Mechanics and Physics of Creep, Shrinkage, and Durability

Mini-symposia

Details on abstract submission and link to online submission is available >> HERE

 

MS01: Modeling the time-dependent behavior of deteriorating concrete structures

Roman Wendner, Mohammed Alnaggar, Qiang Yu, Giovanni Di Luzio, Gianluca Cusatis

MS03: Interplay between water, shrinkage, and creep

Pietro Lura, Mateusz Wyrzykowski, Matthieu Vandamme

MS04: Discrete modelling of coupled mechanical-transport phenomena

Peter Grassl, John Bolander, Erik Schlangen

MS05: Effects of cracking and damage on diffusion-dominated durability problems in cement and concrete

Ignacio Carol, Joaquin Liaudat

MS06: Aging, creep and fracture in cement hydrates: bridging length scales, simulations and experiments

Emanuela Del Gado, Roland J. Pellenq

MS07: Mechanics of multiphase porous materials in modeling concrete durability and deformations

Dariusz Gawin, Francesco Pesavento, Bernhard Schrefler

MS09: Impact of creep and shrinkage on cracking and deformations of structures – practical experience and consequences

Jan L. Vitek

MS10: Reliability of the prediction creep deformations in concrete structures

Susanne Gmainer

MS11: Steel corrosion in reinforced concrete - mechanisms, assessment, measures, forecast models

Stefan Burtscher

MS12: Evaluating the performance of recycled aggregate concrete

Joachim Juhart, Jürgen Macht, Danilo Schulter

MS13:  Nanotechnology applied to concrete

Jorge S. Dolado,  Juan J. Gaitero

MS14:  Towards the next generation of standards for service life of cement-based materials and structures - Mini-symposium of COST Action TU1404

Miguel Azenha, Stéphanie Staquet

 

MS01: Modeling the time-dependent behavior of deteriorating concrete structures

EmailRoman Wendner1, Mohammed Alnaggar2, Qiang Yu3, Giovanni Di Luzio4, Gianluca Cusatis5

1University of Natural Resources and Life Sciences (Austria), 2Rensselaer Polytechnic Institute(USA), 3University of Pittsburgh (USA), 4Politecnico di Milano (Italy), 5Northwestern University (USA)

 

In recent years topics such as robustness, resilience, sustainability, life-cycle assessment have shifted into the focus of engineering societies. Many concepts have been developed. Yet, accurate and physically based prediction models and modeling concepts for the time dependent behavior and deterioration of concrete structures, which are quintessential inputs, are still scarce. This Mini Symposium will provide a forum for international experts and researchers to discuss recent developments in modeling time-dependent phenomena relevant to the performance of concrete structures. In particular, authors working on research related to creep and shrinkage and the age-dependent change of mechanical properties by itself but especially in combination with deterioration mechanisms such as but not limited to alkali-silica reaction, carbonization, freeze and thaw, corrosion, and sulphate attack are encouraged to submit abstracts. Further topics of interest include the coupled problems of cracking damage with moisture transport and other transport processes relevant to deteriorating concrete structures. Contributions comparing the use of rate-type formulations with traditional hereditary concepts are especially encouraged.

MS03: Interplay between water, shrinkage, and creep

EmailPietro Lura1, Mateusz Wyrzykowski1, Matthieu Vandamme2

1Empa, Swiss Federal Laboratories for Materials Science and Technology (Switzerland), 2Université Paris-Est, Laboratoire Navier, Paris, France

 

In concrete, the moisture state has a profound influence on the time-dependent deformations under load (creep). One of the most significant manifestations of such dependence is the Pickett effect, i.e. the difference between creep in sealed conditions (basic creep) and the considerably higher creep in unsealed conditions (drying creep). A further aspect is the influence of viscoelastic deformations on concrete shrinkage, both autogenous and drying, in the absence of any external load. Even though this issue has been discussed by a number of experimentalists and modelling experts, no consensus has been reached yet. As a consequence, radically different interpretations of experimental data and radically different modelling approaches have been proposed. The problem is especially challenging on the one hand due to the very complex mechanisms underlying creep and moisture changes. On the other hand, it is extremely difficult both to separate experimentally the elastic and the viscoelastic component in the measured shrinkage deformations and to assess the influence of the moisture state on creep of a drying cementitious system.

