Due to the requirement to protect natural resources, the demand for the use of recycled materials is increasingly common in construction practice, especially since the construction sector is a major consumer of natural resources. The use of recycled aggregates for concretes with cement binder means less consumption of natural aggregates. On the other hand, concrete with recycled aggregates has to meet the same requirements for strength, durability and other characteristics than conventional concrete, since there is otherwise the possibility of reducing the safety of concrete structures. In the course of this thesis, I identify the impact of crushed mixed construction demolition waste on concrete properties in fresh and hardened state. The waste was sieved through a sieve of 30 x 30 and thus recycled aggregate was obtained. In the laboratory, I first established properties of the recycled aggregate and designed three concrete compositions with recycled aggregates. In the first concrete I replaced 30% of the coarse aggregate fraction with coarse recycled aggregates. In the second concrete I replaced whole coarse aggregate with the recycled coarse aggregate. In the third concrete, I used only recycled aggregate. All concretes had the same amount of cement, the same proportion of superplasticizer and the same water-cement ratio. In the end I mixed the three concretes, tested the properties in the fresh state and cast the concretes into moulds. In hardened state I determined the density, compressive, flexural and splitting strengths and resistance to penetration of water under pressure. Based on the obtained results I placed concrete mixtures in the appropriate compressive strength classes and suggested possible applications of concrete mixtures with different contents of
recycled aggregate.
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