In early days, gravel pits and quarries used traditional products. Hoppers were built with mild steel. When the aggregate wore a hole in the bin or chute, they patched it with another pc of steel. As steel advanced they came out with hardened steel (Hardox, T1, etc) that lasted longer than mild steel. So, everyone started patching their equipment with this. In hard to reach areas, cranes were needed as this is very heavy material.
The trouble is, even the hardened steel was wearing out. The goal was to get it to last a season, and then in the winter, when the bone chilling cold winds are blowing through the quarry, you replace it or patch it so you can get another 6 months or a year out of it.