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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]

The durability of reinforced concrete structures exposed to aggressive environments is affected by corrosion of carbon steel reinforcement. For this reason, it is of great practical interest to look for alternative solutions guaranteeing durability through the incorporation of corrosion‐resistant materials, such as stainless steel rebars. This type of steel is specially recommended for structures with a long lifespan, located in aggressive environments, with chlorides or de‐icing salts, and for structures where repair, inspection and rehabilitation is complicated. This solution presents a challenge from the point of view of the materials themselves, the mechanical design and their durability. This article presents the material properties of stainless steel and their influence on concrete structures. Furthermore, it is explained how these properties have been taken into account in the latest draft of the second‐generation Eurocode 2. [ABSTRACT FROM AUTHOR]

Compared with the ground service environment, the evolution of concrete performance under a water pressure service environment is quite complex with variable conditions. Because of the coupling effect of load and pressure, water has a special impact on the strength and deformation of concrete. Meanwhile, harmful ions usually react with the cement matrix as pressure water seepages into concrete, resulting in the reduction of concrete durability. Based on this, this study provides a comprehensive review of the strength, deformation, and durability of concrete under water pressure environment. It is found that microcracks in concrete tend to propagate and connect after exposure to water pressure, leading to a decrease in strength and deformation performance. The average loss rate of strength and elastic modulus increased by 12.15% and 10.97%, respectively, when water pressure increased by 1 MPa. However, the loading process of water‐confining pressure makes concrete more compact, where the static and dynamic mechanical performance can be improved. Besides, due to the enhancement of excess pore water pressure, concrete strength under a high strain rate increases by 61.79% compared to static load. The effect of water pressure increases the ability of the liquid to penetrate concrete, and corrosive ions trapped within the liquid and freeze–thaw caused by external temperature changes would further reduce the concrete durability. This study points out that static and dynamic loading characteristics and durability of concrete under multi‐factor coupling in a water pressure environment will be the future research direction. The summarized contents can provide guidance for construction and research of concrete engineering under a water pressure environment. [ABSTRACT FROM AUTHOR]

Reinforced concrete structures can experience various harsh environments during their service life, among which chloride ion exposure, especially in marine environments, can cause the durability reduction and deterioration of concrete structures. Artificial intelligence (AI)‐based modeling of the non‐steady‐state apparent chloride diffusion coefficient (DC) of concrete for a long exposure time using the experimental field results can assist in identifying the influential factors and better estimating the service life of a concrete structure. In this study, two novel extensions of ensemble AI algorithms, including genetic programming forest (GPF) and linear genetic programming forest (LGPF) algorithms, were proposed to model the DC of concrete. The experimental field data were gathered from the literature. Different structures of the proposed ensemble methods were developed and examined, and the best‐developed model was selected for further analysis, including sensitivity analysis and parametric study. In addition, the random forest (RF) method was used as the control ensemble technique to have a comparison. The results show that the best LGPF model possesses superior performance than the best‐developed GPF and RF models. In addition, the results show that silica fume‐to‐binder ratio, exposure time, and exposure conditions have the most significant impacts on the DC of concrete. This study contributes to the civil engineering practice by developing a new tool to model the DC of concrete that facilitates the durability assessment of concrete structures. [ABSTRACT FROM AUTHOR]

Multiple initiatives advocate for reducing embodied carbon (i.e., greenhouse gas emissions) associated with concrete production. Even though readily implementable strategies exist, practitioners are concerned that reducing embodied carbon emissions may adversely affect concrete performance and durability, resulting in detrimental effects from a life cycle perspective. To address such concerns, this study investigated the correlations between embodied carbon of concrete mixtures, mixture design parameters, and experimentally measured mechanical and durability properties. The analyzed datasets included 145 mixtures, featuring a variety of mixture designs from laboratory and field studies. The results indicate that the cement content is the most significant predictor of global warming potential (GWP) and that considerable GWP savings can be achieved by reducing and replacing cement without compromising performance. Clear correlations of GWP with compressive strength were not identified, while the results demonstrated that reduced GWP and increased electrically based resistivity (the utilized durability indicator) often occur in synergy. [ABSTRACT FROM AUTHOR]

