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Plasterboard, a commonly utilized construction material, comprises a gypsum core nestled between two paper layers. Gypsum after demolition of plasterboards is a recyclable waste that has been reused into new plasterboard or other purposes such as agricultural products. However, there is a lack of understanding on the potential for recycling the paper layers. This study investigates the use of wastepaper fibers, obtained from the paper layers, as a reinforcing material and metakaolin as a partial cement replacement material in concrete. This study demonstrates the ability of the paper from waste plasterboard for reinforcing concrete. Wastepaper fibers were used at different concentrations ranging from 0 to 2.5% by weight of binder. Bending test was conducted for assessing fracture behavior of concretes, including load bearing capacity, modulus of rupture, crack mouth opening displacement (CMOD) at the load bearing capacity, fracture toughness, and fracture energy. Slump, axial compression, and scanning electron microscopy (SEM) were also conducted on the concretes. It is found that incorporating wastepaper fiber by up to an optimum content of 1.5% results in an increase in the compressive strength (57%), flexural load bearing capacity and modulus of rupture (31%), CMOD displacement at load capacity (14%), fracture toughness (37%), and fracture energy (73%) of the metakaolin‐based concrete. However, further increase in the wastepaper fiber content results in decreased mechanical properties of the concrete, which is due to the fiber agglomeration and non‐uniform distribution within the concrete matrix. Based on the results, the concrete with 20% metakaolin and 1.5% wastepaper fiber experiences similar mechanical properties to the conventional concrete. The results of this study underscore the substantial potential of leveraging waste materials such as wastepaper and by‐products like metakaolin to diminish reliance on conventional cement. This approach not only enhances the mechanical properties of concrete but also fosters sustainable building practices by promoting the recycling of waste materials, reducing carbon footprint, and mitigating the environmental impacts inherent in traditional concrete production. [ABSTRACT FROM AUTHOR]

Crystalline admixture (CA) has been extensively utilized as the commercial product for improving the performance associated with strengthening self‐sealing of cracks or decreasing the permeability of concrete. However, few researches characterizing the restrained shrinkage and cracking potential of concrete with CA at early age. This paper aimed to expand the limitation by means of the experiments including mechanical properties test and restrained ring test on high‐strength concrete (HSC) with CA from Xypex. The proportion of CA was 0%, 0.5%, 1.0%, and 1.5% by the mass of cement. The incorporation of CA enhanced the compressive and splitting tensile strength as well as modulus of elasticity tested in this paper. A significant increase was observed in free and restrained shrinkage of HSC with CA. Although incorporation of CA ameliorated the stress relaxation, residual stress in restrained concrete ring developed rapidly with the incorporation of CA due to the significant increase in restrained shrinkage at early age. Restrained concrete ring with CA demonstrated a higher stress rate, which implied a higher cracking potential. When CA proportion increased from 0% to 0.5%, 1.0%, and 1.5%, a higher cracking potential was revealed through calculation, and restrained concrete ring exhibited earlier cracking age. Caution should be exercised with the application of such CA in concrete mixtures under restrained conditions. [ABSTRACT FROM AUTHOR]

The paper presents integrated effects of concrete samples size and fibers amount on compressive strength of high‐ and ultra‐high strength concretes based on reactive powders. Ready to use the self ‐ compacting mix of high‐performance concrete, was applied. The main aim of the work was to determine compressive strength correlation coefficients for size of cubic samples and integrated compressive strength correlation coefficients for the size of cubic samples including fibers ratio. The article presents the results of experimental tests of compressive strength for 3 sizes of cubic samples, i.e. 40, 100, and 150 mm, with the application of the steel fibers ratio of 0%, 2%, 4% for each sample size. Concrete air content and cone flow test studies were performed for all research series. The obtained results show a diversified influence of the size of the samples and the amount of steel fibers on the results of concrete compressive strength of high‐ and ultra‐high strength concretes based on reactive powders. Namely, the compressive strength correlation coefficient for the size of cubic samples was determined in the range 1.0–1.3, while the integrated compressive strength correlation coefficient the for size of cubic samples including fibers ratio is in the range 1.0–1.47. [ABSTRACT FROM AUTHOR]

This paper describes the use of joints with bent bars and postcast ultrahigh‐performance concrete (UHPC) joints to enable formwork‐free and support‐free construction of composite slabs. To investigate their flexural performance, static loading tests on three full‐scale simply‐supported slabs and one monolithic slab were carried out. Flexural capacity, stiffness, and crack development were recorded, resulting on flexural failure experienced by all specimens. Main cracks of composite specimens developed along the UHPC–normal concrete interface, and cracks on both sides of the UHPC joint developed evenly, similar with that of the monolithic specimen. Besides, composite slabs and a monolithic slab showed similar flexural capacity. UHPC joint was not cracked when failure occurred, and bottom bars were anchored and connected in the UHPC joint, proving that the flexural anchorage method is feasible. The average strain of the composite specimen across the UHPC joint was still consistent with the assumption of plain section, and there was an approximate linear relationship between the expansion width of the joint at the bottom of the slab and the maximum crack width at bottom bars. Moreover, middle bars contributed to the flexural capacity and stiffness of composite specimens, while horse stool reinforcement may effectively prevent the interface shear failure on the composite interface. Based on test results, the formula to control cracking of UHPC is given in this paper. The design methods on flexural capacity, stiffness, and expansion width of composite slabs are also presented and discussed. [ABSTRACT FROM AUTHOR]

For the assessment of concrete structures in the new fib Model Code 2020 (fib MC 2020), three categories are distinguished: (1) the residual capacity of existing structures without damage, (2) the residual capacity of structures suffering deterioration, and (3) the residual capacity of structures with noncompliant details. In the accompanying paper by Walraven and Dieteren in this volume, the backgrounds for this subdivision have been explained, and indications for the assessment of existing concrete structures in those categories have been given. In the actual paper, examples are given how to perform an assessment of concrete structures for the categories mentioned above. These examples have contributed to the formulations of the recommendations proposed for fib MC 2020. [ABSTRACT FROM AUTHOR]

