Department of Mining, Industrial and ICT Engineering, Polytechnic University of Catalonia, Barcelona, Spain.
IFSTTAR, Aggregates and Materials Processing Laboratory, Nantes, France.
Waste Manag Res. 2020 Apr;38(4):392-399. doi: 10.1177/0734242X20902835. Epub 2020 Feb 12.
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, 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.
每年在世界各地都会产生大量的建筑和拆除废物。这些材料的一部分在回收工厂进行处理。在去除金属、细料和轻料之后，建筑和拆除废物被粉碎和分级，可以用作低阻力混凝土的骨料，用于道路底基层、城市垃圾填埋场和其他低附加值的应用。为了将其用作结构混凝土的粗骨料，建筑和拆除废物必须表现出高密度和材料的规则性。这种材料通常存在于拆除的混凝土中。大约 20%的拆除混凝土中的颗粒可以用作粗骨料，替代结构混凝土中部分天然骨料。本文介绍了使用气动跳汰机回收拆除混凝土的研究。所有跳汰机试验均使用三种不同强度等级的混凝土进行：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。基于三种混凝土的密度分布，有合理的质量密度超过 2.7 g/cm，被认为适合用作结构混凝土的粗骨料。这些混凝土具有不同的密集颗粒（不同的解放）的质量回收率。通过使用空气跳汰机可以回收合理质量的粗骨料：高强度混凝土约为 65%，低强度混凝土约为 75%。跳汰机浓缩效率取决于混凝土的解放、密度和粒度分布。
