Importance of Gravel and Sand for Concrete | Hunker
Apr 12, 2018· Cement consists of limestone, sand, silica sand, shale and clay. After mixing these items together, they''re heated in the oven until they break down. In this state, they''re ready to use as a binding agent. ... Use the fine aggregate for concrete slabs or other smooth surfaces. A "coarse" aggregate means using larger pieces of gravel.