Too often, designers mistakenly equate concrete durability with compressive strength. But the American Concrete Institute Committee 201, in its "Guide to Durable Concrete," defines durability of concrete as its ability to resist weathering, chemical attack, abrasion, or any other process of deterioration. Concrete isn't durable if poor quality or improper materials are used to produce it. Using too much water, not enough cement, or the wrong type of cement can cause premature deterioration. Fine and coarse aggregate generally take up 60 percent to 75 percent of the concrete volume, so using good quality aggregate helps to achieve durable concrete.
Air entrainment is necessary for durability of concrete that is exposed to cyclic freezing and deicing salts. Average air content for concrete containing three-quarter-inch-maximum-size aggregate should be 6 percent for severe exposure and 5 percent for moderate exposure. Low permeability concrete is more resistant to cyclic freezing, sulfate attack, other chemical attack, and chloride ion penetration. Sufficient cement content, low-water ratio, good aggregate gradation, and moist curing for at least 7 days makes concrete less permeable. Cracks also decrease concrete durability by allowing water, deicing salts, and other aggressive chemicals to penetrate the concrete. Keeping the water content of fresh concrete as low as possible will help control cracking.