Evaluation of Methodologies for Assessing Self-Healing Performance of Concrete with Mineral Expansive Agents: An Interlaboratory Study

Abstract

Self-healing concrete has the potential to optimise traditional design approaches; however, commercial uptake requires the ability to harmonize against standardized frameworks. Within EU SARCOS COST Action, different interlaboratory tests were executed on different self-healing techniques. This paper reports on the evaluation of the effectiveness of proposed experimental methodologies suited for self-healing concrete with expansive mineral additions. Concrete prisms and discs with MgO-based healing agents were produced and precracked. Water absorption and water flow tests were executed over a healing period spanning 6 months to assess the sealing efficiency, and the crack width reduction with time was monitored. High variability was reported for both reference (REF) and healing-addition (ADD) series affecting the reproducibility of cracking. However, within each lab, the crack width creation was repeatable. ADD reported larger crack widths. The latter influenced the observed healing making direct comparisons across labs prone to errors. Water absorption tests highlighted were susceptible to application errors. Concurrently, the potential of water flow tests as a facile method for assessment of healing performance was shown across all labs. Overall, the importance of repeatability and reproducibility of testing methods is highlighted in providing a sound basis for incorporation of self-healing concepts in practical applications.

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

“…As self-healing concrete research has been actively pursued, the water permeability test is receiving more attention. Although it has been primarily used as an evaluation tool, the detailed experimental procedures have been different for each researcher [3,[14][15][16][17][18]. As no standardized method is available for the permeability test, there are large variations in the permeability test results, even for specimens with similar crack widths.…”

“…In addition, the degree of the surface crack filled cannot be representative of the healing of the whole depth of the crack. Thus, this self-healing process is generally estimated from the evaluation of other properties, such as water permeability, chloride permeability, or flexural strength [11,[15][16][17][18]. A computed tomography (CT) based on 3D scanning can effectively capture the information of the filled crack [29].…”

“…Research to develop a test method suitable for self-healing concrete with cracks is also of interest [9][10][11][12]. However, because studies in the field of self-healing technology for concrete structures have only been actively conducted over the last two decades, standardization of evaluation methods and protocols for self-healing performance have not yet been established along with criteria and indexes, although several have been proposed [13][14][15].…”

“…The water permeability test can evaluate the performance of self-healing by measuring the amount of water passing through a crack. As self-healing concrete research has been actively pursued, various types of water permeability tests have been used [1,3,8,[11][12][13][14][15][16][17][18][19][20]. However, because no standardized method is available for the permeability test, there is a large variety of permeability test results, even for specimens with similar crack widths.…”

Assessment of the self‐healing capacity of cementitious materials through active thin sections

“…Currently, the self‐healing capacity of engineered cementitious materials is generally assessed by two main methods, which are based on observing crack closure during time and by evaluating the recovery of functional properties of interest (i.e. water tightness) 16,17 . Even though the proposed methodologies help to compare some parameters inherent to the self‐healing mechanism as well as the magnitude of recovery of the functional property, there are still some limitations about the accuracy of the healing products quantification.…”