Drying of Porous Media: Numerical and Experimental Approach

Drying of porous media, such as cement paste, is observed through different types of experiments at meso- and micro-scales. Important aspect is the transport of water through the porous material. The results from Nuclear Magnetic Resonance (NMR) drying experiments have been numerically modeled by means of Lattice Gas Automaton (LGA) from...

Preliminary Investigation of Drying Shrinkage Cement Paste Specimens

In order to perform drying shrinkage observations in ESEM (Environmental Scanning Electron Microscope), a preparation procedure for cement paste samples is developed. Instead of casting standard prisms (40 x 40 x 160 mm3), cement paste samples were cast in specially designed moulds of 30 x 30 x 2 mm3 and 10 x 10 x 2 mm3 in size. A special...

Drying Shrinkage Microcracking in Cement-based Materials

In this paper the nature of drying shrinkage microcracking in a variety of model cementbased materials, as well as in more practical types of concrete is described. The model mixtures were studied to elucidate the mechanisms of drying shrinkage microcracking and the factors that influence these mechanisms. This fundamental knowledge is important...

Numerical Analysis of Moisture Flow and Concrete Cracking by means of Lattice Type Models

Modelling of fluid-flow and the resulting effects on shrinkage and microcracking by means of a combination of two lattice models are presented. For the moisture transport, a Lattice Gas Automaton (LGA) is adopted since it can effectively model moisture loss, whereas for cracking simulation a Lattice Fracture Model (LFM) is used. The resultant...

Crack Development in Concrete due to Moisture Flow

The goal of this study is to develop a numerical model for the simulation of crack growth due to moisture flow in the porous zone between aggregate and matrix (interfacial transition zone, ITZ), where cracking in concrete originates. Two models are coupled based on similarities in their mesh shape: a Lattice Gas Automaton for moisture flow and a...

Experimental and Numerical Research Programme for the Design and Optimization of Various Aspects of Concrete Behaviour

Single Fibre Pullout from Hybrid Fiber Reinforced Concrete

Hybrid fiber reinforcement can be very efficient for improving the tensile response of the composite. In such materials, fibers of different geometries can act as bridging mechanisms over cracks of different widths. The fiber bridging efficiency depends on the interface properties, which makes interface characterization very important. Therefore...

Single fiber pullout from hybrid fiber reinforced concrete

Hybrid fiber reinforcement can be very efficient for improving the tensile response of the composite. In such materials, fibers of different geometries can act as bridging mechanisms over cracks of different widths. The fiber bridging efficiency depends on the interface properties, which makes interface characterization very important. Therefore...

De kunst van breken en scheuren

Size effect of concrete and sandstone

A series of uniaxial tension experiments has been conducted to investigate the size effect on strength and fracture energy of concrete and sandstone. The experiments were carried on specimens of six different sizes in a scale range of 1:32. Depending on the material and the curing conditions a stronger or weaker size effect on the nominal...

Special issue on compressive failure of concrete and rock

Field evidences and theoretical analysis of the gravity-driven wetting front instability of water runoffs on concrete structures

A series of field observations of the evolution of water runoffs over several vertical concrete walls directly exposed to rain falls is reported in this note. In all the cases, the main water flow originated from the top horizontal surface of the walls. The observations show that the gravity-driven wetting front may propagate in a very unstable...

METHOD AND APPARATUS FOR MANUFACTURING A REINFORCED CONSTRUCTIONAL ELEMENT, AND SUCH CONSTRUCTIONAL ELEMENT

Abstract of WO 9634727 (A2) A method for manufacturing a constructional member, wherein a number of longitudinal elements which extend in at least one direction and which enhance at least the tensile strength of the constructional element in the or each relevant direction, are provided in a formwork (1) or a like mold cavity, after which the...

Analysis of hygral induced crack growth in multiphase materials

In this paper a numerical model for simulating crack growth processes caused by moisture movement in a porous multiphase material like concrete is proposed. In the model, the material is schematized as a regular triangular network of beam elements. The meso-material structure of the material is projected on top of the lattice and different...

Damage evolution in different types of concrete by means of splitting tests

A new splitting test has been used for evaluating damage in different types of concrete. The set up was developed at the Stevin Laboratory of Delft University of Technology and comprises a completely new loading device in which a perfectly horizontal splitting load can be applied to concrete specimens. In addition to classical mechanical...

Fracture mechanics of concrete: Will applications start to emerge?

Fracture mechanics of concrete has developed into an active field of research in the past decades. It promises a rational solution technique to structural problems in reinforced concrete in the limit state. Numerical tools have been developed on the basis of fracture mechanics theories. The question to be addressed is how much of the early...

An Experimental Study of Shear Fracture and Aggregate Interlock in Cementbased Composites

In the present paper the results of an exploratory study with the recently developed biaxial tension/shear apparatus of the Stevin Laboratory of Delft University of Technology are presented. The apparatus is unique in the sense that square double-edgenotched concrete plates up to a size of 200 x 200 mm can be loaded in any combination of tension...

Examples of Non-Linear Analysis of Reinforced Concrete Structures with DIANA