  Disk-integrated photometric data of asteroids do not contain accurate
information on shape details or size scale. Additional data such as
disk-resolved images or stellar occultation measurements further constrain
asteroid shapes and allow size estimates. We aim to use all available
disk-resolved images of about forty asteroids obtained by the Near-InfraRed
Camera (Nirc2) mounted on the W.M. Keck II telescope together with the
disk-integrated photometry and stellar occultation measurements to determine
their volumes. We can then use the volume, in combination with the known mass,
to derive the bulk density. We download and process all asteroid disk-resolved
images obtained by the Nirc2 that are available in the Keck Observatory Archive
(KOA). We combine optical disk-integrated data and stellar occultation profiles
with the disk-resolved images and use the All-Data Asteroid Modeling (ADAM)
algorithm for the shape and size modeling. Our approach provides constraints on
the expected uncertainty in the volume and size as well. We present shape
models and volume for 41 asteroids. For 35 asteroids, the knowledge of their
mass estimates from the literature allowed us to derive their bulk densities.
We clearly see a trend of lower bulk densities for primitive objects
(C-complex) than for S-complex asteroids. The range of densities in the
X-complex is large, suggesting various compositions. Moreover, we identified a
few objects with rather peculiar bulk densities, which is likely a hint of
their poor mass estimates. Asteroid masses determined from the Gaia astrometric
observations should further refine most of the density estimates.
