Cost Action TU1404 invites researchers to submit proposals for Short Term Scientific Missions (STSM). Applications from Early Stage Researchers (ESR) are particularly encouraged.
Short Term Scientific Missions (STSM) are aimed at supporting individual mobility, strengthening the existing networks and fostering collaborations by allowing scientists to visit an institution or laboratory in an eligible country, namely: another Participating COST Country, an approved COST Near Neighbour Country (NNC) or an approved International Partners Country (IPC).
A STSM should specifically contribute to the scientific objectives of the COST Action TU1404, while at the same time allowing applicants to learn new techniques or gain access to specific instruments and/or methods not available in their own institutions.
The selection of applicants is based on the scientific scope of the STSM application that must be in line with the Action objectives.
STSM applicants must be engaged in a research programme as a postgraduate student or postdoctoral fellow, or be employed by or officially affiliated to an institution or legal entity. This institution is considered as the Home institution. Institutions may be public or private entities.
All COST TU1404 members and their students/colleagues involved in WG activities are invited to submit one or more STSM applications.
The applications should be submitted in response to permanently open call issued by the COST Action TU1404 STSM Committee.
The grantee is required to submit a short scientific report to the host institution (for information) and to the STSM Committee for approval within 30 days after the end date of the STSM.
Payment of the grant will be issued only after receipt of the approval that the STSM has been successfully accomplished.
Within the COST TU1404 action there were eight STSMs finished by the end of April 2016. In May 2016 a call for the best STSM award for the period January 2015 to April 2016 was launched by STSM Committee members.
PhD students and early stage researchers who had successfully finished STSM by April 2016 were directly addressed to prepare posters in order to present the most important outcomes of their research work and publications, which have resulted or will result from the research within the STSM.
By the deadline for the submission of the posters (20 June 2016) the STSM Committee received five posters (out of eight) that underwent evaluation process, together with the scientific reports resulting from each STSM.
The STSM Committee decided to grant awards in two categories – best STSM of an Early Stage Researcher and best STSM of a PhD Student.
Won the award for the best Short Term Scientific Mission of an Early Stage Researcher
Won the award for the best Short Term Scientific Mission of a PhD student.
The announcement of the best STSMs was during the COST TU 1404 conference “Service life of cement-based materials and structures” in Denmark (August 2016). The best STSM is directly entitled to financial support for all COST meetings within 1 year after the attribution of the award.
Violeta Bokan Bosiljkov COST Action TU1404 STSM Coordinator
The long-term structural performance and durability of cement-based structural elements is strongly influenced by curing conditions and early age events (thermal cracking, scaffolding removal, loadings). Hence, the capacity of characterizing and/or simulation the evolution of mechanical properties, such as E-modulus, since casting assumes crucial importance. This mission aims to create a bridge between the experimental and numerical research, through the implementation of a new experimental method, the EMM-ARM, capable of estimate the E-Modulus of a cement paste since mixing. During this mission the applicant pretends to: implement the EMM-ARM method at the Laboratoire de Matériaux de Construction at École polytechnique fédérale de Lausanne; perform a comprehensive experimental program to characterize the physical properties of several cement pastes in order to compare the results obtained by several experimental methodologies, including the EMM-ARM. With the results obtained it will be possible to perform an additional validation and to disseminate the EMM-ARM methodology; and simulate de E-Modulus of the same cement pastes studied in the previous point and compare the results with the experimental data obtained in order to eventually validate and/or highlight the strengths and the limitations of the model used.
