Self-healing and expansion characteristics of cementitious composites with high volume fly ash and MgO-type expansive agent. (30th November 2016)

• Record Type: Journal Article
• Authors: Sherir, Mohamed A.A.; Hossain, Khandaker M.A.; Lachemi, Mohamed
• Is Part Of: Construction & building materials. Volume 127(2016)
• Page Start: 80
• Page End: 92
• Publication Date: 2016-11-30
• Subjects: Engineered cementitious composite -- MgO -- Self-healing system -- Expansive additive -- Supplementary cementing materials -- Autoclave test -- Linear expansion test -- Microstructure -- Compressive strength; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2016.09.125
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Developed engineered cementitious composites with self-healing property. Studied effectiveness of MgO as self-healing agent in combination with fly ash. Examined self-healing performance based on strength recovery and crack healing. Illustrate microstructural densification through SEM. Abstract: Discovering new cement based materials characterised with self-healing capability is essential for sustainable infrastructure with longer service life. Engineered cementitious composite (ECC) with high potential of micro-crack healing can enhance ductility and durability of concrete structures. MgO-type expansive agent (MEA) having low water demand and with the ability of densification of concrete microstructure was utilized in this research to develop ECC-MgO self-healing system. The effect of dosages of MEA and fly ash of different types as cement replacements was investigated based on lower expansion characteristics of ECC-MgO bar specimens through both water and autoclave linear expansion tests. The performance of ECC-MgO self-healing system was examined based on compressive strength recovery of pre-cracked cubic specimens and matrix micro-structural densification through Scanning Electron Microscope (SEM). Test results indicated that 5% lightly burnt MgO in combination with high volume of Class-F fly ash with 55% cement replacement should be used to design ECC-MgO self-healing system just to heal micro-cracks without affecting the durability. The higher compressive strength of 50% and 80% pre-cracked ECC-MgO cubic specimens cured under accelerated autoclaved conditions compared to ECC-control (without MEA) confirmed the self-healing capability and potential of the proposed ECC-MgO system.