Discussion after the Lecture of D. Tabor

Abstract

Participants were eager to discuss the points underlined by Tabor in his conclusions as possible areas of research:

• If Portlandite determines strength, surface treatment will not improve bond, because Portlandite is always present in the inter- laminar areas whereas if CSH is important, surface treatment may be effective

• Densification as investigated in an experiment placing a wire in cement paste, revealing that the paste density in the vicinity of the wire is lower than in the bulk Applying hydrostatic pressure caused little effect, but adding shear to this pressure increased the densification between wire and cement paste because the true area of atomic contact is increased, thereby improving strength.

• Regarding the problem of facilitating fragmentation, suggestions were made of using thermodynamics, incorporating a surface agent to decrease bond, fracture mechanics with lowering temperature.