In by Mark Goodman

The chipping or flaking of concrete, bricks or other masonry when improper drainage or venting and freeze-thaw cycling exist.

spalling (Wikipedia)
Very high speed photography of a small projectile striking a thin aluminum plate at 7000 m/s. The impact causes the projectile to disintegrate, and generates a large number of small fragments from the aluminum. This can occur without penetration of the plate.

Spall is flakes of a material that are broken off a larger solid body and can be produced by a variety of mechanisms, including as a result of projectile impact, corrosion, weathering, cavitation, or excessive rolling pressure (as in a ball bearing). Spalling and spallation both describe the process of surface failure in which spall is shed.

The terms spall, spalling, and spallation have been adopted by particle physicists; in neutron scattering instruments, neutrons are generated by bombarding a uranium target with a stream of atoms. The neutrons that are ejected from the target are known as spall.

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