Pulled 4 pallets of reclaimed brick out of a dead warehouse on 9th St and lost 30% of them to spalling after 6 weeks outside | Bricklayers - Freelance Forum - The Community for Independent Professionals
Buddy of mine did the same thing with a barn teardown. Stacked them on gravel, no cover, and half turned to dust by spring.
Brick needs to breathe but not soak. Tarp on top only, keep the sides open.