Air-entrained concrete MUST be used for all of the following EXCEPT?

Air-entrained concrete is specifically designed to enhance durability and protect against freeze-thaw cycling when exposed to moisture. This property is particularly essential in environments where concrete will face harsh weather conditions, such as freezing temperatures where moisture can expand within the concrete and lead to damage.

In the context of the options provided, air-entrained concrete is necessary for structures subject to frequent moisture exposure and freezing conditions. Garage floor slabs, porches exposed to weather, and basement walls that are exposed to weather all fall into categories where air-entrained concrete is beneficial to maintain integrity and longevity.

However, interior slabs on grade are typically not subject to the same level of environmental stress as exterior components. Since these slabs are installed indoors and not exposed to the freeze-thaw cycles or harsh weather elements, they can be formed using standard concrete without the need for air-entrainment. This makes air-entrained concrete unnecessary in such applications, as it does not provide any additional benefit over regular concrete in these specific conditions.