Recovery of protective performance of cracked ultra high performance-strain hardening cementitious composites (UHP-SHCC) due to autogenous healing

Abstract

A new strain hardening cementitious composite with a dense matrix, Ultra High Performance-Strain Hardening Cementitious Composites (UHP-SHCC), has been developed. This material combines excellent protective performance with a significantly higher tensile strength and strain hardening at tensile strength. Further, the material has controlled fine cracks (less than 30 microns). A low water to binder ratio with silica fume that causes a pozzolanic reaction is used in UHP-SHCC. These characteristic may give advantages for autogenous healing after the cracking. This paper presents autogenous healing behavior of cracked UHP-SHCC, and discusses about recovery of protective performance through air and water permeability test results. It was confirmed that UHP-SHCC has potentially autogenous healing properties. The air permeability coefficient and water permeation were dramatically decreased by increasing of re-curing period. Re-curing in water was more effective than re-curing in air for recovery. The effect of induced damage level on recovery of the used indices was not significant, because crack width was controlled and was almost the same among all the cracks. The repeatability of autogenous healing (twice in this study) was confirmed. Copyright © 2012 Japan Concrete Institute.