The use of construction waste obtained from building demolition as aggregates for the production of new concrete has become more common for the last decade. It is actually a promising way to handle construction waste and reduce the depletion of nonrenewable resources. The French National Projects RECYBETON and ECOREB aims at developing recommendations for the use of recycled aggregates in building materials. The experimental study performed in my PhD deals with the early-age behaviour of recycled concrete. The main objective is to assess the risk of cracking induced by plastic shrinkage. All the tests performed in the home laboratory (GeM) allowed me to understand major parameters of recycled concrete such as elastic properties, plastic shrinkage and tensile strength. This STSM will have a benefit for me to valorise the experimental work done in the framework of my PhD in Nantes and provide the scientific community with a comprehensive study on the risk of cracking of recycled concrete at early age. The goal of the STSM is actually to use the Temperature Stress Testing Machine (TSTM) device developed at ULB and combine the monitoring of the properties of recycled concrete at very early age. Since 2007 GeM-Centrale Nantes and BATir-ULB laboratories have developed a collaboration involving several PhD students and researchers to develop experimental studies on innovative cement-based materials and benchmarks on advanced tests. The STSM is an opportunity to valorise existing studies on recycled concrete at GeM and TSTM device at BATir.
Concrete has the intrinsic capacity to heal autogenously, mainly by hydration of unhydrated cement particles and dissolution and subsequent carbonation of Ca(OH)2. Since these mechanisms are rather slow, researchers are looking to incorporate (encapsulated) healing agents in the concrete in such a way that cracking is a trigger to activate the autonomous healing mechanism. The aim of this study is to perform some more fundamental research with regard to characteristics of the healing agents and their interaction with crack faces. Moreover, also the effect on durability issues will be considered. In detail, we will study:
(i) the growth of CaCO3 or hydration products precipitated in the crack and at the interface and their mechanical properties in the case of autogenous healing and autonomous healing by incorporation of super absorbent polymers or bacteria (technique used: SEM in combination with nanoindentation) (ii) the mechanical properties and elasticity of polymeric healing agents, their bonding with the concrete matrix and their failure mode (technique used: tensile testing in combination with SEM) (iii) the capacity of self-healing to limit/prevent the ingress of chlorides in concrete and thus to increase the service life (technique used: EPMA and SEM).
Study of the development at early ages of the modulus of elasticity of eco-concretes with biomass ashes coming from a paper factory. Thanks to the utilization of the EMM-ARM, it will be possible to observe the influence of the biomass ashes in that development. For this purpose, it will be performed an experimental campaign with three dosages under study; a reference dosage (conventional concrete) and two dosages with a 10% and 20% replacement of cement by biomass ashes (eco-concretes). Nowadays, no studies that monitor the development of the modulus of elasticity of eco-concretes with biomass ashes have been found. This study aims to make a comparative study of concretes with different replacements of biomass ashes.
From the point of sustainability, it has a double advantage. On the one hand, a waste product (biomass ashes) is transformed in a raw material and, on the other hand, the amount of cement utilized is reduced (the pollution caused by cement production is a factor that must be considered). Therefore, this concrete would be doubly an eco-material. Additionally, it will be useful to compare the methodology of the EMM-ARM with other methods such as ConSensor (conductivity) and/or ultrasonic. This STMS is an opportunity to develop a novel study about the properties of eco-concretes at early ages, make possible the collaboration and synergy among the members of the COST TU1404 and employ and compare techniques developed to estimate the modulus of elasticity at early ages.
The objective of this STSM is to develop the numerical simulation skills to model chloride ion flow in multi ionic regime (Na, Si, S, K, OH, Ca) such as geopolymer or alkali activated systems. The proposer has prior testing expertise in geopolymer concrete and recently supervised a PhD project in the same topic. The host is world renowned expert in microstructural modelling. It is expected that the proposed scientific mission will help to identifying critical variables in geopolymer systems and develop a numerical model for chloride ion transport in multi-ionic systems. The same model can also be used in high volume replacement cementitious systems and is an essential tool in establishing the market for geopolymer concretes. The mission includes 2 weeks of in house placement at Technical University Darmstadt and followed by four weeks of consultation and regular meetings to ensure progress.
Study heat of hydration of the alkali-activated slag Portland cement and heat evolution of the concrete vs. contents of Portland cement clinker and slag constituents, type and content of the alkaline activator in the cement; Study deformation properties (shrinkage, creep) and performance (strength) properties of the alkali-activated slag Portland cement concrete in parallel with measuring of heat evolution of the concrete; Study thermo-stressed state of the alkali-activated slag Portland cement concrete and its crack resistance.