Understanding and predicting concrete carbonation are significant in designing durability and maintaining the service life of reinforced concrete structures. However, this purpose can hardly be reached because of complex carbonation mechanisms depending on various variables such as cement content (C), fly ash content (FA), water content (W), concentration of CO2, relative humidity (RH), temperature (T°C), and exposition time (Time). This investigation proposes a machine learning (ML) approach including eight ML algorithms such as four single ML models: XGB, GB, RF, and SVM, and four hybrid ML models: XGB_RRHC, GB_RRHC, RF_RRHC, and SVM_RRHC for investigating and predicting concrete carbonation depth containing fly ash. To achieve this purpose, a dedicated database consisting of 688 samples and seven input variables is built, and the performance of eight machine learning models is compared. Single ML model Extreme Gradient Boosting (XGB) using the default hyperparameters exhibited the highest performance with R2 = 0.9770, RMSE = 2.2725 and MAE = 1.5218. Shapley Additive exPlanations (SHAP) identifies the most influential feature and order of feature effect on concrete carbonation depth. The first four important features can be sorted in order: time of exposition > cement content > water content > CO2 concentration. Moreover, at a higher value of exposition time, water content, CO2 concentration, fly ash content, temperature and relative humidity, the carbonation depth of concrete increases. Using high content of cement can reduce the carbonation depth of concrete. [ABSTRACT FROM AUTHOR]

The disposal of waste from coal plants and waste glass (WG) is causing significant environmental problems all around the planet. Currently, the amount of discarding of these wastes is increased. One possible option is to utilize fly ash (FA) from coal plants as a partial substitute for the cement and EG as a fractional substitute for sand in concrete, respectively. Besides, fibers can improve the strength and durability of concrete; explicitly speaking, using coconut fibers (CFs) is in trend due to their highest toughness among natural fibers making it suitable material as fiber reinforcement in concrete. This research studies the concrete behavior with 15% FA as a partial substitute of cement with 2% CFs and waste beverage glass as sand at various replacement levels (14%, 15%, 16%, 17%, 18%, 19%, and 20%). Mechanical and durability characteristics of concrete were assessed, such as compression strength, water absorption, flexural strength, density, workability, and water absorption. The current study results show that adding FA, CFs, and WG improved microstructure quality at 16% replacement of sand. The study showed that the M4 mix has enhanced the properties of concrete samples as compressive and flexural strength was improved to 47.2 and 6.2 MPa and improved apparent density by 20%. Adding more WGP than the optimal proportion (16%) led to detrimental effects on void ratio, permeability, and water absorption. Therefore, 16% of sand with WG and 15% of FA with cement can be substituted with 2% CFs to develop sustainable concrete. [ABSTRACT FROM AUTHOR]

Post‐filling coarse aggregate concrete is a new type of green concrete that not only saves the cost of cementitious material, improves the strength, cracking resistance and durability of concrete, but also reduces the carbon footprint. In view of the lack of research on the seismic performance of post‐filling coarse aggregate concrete, this study designs eight interior beam‐column joint specimens made of post‐filling coarse aggregate concrete and three beam‐column joint specimens made of conventional concrete. It studies the influence of post‐filling coarse aggregate ratio, axial compression ratio and stirrup volume ratio of node area on the seismic performance of joint specimens. Through low cyclic reversed loading test, the failure process and the failure pattern, hysteresis curves, skeleton curves, ductility, stiffness degeneration, residual strength and residual displacement, and plastic hinge rotation of interior joints with post‐filling coarse aggregate concrete are analyzed. Test results show that the failure mode of post‐filling coarse aggregate concrete joints is similar to that of the conventional concrete joints. As the axial compression ratio increases, the seismic performance of the joints shows a trend of increasing first and then decreasing, and it reaches the peak when the axial compression ratio is 0.2. It also demonstrates that the seismic performance of the joints is increased by increasing the stirrup volume ratio of node area. Ultimately, under the same axial compression ratio, the seismic performance of the post‐filling coarse aggregate concrete is not significantly different from that of the conventional concrete. It proves that the reinforced beam‐column joint made of post‐filling coarse aggregate concrete could fulfill the comparable seismic performance as that of conventional concrete. [ABSTRACT FROM AUTHOR]

