Self-Healing Performance Evaluation of Concrete Incorporating Inorganic Materials Based on a Water Permeability Test

Abstract

Research activities that have focused on the development and understanding of self-healing concrete have proposed various technologies intended to enhance self-healing capacity. The self-healing performance cannot be identified sufficiently with either a single test or a specific parameter because there are a number of factors that influence the performance of self-healing. Thus, it has become necessary to provide standardized test methods that make it possible to verify and compare the performance of self-healing materials. In this paper, self-healing mortars based on inorganic admixtures, which are developed for sealing 0.3 mm cracks with a healing index of 90%, are produced and used to validate the water permeability test and to propose protocols for the evaluation of self-healing performance. The healing performances of three self-healing mortars and a plain mortar as a reference are evaluated with a comparative study. The equivalent crack width, which can be estimated from the water flow rate, is suggested as a rational evaluation index. Finally, a self-healing performance chart is proposed to comprehensively show the healing performance of cement-based materials.

Fundamental Properties and Self-Healing Performance of Repair Mortar with Solid Capsules Made Using Inorganic Reactive Powder

“…Figure 7 and Figure 8 show the test results for the crack inducing age of 28 days as the healing index (%) vs. healing period and healing index (%) vs. crack width, respectively. As shown, the healing index increased rapidly during the initial seven days of the healing period, and then increased more slowly during days 7 through 28 [ 31 ].…”

“…A constant water head permeability test was adopted to measure the water flow rate of the crack-induced specimen and to evaluate the self-healing performance of repair mortars [ 31 ]. For the water permeability test, cracked specimens were produced through several steps.…”

“…The cracked specimens were cured in a water bath at 20 °C during the healing period. As there is no specific standard for the water temperature during the healing period, a water curing temperature of 20 °C was adopted [ 27 , 31 ]. The water permeability test was conducted after healing periods of 0, 7, 14, 21, and 28 days.…”

“…Through the water permeability test, the healing index, SH q , can be calculated using the water flow rate reduction ratio as follows [ 2 , 31 , 32 , 33 ]: where q 0 is the initial water flow rate measured just after the specimen is cracked, without any healing effect, and q ( t ) is the water flow rate after a healing period, t .…”

Influencing Factors on the Healing Performance of Microcapsule Self-Healing Concrete

“…Self-healing concrete is used to prevent concrete deterioration and improve durability [ 1 , 2 , 3 ]. Since there are insufficient human and material resources for damage detection and the timely repair of concrete components, scholars proposed a self-healing concrete with bionic characteristics.…”