International Concrete Abstracts Portal

Mechanics and materials are essential elements in all of the transcendent techynologies in the twenty first century and in the New Economy. Information technology and biotechnology. Research opportunities and challenges in theoretical and applied mechanics as well as engineering materials, including cement-based materials, in the exciting information age are presented and discussed.

An intoductory construction materials course was developed for first year civil and environmental engineering students at the University of Maine. Because it is typically the first engineering course in which most civil engineering students enroll, the course also serves as an introduction to principles of engineering aalysis and desing. We have adopted a materials science approach in our coverage of construction materials. That is, we emphasize how material properties are a function of their microstructure, and that we control microstructure through processing. We have found concrete to be an ideal material with which to illustrate this concept. Students are easily able to observe the processing-microstructure-properties links through laboratory and homework exercises in concrete mix design and testing. In the broader context we have found materials in general, and concrete in particular, to be excellent model topics for intoducing the general topics of engineering analysis and design.

This paper reviews the opportunities that the Portland Cement Association has taken to address part of the education needs of the cement and concrete industries. Addressed are current educational efforts and a review of how research at universities addresses both the educational and technical needs of the industry. A. list of concrete related web sites is included. Through education the concrete industry can meet the need for informed professionals who are necessary to sustain concrete as the building material of choice for this century.

In most curricula, students have numerous opportunities to work as part of a team, but they are seldom instructed on how to function as part of a team, a valuable skill in the corporate environment. As part of a larger initiative to develop five fundamental skills, Tufts University's School of Engineering has implemented a program to introduce teamwork skills to all engineering students. This program is designed to develop good habits for functioning as part of a team. In context of the work being presented, the team working skills were introduced into a sophomore level civil entgineering materials course (including concrete, of course!). Students were given two lectures followed by laboratory exercises to emphasize the teamwork concept of defining and working towards a common goal and not being so driven by the task. The students then practiced their skills throughout the course by functioning as teams in all their laboratory exercises and report writing. Through roper functioning teams, cooperative learning is promoted, and students learn the material beeter and more efficiently. Team performances were periodically assessed. Overviews of the School of Engineering's five fundamental skills program and teamwork initiative are presented. Outcomes from the teamwork program incorporated into the civil engineering materials course were assessed at several stages uring the class and are reported.

A newly developed powerful version of microplane model, labeled model M4, is exploited to study two basic phenomena in fracturing concrete:(a) The vertex effect, I.e., the tangential stiffness for loading increments to the side of a previous radial loading path in the stress space, and (b) the effect of confinement by a steel tube or a spiral on the suppression of softening rsponse of columns. In the former problem, the microplane model is used to simulate the torsional response of concrete cylinders after uniaxial compression preloading to the peak compression load or to a post peak softening state. Comparisons with new tests carried out at Northwestern University show the microplane model to predict the initial torsional stiffness very closely, while the classical tensorial models with invariants overpredict this stiffness several times (in plasticity of metals, this phenomenon is called the vertex effect because its tensorial modeling requires the yield surface to have a vertex or corner at the current state point of the stress space). In the latter problem, microplane model simulations of the so called tube squash tests are presented and analyzed. In these tests, recently performed at Northwestern University, steel tubes of different thicknesses filled by concretre are squashed to about half of their initial length and very large strains with shear angles up to about 70 degrees are achieved. The tests and their simulations show that in order to prevent softening and thus brittle failure and size effect, the cross section of th etube must be at least 16% of the total cross section area, and the volume of the spiral must be at least 14% of the volume of the column. When these conditions are not met, which comprises the typical contemporary designs, one must expect localization of damage and size effect to take place.