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Particle-laden horizontal turbulent pipe flow is studied experimentally in the two-way coupling regime with a focus on delineating the effects of particle-to-fluid density ratio 
$\rho _{p}/\rho _{f}=1$ and 1.05 on the fluid and particle statistics. Particle volume fraction 
$\phi _{v}$ up to 
$1\,\%$ and viscous Stokes numbers ranging from 
$St^+ \approx 1.2$ to 
$St^+ \approx 3.8$ are investigated at friction Reynolds number 
$Re_\tau \approx 195$ using time-resolved two-dimensional particle image and tracking velocimetry. Substantial differences are observed between the statistics of neutrally buoyant (i.e. 
$\rho _{p}/\rho _{f}=1$) and denser (i.e. 
$\rho _{p}/\rho _{f}=1.05$) settling particles (with settling velocities 0.12–0.32 times the friction velocity), which, at most instances, show opposing trends compared to unladen pipe flow statistics. Neutrally buoyant particles show a slightly increased overall drag and suppressed turbulent stresses, but elevated particle–fluid interaction drag and results in elongated turbulent structures compared to the unladen flow, whereas 
$\rho _{p}/\rho _{f}=1.05$ particles exhibit a slight overall drag reduction even with increased radial turbulent stresses, and shorter streamwise structures compared to the unladen flow. These differences are enhanced with increasing 
$St^+$ and 
$\phi _v$, and can be attributed to the small but non-negligible settling velocity of denser particles, which also leads to differing statistics in the upper and lower pipe halves.
