In spite of our rapid technological growth, there has been no major change in the basic materials of construction for many years. These materials- wood, concrete, and steel- have been improved and new and better methods of using them have been developed, but basically the materials are the same. This being the case, the introduction of a new material which has the potential of making beneficial changes in many long-term practices and techniques of the construction industry creates a certain amount of interest. Such a material is Wirand concrete. Wirand concrete is a different material although it is still composed of sand, aggregate, cement, steel and water. In the first place, it has flexural strength and can be designed so that it will not crack. It has impact strength and resistance to fatigue along with abrasion resistance. It presents a novel design approach for concrete in that it can be designed as a homogenous material, much as is steel itself. It follows that in many cases conventional reinforcement will no longer be needed and wall thicknesses and, correspondingly, weight, can be reduced. Wirand concrete consists of a mortar or concrete mix to which fine ferrous fibers in amounts up to 2 volume percent have been added. They are about the diameter of a common pin and are on the order of an inch long. These fibers serve as crack arrestors and as such prevent microcracks which may occur in the concrete matrix from propagating. Consequently, the material assumes properties quite different from those of brittle concrete. Wirand concrete is not reinforced concrete; the steel additions in reinforced concrete and those in Wirand concrete perform entirely different functions. Conventional reinforcing steel is intended to act as a substitute for the low and undependable tensile strength of concrete. Conventionally reinforced concrete is expected to crack in tension and the steel is expected to support the tensile load to which the reinforced concrete member will be subjected. On the other hand, the steel fiber in Wirand concrete is not intended to support the tensile load; consequently its strength is relatively unimportant to the design.
Wirand Concrete -- a New Structural Material
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