Influence of cracking and healing on the gas permeability of cementitious composites

• Influence of cracking and self-healing on the gas permeability of ECC were studied.
• Gas permeability, resonant frequency and crack analysis tests were conducted.
• Self-healing was strongly influenced by the chemical compositions of the mixtures.
• Application of pre-loading led to significant increases in GP and RF results.
• Recovery in GP results could be increased to 96% through proper curing.

The main objective of the study presented in this paper was to investigate the influence of cracking and self-healing on the gas permeability of Engineered Cementitious Composites (ECC). To deliberately introduce microcracks, specimens were pre-loaded to different deformation levels under splitting tensile loading and exposed to different environmental conditionings for the assessment of self-healing. Gas permeability (GP) and resonant frequency (RF) tests, crack characteristics observation and microstructural analysis were conducted to analyze the effect of cracking and healing on the properties of cementitious composites. Test results indicate that the self-healing effect determined through GP and RF tests was strongly influenced by changes in the chemical compositions of the mixtures. Application of pre-loading led to significant increases in GP results, so that even microcracks of less than 50 μm caused a GP coefficient fifty times higher than that of sound specimens. However, the recovery in GP results could be escalated up to 96% after only a month through proper material design and conditioning. It therefore appears that microcracking and subsequent healing is influential on the GP recovery rates of specimens, but not on RF recovery rates.