Fires are rare events, but in the case of their occurrence, they can have a significant effect on the structure. Concrete is a durable noncombustible material but can be damaged by fire. This damage does not often lead to structural collapse, but can significantly hinder the structure's future performance. A thorough post‐fire assessment of concrete structures is essential to determine the condition of the structure and select the best course of action to take. This paper reviews the current state of knowledge on the post‐fire assessment of concrete structures. The techniques that are commonly used are presented and discussed, highlighting their advantages and disadvantages. Furthermore, based on the literature case studies, an overview of different approaches and techniques is presented. Finally, the framework and goals of the post‐fire assessment are investigated. The paper concludes with a summary of the current state of knowledge and a list of key research needs. [ABSTRACT FROM AUTHOR]

The 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. [ABSTRACT FROM AUTHOR]

This paper proposes a novel glass fiber‐reinforced polymer (GFRP)‐timber‐steel tube‐concrete composite column (GTSC) that combines an outer steel tube with GFRP fabric reinforcement, an inner timber core, and concrete for the rest of the space. The mechanical behavior of eight specimens of novel composite columns was investigated considering diameters of timber cores, layer numbers, and angles of GFRP laminates. The results showed that as the size of the timber core increased from 0 to 50 mm, the ductility and the energy dissipation capacity of the composite column maximum increased by 61.5% and 63.4%, respectively. Conversely, the ultimate load carrying capacity and stiffness decreased. It was also found that the timber core weakened the strength of the confined concrete. However, timber core reduced the weight of columns, which slowed down the reduction of the ultimate load carrying capacity of per unit GTSCs, with the stiffness remains unchanged. GFRP laminates with an angle of 60° provide the best stiffness and ductility, and the layer numbers of GFRP has a positive effect on GTSC's mechanical performance. In addition, an analytical model was proposed based on the ultimate equilibrium method, which accounts for the ultimate bearing capacity of GTSC based on the influence of timber. Analyses revealed a good correlation between analytical and experimental results. [ABSTRACT FROM AUTHOR]

The joints between precast reinforced concrete pile segments in deep foundations are typically mechanically lockable. They include anchor bars embedded inside the ends of each segment, forming lap splices with the main bars. Because of their particular technology, these lap splices are somewhat different from traditional lap splices, as shown in the first part of this paper, where the impact of their specific characteristics on the tensile behavior of the joints is discussed. The experimental section presents the results of 19 tensile tests on these lap splices and compares them with established theoretical models. The roles of various parameters (lap length, type and amount of confining reinforcement, type of anchor bars, and concrete cover thickness) are investigated. One of the major findings indicates a significantly lower lap capacity when using plain‐bar spirals compared to closed‐ribbed stirrups. Additionally, at low stress levels, the models tend to be unconservative. Building on this insight, a modified model is proposed for lap splices provided with plain‐bar spirals. [ABSTRACT FROM AUTHOR]

Alkali‐aggregate reaction (AAR) is a detrimental reaction between alkalis originating from cement and aggregates that contain reactive minerals. This reaction produces an expansive gel in hardened concrete that may cause internal stresses and cracking, after which it would be critical to evaluate the safety of the AAR‐affected structure. This paper presents a calculation framework primarily using the finite element method to simulate the structural behavior of reinforced concrete members affected by AAR. Numerical subroutines are used to calculate the anisotropic distribution of AAR‐induced expansions at each integration point, considering the stress field at each time step, whereas changes in the properties of concrete due to the progression of AAR are also considered. The modeling approach is successfully validated based on experimental data from several studies on AAR‐affected members that were reinforced in 1, 2, and 3 orthogonal directions in terms of load–deflection behavior and damage patterns. The mechanical properties of concrete were found to negligibly affect the distribution of AAR expansions. A better correlation was observed with experimental data if compressive and tensile strengths of concrete are assumed unchanged and only the modulus of elasticity of concrete is reduced as a function of AAR‐induced expansion. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to use the data‐driven approach to predict and evaluate the mechanical properties of concrete made with recycled concrete aggregate (RCA), including compressive strength and elastic modulus. Using 358 data samples, including 10 input variables, 10 popular machine learning (ML) algorithms are introduced to select the best ML performance model for predicting RCA concrete's compressive strength and elastic modulus. Gradient Boosting and Categorial Boosting have the best performance in predicting the compressive strength of RCA concrete, with R2 = 0.9112, RMSE = 5.3464 MPa, MAE = 4.0845 MPa, and R2 = 0.9175, RMSE = 5.1520 MPa, MAE = 3.7567 MPa, respectively. Light Gradient Boosting and Categorial Boosting have the best performance in predicting the elastic modulus of RCA concrete, with R2 = 0.8775, RMSE = 2.3560 GPa, MAE = 1.8330 GPa, and R2 = 0.9300, RMSE = 2.3560 MPa, MAE = 1.2589 MPa, respectively. Based on the Shapley Additive Explanation analysis, the influence of main factors on compressive strength and elastic modulus of RCA concrete values has been analyzed qualitatively and quantitatively. RCA replacement level and cement/sand ratio slightly affect compressive strength but have a dominant influence on the elastic modulus of RCA concrete. [ABSTRACT FROM AUTHOR]

To enhance the mechanical and constructional performance of the ultra‐high performance concrete (UHPC) beams, the steel plate placed at the bottom surface of the UHPC beam is utilized to replace the ordinary steel rebars. In this paper, four 3.2 m UHPC T‐shaped beams with different reinforcement patterns of ordinary steel rebars and external steel plate were fabricated and comparatively tested under flexure loading. Their damage patterns, load versus deflection behavior, flexural capacity, load versus strain behavior, moment versus curvature behavior, stiffness, and crack development were investigated. The flexural experiments indicated that the external steel plate, positioned at the bottom surface of the UHPC members, could resolve the difficulty of installing ordinary steel rebars in slender UHPC components and improve its constructional performance. Compared with the inside steel rebar reinforcement, the employment of the steel plate at the bottom surface of the UHPC beam can effectively increase the distance from the neutral axis to the tensile reinforcement at the serviceability and ultimate states, thereby improving its flexural capacity and stiffness. Additionally, the configuration of the external steel plate was beneficial to reduce the tensile stress level of the tensile reinforcement and limit the opening of UHPC crack width, and thus their crack resistance can be effectively enhanced. Moreover, increasing the thickness of the steel plate or rebar ratio can also significantly improve the flexural capacity, stiffness, and cracking resistance of UHPC beams. [ABSTRACT FROM AUTHOR]

