Chemical-based self-healing concrete: a review

Abstract

Abstract The emergence of cracks in cementitious composites and concrete, stemming from both autogenous processes and external stressors, poses a significant challenge to the long-term durability and safety of structures. In response to this challenge, researchers have developed an innovative method featuring inherent capabilities for autonomous crack repair, known as self-healing concrete, which offers promising benefits for enhancing structural longevity and reducing environmental impact. This method offers not only an autogenous healing mechanism but also the potential for autonomous repair, significantly reducing the need for maintenance while concurrently extending the lifespan of concrete structures. This paper comprehensively reviews the working principles, fabrication techniques, and self-healing capabilities, specifically in relation to crack recovery and mechanical performance, of concrete incorporated with chemical-based self-healing agents. These agents encompass a range of materials, such as sodium silicate, calcium nitrate, dicyclopentadiene, calcium hydroxide, calcium sulfoaluminate (CSA), silica, and superabsorbent polymers. In this review, both autogenous and autonomous self-healing were considered, and literature studies suggested cracks can effectively heal, and mechanical performances can be significantly restored. Healing performance and mechanical performance restoration can vary significantly with the type of healing agents and their concentrations. Many researchers have achieved more than 100% restoration of mechanical performance and fully healed crack depths. Superabsorbent polymers (SAP) are highly effective self-healing agents, particularly when combined with autogenous healing agents like calcium nitrate or CSA. This combination can lead to significant healing in cracks up to 750 μm. Chemical-based self-healing agents can be an efficient way to enhance the durability of concrete, ensuring safety and promoting their practical application.

Keywords

• Self-healing concrete
• Superabsorbent polymers
• Sodium silicate
• Calcium nitrate
• Dicyclopentadiene
• Mechanical strength recovery