Comparative analysis of three different types of self-healing concrete via permeability testing and a quasi-steady-state chloride migration test

Concrete is the most used construction material in the world and with the growing world population, the demand for housing and infrastructure keeps increasing. Due to its low tensile strength, concrete cracks easily and these cracks have a negative effect on the durability. Different studies have already been conducted on the development of self-healing concrete, which has the ability to heal its own cracks. Unfortunately, due to a lack of standardized test methods, the boundary conditions in these studies are often different, making it difficult to do an accurate comparison. In this research, three different healing agents are tested using the same test methods under the same boundary conditions: a powder of organic/inorganic composite material (WM), solidified calcium sulfoaluminate capsules (SMU) and bacterial pellets (KU). The healing efficiency of the agents is tested with (1) a low-head water flow test on prismatic specimens cracked in a three-point bending test with subsequent active crack width control, (2) a Korean water permeability test on cylindrical specimens cracked by a Brazilian splitting test, (3) a chloride diffusion test and (4) a quasi-steady-state chloride migration test. The results showed that WM performed superior with respect to the reference mix and the other healing agents in the two water permeability tests and the quasi-steady-state chloride migration. The performance of SMU and KU was depending on the healing condition. When fully saturated during healing, the KU specimens had a good behaviour and SMU performed poorly. For the cylindrical specimens, with the specimen partly immersed in water, SMU and KU had a similar performance which was better in comparison to the reference.