Self-Healing Efficiency of Cementitious Materials Containing Microcapsules Filled with Healing Adhesive: Mechanical Restoration and Healing Process Monitored by Water Absorption

Abstract

Autonomous crack healing of cementitious composite, a construction material that is susceptible to cracking, is of great significance to improve the serviceability and to prolong the longevity of concrete structures. In this study, the St-DVB microcapsules enclosing epoxy resins as the adhesive agent were embedded in cement paste to achieve self-healing capability. The self-healing efficiency was firstly assessed by mechanical restoration of the damaging specimens after being matured. The flexural and compressive configurations were both used to stimulate the localized and distributed cracks respectively. The effects of some factors, including the content of microcapsules, the curing conditions and the degree of damage on the healing efficiency were investigated. Water absorption was innovatively proposed to monitor and characterize the evolution of crack networks during the healing process. The healing cracks were observed by SEM-EDS following. The results demonstrated that the capsule-containing cement paste can achieve the various mechanical restorations depending on the curing condition and the degree of damage. But the voids generated by the surfactants compromised the strength. Though no noticeable improved stiffness obtained, the increasing fracture energy was seen particularly for the specimen acquiring 60% pre-damage. The sorptivity and amount of water decreased with cracks healing by the adhesive, which contributed to cut off and block ingress of water. The micrographs by SEM-EDS also validated that the cracks were bridged by the hardened epoxy as the dominated elements of C and O accounted for 95% by mass in the nearby cracks.

Use of Sustainable Materials in Self-Healing Concrete

“…For cement-based materials, different methods can be found in literature (Table 4); the first breakthrough involves the use of encapsulated sealant or adhesive [19]. These are stored in fibers [39,40] or in longer tubes [60]. Filling of the voids and cracks with expansive material can propel carbonation when water percolates [61,62].…”

A review study on encapsulation‐based self‐healing for cementitious materials

“…Promoting durability recovery is the primary goal for self‐healing concrete, which determines indication for self‐healing efficiency assessment. Fluid permeability is a direct indication for concrete durability to evaluate the service life of concrete infrastructure . Therefore, permeability coefficient test is the most prevailing method to assess the durability of self‐healing concrete.…”

A Review: Novel Routes towards the Realization of Self-Healing Function in Cementitious Materials

“…To solve this problem, one-component epoxy microcapsules was developed to increase the efficiency of self-healing [11,12]. Recently, Wenting et al [13] demonstrated the work which employing one-component epoxy filled microcapsules to achieve mechanical restoration of cementitious materials. To decrease the viscosity of epoxy, they also proposed using benzylalcohol (BA) to adjust the viscosity of epoxy into an ideal value.…”