Concrete Ingredients

Concrete results from a careful mixture of portland cement paste and aggregates such as sand, gravel, crushed stone, and other materials. A chemical reaction called hydration causes the mixture to harden into the rock-like mass we know as concrete. When it is first mixed, concrete is soft and malleable, but when it hardens it is strong and incredibly durable. A concrete mixture is usually about two-thirds aggregate and cement and the rest is water and air. The characteristics of the concrete are determined by the quality of the cement paste. Creating good quality concrete means lowering the water-cement ratio as much as possible and still having a manageable mixture.