This piece is in ABACA, with repeats of the A, BA and CA sections. There are no transitions, so it can't be a Sonata-Rondo ... must be a normal, 5-part rondo!
A section: It's a contrasting, assymetrical period. The first phrase ends on a IAC, and the second has a cadential extension that eventually ends on a PAC. This section is repeated, ending on Measure 24. The double bar lines and change in dynamics from forte to piano signal a change of section.
B section: We move to the dominant, F Major. This section is sort of developmental of the A section. It ends on Measure 33. Afterwards there's a recapitulation of the A section in its original form and key. Again, we have double bar lines and a change in dynamics - to pianissimo.
C section: This is very tonally unstable - no distinct cadences. This section is also developmental, and is in gb minor. This section modulates back to Bb Major, ending on Measure 52. After this we return to the A section one last time!
Changes in tempo also serve as structural phenomena - we always return to a tempo when we get back to the A section.