The influence of microstructural changes on concrete properties at elevated temperatures is presented and discussed in this paper, as the exposure to elevated temperatures brings in marked changes in concrete thermal, mechanical and kinematic properties owing to the heat‐induced evolution of material's microstructure. The major microstructural changes consist in increasing pore size, occurrence of microcracking and activation of chemo‐physical processes in the hardened cement‐paste. These processes (like portlandite dissociation and crystalline change in quartzitic aggregate) occur above 400°C and are more pronounced in high‐strength than in normal‐strength concrete. Increasing pore size and microcracking, however, yield the largest contribution to concrete strength‐loss, that occurs mainly between 400 and 800°C, depending on aggregate type and initial moisture content in the mix. On the whole, calcareous (or carbonate) aggregate behaves better than siliceous aggregate face to increasing temperatures. Initial moisture content favors concrete thermal spalling, mostly between 200 and 400°C, but such a complex phenomenon is still open to investigation, as demonstrated by the various theories found in the literature, each with its chemo‐physical mechanisms and limitations. Three theories are discussed in this paper, and these theories together with other critical issues allow to focus on future work. [ABSTRACT FROM AUTHOR]

The effect of the boundary conditions, defined as the thermal expansion restraint imposed by the external uniaxial compressive load in plain concrete subjected to high temperatures, is discussed. A numerical mesoscopic investigation uncoupled the load induced thermal strain (LITS) into three main components (aggregates and matrix strain contributions and the effect of the thermal expansion restraint). The analyses demonstrate that LITS depends on the materials properties (viscous‐plastic behavior) and also on the boundary conditions, which is function of the test setup and seems to be not related to the material properties. In this paper, the role of the boundary conditions on 1‐phase (homogeneous) and 2‐phase (matrix + aggregates) numerical analyses are investigated. A LITS semi‐empirical model is incorporated in the numerical modeling to account for the stiffness degradation. It is demonstrated that in 1‐phase models, the effect of the boundary conditions is absent, which is not true for mesoscale analyses. In this case, the effect of the boundary conditions should be taken into account and subtracted from the results to avoid an overestimation of the material response. It is important mentioning that the analyses of concrete behavior at elevated temperatures and transient creep experimental procedures completely neglect the role of the boundary conditions. [ABSTRACT FROM AUTHOR]

This paper introduces the conservation and intervention provisions included in the latest edition of the fib Model Code for Concrete Structures (MC2020). This is the first international code which addresses life‐cycle management issues for both new and existing concrete structures. Accordingly, the contents relating to conservation (maintenance and interventions) have been extensively enhanced compared with the provisions included in the previous MC2010, with these now including monitoring. Much of the contents on interventions are newly‐added provisions in MC2020. A new chapter (19) is introduced to show the available materials/systems and the properties necessary for these materials. The necessary properties required to make successful interventions also include consideration of the long‐term performance of materials/systems and compatibility with the substrate concrete. All the processes for interventions, including intervention strategies, selection of intervention methods, survey for interventions, design of interventions and execution of interventions are explained in chapter (38) on conservation and a new chapter (37) on execution of interventions. Selection of intervention methods should be made according to the intervention strategies and the causes and extent of deterioration/damage. In the future the issues of repairability and the standardization of intervention methods are expected to have greater importance. Repairability is the ability to physically repair a structure or structural element which has deteriorated or been damaged by the effects of the considered actions, thus restoring its functionality, but while incurring acceptably low economic cost, environmental burdens and societal disruption. [ABSTRACT FROM AUTHOR]

Sustainability is a global goal of sustainable development aimed at ensuring a quality life on the Earth for the future generations. Buildings, infrastructure and the entire built environment should be better prepared for the new conditions—they should be sustainable, resilient and adaptable to new situations. This requires new technical solutions for the construction, reconstruction, and modernization of buildings and all other engineering structures. Concrete is gradually becoming a building material with great potential for realizing technical solutions that meet new requirements, leading to the necessary reduction of environmental impacts and consequent improvement of social and economic conditions. The paper presents implementation of sustainability principles in the new fib Model Code 2020 (MC2020). This represents a contribution of the International Federation for Structural Concrete (fib) to the achievements of the Sustainable Development Goals (SDGs), set by the United Nations in 2015 as an action plan for the period up to 2030. [ABSTRACT FROM AUTHOR]

The fib Model Code 2020 (MC2020) is developed to serve as the basis for future international codes and standards for the design of concrete structures by summarizing international research and experience and converting this knowledge into a practical document. The chapter "Concretes" contained therein provides a clear set of application rules in combination with sufficient background information and related references. This paper gives a concise overview of the contents of the Chapter 14 "Concretes" in the 2nd draft of MC2020. Instead of presenting numerous details on changes in the text and equations compared with the previous MC2010, major fundamentals on modeling concrete behavior are indicated. New sections in MC2020 on non‐conventional concretes, durability specifications and environmental performance are covered. Extended state‐of‐the‐art chapters on concrete transport properties and durability design conclude this contribution. [ABSTRACT FROM AUTHOR]

The next edition of the fib Model Code for concrete structures, Model Code 2020 (MC2020), is under development with the aim of issuing a first partially harmonized draft for comment in early 2023. MC2020 is a single code dealing with both new and existing concrete structures, that is both the design of new structures and the various activities associated with the assessment, interventions upon and life‐cycle management (LCM) of existing concrete structures. The paper outlines the overarching sustainability framework and the performance‐based or outcomes‐based approaches (PBA) adopted by MC2020. There is a pressing need to reduce barriers to the evolution in concrete construction materials and the technical aspects of design and the LCM of existing structures, in order to meet pressing climate change drivers and the goal of achieving lower carbon construction. MC2020 also addresses significant advances made on a wide range of issues including those relating to structural design and analysis methods, seismic design and assessment procedures, durability, structural monitoring, service life design, structural assessment through‐life and making interventions to adapt existing structures or enhance their performance or extend their useful life. [ABSTRACT FROM AUTHOR]