This symposium will create an opportunity to discuss the presented problem, exchange recent experimental observations and formulate the necessary steps for better understanding the mutual interrelations between creep, shrinkage and changes in the moisture state.

MS04: Discrete modelling of coupled mechanical-transport phenomena

EmailPeter Grassl1, John Bolander2, Erik Schlangen3

1University of Glasgow (UK), 2University of California, Davis (USA), 3Delft University of Technology (Netherlands)

 

Mechanical loading typically modifies the mass transport properties of structural continua. This observation applies, for instance, to distributed cracking, in the form of microcracks, and to discrete cracks that run for longer distances within the structural domain. Mass transport (e.g.moisture diffusion due to drying) can lead to non-uniform straining and crack formation. This two-way coupling between fracture and flow phenomena is particularly relevant for the durability mechanics of structural materials.

This mini-symposium seeks contributions on discrete (lattice) modelling approaches for coupled fracture-flow phenomena.  Contributions are expected on discrete modelling of flow along cracks and from cracks into the bulk material for deterioration processes such as corrosion, restrained drying shrinkage, alkali-silica reaction.

MS05: Effects of cracking and damage on diffusion-dominated durability problems in cement and concrete

EmailIgnacio Carol, Joaquin Liaudat

Technical University of Catalonia (Spain)

 

A variety of durability problems in cement and concrete are the result of the interaction of diffusion processes combined with chemical reactions that produce volume changes. In such processes, the availability of one or more of the substances or reactants depend on diffusion process, such is the case of sulfate ions in external sulfate attacks, alkali ions in ASR degradation, or carbonate ions in carbonation/carbonic acid attack. But these processes may also produce cracking and damage, that in turn may change the diffusion properties dramatically, in general increasing diffusivity and accelerating the process. In terms of equations, this means coupling between the mechanical and chemical processes, which in general complicates numerical analysis and makes non-linearity more pronounced.
This minisymposium is intended to gather the engineers and scientists interested in the topic including those oriented to experimental, theoretical and numerical modeling, and to provide a forum of exchange for new ideas and developments as well as advanced applications of existing methods and tools.

MS06: Aging, creep and fracture in cement hydrates: bridging length scales, simulations and experiments

EmailEmanuela Del Gado1, Roland J. Pellenq2

1ETH Zurich (Switzerland), 2MIT (USA)

 

Time-dependent properties and non-linear mechanics of cement hydrates are key to concrete creep and fracture. Most of the experimental characterization and models still used to predict and design cement performance have been developed at a macroscopic level, but it has become increasingly clear that the structural complexity of the material over the nanometer and micrometer scales is a major source of its unique features. Recent developments on microscopic plasticity and yielding in amorphous solids and nano-scale investigations of calcium-silicate-hydrates are progressively obtaining significant new understanding. Using this new knowledge to inform larger scale models and approaches is crucial to make progress on issues ranging from material optimisation to durability. Linking nano-scale observations to micro and eventually macro-scale models and experiments is an outstanding challenge and the aim of the symposium is hosting and promoting, within CONCREEP10, a discussion on these themes. The idea is to bring together world leading scientists working on non-linear mechanics of concrete, nano- and micro-mechanics of cement, molecular simulations and meso-scale approaches, non-linear dynamics and plasticity in amorphous solids.

MS07: Mechanics of multiphase porous materials in modeling concrete durability and deformations

EmailDariusz Gawin1, Francesco Pesavento2, Bernhard Schrefler2

1Łódź University of Technology (Poland), 2University of Padova (Italy)

 

The proposed minisymposium concerns mathematical and numerical modelling, and experimental studies of hygral-, thermal- and chemical processes in porous materials, including their thermo-chemical and stress-induced deterioration. Due to complex inner structure of porosity, such materials usually contain certain amounts of gaseous and liquid (and sometimes also solid) phases of water within their pores. Chemical substances can be dissolved in pore water or precipitated from it, due to phase changes or/and chemical reactions. For this reason, such materials should be described as multiphase porous media.

