPC mixes containing fRA. Mixes with replacement rates of cement with fRA by 10 vol%, 20 vol%, 30 vol%, 40 vol%, and 50 vol% were produced. A comprehensive experimental protocol consisting of rheological studies (static and dynamic yield stress), dynamic elastic modulus determination (first 24 h of hydration), flexural and compressive strengths (2 d and 28 d), and an open porosity test was performed. The obtained results were verified by printing tests. In addition, an economic and environmental life cycle assessment (LCA) of the mixes was performed. The results indicate that up to 50 vol% cement replacement with fRA is feasible, albeit with some technical drawbacks. While fRA incorporation enhances sustainability by reducing CO2 emissions and material costs, it adversely affects the printability window, green strength, setting time, and mechanical properties, particularly in the initial curing stages. Therefore, with higher replacement rates (above 20 vol%), potential optimization efforts are needed to mitigate drawbacks such as reduced green strength and buildability. Notably, replacement rates of up to 20 vol% can be successfully used without compromising the overall material properties or altering the mixture design. The LCA analysis shows that reducing the cement content and increasing the fRA addition results in a significant reduction in mix cost (up to 24%) and a substantial decrease in equivalent CO2 emissions (up to 48%). In conclusion, this study underscores the potential of fRA as a sustainable alternative to cement in 3D printed concrete. [ABSTRACT FROM AUTHOR]

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Textile-reinforced concrete (TRC) has gained a lot of attraction in recent years. Adequate bond between the phases in this system allows to transfer high loadings, thus enabling high performance. The terminus textile reinforcement, however, comprises many different types of fabrics, which differ in their chemical composition, geometry, surface properties etc., and thus exhibit substantially different bond properties. In the course of RILEM’s Technical Committee 292 work on TRC it was found that a comprehensive understanding of the complex interactions between individual parameters is still lacking. This is amplified by the fact that different types of textile reinforcement are preferably used in different regions of the world. This paper therefore attempts to compile findings from literature on the bond in TRC. The database used was created in the course of the TC work. Additional papers of relevance were identified by scanning scientific web databases. The different influencing parameters are given in this paper in a hierarchical order, starting from the level of the individual constituents (filament and matrix) to impregnated fabrics and the influence of textile manufacturing and architecture on the bond. Finally, by mapping all the cited literature used in this paper based on grouped keywords the complex intercorrelations are visualised. [ABSTRACT FROM AUTHOR]

Time-zero is of considerable significance for determining both deformational and mechanical properties of high-performance concrete from very early ages. In this paper, four methods for determining the time-zero are investigated comparably, including stress evolution measurement, autogenous strain method, ultrasonic testing, and temperature rate method. A critical review of the theoretical basis behind each method is presented, with emphasis on the applicability and limitations of each method. Based on a case study, the practical capabilities of all four methods for determining the time-zero of high-performance concrete with a water-binder ratio (w/b) of 0.25 are experimentally assessed. It is found that the ultrasonic testing and temperature rate methods are better suited due to their simplicity and availability compared to the other two methods. Besides, the temperature of cement-based composites at very early ages can affect the determined values of time-zero, which needs further research. [ABSTRACT FROM AUTHOR]