Barbara Klemczak

Barbara Klemczak
Silesian University of Technology · Department of Structural Engineering

Professor

About

53
Publications
36,947
Reads
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521
Citations
Additional affiliations
February 2018 - present
Silesian University of Technology
Position
  • Professor (Full)
July 2009 - January 2018
Silesian University of Technology
Position
  • Professor (Associate)

Publications

Publications (53)
Article
Full-text available
In this paper, the focus is placed on essential aspects of finite element modelling of thermo-mechanical behaviour of massive foundation slabs at early ages. Basic decision-making issues are discussed in this work: the potential need to explicitly consider the casting process in the modelling, the necessary size of the underlying soil to be modelle...
Article
Full-text available
This paper presents the results of research into the heat of hydration and activation energy of calcium sulphoaluminate (CSA) cement in terms of the dependence on curing temperature and water/cement ratio. Cement pastes with water/cement ratios in the range of 0.3–0.6 were tested by isothermal calorimetry at 20 °C, 35 °C and 50 °C, with the evolved...
Article
Full-text available
A rising demand for efficient functional materials brings forth research challenges regarding improvements in existing materials. Carbon infused cementitious composites, regardless of being an important research topic worldwide, still present many questions concerning their functionality and properties. The paper aims to highlight the most importan...
Article
Full-text available
Mass foundation slabs represent unique structures because of the considerable thermal effects generated by the exothermic reactions of cement hydration that occur during concrete curing. Arising temperature variations in early age concrete generate tensile thermal stresses that may reach values resulting in cracking in foundation slabs. That is why...
Article
Full-text available
Mass concrete members such as thick foundation slabs and blocks have always been an integral part of our human-created environment. Building with mass concrete is a challenging task as improper design or performance of the execution process may lead to considerable risk of thermal cracking. The presented paper is initially focused on a summary of e...
Article
Full-text available
The heat released during cement hydration results in temperature-induced non-uniform volume changes in concrete structures. As a consequence, tensile thermal stresses of significant values may occur. The level of these stresses can be lowered by using various technological measures during the construction process and a proper concrete mix compositi...
Article
Massive foundation slabs are one of the structures in which early age effects play a significant role. These effects are mainly related to the exothermic nature of cement hydration and a consequent temperature rise in the structure. The inhomogeneous volume changes have consequences in arising stresses in a concrete foundation slab. Two types of ea...
Article
Full-text available
Prediction of hydration temperature and induced stresses in mass foundation slabs, due to the hydration effects is a difficult task. The complexity of this issue is compounded by transient and non-linear thermo-mechanical phenomena as well by a significant number of contributing technological and material factors that affect the early-age volume ch...
Article
Modeling the structural behavior of concrete at early ages is one of the most challenging, yet fundamental, tasks for civil engineers working on mass concrete. To obtain a reasonably accurate model, a number of factors should be taken into account. Considerations should include both external influences as well as the changes occurring in the comple...
Article
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Article
Full-text available
The current work presents the complex investigation of the influence of cement and aggregate type on the thermo-mechanical behavior of mass concrete. Six types of cement with different amounts of non-clinker constituents and four types of aggregates are used in experimental tests. Particular attention was given to the low clinker cements with high...
Chapter
Cement concrete is currently one of the most popular building material. This trend probably will not change during many years, however still growing requirements lead to necessity of modification properties of concrete mixtures and hardened concrete, making traditional concrete technology no more useful. Presently it becomes priority to obtain conc...
Article
Full-text available
The aim of the presented study is to simulate the restrained stresses in early age massive foundation slabs. The character of self-induced stresses related to internal restraints resulting from inhomogeneous distribution of thermal-humidity fields as well as restraint stresses related to limitation of structure deformations freedom are described in...
Article
Full-text available
The main cause of early age cracks often observed in massive concrete structures is inhomogeneous volume changes associated with thermal and moisture gradients occurring in these structures due to the hydration process. Significant impact on a temperature rise which is the main reason of significant changes in concrete volume, and as a consequence,...
Conference Paper
Full-text available
Still growing requirements for concrete lead to modification of concrete mix and hardened concrete properties. Modern material solutions are, among others, based on the introduction of polymers into concrete mix. In the article a review of experimental research of polymer-cement concretes with respect to the influence of polymer additives on mechan...
Article
Full-text available
Recent experiences have shown that thermal–shrinkage cracks in reinforced concrete walls are a common phenomenon. The cracks appear above the joint between the wall and the foundation at the construction phase of these structural members. This problem affects, among the others, bridge abutments, retaining walls, tank walls and radiation protection...
Article
The review of the most commonly used models for assessment of the concrete strength development is presented. The simple time-dependent models proposed by ACI C. ommittee 209, CEB FIP M. odel C. odes, E. urocode 2 and JSCE are outlined in the paper. More complex model based on the degree of hydration is also discussed.These models have been validat...
Book
Full-text available
About 30% of European citizens are concentrated in 500 largest cities of the continent. Most of these cities are now subjected, or will be in the near future, to significant modification of their urban texture, brought about by the exploitation of new areas and by redevelopment of old industrial sites or the construction of big and pervasive infras...
Article
Full-text available
The degree of restraint is a useful concept for characterisation of early-age thermal–shrinkage stresses occurring in externally-restrained concrete elements such as walls. It can be used not only in manual calculations, but also in numerical analysis to determine the values and distribution of stresses in walls. The issues that must be addressed w...
Article
Full-text available
The hydration heat evolution of low clinker cements is studied in a dependence on the testing method and temperature. Four substitution rates of ordinary Portland cement by ground granulated blast furnace slag or siliceous fly ash were used-10, 30, 50 and 70 %. In all cases, the water/binder ratio of the cement paste was 0.5. The heat evolution and...
Article
Full-text available
The hydration heat evolution of low clinker cements is studied in a dependence on the testing method and temperature. Four substitution rates of ordinary Portland cement by ground granulated blast furnace slag or siliceous fly ash were used—10, 30, 50 and 70 %. In all cases, the water/binder ratio of the cement paste was 0.5. The heat evolution and...