As an important antiseepage structure of concrete face rockfill dam, the durability of concrete face slab is very important for the long‐term safe operation of the dam. Polypropylene fiber (PPF) and polyacrylonitrile fiber (PANF) are used as research objects to study the salt frost resistance of dual fiber Face slab concrete. The corrosion resistance of PPF and PANF concrete under different fiber volume was compared. The mass loss, residual compressive strength, relative dynamic modulus of elasticity and microstructure were evaluated in salt freezing environment. The results show that adding PPF and PANF to concrete can effectively improve the frost resistance of concrete, and the performance law is similar under the coupling failure of chloride and freeze–thaw cycles. Under the same volume, the effect of PPF concrete is more significant than PPF concrete, and the effect of adding two kinds of fibers at the same time is better than adding one fiber alone. Within the evaluation range, choosing 0.5% PPF and 0.5% PPF as additives is the best choice to improve the salt frost resistance. The results of scanning electron microscopy microstructure analysis of corrosion products are consistent with that of macro property analysis. [ABSTRACT FROM AUTHOR]

As a nanometer material, carbon nanotubes can inhibit the expansion of microcracks and is of great significance to improve the mechanical properties and durability of concrete. In order to explore the mechanism of dynamic mechanical properties enhancement of carbon nanotube reinforced concrete under impact load after freeze–thaw cycles, the dynamic compression test of carbon nanotube reinforced concrete samples was carried out by using the control variable method with freeze–thaw cycles and impact air pressure as variables. The results showed that under the same impact pressure, the peak stress of carbon nanotube reinforced concrete sample decreased gradually with the increase of freeze–thaw cycles. The corresponding strain increased slightly, and the stress–strain curve moved to the right and down as a whole. Under the same freeze–thaw cycle, the peak stress of carbon nanotube reinforced concrete sample increased with the increase of strain rate, and the dynamic strength growth factor DIF also increased, showing an obvious strain rate strengthening effect. In addition, under the same freeze–thaw cycles and external impact load, the dynamic strength of carbon nanotube concrete is 41.97 and 54.21 MPa, respectively, which is 22.27 and 25.81% higher than that of ordinary plain concrete. The results show that carbon nanotube reinforced concrete samples have higher dynamic mechanical properties and freeze–thaw cycle resistance than ordinary plain concrete samples. [ABSTRACT FROM AUTHOR]

The present study is focused on the compressive strength, water retention, and workability by varying the percentage of poly ethylene glycol 200 and liquid paraffin wax from 0% to 1% by weight of cement for self‐compacting concrete and compares it with conventional SCC. Percentages of 0.1%, 0.5%, and 1% (in proportion to the weight of cement) were adopted in the study. The comparison was done in a grade concrete and with cases such as indoor curing and water‐based curing. Slump‐flow test and V‐funnel tests were carried out on the fresh concrete to evaluate the workability of concrete. Concrete weight loss with time is evaluated to determine the water retention capacity. Compressive strength of cube specimens was conducted at the end of 7 and 28 days of curing. The durability of the concrete was assessed by immersing the concrete specimens in acids. The fresh properties were satisfied according to EFNARC specifications. Based on the weight loss percentage and satisfaction of compressive strength, the dosage of a self‐curing compound was determined. XRD analysis of the concrete was also performed on the concrete specimens. [ABSTRACT FROM AUTHOR]

This study utilizes the machine learning technique to solve the complex fatigue problem of concrete materials. To this end, several learning algorithms were addressed including the random forest (RF), support vector machine (SVM), and artificial neural networks (ANNs) models. Extensive experimental data were collected from literature to train the machine learning models for estimating the maximum number of cycles at failure (i.e., the so‐called fatigue life). A machine learning model providing the best correlation was chosen through verifications. On this basis, a strength degradation model of concrete under fatigue loading was finally proposed to evaluate the residual strength of concrete after fatigue damage, which is a key factor in determining the remaining service life of concrete structures. [ABSTRACT FROM AUTHOR]

