To produce high quality long lasting concrete structures, cements of a high and consistent quality must be employed. Worldwide, the cement industry spends countless hours assuring the quality of its products, mainly based on laboratory tests. In the USA, most physical testing of cements is performed according to ASTM standards [1]; in Germany, testing is generally governed by the European Norm [2]. Technologies that could reduce the number of physical tests needed for cement production (and optimization) would clearly be a welcome addition. One such potential technology is the use of virtual testing. In virtual testing, starting materials are characterized and their performance predicted via the use of computer models. This should result in savings in both resources (materials, labor, etc.) and time, as 28 d performance can be simulated in just a few hours of computer time. An additional benefit of virtual testing is the capability to perform a large number of "what-if" type computations to explore new material systems and optimize existing ones, e.g., what is the optimum sulfate content and form for a particular cement or how will the performance of a cement change if its Blaine fineness is increased by 10 m2/kg?
To address this goal of reducing the necessary physical testing of cement and concrete, in January 2001, the Virtual Cement and Concrete Testing Laboratory (VCCTL) consortium was formed. The consortium is a U.S. government/industry collaboration headquartered in the Building and Fire Research Laboratory at the National Institute of Standards and Technology (NIST). At NIST, the Information Technology Laboratory and the Materials Science and Engineering Laboratory also participate in the consortium's research projects. Current industrial members of the consortium include: Cemex, Dyckerhoff Zement GmbH, Holcim Inc., Master Builders Technologies, the Portland Cement Association, Verein Deutscher Zementwerke E.V. (the German Cement Association), and W.R. Grace & Co. - Conn. Version 1.0 of the VCCTL software is available to the general public at http://vcctl.cbt.nist.gov. A user's manual [3] is available online as menu selection 0 from the main VCCTL menu. In this paper, the VCCTL will be applied to predicting a variety of physical properties of cement pastes to illustrate its potential usefulness to the cement industry.