Easily renovated expansion joint for a concrete slab formwork system

An expansion joint configured for placement between first and second concrete slabs positioned adjacent thereto, the expansion joint defining an air space that absorbs variations in volume of the first and second concrete slabs under an action of shrinkage, said joint incorporating first and second longitudinal segments positioned side by side in a same horizontal plane, and being configured to each be integral with an upper and horizontal edge of the first and second concrete slabs, the first longitudinal segment being secured to a vertical separation means between the first and second concrete slabs defining a vertical plane horizontally offset with respect to a vertical plane defined between the first and second longitudinal segments such that under the action of shrinkage of the first and second concrete slabs, the first and second longitudinal segments move apart from each other but still remain bearing against one of the first and second concrete slabs, the first and second longitudinal segments comprise fittings opening at upper horizontal walls of said first and second longitudinal segments, and that enable a removal of at least a removable part of each of the first and second longitudinal segments, for replacement of said removable parts;

• wherein the first longitudinal segment comprises a stack of three layers of material, with one intermediate layer having a smaller width than the other two layers, such that the first longitudinal segment has a U-shaped cross section, and the second longitudinal segment comprises a stack of three complementary layers of material, with one intermediate layer having a greater width than the other two layers, so as to form a transverse projection configured to fit into the hollow of the U-shaped shape of the first longitudinal segment.