Computational Modelling for the Effects of Capsular Clustering on Fracture of Encapsulation-Based Self-Healing Concrete Using XFEM and Cohesive Surface Technique

Abstract

The fracture of microcapsules is an important issue to release the healing agent for healing the cracks in encapsulation-based self-healing concrete. The capsular clustering generated from the concrete mixing process is considered one of the critical factors in the fracture mechanism. Since there is a lack of studies in the literature regarding this issue, the design of self-healing concrete cannot be made without an appropriate modelling strategy. In this paper, the effects of microcapsule size and clustering on the fractured microcapsules are studied computationally. A simple 2D computational modelling approach is developed based on the eXtended Finite Element Method (XFEM) and cohesive surface technique. The proposed model shows that the microcapsule size and clustering have significant roles in governing the load-carrying capacity and the crack propagation pattern and determines whether the microcapsule will be fractured or debonded from the concrete matrix. The higher the microcapsule circumferential contact length, the higher the load-carrying capacity. When it is lower than 25% of the microcapsule circumference, it will result in a greater possibility for the debonding of the microcapsule from the concrete. The greater the core/shell ratio (smaller shell thickness), the greater the likelihood of microcapsules being fractured.

Recent Advances of Self-Healing Materials for Civil Engineering: Models and Simulations

“…Comparing concrete beams with elongated capsules in three-point bending tests, the model was found to exhibit similar nonlinear responses in bending and tension, indicating that the model well simulates the elastic and breaking stress with volume fraction, while the anticipated homogeneity of the material aligns well with the observed experimental tendencies. Hanna et al [132] further developed a simple 2D calculational simulation method based on these two above techniques to investigate the effect of microcapsule size and distribution on microcapsule rupture in self-healing concrete. The findings revealed a direct correlation between the microcapsules' circumferential contact length and their abil- Hanna et al [132] further developed a simple 2D calculational simulation method based on these two above techniques to investigate the effect of microcapsule size and distribution on microcapsule rupture in self-healing concrete.…”

“…Hanna et al [132] further developed a simple 2D calculational simulation method based on these two above techniques to investigate the effect of microcapsule size and distribution on microcapsule rupture in self-healing concrete. The findings revealed a direct correlation between the microcapsules' circumferential contact length and their abil- Hanna et al [132] further developed a simple 2D calculational simulation method based on these two above techniques to investigate the effect of microcapsule size and distribution on microcapsule rupture in self-healing concrete. The findings revealed a direct correlation between the microcapsules' circumferential contact length and their ability to support load.…”

Self-Healing Concrete Techniques and Technologies and Applications

“…Experimentally studying such behavior is challenging because some interface parameters between the concrete matrix and the capsule surface are difficult to determine. Therefore, computational modeling of the interaction between the concrete matrix and the capsule surface can provide helpful information about the fracture probability or debonding of the capsule when it counters the crack [3,4]. The interface strength between the capsule and the concrete should be high enough to avoid interface failure, so studying the cracking process is very important to guarantee that the capsules will break to release the healing agent; hence, the transportation and solidification process can begin properly.…”

“…Computational modeling of encapsulation-based self-healing concrete has shown its privilege to study the physical phenomena that are challenging to investigate experimentally. Such as capsular clustering effects, interfacial fracture properties between the capsules and the concrete matrix, and effects of healed crack length and interfacial cohesive properties between the solidified healing agent and the cracked surfaces [3][4][5]. This paper comprehensively reviews the development, definitions, concepts, and techniques of self-healing concrete.…”

Computational Fracture Modeling for Effects of Healed Crack Length and Interfacial Cohesive Properties in Self-Healing Concrete Using XFEM and Cohesive Surface Technique

“…Many laboratory studies and experiments have been conducted to investigate the fracture of the capsules and the bonding interaction between capsules and the concrete matrix, as well as the healing efficiency and fracture mechanism, such as in [2,3]. However, computational modeling has shown advantages in modeling physical phenomena that are challenging and difficult to investigate experimentally, such as capsular clustering [4]. Most computational modeling in SHC has focused on the investigation of the fracture interaction between capsules and the concrete matrix using a variety of modeling techniques such as cohesive elements, which is based on the cohesive zone model (CZM) [5] and the extended finite element method (XFEM) with a cohesive surface (CS) technique and has shown high accuracy [6,7].…”