The present disclosure is directed to a joining element elongate in a longitudinal direction including an inner core extending substantially in the longitudinal direction and an outer sleeve surrounding at least a portion of the inner core. The sleeve includes a lattice that defines at least one angle with respect to the longitudinal direction and the core is swellable against the sleeve along a direction perpendicular to the longitudinal direction to thereby increase the angle with respect to the longitudinal direction. The disclosure is further directed to a method of joining a first a second material including the joining element of the present disclosure.