The complex macroscopic properties of concrete are substantially influenced by its heterogeneous structure. Instead of using complex, phenomenological motivated macroscopic formulations, the meso-structure of concrete is directly modeled. Concrete is simulated as a three-phase composite with aggregates, mortar matrix and interfacial transition zone. Only the recent advance in computer technology enables the simulation of complex multi-physics problems on multiple scales with realistic failure modes. The aim of this STSM is to apply a high-performance model reduction method to a concrete material model on the mesoscale to decrease the computational effort. This will be done in two steps. First, the numerous element shape functions are replaced by a few characteristic global ansatz functions. This drastically decreases the size of the resulting system of equations. In the second step, the computational costs of setting up these equations is reduced by only evaluating certain representative integration points. Methods for choosing the global ansatz functions and integration points will be investigated with respect to accuracy of the solution and the reachable computational speed-up.
The subject of this STSM is a detailed investigation of rheological modeling approaches for early age concrete creep. It aims at a better understanding and a more general description of this type of modeling approaches, particularly with regard to their validity for different stress-strain histories and the description of the influence of the hardening state and the temperature. Furthermore, creep data of various concrete mixes will be used for calibrating the models. From the comparison of the resulting model parameters, suggestions and restrictions for their general description can be derived. These investigations make an important contribution to the further development of rheological models for the description of early age concrete creep which is an important step towards the general use of this type of models in engineering calculations and their implementation in standards and guidelines.
The objective of this STSM is the experimental as well as the analytical modelling of polymer-modified concrete (PCC). It aims at a better understanding of the elastic and viscoelastic properties of PCC since these properties differ significantly from standard concrete. A recently experimental testing procedure will be performed to investigate the elastic and viscoelastic properties of the polymer component as well as the elastic and viscoelastic properties of the compound material. By means of the experimental data, the micromechanical modelling of the mechanical behaviour of PCC can be carried out. These investigations make an important contribution to the general description of the elastic and viscoelastic properties of different types of PCC at different hydration stages. The improvement of prediction models for PCC represents an important step towards the use of this type of concrete for construction purposes and accelerates their implementation in guidelines. Methods for choosing the global ansatz functions and integration points will be investigated with respect to accuracy of the solution and the reachable computational speed-up.
Increased durability of mortars and concretes is achieved by providing a range of properties, formation of which starts at the level of viscoplastic system and continues in hardened material. Modern material science allows regulating such properties, including by use of chemical admixtures. In its turn, admixtures cause some extra issues concerning their influence on durability of modified materials. Aims of this STSM are to obtain experimental data of influence of chemical nature of admixtures on fresh and mechanical properties of highly flowable mortars based on alkali activated cement, which allows to predict durability and to regulate properties in normative documents. Determination of nature and degree of compatibility of cellulose ethers, redispersible polymer powders and surfactants (plasticizers) with alkali activated cement and their influence on fresh and mechanical properties of mortars, to be carried out at Delft University of Technology.
Research activities extend over 6 month. As the samples have already been cast and prepared, the tests can be started immediately and the simulation strategy can be developed within a few months. Three simultaneous experimental campaigns separately with water drying and uptake phenomena on one hand and the drying-imbibing coupling on the other hand.
The main aim of the short term stay at TU Graz is creating functional macroscopic calculation models of chosen critical structural details. Thus, the whole period will be spent by developing models for simulation of hardening-induced stresses as well as fundamentals on realistic assessment of associated crack risk. This would enable further studies on crack assessment and practical design tools. Of course, the final proposed solution will take into account the state of the art of multi-physical macroscopic calculation models with respect to the solution of the transient thermal and moisture field according to the hydration heat release and shrinkage as well as stiffness evolution and viscoelastic effects of the young concrete.
