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.

Curable Area Substantiation of Self-Healing in Concrete Using Neutral Axis

“…Although in a few cases it was observed that the specimens cured in air could be healed if the healing period was sufficiently long, the water condition was better for the self-healing of concrete. The healing tendency according to the healing condition is consistent with the results of many other studies [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][36][37]41,43]. It is a reasonable The results of the flexural strength comparison and the initial flexural stiffness comparison are similar if we look at the results themselves.…”

“…Another famous active method was proposed based on the use of microorganisms [21][22][23][24], which help deposit crack-restoring substances. Moreover, many passive methods exist, for example, improvement of self-healing environment using fibers that prevent the occurrence of a single large crack and induce multiple cracks of small width [25][26][27][28]. The recovery due to self-healing is not only general strength recovery but also durability recovery such as decreased water permeability [29][30][31][32][33].…”

Autogenous Healing Effect of Ultra-High Performance Cementitious Composites

“…After this time, its flexural tensile strength was approximately 30% higher than that of the reference material that was stored in air-dry conditions. Also, the research conducted by (Kunieda et al 2012) unambiguously confirms the ability of UHPC to selfheal its structure. Investigations of this phenomenon conducted by the authors were based, inter alia, on the characteristics of the composites ability to transport liquid and gas media.…”

Review of Cementitious Composites Containing Polyethylene Fibers as Repairing Materials

“…Fine cracks were observed as healed using hybrid fibers. Kunieda et al [132] used a high strength matrix and 88 GPa high-stiffness PE fibers to produce PE-ECC, which exhibited a good self-healing effect. The crack width in the research was less than that of normal ECC due to the strong restriction by PE fibers.…”