Engineering students from Iowa have invented a new mix design for concrete that is not only virtually impermeable for water, but can withstand a load bearing ratio of 5 times a normal concrete mix design. Science Daily.com’s article titled “Better Bridges,” explains that the ingredients for this concrete are not a new invention, but it is the new physics applied that they say are making the difference. The article says that the new mix design includes a finer gradation of sand, steel fibers, water, and cement. Normal concrete includes some sand and mostly a larger gradation of soils that give it cohesive strength. But these students say that leads to high stress points around the larger rock in the concrete, leading to crack that make the concrete fail quickly. Using a smaller soil and steel fibers creates a denser material that now won’t allow water into it to degrade the finished product over time, but also makes it stronger. The article describes the student team loading a 71 foot concrete beam with a 3 point bending test in which it took almost 600,000 pounds of pressure force until it failed. This is the equivalent of 7 semi trucks. I am amazed by this article. The environment will be helped because less concrete will have to be used since the bridge decks will take much longer to fail. The author kept my attention, but is obviously writing to an audience that is versed in engineering. Without basic engineering knowledge the audience would understand some of the information, but not all of the information presented. There are enough specific details that can also be checked to make sure the article is accurate and precise on what is presented.

http://www.sciencedaily.com/videos/2006/0108-better_bridges.htm