Effect of different exposure conditions on the self‐healing capacity of engineered cementitious composites with crystalline admixture

Abstract

In this study, the effect of different exposure conditions of ambient air, tap water, and seawater on two levels of crack widths in engineered cementitious composites (ECC) were investigated. Crystalline admixture (CA) was implemented in the ECC mix to promote self-healing capacity. Flexural testing on prism specimens (100  100  350 mm) was conducted to evaluate self-healing by recovering the stiffness in the specimens with crack widths below 200 μm. Water permeability test was also carried out to assess the crack-filling capability of ECC disk specimens (100-mm diameter  50-mm thickness) with single crack widths over 1 mm. Digital image correlation technique was used to monitor crack propagation patterns and crack widths. To analyze the microstructure of the healing products, X-ray diffraction test was conducted on groups of tap water and seawater exposures. Concluding results proved seawater to be a promising environmental condition for the self-healing process in ECC specimens incorporating CA, in terms of recovery of mechanical and transport properties. Brucite was found to be formed as the additional healing agent that promoted self-healing in this condition. These results can be applied for coastal concrete structures.

Self‐healing of engineered cementitious composites under reversed and sustained loading conditions

“…The inevitable repetition of external loads/harsh environments that induce cracking over the lifetime of the infrastructure, accompanied by the localized cracking behavior of cementitious composites, makes the repeatability of the mechanisms that mainly rely on the formation of low‐strength and low‐toughness healing products (e.g., portlandite or Polymorphs of such as aragonite or vaterite) is threatened 21 . It also questions the micro and macro encapsulation techniques when the healing agents are released after the first cracking and hardened inside the cracks space, taking away the healing capability for any further damage that may occur, 17,22 even though there have been studies on the encapsulation of flexible polymers which are able to adhere to the crack walls even when cracks were opened further 10 . The repeatability of a self‐healing mechanism is also a crucial asset for justifying the life cycle cost of a self‐healing mechanisms for industry 23 .…”