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.
Highlights
Concrete is a widely used construction material because it possesses several beneficial features, such as its high compressive strength, economic feasibility, and tractability
We present a protocol for the self-healing performance evaluation of concrete that is based on a constant water head permeability method using a cylindrical cracked specimen
The final crack width that can be attained though the healing process is one of the most important factors for engineers when choosing self-healing materials
Summary
Current self-healing technology aims to recover the water tightness of cracks or the mechanical performance in concrete, and appropriate performance evaluation methods have been used [3]. We present a protocol for the self-healing performance evaluation of concrete that is based on a constant water head permeability method using a cylindrical cracked specimen. In cases where the crack width is difficult to measure or the measurements are not reliable, the crack width can be theoretically evaluated using the water permeability test results. In this case, the crack width can be estimated using the pre-determined coefficient α with: w(t) = (q(t)/α) 3. Even though the equivalent crack width is not the actual crack width, it can be a reasonable basis for evaluating the self-healing performance
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