The efficacy of limestone-blended cements was a popular topic at the recent Transportation Research Board (TRB) meeting in Washington, D.C. Paul Tennis, manager of cement and concrete technology, presented the paper, “Environmental Benefits and Performance Equivalence of Portland-Limestone Blended Cements,” which he co-authored with John Melander, Portland Cement Association's director of product standards and technology.
The paper notes limestone-blended cements are similar to portland cements in regard to properties such as strength development and setting time. However, because they contain a proportion of uncalcined limestone as an ingredient, blended cements have a lower environmental impact. It cited recent case histories from Canada and the U.S. (up to 10% limestone) as well as decades of use in European and other countries where cements with up to 15% limestone can be effectively used in concretes with or without SCMs and used as an ingredient in ternary blended cements.
Based on its popularity during the technical sessions, the TRB is planning to host a two-hour webinar on portland-limestone blended cements this summer. For the first time, TRB’s annual meeting reached the 12,000-attendee mark. Participants included policy makers, administrators, practitioners, researchers, and representatives of government, industry, and academic institutions.