Concrete is a mixture of cement, water and aggregates, such as sand, coarse gravel or crushed rock. After it hardens, concrete is resilient, durable, resistant to environmental extremes and capable of supporting heavy loads. Grout is similar to concrete in its ingredients, but with a fine aggregate grade and a higher water content that allows it to flow easily and be used as a filler or joint sealer.
Grout is often used to fill the spaces between tiles after the adhesive mortar below them has dried. It is also used to attach and connect pre-cast sections of concrete.
Cement is the ingredient in concrete and grout that binds both the aggregates and the connecting surfaces together. Limestone and clay are the typical natural sources of the calcium oxide and silicon dioxide used in the making of modern-day cement.