Despite their successful applications in practice for over a century, the design of concrete hinges still entails considerable modeling uncertainty. Their dimensioning still relies on semi‐empirical recommendations originally proposed for admissible stress design, based on limited experimental data and generalized with engineering judgment. This presumably results in overly conservative designs in many cases, particularly when applied with modern design codes based on partial safety factors. This paper addresses these issues by revisiting the analytical modeling for one‐way Freyssinet concrete hinges under general loading based on approaches compatible with current design codes. A cross‐sectional analysis with confined concrete properties is proposed for the behavior under axial forces and bending moments, where the strength of the triaxially compressed concrete in the hinge throat is determined with a discontinuous stress field. The hinge resistance to shear forces is investigated with failure mechanisms inspired by failure modes observed in experiments. Based on the shear strength, a simple approach to estimate the torsional resistance of the throat is proposed. Remarks are also made on the analysis of combined actions. The predictions of the proposed models are validated against a wide range of test data, including a series of recently conducted own experiments. Overall, the proposed models agree better with the available experimental data than the existing approaches, potentially allowing for a more efficient design of new and assessment of existing concrete hinges. [ABSTRACT FROM AUTHOR]

Concrete which is the most commercialized construction material and thus it plays a key role in this era of development and hence its evolution is of utmost importance and therefore the evolution of the quality of concrete to that of its highly evolved type namely, ultra‐high performance concrete (UHPC) is undeniably the boon to this sector. Though, the correlations between the technical characteristics of UHPC and the composition of its mixture are complicated, nonlinear, and complex to characterize using standard statistical techniques. This paper is intended to use both deep neural network and ensemble machine learning algorithms namely gradient boosting, extreme gradient boosting, random forest regressor, extra tree regressor, and voting regressor trained with an 810 UHPC mixture collections with 15 input variables to predict its compressive strength. After adjusting a regression model, the prediction efficiency and generalization ability of the developed models are validated using a number of performance parameters. It was established that all employed models performed better at forecasting result, the extra tree regressor was the most accurate followed by extreme gradient boosting. [ABSTRACT FROM AUTHOR]

In this paper, the residual mechanical properties, mass loss, and cracking behavior of hybrid‐fiber‐reinforced high‐strength concrete (HFRHSC) containing 0%, 30%, and 60% ground granulated blast furnace slag (GGBFS) in normal and high temperatures have been investigated. Chopped aramid and steel fibers at 0%, 0.5%, and 1% by volume, either individually or in different combinations, were used to reinforce the HSC. In total, 24 different mix proportions were designed. The experimental results showed that the residual compressive strength of the majority of specimens increased at 400°C while this property of all of them decreased at 800°C. Also, the test indicated that the use of GGBFS did not reduce flexural and compressive strength of HSC significantly, and in some mixed designs, the presence of GGBFS slightly increases the strength. Moreover, another result that can be inferred is that although the utilization of hybrid fibers in concrete increases flexural strength, it may decrease its compressive strength. In addition, the residual flexural strength of most specimens was reduced at 400°C, but this property of all samples decreased at 800°C. The results showed that the simultaneous presence of GGBFS and hybrid fibers can improve the flexural strength of most specimens at different temperatures. [ABSTRACT FROM AUTHOR]

High‐performance fiber‐reinforced concrete (HPFRC) can be considered a promising material for the construction of precast concrete girders for road bridges. This paper presents conceptual considerations and numerical analysis to support this statement. The HPFRC is a compromised alternative between FRC and UHPFRC mixes. Specifically, a tailor‐made mix design of HPFRC jointly developed by ACCIONA and the authors is presented, and then compared with the other types of fiber‐reinforced concretes collected from the technical literature. In addition, some trends observed in the database are described. This material characterization is followed by a conceptual analysis of the advantages of the application of HPFRC to road bridges. Specifically, a proposed bridge for the case of a 60 m‐span box girder is analyzed. A comparison between alternatives based on the use of HPFRC and conventional reinforced concrete is discussed. The results shed light on the viability of this material for bridge application. Specifically, the main finding show potential significant material savings in structural elements of the superstructure. Finally, ongoing and future research for a wide application to the construction sector are briefly discussed. [ABSTRACT FROM AUTHOR]

Neither the shear transfer behavior of unreinforced hydraulic concrete structures nor experimental procedures for its determination have been standardized in recent building codes and regulations. This poses uncertainty for the assessment of the integrity of hydraulic structures. This paper adapts direct shear tests, which are an established method in rock mechanics, for the assessment of unreinforced concrete joints and expands the evaluation method through recognizing surface inclination as a contribution to the coefficient of friction. The evaluation is subsequently performed on direct shear test results performed on specimens taken from a lock built in the early 20th century. Based on the initial state of the concrete joints—intact or cracked bond—results for the basic friction angle and the inclination angle are discussed. Using entire shear stress‐deformation‐curves as opposed to singular values was found to yield more stable results of shear transfer parameters and additional insight on the validity of the test. [ABSTRACT FROM AUTHOR]

Shells are impressive structures due to the high load‐bearing capacity they exhibit when appropriately designed. Their construction, however, is usually associated with great efforts. In this paper, a novel approach for shell‐construction is presented that circumvents the necessity for doubly curved formwork. Instead, shells are erected from flat plates to which an eccentric force is applied causing them to bend into a desired curved shape. The form‐activating forces are induced by coupling a system of tendons to a thin—thus flexible—plate made from reinforced concrete. This approach may seem controversial as concrete exhibits a small ultimate strain and a brittle failure behavior. Therefore, it does not appear suited for the large deformations expected during the construction of actively bent structures. The investigations presented in this paper show the suitability of textile‐reinforced concrete for the fabrication of actively bent shells. [ABSTRACT FROM AUTHOR]

Shrinkage of concrete refers to the volumetric change of concrete due to cement hydration (i.e., self‐desiccation) and environmental drying (i.e., water evaporation). It creates dimensional instability and induces tensile stress when the concrete is restrained that may be large enough to cause cracking. The most fundamental way to mitigate concrete shrinkage is to decrease the shrinkage of cementitious paste in the mix design. Some major factors of concrete mix design affecting the shrinkage include water‐to‐cementitious material (W/CM) ratio, dosage of superplasticizer (SP), concrete strength, and cementitious paste volume (CPV). While the effects of concrete strength and CPV on shrinkage are straightforward, those of W/CM and SP are more complicated because they also affect the pore size and distribution that influence the moisture movement. In this paper, it is advocated to study the concrete shrinkage by its wet packing density (WPD). Considering that the shrinkage of concrete is associated with the moisture movement in capillary pores and that the WPD accounts for the void ratio in fresh concrete, it will be shown in this paper that the shrinkage can be correlated negatively to the WPD with the consideration of CPV. The paper thus provides a new insight to the interdependence amongst shrinkage, CPV, and WPD of concrete. [ABSTRACT FROM AUTHOR]

