Effects of healing start time and duration on conventional and high-performance concretes incorporating SAP, crystalline admixture, and sepiolite: A comparative study

Abstract

This research investigates the self-healing capability of conventional and high-performance concrete containing either a superabsorbent polymer (SAP), a crystalline admixture (CA), or water-encapsulated in sepiolite by quantifying the recovery of water tightness through the water permeability test and chloride permeability via cracks and matrix penetration on healed specimens. Specimens were pre-cracked to a crack width range of 50–450 µm at 28 days. Specimens were healed under water in four time combinations: healing starting at the concrete age of 28 days or 56 days and a healing duration of 28 or 56 days. Additionally, a healing condition of presaturation during 1 day of water immersion and storage in a humidity chamber for 27 days was studied. The results show that delayed healing reduced the self-healing efficiency, and extending the duration to 56 days enhanced healing, especially for narrow cracks (≈100 µm), and reduced chloride permeability. Specimens with SAP showed superior early-stage healing, but low delayed healing. Sepiolite enhanced healing for delayed cracks with variable effectiveness. CA improved healing for both early and delayed healing, exhibiting low chloride penetration in healed specimens.

Keywords

• Self-healing
• Water permeability
• Chloride penetration
• High-performance concrete
• Crystalline admixture
• Superabsorbent polymer