Concrete is the most widely used man-made product; in the United States we use about two tons per year per person. It has been estimated that the replacement value of concrete structures is over six trillion dollars, and that over one trillion dollars needs to be spent in the repair and rehabilitation of these structures over a 20-year period. By contrast, the resources devoted to the materials issues of the industry have been meager. This neglect may in part explain why the development of the science of cementitious materials had lagged behind that of other materials. The situation has been changing rapidly in recent years, however, and the articles in this issue have been selected to illustrate some of the advances that are being made.

One key to the resurgence in research in cement-based materials is the realization of the pressing need to upgrade our deteriorating infrastructure. Another is the realization that a materials science and engineering approach is needed to provide a solid knowledge base to underpin new technologies. Chemistry took us a long way in the 1950s and 1960s, but an appreciation of how chemistry and processing could combine to create desirable micro-structures that would achieve desirable bulk properties came much later. It is significant that, with the noticeable exception of the Pennsylvania State University, cement research in universities in the United States previously was funded through civil engineering departments. Similarly, in Europe and Japan, research was conducted primarily in engineering faculties, although there were programs in a few chemistry departments. Now, however, on both sides of the Atlantic Ocean, research groups are well established in materials science departments. It is noteworthy that on an NSF Science and Technology Center devoted to advanced cement-based materials is funded through the Division of Materials Research.