Concrete resists weathering, chemical attack, and other types of deterioration. The quality of concrete determines how long it lasts. Good concrete has properties that match its application and expected exposure conditions. Identify the likely causes of concrete deterioration: abrasion, chemical attack, corrosion of reinforcement, freezing and thawing, reactive aggregates, or scaling before you begin a project. Materials and quantity, admixtures, compressive strength, air-void system, and other factors will be determined from this information. Materials and mixes to be used, and precautions to be taken during construction, are recommended based on best practices and recognized consensus code requirements. All of these mix recommendations share the concept that durability is improved when the mix proportions are selected to produce concrete that is more dense or less permeable to water and harmful chemicals than conventional mixes. The chemical intrusion of soil, water, and air is ...