The subject of this STSM is a detailed investigation of the effect of realistic thermal variation on the development of the early age properties of several cement based materials. The study focuses more specifically on the evolution of the coefficient of thermal expansion, the autogenous strain and the viscoelastic properties. Four different compositions are studied: a reference concrete, an eco-concrete with 75% of cement substituted by slag and limestone filler, an UHPC and the so called Vercors concrete used for nuclear power plant. Based on the experimental measurements, the parameters of the models will be calibrated. From the comparison of the resulting model parameters, suggestions and restrictions for their general description can be derived. These investigations make an important contribution to the further development of models for the description of early age concrete properties which is an important step towards the general use of this type of models in engineering calculations and their implementation in standards and guidelines. COST Action TU1404 STSM Coordinator: Prof. Violeta Bokan Bosiljkov (firstname.lastname@example.org)
The work at TU Graz aims at validation of complex thermo-mechanical material models on basis of macroscopic experiments as well as on the identification of important parameters for reliable computational prediction of hardening-induced cracking of concrete structures. Next to a thorough reanalysis of the recalculated restraining frame experiment, this includes also a sensitivity study with MPSDamMat material model on the input parameters of such calculations. All work is carried out in open-source OOFEM package which allows easy transition to other participants.
The objective of the proposed research is to obtain the fifteen parameters required for input into the LDPM, from different simulation tests on the mortar scale. The lower scale models have some shortcomings with several simulation tests and do not describe the failure criterion correctly as an input for the LDPM. Therefore, the lower scale models need to be adjusted in order to capture these failure modes. The simulation tests that will be consider during the visit are: o Hydrostatic test o Combined shear and tension loads o Combined shear and compression loads Step 1 - The simulation program is based on the Timoshenko theory and efforts will be made at BGU to study the failure criteria, with the aim of identifying the incorrect input parameters and achieve an effective simulation. This step is in a preliminary stage at BGU. Step 2 - Modification of the sub-routine in order to overcome the simulation difficulties that prevent full execution of the model. (at TU-Delft). Step 3 - The professional expertise of Delft University regarding the numerical simulations of the lower scales will be instrumental in bridging between scales and will enable improvements to be made to the formulation of some failure modes of the lower scale. (at TU-Delft). Step 4 - Bridging between the mortar, lattice model, concrete, and LDPM by using the enhanced simulation tests. The LDPM will be simulated using the parameters obtained from these simulations, in order to evaluate the mechanical performance of concrete at the mesoscale. (at TU-Delft) Step 5 - Validating and calibrating the numerical simulation with experimental results, using uniaxial compression tests of concrete specimens (the validation will take place at TU-Delft the experimental results are already obtained). Step 6 - Publishing articles. This step can take place at both institutions depending on the time remaining. The completion of this research will provide an extremely powerful methodology for industrial applications, mainly for cement producers, as well as for designers of specific structures, worldwide.
First, an initial training with the testing machines to be used during the stay is planned. Tests for determination of the mechanical properties, e.g. Young’s modulus, Poisson’s ratio, tensile strength, fracture energy and creep behavior in compression, and hygric properties, e.g. sorption isotherms, are carried out.
A low water-to-cement ratio mortar that self-desiccates rapidly during hardening is investigated in terms of drying shrinkage and autogenous shrinkage. The experimental tests in this part of the work account for the restraint type (internal, external) and the extent of restraint in the specimen, i.e. the mechanical boundary conditions can be varied in a pre-defined manner. The specimen is also investigated with X-ray microtomography, so that the evolution of the crack during testing can be evaluated non-destructively on the same specimens.
The results are organized in form of a report containing a detailed test description, obtained material data and curves as well as the microtomography results.
The complex behaviour of cement-based materials at elevated temperatures, including shrinkage and creep, is difficult to model. Using complex nonlinear formulations for the mechanical behaviour without tracking the diffusion of temperature and moisture in the cement matrix leads to limited applicability to new mixes or different length scales.
The first work package includes evaluating approaches to modeling the phase transition occuring during supercritical moisture transport in cementious materials with the help of the researchers at CVUT. The next step is to implement one model using the finite element method, which necessarily includes verifying the solution procedure.
