  When random quantum spin chains are submitted to some periodic Floquet
driving, the eigenstates of the time-evolution operator over one period can be
localized in real space. For the case of periodic quenches between two
Hamiltonians (or periodic kicks), where the time-evolution operator over one
period reduces to the product of two simple transfer matrices, we propose a
Block-self-dual renormalization procedure to construct the localized
eigenstates of the Floquet dynamics. We also discuss the corresponding Strong
Disorder Renormalization procedure, that generalizes the RSRG-X procedure to
construct the localized eigenstates of time-independent Hamiltonians.
