Generally speaking, users of concrete have little need to become involved in portland cement specifications. But any concrete builder worth his salt should know something about the various types of portland cement that are available, and have some knowledge of the purposes for which each is used. Type I cement will provide excellently for most of the conditions normally met in concrete construction. Type II is also an excellent all-purpose material, but in addition provides moderate alkali resistance and less heat of hydration. Type III is used where rapid strength development is necessary, and Type IV where low heat generation is a major consideration. Type V is used whenever sulfate conditions are expected.