Research argues in favor of using recycled aggregates in structural concrete. However, lack of specific clauses in standards for recycled aggregate concrete design hinders the use of recycled aggregate concrete by the industry. Recycled aggregate concrete‐specific design clauses are hindered because conventional research must be complemented with experiments directed towards stochastic modeling, so that reliability concepts may evaluate whether the probabilities of failure of design comply with the expectations of Society or whether specific design rules are needed. This article compares the within‐batch variability of carbonation under accelerated conditions of four natural aggregate concrete and four analogue recycled aggregate concrete mixes and analyses the reliability of Eurocode 2 cover design for carbonation exposure. In general, the incorporation of coarse recycled concrete aggregates worsened the mean durability behavior of concrete, including resistance to carbonation. However, the variability of carbonation depth was not meaningfully affected by the recycled aggregates used (coarse recycled aggregates produced from concrete waste) and the reliability of concrete cover design only decreased due to the effect of the recycled aggregates on the mean resistance to carbonation. A 5 mm increase of concrete cover was found to more than offset the detrimental influence of full incorporation of recycled aggregates on the reliability of concrete cover design. [ABSTRACT FROM AUTHOR]

Conformity control is applied in order to safeguard the quality of produced lots. Conformity criteria are characterized by an operating characteristic curve, quantifying the probability of acceptance in relation to a concrete lot with a specific quality. By applying conformity control, certain lots of concrete are accepted or rejected. This induces a filtering effect, which in case of conformity control of durability parameters leads to an effect on the design service life. For durability, limiting values for durability‐related properties can be proposed. Specifying conformity criteria for the durability parameters of concrete can enable to safeguard the quality of concrete products in relation to durability. This conformity control has a filtering effect on the distribution of these durability parameters. When, for example, considering the diffusion coefficient of concrete, this filtering effect results in a lower mean value and standard deviation, consequently (positively) influencing the service life. In this paper, conformity criteria for durability parameters are developed, and their effect on the design service life of reinforced concrete elements is quantified. [ABSTRACT FROM AUTHOR]

The durability of concrete material after exposure to elevated temperatures is important for the serviceability prediction of concrete structures in a fire disaster scenario. Existing researches show that an appropriate amount of basalt fiber can significantly improve the splitting tensile strength and chloride penetration resistance of concrete. However, the mechanical properties of basalt fiber concrete after elevated temperatures and its durability properties are still not clear. In this paper, the mechanical properties, carbonization law, and chloride ion penetration law of ordinary concrete and basalt fiber concrete under high temperatures are studied. The concept of a burnt layer for concrete exposed to elevated temperatures is proposed, and the thickness of this burnt layer for concrete under different temperatures was measured. The results show that the addition of basalt fiber can inhibit the carbonization of concrete at elevated temperatures, diminish the thickness of the burnt layer, and significantly improve the chloride penetration resistance of concrete. [ABSTRACT FROM AUTHOR]

The focus of this study is to investigate the effect of using coarse recycled concrete aggregates (RCAs) as an alternative material to natural coarse aggregate on the fresh, mechanical and durability behavior of concrete reinforced with steel fiber. Eighteen unique concrete mixes with RCA content of 0%, 50%, and 100% and steel fiber content of 0%, 1%, and 2% were prepared, and tests were performed to study slump, density, compressive and splitting tensile strengths, flexural behavior, surface hardness, surface abrasion resistance, water absorption, and sorptivity of each mix. It is shown that concrete containing RCA has a lower unit weight, compressive, splitting tensile and flexural strength, flexural toughness, surface hardness, and abrasion resistance, and a higher water absorption and sorptivity in comparison with conventional concrete. An increased compressive, splitting tensile and flexural strength, flexural toughness, surface hardness, and abrasion resistance, and a decreased water absorption and sorptivity of concrete with an increased steel fiber content from 1% to 2% is less significant compared to those from 0% to 1%. The results also show that, at RCA content of 50%, incorporating 1% steel fiber develops a concrete mix with similar or even better properties compared to unreinforced conventional concrete. At 100% RCA content, incorporating 2% steel fiber develops a concrete mix with similar properties to unreinforced conventional concrete having water to cement ratio of 0.3, but inferior properties to unreinforced conventional concrete having water to cement ratio of 0.5. These findings indicate that recycled aggregate concrete with similar or even better properties compared to concrete with natural aggregate can be developed through properly designing mixes, providing a great avenue toward the production of green construction material for structural applications. [ABSTRACT FROM AUTHOR]

