Aggregate
Aggregate turns up in 2 fields: concrete, waterproofing. Here is what it means to the people in each one.
Aggregate in concrete
The sand, gravel and crushed stone that make up 60 to 75 percent of a concrete mix by volume.
Granular mineral filler split into fine aggregate (sand passing the No. 4 sieve, 4.75 mm) and coarse aggregate (gravel or crushed stone retained on it). Gradation, maximum size, particle shape, absorption and soundness set how much paste the mix needs, which drives shrinkage, cost and strength. Common coarse sizes in US work are No. 57 stone (1 in down to No. 4) and No. 67 stone (3/4 in down to No. 4).
"Plant switched the coarse aggregate to round river rock, so the same mix is coming in wetter and pumping easier."
Aggregate in waterproofing
Crushed stone, slag, or gravel spread over a built-up roof membrane.
Loose stone, river rock, or crushed slag applied as the top layer of a built-up or protected membrane roof. The rock provides ballast to hold the system down against wind uplift and protects the underlying asphalt and felts from ultraviolet degradation and physical damage.
"We need a crane to hoist the aggregate up to the plaza deck before the wind picks up."