  We present a cluster expansion EoS model for strongly-interacting matter
based on the generalized Beth-Uhlenbeck formalism to describe hadrons as bound
clusters of quarks. This formalism can describe both confined and deconfined
phases. Our emphasis is on the region of vanishing baryon densities, where
numerical solutions available from Lattice QCD predict a smooth crossover
transition from hadron to quark matter. Medium effects are taken into account
as self energies, which are motivated from both perturbative QCD calculations
and phenomenological models. Parameters are tuned to Lattice QCD data and
result in a good agreement of the thermodynamics.
