The effect of demolition concrete waste on the physical, mechanical, and durability characteristics of concrete

With the development of urbanization, more and more construction and demolition waste (CDW) is generated. To enhance the mechanical properties and durability of concrete through the incorporation of recycled aggregate, the water/cement ratio was controlled to optimize the properties of concrete. In this work, one reference concrete with a water/cement ratio of 0.5 was prepared. The demolition concrete waste from East China was used, and 50% and 100% of the natural aggregates of the reference concrete were substituted. Furthermore, the water/cement ratio of concrete with 50% and 100% CDW was reduced to 0.3, and the superplasticizer was used to justify the workability of fresh concrete. Finally, the workability of fresh concrete was determined. After curing for 28 days, the density, water absorption, and resistance to chloride penetration of concrete were realized. The compressive and flexural strength were examined at 14 and 28 days, and the electrical resistivity test was conducted at 7, 14, and 28 days. The results indicate that with increasing CDW content, the mechanical properties and durability of concrete decreased. However, when the water/cement ratio decreased to 0.3, the concrete properties were optimized, such as the compressive strength and resistance to chloride penetration of concrete with 50% CDW increased by 74.2% and 28%, respectively. This work was partly financed by FCT/MCTES through national funds (PIDDAC) under the R and D Centre for Territory, Environment, and Construction (CTAC), under references UIDB/04047/2020 and UIBD/152844/2022.