Concretes prepared with recycled aggregate and metakaolin: aspects of mechanical resistance and electrical resistivity

Concretos preparados com agregado reciclado e matacualim: aspectos da resistência mecânica e resistividade elétrica

Resumo

Waste recycling is shown as an efficient alternative to minimize the impacts caused, such as the recovery of construction and demolition waste (CDW), but the properties should be studied and analyzed for their better use in concretes. In addition to environmental concern in the aggregate of concrete, another factor is the emission of CO2. Several studies are being done to replace part of the cement mass with other concrete components. Among these additions, it is possible to emphasize as the most used, in Brazil, the metakaolin. Studies show that concretes prepared with CDW generally tend to have a higher permeability, lower mechanical strength and difficulty in workability, and metakaolin as an additive that enhances the cementitious composite, compensating for the possible technical disadvantages of CDW as an aggregate. This work has as objective the macrostructural and microstructural analysis of concretes prepared with metakaolin and recycled aggregate CDW. A reference concrete, class 30, with consumption of 442 kg / m³, and families using CDW source aggregate with 25% and 50% substitution percentage and metakaolin in place of cement in 5 and 10% was prepared. The results show optimized behavior of the concretes prepared with metakaolin and CDW aggregate.