Stereological methodology for damage analysis - application to freeze-thaw cracking in cement paste

摘要

Freeze-thaw deterioration is a relevant phenomenon in studies of durability of cementitious materials. When subjected to freeze-thaw cycles, internal micro-cracks will be introduced and severe cracking in the surface layer of material would lead to surface scaling and damage to material performance. Hence, insight into the characteristics of freeze-thaw cracking and the influences of technical parameters thereupon is of significant importance. This paper applied a modified stereological approach to the quantitative analysis of freeze-thaw cracking in cement paste, providing 3D information of damage parameters. The outcomes reveal that the surface layer of specimen suffered from serious degradation, especially for the cement paste with lower w/c ratio. This damage is represented by significant increase in total crack length, crack tortuosity, specific surface area of cracks, as well as a decline in degree of orientation in the crack distribution. The interior part of the specimen presented only slight changes. This contribution also reveals the biases associated with automatic image analysis approach.