20-09-2017, 04:58 PM
The hardenable cement based compounds (SHCC) withstand a higher tensile stress after the first cracking, over a significant range of tensile stress. This increased strength and deformability is achieved by an effective crack bridge through fibers, through multiple cracks of widths in the micro-range. In this paper we examine whether the crack width limitation translates into greater durability through delayed entry of moisture, gas and other harmful substances. This is done by evaluating the results of the recent testing of several laboratories at the international level. The question of whether these small crack widths are maintained under sustained, cyclic or other load paths is also addressed, concluding that crack widths are not independent of the load path. This contribution summarizes the status report prepared in the period 2005-2009 by Sub-Committee 2 of RILEM TC 208-HFC: Durability of SHCC. The potential of the comparatively new composite material becomes obvious, however, it is clearly indicated that further research is needed before fully understanding the basic mechanisms underlying the durability of SHCC. The JSCE Recommendation for Designing Structural Elements of SHCC (HPFRCC) is a useful tool, but should be complemented by a recommendation on the design of shelf life in the future.