Cement Stabilized Gravel Stratum

Frozen Gravel Stratum

Gravel Stratum

Gravel-cobble

Sand and gravel stratum

sand gravel stratum

saturation round gravel stratum

Water-soaked sand and cobble stratum

additional gravel

after pump gravel injection system

alluvial gravel bed

antiscour gravel

artificial gravel

as dug gravel

asphalt gravel mixture

asphalt stabilized gravel base

assorted sand and gravel

band-run gravel

bank gravel