Investigation of medium-term self-healing performance of strain-hardening cementitious composites incorporated with colloidal nano silica

Abstract

• Colloidal nano silica (CNS) improved the mechanical performance of the cementitious composite. • The regaining of the mechanical performance of the pre-damaged sample was improved by CNS. • The addition of CNS improved the hydration degree and pozzolanic reaction. In this research, the properties of the colloidal nano silica-incorporated strain-hardening cementitious composite (SHCC) were investigated. Specifically, mechanical properties and medium-term (three months) self-healing performance were evaluated through various testing methods. The critical mechanical behaviors, including compressive, tensile, flexural properties, and bonding strength were assessed. The results indicated that the incorporation of colloidal nano silica (CNS) can effectively improve the mechanical properties of SHCC. Both non-destructive and destructive testing methods were implemented to monitor the medium-term self-healing performance of the SHCC with various CNS incorporation ratios. The SHCC samples were pre-cracked and placed under two separate environmental conditions during the healing period. It was found that the incorporation of the CNS can effectively improve the regaining of the mechanical performance of the SHCC within one season (three months) after subjected to damage. The thermal gravity analysis (TGA) and scanning electron microscope (SEM) were conducted to understand the hydration conditions of each sample. It is summarized that the CNS incorporation ratio between 0.3 and 0.6 percent would be optimal for SHCC to reach excellent mechanical properties and self-healing performance. This study provides insight for the design of the high-performance cementitious composite with longer service life by enhancing the self-healing efficiency.