Multiple Cracking Characteristic of Strain Hardening Cement-based Composites and the Cracks' Autogenous Self-healing
LIU Hongbiao1, ZHANG Qiang1, GUO Chang1, ZHANG Peng2
1 Tianjin Research Institute for Water Transport Engineering, National Engineering Laboratory for Port Hydraulic Construction Technology, Tianjin 300456; 2 School of Civil Engineering,Qingdao University of Technology, Qingdao 266033
Abstract: SHCC (Strain hardening cement-based composites) is a type of ultra-high performance concrete (UHPC). Cracks were introduced into ordinary cement mortar and SHCC specimens by means of three-point bending test, and the cracking characteristic and crack distribution were investigated. The results indicated that SHCC displayed higher bearing capacity and strain capacity than ordinary cement mortar, as the former's initial cracking load was about 1.5 times higher than the latter. The bridging effect of PVA fibers effectively delays crack initiation and propagation in SHCC, and causes the transform of lesser, wider cracks in ordinary mortar into much more and finer cracks in SHCC, which implies a multiple cracking characteristic. The crack width measured in SHCC specimens coincided well with normal distribution, and moreover, 90% of the cracks had <30 μm width. These micro-cracks were capable of autogenous self-healing under humid condition, as higher self-healing degree and self-healing rate were observed in water than those in humid air.
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2017, Vol. 31 
