Inventário do ciclo de vida aplicado à produção de agregados a partir de resíduos de construção e demolição

Abstract

The high generation rates and the irregular disposal of construction and demolition waste (CDW) are among the biggest environmental problems caused by the construction industry. However, this waste has the potential for reuse and recyclability with possibilities to mitigate the impacts caused. Thus, the objective of the present study was to identify environmental aspects that can be improved within the production process of the recycled aggregate from CDW. The method used was life cycle assessment (LCA), with the stages of objective, scope, and life cycle inventory (LCI) being developed to study energy consumption, CO2 emissions and waste production in the recycled CDW aggregates manufacturing process. The system limit applied was from the “gate to gate” of a CDW beneficiation unit in the region of Cascavel, Paraná and the functional unit adopted was 1 m³ of dry recycled aggregate. The survey of primary data was carried out with a questionnaire developed, pretexted and, later, passed on to the company which provided self-declared information regarding 12 months of factory production. At the same time, a technical visit was carried out to collect information “on site”. The products from the studied CDW recycling process were recycled sand, recycled gravel, recycled gravel nº 1, recycled spout and recycled crack. As a result, to produce 1 m³ of recycled aggregate, the input of raw material (CDW) varied from 1.01 m³ to 1.67 m³. As an output, there is a variation of incorporated energy from 2.22 MJ/m³ to 4.35 MJ/m³, of incorporated water from 15.38 L/m³ to 30.30 L/m³ and for CO2 emissions the variation was from 5.07 to 6.20 KgCO2/m³. A study was also made of the CO2 emissions associated with the transport of the CDW and the CDW RA in which transport has been optimized with emission from 0.27 to 7.68 KgCO2/m3 and non-optimized transport with a variation of 0.53 to 15.35 KgCO2/m3. The study developed is of relevance in the context of the circular economy, corroborating the closure of the life cycle of materials used in the civil construction sector by identifying the impacts resulting from the CDW recycling process for the production of recycled aggregates and their application in civil construction.