Cement Lab

 

Cement

Corrosion

Other

     
About Research Techniques Publications Cement and Art Photo Gallery Links Contact Home
 
Thermal Analysis
  Differential thermal analysis (DTA) and differential scanning calorimetry (DSC) are among thermal analysis techniques that can provide useful information of chemical materials. Since various elements and compounds have a specific heat energy and also chemical transformations involve adsorption or the generation of heat, unknown materials in the sample are being identified using this method.

In DTA the difference of the temperature between the sample and a reference material is monitored over a range of varying temperature. In DSC, the heat required for keeping the temperature of sample and reference the same over the range of varying temperature is measured.

Helium Inflow 
  Helium atoms can be used as nanostructural probe to detect qualitatively the existence of small spaces that are not accessible to helium instantly. A simple helium pycnometer, conventionally used for solid volume measurements, is employed for this purpose. This pycnometer that is always kept at constant gas pressure first measures the true volume of the material. After that over time helium penetrates smaller pores and spaces. There is then a reduction in the pressure of the helium chamber that can be corresponded to the volume change in order to keep the pressure constant.

This technique has been widely used by R. F. Feldman and P. J. Sereda in order to study the volumetric changes associated with the structure of the hydration products of cementitious materials at various humidity conditions.

X-Ray Diffraction
  The X-ray generated by the instrument is reflected when it hits the lattice surfaces of a crystalline material. This reflection is unique for each lattice and can be detected by the instrument in a specific angle (usually referred to as 2q). The intensity of the collected reflections varies for each lattice based on the order and arrangement of the crystal structure of a material.

The full spectrum of the intensities versus 2q is the X-ray pattern and unique to each material like a fingerprint. Usually three or four main high intensity reflections are used for comparison purposes.

FTIR
  This technique is employed to evaluate the bonding characteristics between polymers and C-S-H in nanohybrid preparations. The absorption of the IR energy by stretching or rotating bonds in a molecule at a specific wavelength can be detected and analyzed to study various types of bonding between the atoms.
Scanning Electron Microscopy
  Although the current SEM instruments are not able to provide images at the nano level, the morphology of calcium silicate hydrates in the range of 0.5 to 1 micrometer can be easily evaluated. Backscattered micrographs are not very useful because of the close atomic number of Ca and Si.  
Nuclear Magnetic Resonace
 

The environment in which each atom is located can be studied using NMR. This technique provides the information on the structural information about the bonds between atoms in a material. In my research, 29Si MAS NMR is mainly employed in order to investigate the silica tetrahedra connections together at various levels of humidity in the C-S-H.

© 2007-2011 Rouhollah Alizadeh, all rights reserved