Definition of spalls:
(n) :
(countable) A splinter, fragment or chip, especially of stone.
(v) :
(ambitransitive) To break into fragments or small pieces.
(n) :
(uncountable, especially concerning ferroconcrete structures or metal objects) A process of weathering, aging, or other wear that involves the crumbling of the substrate.
(v) :
(especially of ferroconcrete structures or metal objects) To undergo weathering, aging, or other wear that involves the crumbling of the substrate.
(v) :
(transitive) To reduce, as irregular blocks of stone, to an approximately level surface by hammering.
(n) :
(obsolete, rare) The shoulder.