This paper presented the experimental results of the strength capacity of studs embedded centrally in concrete with red mud synthetic coarse aggregates, with the variation of the handcrafted headed stud thickness (3.17, 4.76, 6.35, and 7.9 mm) and no shank bond influence with concrete. The results regarding the compressive strength of concrete showed considerable strength gain with synthetic coarse aggregate, ranging from 27.00 to 43.50 MPa, while in concrete with natural coarse aggregate, the variation was 27.00 to 36.50 MPa. Also, it was observed that the cracking in the concrete matrix of the synthetic coarse aggregate occurred in the aggregate instead of the transition zone, as occurred with the natural coarse aggregate concrete. However, the solid morphological formation of synthetic coarse aggregate provided excellent chemical adhesion to the headed stud, providing a hardening failure behavior after reaching the yield strength value of the steel bar with higher displacements. This can enable the optimized consumption of materials in the dosage of low‐strength structural concrete and the anchoring application of studs with smaller‐headed thicknesses, up to 8% of head diameter, generating economy and sustainability. [ABSTRACT FROM AUTHOR]

This paper presents a state‐of‐art regarding the punching of flat slabs made with coarse recycled concrete aggregate concrete (CRCAC). Punching shear is a phenomenon that occurs in reinforced concrete slabs when concentrated loads are applied near a column or other support. It refers to the failure mechanism where the concrete reaches shear failure at a critical section around the column. CRCAC is a structural material that conforms with circular economy concepts, but its design for punching using current formulae may be unsafe due to the lower strength of the concrete that can be caused by the shape or the surface cleanness of the recycled aggregates when compared with the natural ones. The results highlight the need for further research on this area, since the available experimental results are few and mainly from tests with thin slab specimens. Since the punching phenomenon is dependent on the scale effect, it is mandatory to have more results for slabs with representative thickness. The applicability of the models for punching resistance in EC2, ACI318‐19, and the upcoming second generation of EC2 was also investigated. These codes can produce safe estimates for CRCAC slabs. However, it was found that the second generation of EC2 is less conservative than the other models. [ABSTRACT FROM AUTHOR]

Achieving traceability of concrete materials is a crucial step toward promoting sustainable concrete use. This includes creating accurate Environmental Product Declarations, minimizing mistakes during concrete placement, and improving understanding of the relationship between concrete constituents and performance. Despite these benefits, effective traceability for concrete materials has not yet been achieved in the laboratory environment or within wider practice. This work sets out a digital thread for concrete use and the functional requirements for a traceability framework for adoption in a laboratory environment. Traceable resource units (TRUs) are identified, and the primary critical tracking events for each TRU are described. A prototype traceability system is developed to link the necessary properties, constituent material data, production information, and performance results for concrete materials. The prototype system incorporates a novel inkjet printer QR code fingerprinting solution that is demonstrated to be highly effective for concrete specimens and for various media, including paper and metal, used to transport and store raw concrete constituent materials. A laboratory test series demonstrated a 100% readability rate with the proposed QR fingerprinting solution according to standard measures. This work advances knowledge of the appropriate traceable resource units and critical tracking events within concrete practice, develops effective marking procedures and forms a prototype constituent‐to‐product traceability system. [ABSTRACT FROM AUTHOR]

In 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. [ABSTRACT FROM AUTHOR]

The Metro Tunnel is a Victorian Government funded infrastructure project which will create a new end‐to‐end rail line from Sunbury in the west to Cranbourne/Pakenham in the south east, with bigger and better trains, next generation signaling technology and five new underground stations. This article provides a detailed summary of the structural fire testing requirements for the platform tunnel side wall and arch lining in the Metro Tunnel's State Library and Town Hall stations. Contrasted to building fires, tunnel fires are more significant within a few minutes due to the confined space which can cause concrete spalling and jeopardize the bearing capacity of the tunnel, which is a significant concern to designers. The catastrophic European tunnel fire events in 1999 and 2001 led to the development of innovative regulations and recommendations, including guidelines endorsed by the European Federation of National (EFNARC 132F r3:2006) and Efectis R0695:2020. This paper explains the methodology taken to design the fire rated concrete test for the platform tunnel side wall and arch lining in the State Library and Town Hall stations of Melbourne's Metro Tunnel Project for structural stability for the period of a serious fire event. For the first time, uniaxial loading (500T) was applied to five large‐scale flat concrete panels (1800 × 1800 × 400 mm) which are normally unloaded during fire exposure and exposed to the RABT ZTV (rail) fire curve. The first testing program investigated the influence of polypropylene dosage in the concrete mix design and its effect on the magnitude and severity of concrete spalling. The results indicated that the recommended 2.0 kg/m3 polypropylene dosage requirement as specified by Eurocode is conservative. Concrete mix designs with a stable aggregate and the correct curing regime can mitigate spalling at significantly lower polypropylene dosage rates. The water pooling effect was evident during the fire testing and the surface cracking that developed was vertical to the surface, allowing for the release of the pore water pressure build‐up. [ABSTRACT FROM AUTHOR]

The paper describes the authors' contribution to the evolution of numerical simulation of concrete structures based on the nonlinear finite element method. The formulation of constitutive relations for concrete material is a keystone of this approach, whereas cracking is the dominant feature. Two distinct methods of crack modeling were developed, namely, the discrete and the smeared crack models. Blind prediction benchmarks of the experimental tests are used for model verification. Application of the numerical simulation in the design of concrete structures is supported by the global safety format, where the uncertainty sources, due to the material and the resistance model, are considered. A structural assessment of a prestressed reinforced concrete viaduct is shown as an example of application. [ABSTRACT FROM AUTHOR]

The structural behavior of concrete hinges under general loading is far from being properly understood, which is to a large extent due to the lack of pertinent experimental data. This paper contributes to filling this knowledge gap by presenting and discussing the results of an experimental campaign on one‐way Freyssinet concrete hinges. Seven large‐scale concrete hinges were tested in the Large Universal Shell Element Tester, which allowed the investigation of their behavior under general loading by all six stress resultants. A combination of digital image correlation and distributed fiber optic measurements allowed a deeper insight into the structural behavior of the specimens. The tested hinges could sustain very high axial stresses exceeding 4.5 times the uniaxial concrete compressive strength, large rotations of over 60 mrad, and shear stresses in transverse and longitudinal directions up to 2.24 times the axial compressive stress. The resistance to bending moments about the strong axis and torques also proved to be significant. A moderate amount of reinforcement crossing the hinge throat considerably increased the shear resistance at low axial stresses and produced a ductile shear behavior. [ABSTRACT FROM AUTHOR]

