Evaluation of interface rapid bond strength between normal concrete and ternary system fast setting and rapid hardening self-compacting concrete

Abstract

• The rapid bonding performance between NC substrate and TSSCC was investigated. • The bond strength meets the requirements of the executive standard within 2 hours. • Surface-milled revealed higher bond strength of NC/TSSCC composite. • The microstructure and bonding model of the NC/TSSCC interface were studied. • TSSCC is suitable for rapid repair of the reinforced concrete structures. The ternary system (Ordinary Portland cement-sulfoaluminate cement-anhydrite) fast-setting and rapid-hardening self-compacting concrete (TSSCC) is a new type of green and low-carbon material. In this study, the interfacial rapid bond strength and bonding mechanism between ternary system self-compacting concrete (TSSCC) as rapid repair material and normal concrete (NC) substrate was investigated at different ages. Two surface treatment methods, including milling and grooving, were employed to improve the bond properties. Meanwhile, the hydration products of TSSCC and the microstructure of the bonding interface were investigated using TGA-DSC and SEM. The results show that the bond strength of the surface-milled NC/TSSCC composite is about 1.2 times that of the surface-grooved composite. Due to the fast setting and rapid hardening of the ternary system, the 2 h bond strength of NC/TSSCC attained about 50 % of the 28d bond strength. Similarly, the 2 h slant shear bond strength of the NC/TSSCC composite satisfied the 7 d slant shear strength value recommended in the ACI 546R-04 Concrete Repair Guide. The composite NC matrix/TSSCC consists of three zones: the old concrete zone, the transition zone, and the new concrete zone. The NC/TSSCC rapid bond strength is derived from the main hydration product AFt of TSSCC to the pinning of pore cracks in the old concrete, the meshing between AFt, the penetration filling of the hydration product, and the van der Waals force between the old and new concrete hydration products. This study indicates that TSSCC has the potential application for the rapid repair of reinforced concrete structures.