WATER PENETRATION INTO HPFRCC UNDER IMPOSED STRAIN
Author(s): P. Zhang, F.H. Wittmann, P. Wang, and T. Zhao
Book Title: Seventh International RILEM Conference on High Performance Fiber Reinforced Cement Composites (HPFRCC7)
Editor: H.W. Reinhardt, G.J. Parra-Montesinos, H. Garrecht
Publisher: RILEM Publications SARL
Publication year: 2015
Total Pages: 8
Abstract: The pseudo ductility of HPFRCC is essentially due to multiple crack formation and simultaneous crack bridging by fibres under imposed stress. In case a structural element will be placed in contact with water or with an aqueous salt solution the liquid may move quickly and deep into the cracks created in the material by capillary action. By this water movement frost resistance may be reduced and aggressive dissolved ions such as chloride or sulphates may be transported into the composite material.
Water movement into porous materials can be followed in a quantitative way by neutron radiography. In this contribution, neutron radiography was applied to study water penetration into HPFRCC under different levels of imposed tensile strain. The water movement into the multiple fine cracks created under strain can be followed quantitatively. It has been observed that even very fine cracks are water filled after a short time. As expected the amount of water and the penetration depth both increase with increasing applied tensile strain. Water moves out of the water filled cracks into the neighbouring porous material. In an aggressive environment the maximum tolerable strain has to be limited in order to maintain a required durability. Much less water moves into integral water repellent HPFRCC. But under increasing imposed strain water penetration into the cracks cannot be avoided completely. Surface impregnation with a water repellent agent after crack formation due to imposed strain has proved to be an efficient protection of HPFRCC in contact with water and aqueous salt solutions. Under these conditions the enormous ductility of HPFRCC can be used in practical applications only.
Online publication: 2015
Publication Type: full_text
Public price (Euros): 0.00