The paper investigates the freeze–thaw resistance and sorptivity behavior of fine‐grained alkali‐activated concrete cured at ambient temperature. A blended binder system containing fly ash, ground granulated blast furnace slag, and silica fume was used. A combination of sodium hydroxide and sodium silicate was used as an activator. The freeze–thaw resistance was evaluated based on mass loss (scaling), and the extent of internal damage was assessed by testing the ultrasonic time at different cycles. Initial and secondary sorptivity coefficients were calculated based on the cumulative water absorption values at different time intervals. Alkali content, sodium silicate to sodium hydroxide ratio, and water to binder ratio were investigated. The experimental results showed that water to binder ratio is the most significant parameter for the scaling; higher ratios result in higher scaling. In terms of internal damage, alkali content is the most significant. The increase of alkali increased the amount of internal damage in the concrete. The initial sorptivity coefficient increased with the water and alkali content and decreased with the silicate content. The secondary sorptivity coefficient showed no significant change with the investigated parameters. [ABSTRACT FROM AUTHOR]

This paper investigates high‐strength concrete (HSC) exposed to high temperatures using the full replacement of natural aggregates with steel slag. Polypropylene (PP) and steel fibers are used as reinforcements, and the effects of calcium aluminate cement and ordinary cement on the mechanical properties of this concrete are compared. A total of 81 cylindrical specimens of 100 × 200 mm and 81 prism specimens of 100 × 100 × 350 mm were made using different amounts of cementitious materials (cement and silica fume) of 450, 500, and 550 kg/m3, with constant water‐to‐cementitious materials ratio of 0.28. The present results revealed that the HSC made with steel slag aggregates and calcium aluminate cement reinforced with steel fibers, had the greatest compressive strength of 84 and 50 MPa at temperatures of 20°C and 800°C, respectively; and flexural strength of 7.9 and 4.5 MPa, respectively, at the same temperatures. Similar HSC specimens constructed with ordinary cement, on the other hand, performed better at 400°C. Moreover, the flexural strength of the samples placed at temperatures of 400°C and 800°C decreased by 28% and 48%, respectively, compared to the specimens at 20°C. Compared to specimens comprised of polypropylene fibers, the fracture energy and displacement of HSC with steel slag reinforced with steel fibers subjected to high temperatures were increased by approximately 100% and 60%, respectively. [ABSTRACT FROM AUTHOR]

Internal curing (IC) process introduced via a water‐entraining agent using lightweight and porous aggregate has become an essential component in designing high and ultra‐high‐performance concrete (HPC/UHPC). This paper presents experimental results demonstrating the effectiveness of using recycled ceramic tile aggregates (RCTA) derived from waste ceramic tiles as an IC agent for high‐performance structural elements. Previous studies by the author have confirmed the efficiency of both the pre‐saturated recycled porous ceramic coarse aggregate (RPCA) as an IC and shrinkage compensating agents in mitigating autogenous shrinkage and the induced internal self‐stress in HPC mixtures. The main objective of this study is to investigate the effect of two different curing systems (internal curing using the waste ceramic aggregate combined with shrinkage compensating agents) on silica fume (SF) HPC behavior. The shrinkage compensating agents include a combination of shrinkage‐reducing agent (R) and expansive additive (E). The influence of this combined ternary curing system on the mechanical properties, including compressive, flexural, and splitting tensile strengths, modulus of elasticity, autogenous shrinkage, and internal self‐induced tensile stress, were investigated. The obtained results indicate a substantial reduction in the autogenous shrinkage strains magnitude and, consequently, the internal self‐induced tensile stress in the HPC mixtures designed with these two curing systems. It was also found that this combination of the two curing systems resulting in a hybrid curing system, performs much better than the single incorporation of shrinkage‐compensating agents. Besides, a long‐term strengths improvement was recorded for mixtures designed with the RPCA. Incorporating recycled aggregate in the design and production of HPC could further promote concrete sustainability by reducing the amount of virgin extracted non‐renewable minerals, reducing the energy required to extract and process natural aggregates and the CO2 generated, and also reducing solid waste materials disposal. [ABSTRACT FROM AUTHOR]

Crumb rubber (CR) concrete (CRC) characterized with high ductility and environment friendliness, has recently been studied widely in the field of green concrete. Generally, high volume fraction of CR in cementitious system leads to low strength. However, the effect of CR particle size has not been concluded yet. This paper focuses on the impact of CR size on the mechanical and microstructure properties of CRC. Two novel substitution approaches of CR for natural fine aggregate are adopted. In total, 10 groups are designed and experimentally tested for their workability in fresh state and mechanical properties in hardened state. Brittleness coefficient, fineness modulus, and micro‐morphology of CRC were analyzed and discussed. Results show that as size of CR decreases, workability improves significantly, apparent density and strength exhibit a firstly decrease and then increase trend, with the lowest value obtained around 1.18 mm CR size. The brittleness of concrete was significantly improved in the presence of CR, and the improvement was more significant for smaller‐sized CR. Weak ITZs between CR particles and interfacial porosity are the main reasons for the sharp strength deterioration. Crack arresting effect of CR makes the crack propagation path more tortuous, and smaller particle‐sized CR exhibits greater capability. [ABSTRACT FROM AUTHOR]

As acknowledged explicitly or implicitly in most of current design codes, a high level of sustained loading has a detrimental effect on the concrete compressive strength. However, its beneficial effect in terms of deformation capacity is neglected in most cases. This latter topic and its practical consequences are addressed in the present paper on the basis of an experimental and theoretical investigation. In particular, the development of nonlinear creep strains in structural concrete members is investigated, clarifying the internal redistribution of forces between concrete and the reinforcement. The results of an experimental program with refined measurements are presented to better understand the phenomenon and to verify the predictions of a mechanical model developed by the authors on the time‐dependent response of concrete. The experimental program consists of 14 prismatic specimens with different reinforcement ratios tested under a wide range of uniaxial stress rates. The results allow clarifying the material response and validating the mechanical model, both in terms of strength reduction and enhancement of deformation capacity. Finally, the results of parametric analyses, performed considering different concrete ages, reinforcement ratios, and materials properties are presented to evaluate the practical implications of the findings. [ABSTRACT FROM AUTHOR]

