Precast concrete sandwich panels offer numerous benefits, including insulation, durability, and fire resistance. Because they can be made using a high percentage of recycled materials and erected quickly with minimal site disturbance, they can also be major contributors toward construction of cost-efficient, sustainable structures. The result of Fabcon’s latest efforts is VersaCore+Green™, a sandwich panel introduced in March, 2007. The new panels have over 50% recycled content by volume and deliver the highest insulation values in the company’s 37 year history.

Moment-curvature plots and moment-axial force interaction diagrams are essential tools for understanding the load-deformation behavior of structural elements. To make the use of these tools simpler, a user-friendly spreadsheet-based program was created that can generate moment-curvature plots and moment-axial force interaction diagrams for reinforced concrete sections. These plots can include the effects of confinement provided by transverse reinforcement on the stress-strain relationship of concrete. The spreadsheet contains a series of macros written in Visual Basic for Applications (VBA) and can be downloaded for free with the electronic version of this article.

As with all materials, the performance of concrete is strongly influenced by its physical structure. From its earliest origins, however, the performance of cement-based materials has also been controlled by the judicious addition of supplemental chemicals. From the examples discussed in this article, it’s clear that the engineering of concrete performance has historically used both physical and chemical approaches. Future engineering efforts will almost certainly maintain this tradition.