Article
The problem of early age cracking is still underestimated in concrete structures in which limited possibility of deformation under thermal-moisture effects may generate dangerous stresses. Thermal-shrinkage cracking of externally-restrained concrete members is frequently observed in wall members supported on previously cast foundation, such as tank...
Article
The hydration of cement generates heat and can subject structural elements to temperature variations that can be significant, particularly in massive concrete structures. Considerable attention has been focused on this problem dating back to the 1930s during construction of concrete dams in North America. Thermal cracking in massive concrete as wel...
Article
Full-text available
The article presents the results of numerical analysis of a reinforced concrete wall cast against an old set foundation, subjected to early-age thermal and shrinkage deformations. Development of stresses and character of cracks is briefly described in the article. The presented analysis is focused on evaluation of contribution of self-induced and r...
Article
Full-text available
The paper presents the original numerical model for simulation of thermal, moisture and mechanical effects in concrete structures with an example of application. The influence of different curing conditions on the temperature and moisture distribution in RC wall was investigated. The stress state and the damage intensity factor were determined and...
Conference Paper
Full-text available
The walls of reactorcontainments are usually massive concrete elements threatened by the risk of early-age thermal–shrinkage cracking, which is inadmissible in the view of the tightness and durability conditions to be satisfied for appropriate radiological protection. The paper presents numerical analysis of damage intensity of reactor containment...
Article
Full-text available
The article presents two models for determination of thermal-shrinkage stresses and evaluation of cracking risk in bridge abutments in early phases of execution. These are: a simplified, engineering model and spatial numerical model.The analyses performed with use of these models were verified on the basis of real abutment in which early-age cracki...
Conference Paper
Full-text available
The phenomenon of early-age thermal–shrinkage cracking of massive concrete structures is known ever since first dams were erected in the USA in 30s. of the last century. The problem is, however, still underestimated in concrete structures with considerably smaller dimensions, in which limited possibility of deformation under thermal–moisture effect...
Article
Full-text available
The volume changes caused by coupled temperature and moisture variations in early-age concrete elements lead to formation of stresses. If a restraint exists along the contact surface of mature concrete against which a new concrete element has been cast, generated stresses are mostly of a restraint origin. In engineering practice a wide range of ext...
Article
Full-text available
The paper deals with issues related to often observed in practice cracks of concrete structures arising just at the stage of their construction. The main cause of these cracks are inhomogeneous volume changes associated with thermal and moisture gradients occurring in structures due to the hydration process. The paper discusses the influence of con...
Conference Paper
Full-text available
The main cause of early age cracks often observed in massive concrete structures are inhomogeneous volume changes associated with thermal and moisture gradients occurring in these structures due to the hydration process. The paper discusses the influence of selected technological and material factors contributing to the increase of temperature, whi...
Conference Paper
Full-text available
The volume changes caused by coupled temperature and moisture variations in early-age concrete elements lead to formation of stresses. If there exists a restraint along the contact surface of mature concrete against which a new concrete element has been cast, generated stresses are mostly of a restraint origin. In engineering practice a wide range...
Article
Full-text available
The article presents the results of numerical analysis of thermal-shrinkage stresses generated in early phases of curing of RC wall cast against an old set foundation. The analysis covered the influence of the length and thickness of the wall on distribution of thermal-shrinkage stresses. Aditionally, the role of thermal and shrinkage as well as th...
Article
Full-text available
The issues related to early age cracking of concrete structures are discussed in the paper. The main cause of these cracks are inhomogeneous volume changes associated with thermal and moisture gradients occurring in structures due to the hydration process. The paper discusses the influence of the type and dimensions of a structure on the distributi...
Article
Full-text available
The issues related to often observed in practice scratches and cracks of concrete structures arising just at the stage of their construction are discussed in the paper. The main cause of these cracks are inhomogeneous volume changes associated with temperature rise caused by exothermic hydration process of cement as well as with moisture exchange w...
Article
Full-text available
The paper deals with issues related to often observed in practice cracks of concrete structures arising just at the stage of their construction. The main cause of these cracks are inhomogeneous volume changes associated with thermal and moisture gradients occurring in structures due to the hydration process. The paper discusses the influence of con...
Article
Full-text available
The issues related to early age cracking of concrete structures are discussed in the paper. The main cause of these cracks are inhomogeneous volume changes associated with thermal and moisture gradients occurring in structures due to the hydration process. The paper discusses the influence of the type and dimensions of a structure on the distributi...
Article
The issues connected with the determination of thermal and moisture fields in early-age massive concrete are discussed here. The coupled equations, which govern the heat and mass transfer in early-age mass concrete as well as the initial and boundary conditions are presented. Next, the discretization in the space was made using the finite element m...
Conference Paper
Full-text available
The paper presents the original numerical model for simulation of thermal, moisture and mechanical effects in concrete structures. The model can be classified as a phenomenological model in which thermal–moisture and mechanical problems are decoupled. A two stage pro-cedure is used in which coupled thermal and moisture fields are solved first. The...
Article
Full-text available
The issues related to often observed in practice scratches and cracks of concrete structures arising just at the stage of their construction are discussed in the paper. The main cause of these cracks are inhomogeneous volume changes associated with temperature rise caused by exothermic hydration process of cement as well as with moisture exchange w...
Article
The proposition of two failure criteria for young concrete is presented in the paper. The proposed failure criteria refer to well-known Willam-Warnke [1] 3- and 5-parameter model. Slight mo-difications of these models, aiming to fit the experimental evidence better and to remove some shortcomings of the original Willam-Warnke [1] models were introd...
Article
The paper concerns testing and modelling the short-term mechanical properties of young concrete. Uniaxial compressive and tensile strength, the modulus of elasticity and the complete stress-strain curve were determined during the experimental tests. The original triaxial compression tests of young concrete were done on cylindrical specimens using a...

