  The direct discovery of gravitational waves has finally opened a new
observational window on our Universe, suggesting that the population of
coalescing binary black holes is larger than previously expected. These sources
produce an unresolved background of gravitational waves, potentially
observables by ground-based interferometers. In this paper we investigate how
modified theories of gravity, modeled using the ppE formalism, affect the
expected signal, and analyze the detectability of the resulting stochastic
background by current and future ground-based interferometers. We find the
constraints that AdLIGO would be able to set on modified theories, showing that
they may significantly improve the current bounds obtained from astrophysical
observations of binary pulsars.
