Concrete mixtures contain a careful proportioning of materials that include rock aggregates of stone and sand with a cement paste or a cement substitute as a crucial bonding component. Without proper proportioning, the mixture is at risk of containing too little or too much cement paste, which can lead to a poor final product. Concrete without a sufficient amount of paste is difficult to place and can become porous once hardened, while an excess of paste can lead to an increased risk of cracking.
Once the concrete mixture is appropriately measured, concrete developers add water and chemical admixtures to transform it into a malleable solution that becomes strong and durable once hardened. A chemical reaction between water and the cement paste triggers the transformation, as the introduction of water to cement causes it to crystalize and subsequently form concrete. Although significantly malleable when wet, concrete becomes rigid once dried. This durability makes it an ideal material for the construction of structured parking, bridges, skyscrapers, and dams.