244-NUM : Numerical modelling of cement-based materials

Technical Committee 244-NUM

General Information

Chair: Prof. Dr. Ir. Klaas VAN BREUGEL
Deputy Chair: Dr. Ravi PATEL
Activity starting in: 2011
Activity ending in: 2019
Cluster C

Subject matter

Even though models and modeling have a history of centuries in science and engineering, it seems that the presence of powerful computation tools have disclosed new opportunities for both the academic world and the engineering practice to use these tools for unprecedented developments and applications of models and modeling. Numerical models enable us to evaluate complex systems in a quantitative way. They have the potential to support design activities on different levels of observation and to connect these levels in a multiscale approach. Besides connecting phenomena at different scales, also multidisciplinary interactions can be considered in numerical models.

The use of numerical models in science and engineering is not without risks. Apart from problems and risks directly related to the mathematics of numerical models, the adopted material models determine the quality of the output of calculations. Even though this is well-known, there is not much harmonization yet in this field. This can lead to inaccurate and unreliable results of numerical predictions, but also to unfair competition in case different models are used in a competitive game when contractors have to demonstrate that imposed design criteria are satisfied.

Terms of reference

It is the task of this committee to consider, and reconsider, the ‘nature’ of models and modeling in science and engineering, with a focus of the modern evolution of the computation power and computational materials modeling. The following aspects need to be considered:
_Models and modeling in science and engineering
  - General considerations 
  - Nature of problems
  - complexity
  - Relevance for society
  - Goals

_Models - Definitions and classification
  - Material models
  - Analytical models
  - Numerical models
  - Descriptive models
  - Predictive models
  - Accuracy and reliability of models
  - Multi-scale and multidisciplinary of models and modeling
  - Legal aspects
  - Models and modeling in Codes

In depth discussions about these items, preferably in the multi-disciplinary setting, should precede the work of working groups on more specific topics.

Detailed working programme

Main output of the TC is a state-of-art-report which on one hand summarizes the possibilities of different types of modelling with respect to the item investigated and on the other hand gives a critical review of methods of modelling for application and information for young researchers. Different types of modelling will be discussed to explain advantages and disadvantages.

Therefore the group of experts will be organized by creating different working groups (WG) depending on the items dealt with. In a first meeting a kind of workshop will be organized to define the different WG’s and the structure of the TC, also to find chairs for the WG’s.

SG - Steering group

WG Early-age concrete
   - Hydration and microstructure
   - Volume changes
   - Evolution of materials properties (short term, long term)

WG Fresh Concrete
   - (here a chapter given by SFC is expected
   - or a link if usable for the proposed committee)

WG Time dependent properties
   - High loading rates
   - Creep & relaxation
   - Shrinkage

WG Transport in porous cementitious materials
   - Flow, diffusion
   - Transport of water and hydrocarbon

WG Degradation mechanisms
   - Carbonation - ASR - damage in materials
   - Freeze-Thaw damage
   - Acid attack

WG Numerical aspects
   - Mesh dependency
   - Computation time
   - User friendliness
   - Multiscale modelling / interface aspects

WG Legal aspects
   - Use of models for engineering purposes
   - Claims
   - Transparency
   - Responsibility

WG Service life predictions
   - (will be performed later, e.g. by chairs of the different working groups)

Technical environment

Since the 70ies and 80ies the application of the different numerical models has been tremendously increased. A lot of experience has been collected and published. Information on the suitability of models in connection with a special item is spread everywhere and also directly included in the work of RILEM. E.g. the TC SFC focuses on a special topic of modelling. Many results used for recommendations and STARs are underlined by numerical modelling.

Expected achievements

The STAR will give a survey on numerical modelling and therefore will be a useful tool for young researchers to decide what model will be the proper one.

Some workshops will be held to come to a survey of the different models available.

Group of users

The STAR will be valuable for the complete scientific community. The report will address young researchers to support them for the decision on the suitable model.

Specific use of the results