Integral procedure to assess crack filling and mechanical contribution of polymer-based healing agent in encapsulation-based self-healing concrete

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

“…It was found that the capsules are not completely emptied due to the insufficient capillary force, and the healing agent within the crack spreads discontinuously. The same phenomenon was confirmed using the micro‐CT image analysis by Gilabert et al Based on the X‐ray radiographs of the concrete beam slices with realistic cracks, Tittelboom et al concluded that whether a crack propagates through a capsule is based on coincidence, unless the cement paste bars act as weak zones between capsule and cement matrix and attract the crack initiation. Micrographic representation techniques are usually applied to quantitatively determine the width of crack and visualize the distribution of healing agent, as shown in Figure c.…”

“…They suggested that low stiffness might cause poor regained stiffness values, but stiff adhesive can easily transfer stress across cracks, allowing the crack to develop continuously. On the other hand, Gilabert et al evaluated the strength contribution of cured PU‐based healing agent by conducting tensile tests, and a linear relationship was proposed between the tensile failure stress and the crack opening distance. This failure stress ranged from 3.7 MPa for a crack open displacement (COD) of 50.8 μm (COD) to 1.2 MPa for a COD of 381 μm.…”

“…Concerning the flow of healing agent and efficiency of self‐healing, a computational fluid model called “inter foam” was proposed to analyze the relationship between spatial distribution of healing agent and the crack width . The computational domain includes the interior of capsules and the space between two crack surfaces.…”

Concrete composites of double structure formation

“…To accelerate the assessment of concrete frost resistance, a dilatometric method of structure analysis was used [13,14,15]. The measurement procedure for temperaturehumidity deformations is as follows: prior the test, samples of tested concrete, 7x7x21 cm in size, are saturated with water, insulated with frost-resistant rubber, placed in a dial gauge, and then into the freezer; temperature control is carried out in the chamber and in the sample middle; strain readings are recorded every 5° C at the time when the temperature in the chamber and the sample middle is equalized.…”

Validation of Self‐Healing Properties of Construction Materials through Nondestructive and Minimal Invasive Testing

“…Gilabert et al performed experiments in which the outflow of the two components of a polyurethane‐based healing agent (each of them with its own viscosity) was investigated within concrete cubes, with an artificial flat crack with a width of 300 µm, while scanning with X‐rays. Based on the concept of differential imaging, two scans were made per experiment: one before the glass capsules containing the healing agent was broken and one after.…”