Moving towards a realistic implementation of self-healing concrete based on encapsulated polymer precursors

Extensive research has already been performed on self-healing concrete based on a triggered release of liquid polymer precursors from a carrier, especially during the past decade. However, tests on large concrete specimens are still seldom performed and the self-healing techniques used are often not practical or effective if implemented at a large scale. This paper presents an analysis of the most relevant properties for carriers that are critical for moving the technology closer to a realistic implementation. The study contemplates the assessment of the dimensions of tubular glass capsules that result in a high survival rate if directly added to concrete during mixing, while still being able to rupture during realistic crack formation in the host concrete matrix. Finally, a trial implementation of randomly dispersed glass tubular carriers in concrete beams is presented. This system is composed of a typical OPC concrete with tubular glass capsules added during the mixing process. It is shown that this system works and the crack planes cross several capsules that subsequently release the polymer precursor into the crack. However, the dosage used needs to be increased if a satisfying healed area is to be achieved