Projects

Projects (2)
Project
Study on early age thermal-shrinkage stresses in massive foundation slabs
Project
The NRG-STORAGE project will launch a novel breakthrough solution that replaces the currently available insulation materials used in building envelopes, by proposing a multi-functional and eNeRGy saving cementitious Foam (NRG-Foam). The heat-activated foam will be used for passive/active management of energy transfer and will be applied to new building envelopes and to retrofit existing ones. Graphene-based nano-additives will be doped in both cementitious foam matrix and bio-based PCM fraction for improving the thermal storage capacity, volume stability and mechanical properties of the resulting composite. Two active/passive systems will be prototyped and validated. First, an implicit heating system for thermal activation of the added nano-graphene will be installed representing a material-based approach, and, second, a multi-functional energy efficient façade system (MeeFS) will be installed, to diverse and direct the thermal absorption capacity and shadowing of the external building walls for optimizing the NRG-Foam’s. NRG-Foam composites will be optimized to achieve the best compromise between thermal insulating properties (air bubbles) and heat storage capacity (bio-PCMs). A highly conductive cementitious paste will be designed and produced, targeting on an increase in thermal conductivity (once activated up to 10 times for bio-PCM, and 2 times for cement matrix), and an enhanced efficiency of bio-PCM heat storing performance (> 5 times). With this project, the partners will develop an innovative functional material that combines high insulation capabilities (more than 25% of classical layers) and high energy-storage capacity (more than 10% of improvement in active applications). Furthermore, the NRG-Foam layer will be characterized by a high water and air tightness (between 10% and 25% higher than existing solutions) and at least 15% lower costs than the actual solutions available in Europe for insulation purposes of non-residential buildings. https://cordis.europa.eu/project/id/870114 Project information NRG-STORAGE Grant agreement ID: 870114 Start date: 1 April 2020 End date: 31 March 2024 Funded under: H2020-EU.2.1.5.2. Overall budget: € 6 846 750 EU contribution: € 5 602 934,26 Coordinated by: TECHNISCHE UNIVERSITAT DARMSTADT Germany Participants (12) Sort alphabetically NETZSCH GERATEBAU GMBH Germany AGENCIA ESTATAL CONSEJO SUPERIOR DEINVESTIGACIONES CIENTIFICAS Spain WILHELM ROSER SOHNE GMBH CO. KG Germany GBS INZHENERING Bulgaria FUNDACION TECNALIA RESEARCH & INNOVATION Spain TECHNISCHE UNIVERSITEIT DELFT Netherlands CENTRO DE INVESTIGACION COOPERATIVA DE ENERGIAS ALTERNATIVAS FUNDACION, CIC ENERGIGUNE FUNDAZIOA Spain POLITECHNIKA SLASKA Poland GRAPHENEA SA Spain CERVENKA CONSULTING SRO Czechia SPHERA ENCAPSULATION SRL Italy UNIVERSIDAD NACIONAL DEL LITORAL Argentina