  Most protoplanetary discs are thought to undergo violent and frequent
accretion outbursts, during which the accretion rate and central luminosity are
elevated for several decades. This temporarily increases the disc temperature,
leading to the sublimation of ice species as snowlines move outwards. In this
paper, we investigate how an FUor-type accretion outburst alters the growth and
appearance of dust aggregates at different locations in protoplanetary discs.
We develop a model based on the Monte Carlo approach to simulate locally the
coagulation and fragmentation of icy dust particles and investigate different
designs for their structure and response to sublimation. Our main finding is
that the evolution of dust grains located between the quiescent and outburst
water snowlines is driven by significant changes in composition and porosity.
The time required for the dust population to recover from the outburst and
return to a coagulation/fragmentation equilibrium depends on the complex
interplay of coagulation physics and outburst properties, and can take up to
4500 yr at 5 au. Pebble-sized particles, the building blocks of planetesimals,
are either deprecated in water ice or completely destroyed, respectively
resulting in drier planetesimals or halting their formation altogether. When
accretion outbursts are frequent events, the dust can be far from collisional
equilibrium for a significant fraction of time, offering opportunities to track
past outbursts in discs at millimetre wavelengths. Our results highlight the
importance of including accretion outbursts in models of dust coagulation and
planet formation.

Earth and Planetary Astrophysics