Sustainable, Self-Healing, and Functional Building Materials

Dear Colleagues,

Concrete is the most frequently used building material, which accounts for 5–10% of global CO₂ emissions. Due to the brittle nature of concrete, cracking and cracking-related deterioration are among the most important factors threatening the integrity, durability, and safety of concrete structures. Self-healing, a phenomenon originating from biological systems, is a promising concept that can be adopted to treat cracks in cementitious materials. Attaching such new function to cementitious materials can extend the service life of concrete structures and mitigate the depletion of natural resources, energy consumption, and CO₂ emissions associated with concrete production and structural maintenance. This could be an important approach towards the sustainability of the modern cement and concrete industry.

The self-healing of cementitious materials can be achieved mainly through the following three strategies: (i) autogenous healing; (ii) the encapsulation of polymeric materials; (iii) the microbial production of minerals (i.e., calcium carbonate).

In autogenous healing, which is considered a natural phenomenon, concrete cracks are filled through the hydration of unhydrated cement particles or the carbonation of dissolved calcium hydroxide in the presence of moisture or water.

The encapsulation of polymeric materials can contribute to filling cracks by the conversion of healing agent to foam in the presence of moisture. The polymeric adhesives are often designed to provide extrinsic sealing through the polymerization and coalescence of the adhesives. Polymeric adhesives can also fill the cracks and harden when in contact with the alkalis or hydroxide ions.

Biological healing processes are based on the production of minerals by living organisms through biomineralization, which is a widespread phenomenon in nature. In this process, biominerals are formed through the reaction of metabolic products generated by microorganisms with the surrounding environment. Among the various pathways of mineral production through biomineralization—such as carbonates, sulfides, silicates, and phosphates—the precipitation of calcium carbonate has attracted widespread interest due to its efficient bonding capacity and compatibility with concrete compositions.

In this Special Issue, modern trends in self-healing concrete preparation, including the healing fundamentals and mechanisms as well as the properties of healed concrete, are highlighted and discussed. Sustainable techniques and new functional materials related to self-healing cementitious materials will also be covered.

It is my pleasure to invite you to submit a manuscript for publication in this Special Issue. Full papers, communications, and reviews are all welcome.

Prof. Dr. Zhengwu Jiang
Prof. Dr. Biqin Dong
Guest Editors

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