Interfaces

Interfacial Transition Zone (ITZ)

The interfaces between cement paste and aggregate are generally considered to be weak zones in normal strength concretes. Cracks will preferentially propagate along these weak interfaces. The density and bond strength of the ITZ can be controlled by mix design and processing. It is possible to make the ITZ so dense in materials such as high performance concrete that the cracks propagate directly through the aggregate instead of meandering through the interface regions.

SEI of interface between paste and quartz sand grain. (Field width 45 microns, x1760) [David Lange, UIUC]

SEI of interface between paste and quartz sand grain. (Field width 45 microns, x1760) [David Lange, UIUC]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Masonry

BSE of top interface between concrete block (MID) and portland cement-lime masonry mortar. (Field width 2.3 mm, x50) [BEI by H. Dale DeFord and David A. Lange, UIUC]

BSE of top interface between concrete block (MID) and portland cement-lime masonry mortar. (Field width 2.3 mm, x50) [BEI by H. Dale DeFord and David A. Lange, UIUC]

BSE of interface between glass and portland cement-lime masonry mortar. Notice the black high porosity at the interface due to bleed water and lack of absorption into the glass. (Field width 2.3 mm, x50) [BEI by H. Dale DeFord and David A. Lange, UIUC]

BSE of interface between glass and portland cement-lime masonry mortar. Notice the black high porosity at the interface due to bleed water and lack of absorption into the glass. (Field width 2.3 mm, x50) [BEI by H. Dale DeFord and David A. Lange, UIUC]