Microstructure Analysis of Heated Portland Cement Paste

When a concrete structure is exposed to high temperature, the mechanical damage and chemical transformation take place simultaneously, which will change the microstructure of material. On the other hand, the mechanical properties and transport properties depend on the development of microstructure of cement paste. In order to study the...

ESEM drying tests: Microcracking initiation in thin cement paste due to early age drying

Scattered and discontinues microcracking as a subsequent side-effect of deformations due to early age drying, occurs in thin (approximately 1 mm thick) cement paste samples, when stepwise dried in ESEM. Microcracking of cement paste and restrains appear to be practically unavoidable. They are related to a phenomenon of interfaces (‘matrix’ and ...

The use of particle packing models to design ecological concrete

Ecological concrete can be designed by replacing cement with fillers. With low amounts of cement it becomes increasingly important to control the water demand of concrete mixtures. In this paper a cyclic design method based on particle packing is presented and evaluated on the basis of experiments on cement pastes combined with quartz powder....

Nondestructive determination of drying deformations in cement paste by means of ESEM and digital image analysis

Novel modifications of an environmental scanning electron microscope (ESEM) were made in order to measure the local deformations in drying cement paste. These nondestructively determined moisture-induced plane strains, obtained in 1 mm thick cement paste samples, are orthotropic. They vary with variations of relative humidity between 70%-80% and...

3D Lattice Analysis of Cement Paste

In this MSc thesis project, an effort was made to predict the mechanical properties (especially the tensile strength and stiffness) and crack propagation of cement paste using 3D lattice fracture model at the micro-level. This project consists of three modules, namely “3D Lattice Generation”, “3D Lattice Analysis” and “Interpretation of results”...

Study of ‘real’ shrinkage by ESEM observations and digital image analysis

Defining the 'real' shrinkage values of concrete is still a subject of much debate. In shrinkage experiments size effects are inherently present. Through an attempt to determine the real shrinkage of cement-based materials, these size effects have to be eliminated or at least reduced as much a possible. In this contribution drying shrinkage...

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...