Large quantities of construction and demolition waste is generated annually around the world. Part of this material is processed in recycling plants. After removing metals, fines and lights, the construction and demolition waste is crushed and sized and can be used as aggregates for low resistance concrete, for road sub-base, city landfill and other low value-added applications. For their use as coarse aggregate in structural concretes, construction and demolition waste must exhibit high densities and regularity of the material. This material usually is presented in demolished concretes. About 20% of the particles from demolished concretes can be used as coarse aggregates substituting part of natural aggregates in structural concretes. This article presents studies of demolished concretes recycling by the use of a pneumatic jig. All jigging tests were carried out with three different concretes produced in three strength classes: C16/20, ordinary concrete; C50/60, high strength concrete; and C70/85, very high strength concrete. Based on density distribution of the three concretes, there are reasonable masses with densities over 2.7 g cm-3, particle density considered appropriate to the used as coarse aggregate for structural concretes. The concretes present different mass recoveries of the denser particles (different liberation). Coarse aggregates can be recovered with reasonable masses by the use of air jigs: About 65% for high strength concretes and about 75% for the low strength concrete. The jigging concentration efficiency depends on the concrete liberation, density and size distribution.

中文翻译：

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通过使用气动夹具拆卸的混凝土回收利用。

全世界每年产生大量的建筑和拆除废物。这种材料的一部分在回收工厂中加工。去除金属，细料和灯饰后，对建筑和拆除废料进行粉碎和筛分，可用作低电阻混凝土，路基，城市垃圾填埋场和其他低附加值应用的集料。为了用作结构混凝土中的粗骨料，建筑和拆除废物必须表现出高密度和规则性。该材料通常以已拆除的混凝土呈现。拆除的混凝土中约有20％的颗粒可用作粗骨料，代替结构混凝土中的部分天然骨料。本文介绍了使用气动夹具对拆除的混凝土进行回收利用的研究。所有的夹具测试均使用三种强度等级的三种不同混凝土进行：C16 / 20，普通混凝土；C50 / 60，高强度混凝土；和C70 / 85，超高强度混凝土。根据这三种混凝土的密度分布，存在合理的质量，其密度超过2.7 g cm-3，颗粒密度被认为适合用作结构混凝土的粗骨料。混凝土呈现出不同质量的致密颗粒回收率（不同的游离度）。通过使用空气夹具，可以以合理的质量回收粗骨料：高强度混凝土约占65％，低强度混凝土约占75％。夹具的集中效率取决于混凝土的自由度，密度和尺寸分布。