The use of recycled aggregate (RA) to produce recycled aggregate concrete (RAC) is a proven way of decreasing the consumption of natural aggregate (NA) and the landfilling of construction and demolition waste. However, adoption of codes for the design of RAC and RAC structures has been lacking. Within the framework of the new fib Model Code 2020 and Eurocode 2, provisions for RAC can be adopted. Therefore, in this study, a comprehensive and critical review of literature on RAC is performed as well as own meta‐analyses of results. Material properties of RAC and structural behavior of reinforced and prestressed RAC members are analyzed, and based on the findings, code adjustments for RAC are proposed. The results show that, in order to incorporate RAC into design codes, changes are necessary in expressions for physical–mechanical properties (volumetric mass, modulus of elasticity, tensile strength, fracture energy, peak and ultimate strains, shrinkage strain and creep coefficient), durability‐related properties (minimum concrete cover for durability) and structural behavior (shear strength of members not requiring shear reinforcement and deflections). The recommendations are formulated in terms of the total mass substitution ratio of RA that can be classified as Type A according to standard EN 206 for concrete. The results and findings presented herein can provide an important contribution toward the codification of RAC use and the wider utilization of RA in construction. [ABSTRACT FROM AUTHOR]

This article is aimed at investigating the long‐term performance of three original hydrophobic materials, namely, sodium acetate, fluoropolymer, and silicone resin. Their performance was compared with traditional silane when applied to fully dry concrete, fully saturated concrete, and concrete with 2 and 4% moisture content. A recently developed freeze–thaw process, which is based on temperature and humidity variations, was employed in this study to assess the durability of applied materials. The outcomes of the adopted freeze–thaw system were compared with the results obtained from running a conventional freeze–thaw test. Mass change, water absorption, and microcracks development of treated concrete were investigated and compared with untreated concrete after completing 6 months of freeze–thaw cycles. Results confirmed the high affinity of the proposed materials to moisture at application time compared with silane. Additionally, it was demonstrated that moisture content has a critical impact on the bonding between applied materials and concrete, hence their efficacy in enhancing the durability of concrete. [ABSTRACT FROM AUTHOR]

Recycled aggregate (RA) acknowledge with its inferior quality due to high water absorption and lower strength which is mainly due to presence of attached adherent mortar. Concrete made with RA have lower strength and durability properties when compared with natural aggregate concrete (NAC), recorded by many previous researches in past. In order to overcome these difficulties, two‐stage mixing approach (TSMA) is a good tool to improve the properties of recycled aggregate concrete when compared with normal mixing approach (NMA). The main objective of present research work is to study the influence of mixing approaches on concrete made with treated recycled aggregate (TRA). Basically the workability, mechanical and durability properties of concrete have been studied at fresh and hardened state. In this work, four different types of mixing approaches (viz. NMA, TSMA, TSMA1, and TSMA2) were used. In all types of mixing approaches, the natural aggregate was replaced with TRA at different replacement levels viz.: 0, 25, 50, 75, and 100% in a control mix of M40 grade. Based on the experimental results the workability, strength, and durability properties of concrete made with TRA were improved in TSMA2 when compared with all other mixing approaches. [ABSTRACT FROM AUTHOR]

In this study, the deterioration resistant of concrete with and without multi‐walled carbon nanotubes (MWCNTs) against combined freeze–thaw cycles and sulfate attack was studied, and concretes incorporating MWCNTs (i.e., 0.05, 0.10, and 0.15 wt%) as partial replacement of Portland cement were exposed to 5% sodium sulfate solution under freeze–thaw cycles. The performance, including compressive strength, relative dynamic elastic modulus, mass loss, microstructure, deterioration resistant coefficient of concretes were evaluated. Results show that when exposed to 5% sodium sulfate solution, MWCNTs could enhance the mechanical and durability properties of concrete subjected to combined freeze–thaw cycles and sulfate attack, regardless of the dosage of MWCNTs. The deterioration resistant of MWCNTs concrete was not increase with the increase dosage of MWCNTs. And the best resistance performance was obtained in concrete containing lower dosage of MWCNTs. In addition, MWCNTs could promote formation of hydration and corrosion products, and delay deterioration of concrete was demonstrated by SEM and thermogravimetric analysis. [ABSTRACT FROM AUTHOR]

