Water and Chloride Penetration into Strain Hardening Cement-based Composites Under and After Imposed Strain

摘要

The designed and expected service life of reinforced concrete structures is not reached too often in practice. One major reason for this well-known economical and in the meantime also ecological problem is the limited strain capacity of cement-based materials under tensile stress. Cracks due to combined mechanical and environmental loads are preferential paths for ingress of nocuous compounds dissolved in water. By adding PVA fibres to cement-based composites such as fine cement mortar their strain capacity can be improved by a factor of up to several hundred. Multi crack formation is at the origin of this pseudo-ductility of strain hardening cement-based composites (SHCC). However, the high strain capacity is beneficial with respect to durability only if the cracks formed under imposed strain do not lead to significantly increased ingress of aggressive compounds such as chlorides or sulphates for instance. In this contribution experimental results of measurements of capillary suction and penetration of chloride ions into SHCC under different imposed strain will be presented and discussed. The influence of hydrophobic treatment has been studied in particular.