In modeling of porous media different scales of their inner structure are usually considered: microscopic, mesoscopic and macroscopic ones. In order to obtain macroscopic equations of the mathematical model, various volume averaging techniques, theoretical or numerical, should be applied for the so called Reference Volume Element of the material structure. Then, multi-scale modelling approach can be used during analysis of the chemo-hygro-thermo-mechanical processes in order to assess the material durability. The papers concerning the aforementioned theoretical and numerical problems, considered at the material level, as well as their experimental investigations, will be presented during the minisymposium.

MS09: Impact of creep and shrinkage on cracking and deformations of structures – practical experience and consequences

EmailJan L. Vitek

Czech Technical University in Prague (Czech Republic)

 

Creep and shrinkage of concrete have a substantial impact to serviceability and also safety of concrete structures. The Minisymposium will focus on consequences of creep and shrinkage of concrete into design and execution of concrete structures. A series of problems may be addressed, e.g.: 

  1. Shrinkage in thick elements and the necessary reinforcement for control of cracking. Slow drying of concrete and autogeneous shrinkage are of the major importance. The experimental results will be discussed.
  2. Creep and shrinkage effects on deflections of reinforced concrete slabs in buildings. The experience shows that the thin slabs deform in time, which results in damage in built in structures. The restrained shrinkage has also significant effect on cracking and reduction of the bending stiffness.
  3. Deflections of large prestressed bridges. The role of creep and shrinkage of concrete in evaluation of deflections and prestress losses should be addressed.
  4. Shrinkage and impact on cracking at watertight structures. Reasonable reinforcement design of structures, in which admixtures reducing shrinkage in concrete are used, should be discussed.
  5. Technological experience in execution of concrete structures with respect to creep, shrinkage and cracking, e.g. casting procedures of thick slabs, reasonable dimensions of the elements cast in one stage, applying of the shrinkage reducing strips, etc. 

Additional topics which have a direct impact to design of structures and their economy are welcome. The procedures applying the new fib MC2010 rules may be presented. Simplified as well as numerical methods as tools for a good structural design may be also presented.

MS10: Reliability of the prediction creep deformations in concrete structures

EmailSusanne Gmainer

Smart Minerals GmbH (Austria)

 

Research on creep has been carried out for decades. This has resulted in design recommendations which are predominantly based on tests, carried out under constant and well known environmental conditions, and well-measured loads, which were mostly as well constant in time. The expressions derived for the prediction of creep deformations are well calibrated against such experiments. With regard to structures or structural elements in reality, both the environmental conditions and the loads are much less defined. This refers to the estimation of the quasi-permanent load on structures, but as well to an eventual development of the loads in time, like during construction. With regard to the environmental conditions variations in time and in place can mostly not be estimated accurately. Finally the dimensions of structures in practice are considerably larger than the tests specimens used in creep experiments. This raises questions as well with regard to the suitability of a parameter like the nominal thickness of a structure. Measurements of creep deflections of concrete bridges in many countries have shown that the real deflection mostly considerably deviates from the predicted value. This holds true both for the construction stage (cantilever bridges) and the service stage. Another example is the camber of precast prestressed concrete beams, which is important for construction in relation to tolerances which have to be respected.  Here the composition of the concrete, the age of the concrete at prestressing and the temperature are known to play a role. An accurate prediction of the camber at the time of assembly should however not be expected.  Also here more reliable predictions of the camber would be highly welcomed. Theoretical considerations and practical experiences are wanted to develop more reliable creep prediction methods for structural concrete.

MS11: Steel corrosion in reinforced concrete - mechanisms, assessment, measures, forecast models

EmailStefan Burtscher

Vienna University of Technology (Austria)

 

Infrastructure built of reinforced and prestressed concrete is in general durable. Due to considerable physical and chemical influences corrosion occurs after long term exposure. In this Mini-Symposia the special focus is put to corrosion triggered by chloride action. This is especially important when de-icing agents are used nearby the infrastructure.

