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.
Also heard as
- agg
- rock
- stone
- sand and gravel
Related terms
Mix design
The recipe for a concrete mix: the weights of cement, SCMs, water, aggregates and admixtures per cubic yard.
Pea gravel mix
Concrete made with 3/8 in pea gravel instead of standard coarse stone, so it moves through small pump hoses.
ASR
Alkali-silica reaction, a slow internal reaction between cement alkalis and certain aggregates that cracks concrete.
Popout
A small conical crater where a swelling stone just under the surface pushed out a chip of concrete.
Segregation
Separation of coarse aggregate from the mortar in fresh concrete, leaving rock-heavy and paste-heavy zones.