Microstructure characteristics and evolution of the bonding interface between SCC and steam-cured concrete: Fid-Bau Portal

Microstructure characteristics and evolution of the bonding interface between SCC and steam-cured concrete

Li, Wenxu / Xie, Youjun / Ma, Kunlin / Long, Guangcheng / Li, Ning / Jiang, Wei / Peng, Yiming

Highlights • The physical accumulation of the cementitious material and the evolution of pore structure is revealed. • The interface characteristics between steam-cured concrete and SCC are characterized to identify the range of the bonding interface zone during the entire curing cycle. • The evolution mechanism of the microstructure at the bonding interface zone is explored in detail.

Abstract The microstructure of the bonding interface in CRTS III ballastless track structures is critical to the mechanical properties and durability of high-speed railway structures. The microstructure evolution of the bonding interfacial zone between steam-cured concrete and SCC (self-compacting concrete) is widely studied. This paper investigates the pore structure and phase evolution of the bonding interface zone using backscattered electronic and energy dispersive spectroscopy (BSE + EDS). Based on the nanoindentation test, the microstructure characteristics of the bonding interfacial zone were studied. The results show that the microstructure reveals a gradient change at the bonding interface zone, and the gradient characteristics of the microstructure weaken as curing age increases (especially at 7 days and 56 days). The width of the bonding interface zone is about 15 μm, and the width is more about 20 μm at 1 day. The elastic modulus of C-S-H at the bonding interface zone is low and the C-S-H is mostly LD C-S-H. VMA is beneficial to improve the elastic modulus of C-S-H.