  Context: In protoplanetary discs, micron-sized dust grows to form millimetre-
to centimetre-sized pebbles but encounters several barriers during its
evolution. Collisional fragmentation and radial drift impede further dust
growth to planetesimal size. Fluffy grains have been hypothesised to solve
these problems. While porosity leads to faster grain growth, the implied
porosity values obtained from previous simulations were larger than suggested
by observations. Aims: In this paper, we study the influence of porosity on
dust evolution taking into account growth, bouncing, fragmentation, compaction,
rotational disruption and snow lines, in order to understand their impact on
dust evolution. Methods: We develop a module for porosity evolution for the 3D
Smoothed Particle Hydrodynamics (SPH) code Phantom that accounts for dust
growth and fragmentation. This mono-disperse model is integrated into both a 1D
code and the 3D code to capture the overall evolution of dust and gas. Results:
We show that porosity helps dust growth and leads to the formation of larger
solids than when considering compact grains, as predicted by previous work. Our
simulations taking into account compaction during fragmentation show that large
millimetre grains are still formed, but are 10 to 100 times more compact. Thus,
mm sizes with typical filling factors of ~0.1 match the values measured on
comets or via polarimetric observations of protoplanetary discs.