Manufactured sand (MS) has been started utilizing as an alternative in constructions due to the escalated demand for river sand (RS). The microfine aggregate (MFA) is a salient constituent in manufactured sand, which is a crushed reactive form of parent rocks having particles less than 0.075 mm. This paper presents the effects of varying microfine aggregate levels on bleeding, plastic shrinkage cracking (PSC) and compressive strength of MS made concrete. Two types of MS were utilized: MS from Hornblende‐Gneiss rock (MH) and MS from Charnockite rock (MC) and the MFA level was ranged from 0% to 12% at 3% increments and the reference concrete was prepared with RS alone. With the MFA levels, the bleeding of MS concretes was reduced where, at 0% MFA level the maximum bleeding rates were observed for MC (1.63 kg/m2) and MH (0.84 kg/m2) concretes. PSC results were analyzed from an image processing technique, which revealed an increasing trend of mean and maximum crack widths, crack length and crack area with the MFA levels. At 0% MFA, the mean crack width of MC (0.19 mm) and MH (0.17 mm) concretes manifested marginally similar to RS concrete (0.17 mm). The decreasing bleeding with the MFA levels can be attributed to the increasing severity to PSC. Moreover, the optimum 28 days compressive strength of MC (57.5 MPa) and MH (56.1 MPa) concretes was achieved at 3% MFA level which are higher than RS concrete (51.5 MPa). Consequently, the MFA level should be limited to 3% for better plastic and hardened performance of MS made concrete. [ABSTRACT FROM AUTHOR]

Despite offering several benefits in terms of environment and economics, few studies were conducted on the ground granulated blast furnace slag (GGBFS) based alkali‐activated concrete reinforced with recycled tire steel fibers (RTSFs). Therefore, this paper employed the Taguchi method to investigate and optimize the influence of GGBFS content, the alkaline solution to GGBFS content ratio, sodium hydroxide solution concentration, and RTSF volume fraction on splitting tensile strength (STS) of recycled tire steel fiber‐reinforced alkali‐activated slag concrete (RTSFR‐AASC). The microstructural evaluation was done through scanning electron microscopy, and Fourier transform infrared spectroscopy (FTIR) analyses. The results indicated that the fiber content, the most efficient parameter on STS, led to a considerable enhancement in the performance characteristic. Microstructural analysis proved the variations in formation of C–S–H gel. The results of the confirmation experiment on the proposed optimized RTSFR‐AASC mixture with the highest 28‐day STS (7.11 MPa) confirmed the effectiveness of the Taguchi method. [ABSTRACT FROM AUTHOR]

Crack initiators in reinforced concrete structures can facilitate fulfilling the serviceability requirements. They can be used as a design parameter to diminish the minimum reinforcement for members subject to imposed deformation and exposed to the environment as they reduce the crack spacing and width when arranged close enough. While crack initiators in conventional concrete construction are cumbersome to provide (e.g., by construction joints or taperings), they are inherent to layered extrusion processes with digital fabrication technologies: the tensile strength is typically reduced locally in interfaces between layers. Rather than trying to avoid these weak interfaces, this paper discusses the potential of taking advantage of them to act as crack initiators reducing the minimum reinforcement content. A tension chord‐based model is developed to (i) account for the local strength reduction and (ii) predict the effect of weak interfaces on the expected crack spacing and width. As a key finding, the model predicts a reduction of the required minimum reinforcement ratio proportional to the locally decreased concrete tensile strength for a specified maximum crack width requirement under imposed deformations. An experimental campaign on five layered and three reference tension ties confirmed the clearly positive impact of weak interfaces on crack spacings and widths. [ABSTRACT FROM AUTHOR]

This paper introduces the key concepts of sustainability in the construction industry, together with a call for an urgent action to change the culture of all implied agents. The work presents an objective framework to evaluate sustainability through the analysis of the stages of the Integrated Life Cycle Assessment (ILCA). Such approach is applied to the global warming emissions indicator, and different aspects are investigated to support designers toward more sustainable designs. First, the principles for ILCA are introduced and sound values for the emissions of different structural materials are critically discussed and filtered taking into account the recently increased sensitivity to environmental aspects. On that basis, objective comparisons are presented for practical examples related to buildings and bridges. Specific design alternatives, based on the use of different materials and structural typologies, are also illustrated and compared to the original solution. The conclusions help the designer to identify which are the critical decisions leading to projects respectful of sustainability considerations. Specifically, material selection, structural efficiency, and a sound conceptual design are identified as the key aspects of sustainability. [ABSTRACT FROM AUTHOR]

The tensile creep of concrete with supplementary cementitious materials (SCMs) such as fly ash (FA) and ground granulated blast furnace slag (GGBFS) is investigated in this paper. A total of 21 series of tensile creep tests using dog‐bone specimens under uniaxial tensile loading have been carried out. The cement replacement rates considered were 30% fly ash, 40% and 60% GGBFS. The characteristic compressive strength of concrete was ranging from 25 to 100 MPa. The tests were conducted from the age of 2 days until 28 days. It is observed that the tensile creep of fly ash concretes was slightly lower than that of the reference mixtures without SCM. For GGBFS concrete, the higher the GGBFS content, the higher the tensile creep. Existing creep models, originally developed for creep in compression, could not predict the experimental tensile creep results. Thus, a new tensile creep model was proposed including creep prediction for concrete with fly ash and GGBFS. The new model was calibrated only for controlled environmental conditions (23°C and 50% RH) and has been validated by analyzing the development of concrete tensile stress in the restrained ring test. [ABSTRACT FROM AUTHOR]

The equivalent mortar volume (EMV) mixing method has been proposed to prepare recycled aggregate concrete (RAC) with comparable mechanical properties to those of reference natural aggregate concrete (NAC). Previous studies primarily focused on the mechanical properties of EMV concrete with a single replacement ratio of recycled coarse aggregate (RCA). This paper investigates how the mechanical properties of EMV concrete vary with the replacement ratios and particle size distributions of RCA. Five different RCA replacement ratios and two RCA particle size distributions were assessed. A material demand coefficient was principally proposed to quantify the contribution of the EMV mixing method to reduce the environmental impact; the maximum RCA replacement ratio was suggested to obtain sufficient workability of EMV concrete using an effective sand ratio; a drying shrinkage model was theoretically proposed for EMV concrete accounting for the drying shrinkage of residual mortar. The obtained results indicated that the compressive strength and elastic modulus properties of EMV concrete decreased with increasing RCA replacement ratios; using the effective sand ratio of EMV concrete, comparable mechanical properties to those of reference NAC could be obtained for EMV concrete; the proposed shrinkage model was consistent with the available experimental data. [ABSTRACT FROM AUTHOR]