Coupling the newly implemented moisture transport model to existing temperature and damage models is the main problem of the second task. At the end, projecting the continuum values back onto the global behaviour of a concrete specimen will show whether the resulting model exhibits the nonlinear strain as a function of moisture and temperature, while using only a linear thermal expansion model.
The aim of this STSM is to develop a set of ultrasonic numerical simulations to be applied on a wide range of representative microstructure images. It will help to identify the most suitable ultrasonic parameter (attenuation or velocity) and their variation ranges on common microstructures of cement paste and mortars.This will be achieved by completing the following objectives: - To generate microstructure of cement paste and mortars by simulation tools using Matlab uniform and Gaussian functions. The output will be microstructures that will be the basis for the numerical simulation. - To develop the numerical simulation using different kinds of ultrasonic pulse to analysis the attenuation-dependence of the pulse for the wide range of microstructures. - Digital signal processing of simulated waveforms to extract most relevant ultrasonic parameters in the time and frequency domain. - To integrate the findings from the previous objectives to develop a refined methodology for microstructural characterization of CBM using ultrasonic pulse velocity. COST Action TU1404 STSM Coordinator: Prof. Violeta Bokan Bosiljkov (email@example.com)
The mission presented herein aims to perform the numerical simulation of massive RC foundations: accounting for non-conventionally considered phenomena, that are normally simplified (or even disregarded) in the engineering practice, as well as during research-related simulations and design. The research of this STSM intends to provide clear answers about the feasibility of such simplifications, by evaluating the phenomena with all the inherent complexities at the macro-scale. Therefore it is necessary to account for the full thermo-hygro-mechanical model to be directly considered and evaluated.
The range of tasks realized within the mission is directly related to interests and field of studies of the Applicant. The performed numerical simulations accounting for non-conventionally considered phenomena is the way of getting new experiences and create the path for further developments. Furthermore the participation in the mission is the opportunity to work in the international scientific environment, that creates the host institution holding a significant and internationally recognized know-how on structural analysis based on thermo-hygro-mechanical modeling.
This STSM creates opportunity to obtain extensive information on the consequences of directly consideration several phenomena that are normally simplified (or even ignored) in research and design practices. A full 3D multi-physical framework for simulation (thermo-hygro-mechanical modelling) will be applied for such concern. A direct impact is therefore expectable in the interplay between the research and the practicing communities. Even though the STSM is centered on topics related to WG2 (Simulation), an important output towards WG3 is also expectable.
The work will be based on a reference case to be selected (real construction), which will be extensively studied with the 3D numerical framework for thermo-hygro-mechanical simulation available at the University of Minho (combined MATLAB software and DIANA).
To the best of the author’s knowledge, hygro-thermal behavior, the structure, the microstructure and the mechanical properties have not yet been extensively studied for vegetal fiber-reinforced concretes so far. The study of vegetal fiber-based concretes could lead to further prospects in the development of a more sustainable and innovative way of proceeding in the building sector. The assessment of the hygro-thermal properties and their evolution over time is a major concern of the aimed work. Furthermore, from a mechanical point of view, it is essential to be able to understand the microscopic behavior by imagery techniques in order to predict the behavior of the structures on a macroscopic scale. The macroscopic behavior of this material is highly dependent on the mechanisms involved at the microscopic scale.
Today, the use of bio sourced fiber-reinforced concrete, is hampered, in particular, by the unavailability of databases relating to their intrinsic properties and by ignorance of their behaviors over time.
This project will be realized in two laboratories in France. The aforementioned mechanical study of bio based materials concrete have been predominantly developed at the Constructability Research Institute IRC (ESTP Paris-France) with hemp fibers and shives. Furthermore, the Research Institute of Paris-Est is also renowned for the substitution of cement with nanostructured mineral additions. Previous research studies on nanostructured materials and fibers replacement in concrete have been conducted in the IRC laboratories. Hygro-thermal study of bio-based materials will be developed in LMT laboratory (ENS CACHAN).