Development of Self-Healing Ultra-High- Performance Concrete Using Smart Nanocapsules for Enhanced Structural Resilience

Abstract

Ultra-High-Performance Concrete (UHPC) represents a significant advancement in construction materials due to its exceptional strength, durability, and low permeability. However, its dense microstructure and low strain capacity result in microcrack formation under mechanical loading, thermal gradients, and shrinkage effects, which may compromise long-term structural performance. This study presents the development of a smart self-healing UHPC system incorporating polymer-filled nanocapsules designed to autonomously repair microcracks and enhance structural resilience. Nanocapsules with controlled size distribution were synthesized and embedded within the UHPC matrix at varying concentrations. Mechanical performance, crack-healing efficiency, microstructural evolution, and durability characteristics were systematically evaluated. Experimental results demonstrate that self-healing UHPC achieves up to 85% recovery in flexural strength after crack formation and exhibits significantly reduced permeability and chloride ion penetration compared to conventional UHPC. Microstructural analyses confirm effective crack sealing through polymerization and secondary hydration reactions. The findings indicate that nanocapsule- enabled UHPC offers a promising pathway toward sustainable, low-maintenance infrastructure capable of prolonged service life under aggressive environmental conditions.