With the growing usage of supplementary cementitious materials (silica fume, fly ash, and ground blast furnace slag, etc.) in concrete, accurate prediction of green concrete compressive strength (CS) has become an issue worth investigating. In this paper, a green concrete CS prediction model was developed using hybrid artificial neural network with genetic algorithm (GA‐ANN) based on 2479 green concrete CS experiment results. Also two prediction models based on support vector regression (SVR) and ANN algorithm were developed for comparison. Five new parameters were constructed based on the original nine influencing parameters of CS, taking all 14 parameters as input variables, the influence of the constructed parameters on the model performance was studied. Feature selection was then performed based on the maximum information correlation (MIC) and sensitivity analysis results, which could improve the model by deleting several parameters. The results showed that the prediction performance of the SVR, ANN, and GA‐ANN models were improved after adding new parameters, the GA‐ANN model has the best prediction performance. The accuracy and robustness of the GA‐ANN model were effectively improved by deleting the input variables with lower MIC and sensitivity values. [ABSTRACT FROM AUTHOR]

In a recent experimental research, the authors measured the circumferential strains on the cylindrical envelope of concrete specimens during pull‐out tests. This paper presents a theoretical approach, complementing the previous experimental study, aiming at predicting these measured circumferential strains and developing the understanding of the three‐dimensional behavior of the concrete cylinder. The proposed approach accounts for the specimen materials and geometrical parameters including the ribs and strain gauges locations and proposes an expression for the normalized and absolute circumferential strains along the specimen circumference due to ribs actions. This paper presents a new three‐dimensional model of the specimen behvior during a pull‐out test, which provides new insight on bond mechanics and illuminates the role of the radial pressures developed as part of the bond action. Several simulations were performed on specimens with three different diameters, two concrete strengths, and a different number of bonded ribs. All the simulations show very good agreement with the measured strain data. This study enhances the understanding of bond resistance during a pull‐out process and contributes to the understanding of the ring action that is developed in a concrete cylinder during a pull‐out test. [ABSTRACT FROM AUTHOR]

The application potential of recycled aggregate concrete has been realized with the development and utilization of waste concrete. Fibers are added to concrete made with recycled coarse aggregate to enhance its mechanical properties and broaden its application possibilities. Additionally, in practical applications, parts of structural elements are frequently under compression‐shear stress. As a result, the normal stress ratio k (k = σ/fcu, where σ is axial compressive stress, and fcu is concrete cube compressive strength), coarse aggregate replacement rate, and carbon fiber content are used as design parameters to examine the compressive‐shear mechanical properties of carbon fiber recycled aggregate concrete in this paper. The results show that the normal stress ratio and fiber content affect the whole compression‐shear process curve, shear strength, peak shear displacement, and damage evolution. A compressive shear damage model that takes into account the aggregate replacement rate, normal stress ratio, and fiber content is established. And there is good agreement between the experimental findings and the calculation model. [ABSTRACT FROM AUTHOR]

Reinforced concrete (RC) elements suffer continuous deterioration across their lifetime from in situ aggressive environmental factors. Chloride‐induced deterioration of the steel reinforcement presents significant repercussions on the mechanical and seismic behavior of affected RC members. This paper introduces and summarizes experimental work carried out at the University of Canterbury, investigating the long‐term implications of chloride‐induced deterioration on various mechanical properties. The impact of chloride corrosion on bond‐slip behavior, the cyclic flexural response of large‐scale RC piers, and the shear resistance of short RC columns, with particular focus on the latter, is reported. Results indicate that corrosion damage presents more severe consequences to the displacement ductility of RC columns than the load‐bearing capacity. Transverse reinforcement presents a much greater risk and vulnerability to deterioration, leading to a transition in failure mechanism from a ductile response to a brittle shear/shear‐bond failure. Reduced confinement negatively impacts the stress–strain response of the confined concrete and bond‐slip behavior in cracked members, where friction is relied upon as the primary load‐transfer mechanism once mechanical interlock is lost through the generation of rust by‐products and concrete splitting. [ABSTRACT FROM AUTHOR]

This paper presents the comparison of advanced semi‐probabilistic methods for the design and assessment of concrete structures represented by mathematical models solved by non‐linear finite element methods. The special attention is given to the advanced methods focused on the estimation of the coefficient of variation of structural resistance. Numerical examples represent a replication of laboratory experiments of beams with different failure modes. The obtained results are discussed with respect to the accuracy of the employed methods and the influence of the assumed statistical correlation among basic variables. Simplified methods give a good estimation of the design values, though their accuracy is dependent on the type of the failure mechanism. Moreover, it is shown that mutual correlations among random variables may significantly affect the design value of resistance, and they should be carefully defined and modeled. [ABSTRACT FROM AUTHOR]

In this paper, concretes including three different fiber types (carbon steel fiber [CSF], forta ferro fiber [FFF], and polypropylene fiber [PPF]) with different percentages by volume (0.5%, 1%, and 1.5%) and crumb rubber (CR) as a replacement of fine aggregate by volume (5%, 10%, and 15%) are mechanically investigated. Compressive strength, flexural tensile strength, pull out strength, and elevated heat resistance tests are conducted 28 days after casting on the prepared concrete specimens. For the elevated heat resistance test, samples are exposed to 200, 400, and 600°C heat for 2 h and then compressive strength test is applied. According to the test results, fiber reinforcement limits compressive strength decrease and improves flexural tensile strength properties of the rubberized concretes. The positive effect of the fiber reinforcement is also observed on the samples conducted to pull out strength and elevated temperature resistance tests. CSF and PPF reinforced rubberized concretes perform better pull‐out resistance then the FFF reinforced rubberized concretes. Elevated heat resistance test is as expected since with elevation of the temperature strength of the concrete decreases. But according to the test results of the present study, the strength decrease seems to be limited with fiber reinforcement. As a result, incorporation of the fiber and CR could help to utilize more waste tire (CR) in concrete to produce sustainable eco‐friendly concrete. [ABSTRACT FROM AUTHOR]