Q.: Specifications for entrained-air content always include a minimum and maximum limit. I know that too little air reduces concrete's resistance to damage caused by freeze-thaw cycles and deicers. But if the air content exceeds the maximum by a percent or two, how does that affect the concrete?

A.: Strength loss is the major effect of too much air. Each percent increase in air content can reduce compressive strength by 2% to 6% for moderate-strength concrete. The degree of strength loss depends on the cement, admixtures, and other concrete ingredients used.