In recent research projects (Bundesanstalt für Materialprüfung in Berlin, Technische Versuchs- und Forschungsanstalt der Technischen Universität Wien) it was realized that traditional test methods do not provide accurate results of the Chloride-to-cement-content. The major source for the inaccuracy lies in the differentiation of chloride content in aggregates or cement paste and the determination of the cement content. 

The Topics of the Mini-Symposia are 

  • mechanism of chloride induced corrosion,
  • space resolved measurement methods of chloride and cement content,
  • laboratory and field tests
  • discussion of the chloride-to-cement-content
  • interaction with carbonation
  • assessment of infrastructure
  • (models for chloride diffusion and prediction)

MS12: Evaluating the performance of recycled aggregate concrete

Joachim Juhart1, EmailJürgen Macht2, Danilo Schulter1

1Graz University of Technology (Austria), 2Kirchdorfer Zementwerk Hofmann GmbH (Austria)

Recycling of building materials will be a major issue in the very near future leading to a much higher usage of recycled aggregate concrete than today. Hence, it is of highest interest to fully understand the governing processes leading to a different behaviour of recycled aggregate concrete compared to conventional concrete with natural aggregates. The differences may concern fresh concrete properties, mechanical behaviour and especially the durability. The emphases of this mini-symposium therefore are:

  • Testing, properties and characterization of recycled aggregates, e.g. considering the amount and quality of the adhesive hardened cement paste after the crushing process
  • Testing, modeling and analysis of the mechanical behaviour of recycled aggregate concrete containing different amounts and tvps of recycled material (e.g. recycled concrete with varying quality, bricks,..)
  • Evaluating the durability performance of recycled aggregate concrete, e.g. in terms of carbonation, chloride penetration and moisture absorption. Special attention is given to analysis of the transport phenomena into and in recycled aggregate concrete

MS13: Nanotechnology applied to concrete

EmailJorge S. Dolado,  Juan J. Gaitero

TECNALIA (Spain)

The underlying processes that govern many of the engineering properties of concrete take place at the nanoscale. Therefore, it seems clear that nanotechnology can largely contribute to control different key issues in the performance of concrete, like creep, shrinkage or durability. Nowadays, both clinker-nano engineering and gel-nomic engineering (i.e the ability of tuning C-S-H kinetic and structure) are already available technological solutions that in some cases are only discarded by economic reasons.

The synthetic routes of novel nano-nanoparticles and nano-fibers will be analyzed in this mini-symposium in relation to their potential use in concrete. Emphasis of this mini-symposium will be paid to discuss about:

  • New methods of production for nanomaterials.
  • Numerical and computational models (atomostic and colloidal)
  • New nano-characterization methods (AFM, nano-FTIR, nano-indenting, nano…)
  • Performance of cement based materials “empowered” by nanoadditions or nanoparticles.

MS14: Towards the next generation of standards for service life of cement-based materials and structures - Mini-symposium of COST Action TU1404

EmailMiguel Azenha1, Stéphanie Staquet2

1University of Minho (Portugal), 2Université Libre de Bruxelles (Belgium)

This Mini-symposium aims to promote scientific discussion and networking among those interested in participating in the Activities of COST Action TU1404 – “Towards the next generation of standards for service life of cement-based materials and structures”. This COST Action has the objective assisting the development of new generation of guidelines to predict/evaluate the service life of cement based materials and structures by integrating the most recent developments in experimental and numerical approaches.

It is remarked that the Action supports networking activities among its participants, but also among newcomers that wish to join the efforts (both within and outside Europe). The Action comprises two fundamental tools in the scope of WG1 and WG2: experimental round-robin testing and numerical simulation benchmarking.

The mini-symposium is targeted to promote discussion among recent developments among the subjects mentioned above, and submission/participation is open to all interested parties. The Mini-symposium will also include initial presentations on behalf of WorkGroup leaders, providing information on up-to-date efforts of the Action (particularly in regard to the round-robin testing and simulation benchmarking efforts), and promoting the inclusion of new participants in this network.