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Sacrificial concrete shear keys have been recommended and used widely because they can restrain the excessive displacement of the bridge superstructure under normal service loads and protect the substructures from severe damage under the huge earthquake event, whereas the post-earthquake rehabilitation of the traditional shear key (regain its original function) is still a big challenge for bridge engineers. Therefore, this study proposed a replaceable concrete retaining block as an alternative that can provide mostly the same functionality as the sacrificial shear keys. The proposed replaceable concrete retaining block is prefabricated and installed to the cap beam by using the unbonded prestressed tendons. To study the functional feasibility and seismic behavior of the replaceable retaining block, four specimens with identical size were designed and tested under the horizontal monodirectional and cyclical load. The influence of structural materials and forms on seismic failure modes of different blocks was investigated based on both laboratory tests and finite element analysis. It is concluded that the failure modes of the monolithic normal concrete (NC) and the ultra-high-performance-concrete (UHPC) retaining block are the typical diagonal shear failure and the vertical interface damage, respectively. The replaceable NC retaining block performs well in lateral displacement and self-resetting ability, but its final damage is still the unpredictable bending-shear failure mode. The replaceable UHPC retaining block can keep only slight damage but simultaneously satisfy the requirements of higher lateral bearing and displacement capacity. Especially, the self-resetting capacity of the replaceable UHPC retaining block will be greatly improved if the straight joint is used instead of the original mortise-tenon joint. • A novel replaceable concrete retaining block is proposed. • Functional feasibility and seismic behavior of the proposed retaining block are investigated. • Impact of the structural materials and forms on damage mode of the retaining block are assessed. • Finite element models of different retaining blocks are developed. • Replaceable UHPC retaining block is with significant benefit of seismic performance. [ABSTRACT FROM AUTHOR]