Concrete post
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The reinforced concrete is not a real building material but a technique for creating post, designed to optimize the compression efforts, to the benefit of the work of the concrete. The prestress is provided to the post when it is realized. The concrete is made up of two components: the stone (aggregate) and the glue which covers, winds and connects the single stone elements. The stone component, commonly called inert, is constituted by at least two ingredients: the sand (fine stone aggregate) and gravel or crushed stone (aggregate coarse stone). The glue component is constituted by two ingredients: water and binder, the latter can be of different origin, the most important component is the Portland concrete. The concrete is resistant only to mechanical stress compression, but when the concrete metal reinforcements are drowned (reinforcement) inside, the reinforced concrete is able to bear also bending and traction stresses, typical of the reinforcement steel. However very little stresses only, because when they become greater it begins to crack and expose the reinforcement to the environmental degradation. Hence, the need of the evolution to the prestressed reinforced concrete, which differs from the presence of high-quality metal reinforcements, usually steel strands, stretched before the concrete casting, then loosed when the concrete is properly hardened. This operation leads to greater benefits in terms of dimensional stability (especially to the bending). The reinforcement strands are indeed hampered by the hardened concrete adherence in summarizing the original length and remain in tension, while the concrete remains in a state of compression. This compulsion state (of traction in the iron and compression in the concrete) can bear high bending loads before they reach the concrete cracking.
PRESTRESSED CONCRETE WITH ROUNDED CORNERS
IN VIBRATED CONCRETE
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