Life cycle management: Foundations for the application of circular economy in concrete industries of civil construction

The current economic model, inevitably, contains stages of natural resources' extraction, intermediate processing of this raw material, subsequent transformation into materials with different application, according to the society's real or magnified needs, and generation of residues. The growing demand for industrialized products causes, proportionally, an increase in the extraction of natural resources. Economic, social, and environmental factors point to the unsustainability of this linear economic model. The solutions presented are diverse, among them is the circular economy model. The concept of circular economy, although it is object of countless controversies, proposes the reuse of waste, within a productive chain, reducing losses, generating economic, social, and environmental gains. In the present research, a systematic analysis was carried out in the scientific literature, accompanied by visits to three crushed stone mining industries, located in the Monsenhor Gil, Piauí, Brazil, to assess the contribution of mining, in general and, particularly, the crushed stone mining, with the 17 Sustainable Development Goals (SDG) and to analyze the existing environmental legislation for the sector, within the Brazilian Mining Law precepts. The visits aimed to follow the process of extraction, processing, and commercialization of the diabase mineral, from which the crushed stone used in the surveyed industries is produced. In addition, it was used the Life Cycle Assessment to evaluate, environmentally, construction products that use crushed stone as an input: concrete and poles. Based on the NBR ISO 14040 and 14044 standards, and on the EN 15978 e EN 15804 European standards the life cycle of this aggregate was evaluated within the productive chain of civil construction. Two kinds of industries were visited, within this sector, in Teresina, state of Piauí, Brazil: three concrete industries and four pole factories. The purpose of the visits was to monitor the production process of these materials, as well as to collect data through interviews with the managers. Questionnaires were prepared covering all the information necessary for the construction of the Life Cycle Inventory (LCI), which aims to identify all the inputs and outputs of an enterprise. The universe of primary data includes water and energy consumption; description and quantity of machinery and equipment; description of production processes; quantity and type of produced waste; transport and distance traveled from the inputs to the factory and the product to the final consumer, among others. Secondary data were obtained from the scientific literature and specialized reports. Two methods of Life Cycle Impact Assessment (LCIA) were adopted: ReCiPe Midpoint (H) and CML (baseline), which were used together, or separately, according to the objective and scope of each analyzed products. The impact categories selection, for analysis, was also made according to the object under study and with the peculiar characteristics of each production process. In addition, sensitivity analyzes were conducted for both products (concrete and post), with the elaboration of different scenarios, with the alteration of parameters such as the reuse of waste and effluents, simulation of different distances traveled by the transport of inputs, replacement of active silica by sugarcane bagasse ash and reduction of the cement content in the concrete mixture, verifying the reduction of potential environmental impacts for both, concrete and poles, and the possibility of applying industrial symbiosis, for reuse of residues, based on Life Cycle Management (GCV). Thus, the study contributes to the mitigation of impacts generated by these industries once it was possible to establish soma guidelines for the change from the linear economy to an economy closer to the circular, in the civil construction sector that consumes crushed stone.