Source: CONCRETE PRODUCER MAGAZINE
Publication date: November 1, 2006
By Victor C. Li
Over the last few decades, material scientists have improved concrete mix designs using technology that has increased strength, durability, placing, and improved environmental aspects. Perhaps the brittle nature of concrete is the last technological barrier to attack.
Ever since concrete was made by the Romans 2000 years ago, it has been known for this brittleness. Concrete's brittleness has at times been responsible for catastrophic failures of structures, but more often results in a gradual deterioration that requires repeated and costly repairs. Many attempts have been made to modify concrete so it can take tensile load. Today, the most effective modification has been the introduction of fibers, typically made of steel, glass, or polymer, resulting in fiber-reinforced concrete.
It has been a dream of concrete engineers to produce a concrete that retains the beneficial properties of conventional concrete, such as high compressive strength and non-rusting. Yet at the same time, the final product should possess the tensile ductility of steel so yielding, instead of fracturing, occurs when the concrete is overloaded.
It's true that this design feature can be achieved with fiber reinforcement. However, the past strategy has been to use a lot of fibers (more than 5% in volume), often in aligned or fabric form.
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