This article presents the experimental results on accelerated carbonation‐induced corrosion and related durability properties such as AC impendence, half‐cell potential, water permeability, and volume of permeable voids test of concrete made with high‐volume Class F fly ash (FA). Concrete specimens were prepared by substituting ordinary portland cement with FA at varying replacement levels (0–70%). High‐volume FA concrete shows the continuous gain in the compressive strength and ultrasonic pulse velocity over a period of 365 days. The durability properties of concrete made with FA up to 50% shows the significant improvement. The scanning electron microscopy photomicrographs also support the findings and shows that the replacement of cement with FA densifies the concrete matrix due to the formation of more calcium silicate hydrate gels. [ABSTRACT FROM AUTHOR]

The performance of the conventional concrete skin was promoted by ultrasonic surface treatment (UST) in this study, and the newly formed dense and hard concrete skin was termed as ultrasonic hardening layer (UHL). The microstructure of UHL was scanned and analyzed, several durability‐related indicators, such as water vapor penetration rate, surface, and interface hardness, were measured, and it was found that UHL could effectively improve the durability of concretes. The light reflectance of the UHL concrete surface was measured in the spectrum range of UV (200 nm) to NIR (2,500 nm), and it manifested 24.17% less mean reflectance than the conventional concrete skin. Therefore, UHL could serve as a promising road material due to its better melting capacity in cold‐temperate zones. [ABSTRACT FROM AUTHOR]

Surface chloride concentration (SCC) of concrete is an important measure for marine environmental action on oceanic concrete engineering. However, existing models of the SCC could not estimate accurately the chloride attack on concrete exposed to submerged marine environment, as they only involve part of the main influential factors. A quantitative multifactor model for environmental action of submerged marine concrete was developed in terms of the SCC in this study. First, the water‐to‐binder ratio, binder type, chloride concentration of seawater, and exposure time were investigated and adopted as major factors in the computation model of the SCC for submerged marine concrete. The two‐phase multiple nonlinear regression technique was proposed for evaluation of the correction factors for different binder type as well as undetermined coefficients. Then a multifactor computational model for the SCC of submerged marine concrete was developed on the basis of a large number of collected test data. Finally, the effectiveness and advantages of the proposed multifactor model for the SCC were demonstrated by comparison with existing models and test data. [ABSTRACT FROM AUTHOR]

Damage processes in fatigue loaded concrete structures depend on the number and amplitude of the load cycles applied. Damage evolution is linked to a reduction in concrete stiffness, and it is thought that this reduction causes stress redistributions at component level which have a favourable impact on the service life of a structure. Until now, the stiffness reduction and stress redistribution have never been successfully measured in laboratory tests or in situ. It is only known that the real service life is longer than the calculated one and that indicators of stiffness reduction, such as component deflection, increase with the number of load cycles applied. Ultrasonic measurement techniques are considered to be well suited to detecting degradation processes caused by cyclic loading. It is expected that the stiffness reduction in fatigue loaded concrete structures can be recorded reliably with ultrasonic pulse velocity measurements. In the light of this, fatigue tests were performed on small-scale concrete specimens. The aims of the tests were to understand the correlation between the observed stiffness degradation of the specimens and the results of ultrasonic pulse velocity measurements and to estimate the potential for using ultrasonic pulse velocity measurements in continuous structural health monitoring. [ABSTRACT FROM AUTHOR]

At present, prescriptive regulations with regard to concrete cover and composition are applied to provide sufficient durability of reinforced concrete members under exposure conditions with different degrees of severity. In view of current knowledge on deterioration mechanisms and their modelling, it is planned to change from these deemed-to-satisfy specifications to a performance-based design approach in future standards. In such specifications, concrete durability design is based on the statistically characterized performance of concrete, determined in standardized tests with respect to defined classes of concretes with similar performance. This paper presents the results of a study in which concrete mixes were tested and analysed with respect to their carbonation resistance. Compositions with similar performance are grouped into carbonation resistance classes. These classes are described statistically and requirements for performance testing are given. In addition, composition requirements are introduced in order to determine concrete performance depending on mix composition prescriptively. Finally, an example is given for the assessment of concrete performance with regard to carbonation. This work was carried out at the request of JWG under CEN TC 250/SC2 and CEN TC 104/SC1 as an input and starting point for the ongoing committee work to implement the methodology from the fib Model Code for Concrete Structures 2010 in the next generation (2021) of European concrete standards. [ABSTRACT FROM AUTHOR]