Subsídios para a minimização do impacto ambiental de estruturas em concreto armado

Abstract

Studying the environmental impacts of the various economic activities has become increasingly relevant; in this context, it can be highlighted as a condition of carbon dioxide (CO2) released into the atmosphere and which contributes to the greenhouse effect. Namely, among the main economic activities with the greatest environmental impact is the civil construction industry and its production chain - with the processes of extraction, production and transportation of materials - having the concrete among the most used building materials in the world with a considerable and important contribution to these emissions. For this purpose, new studies have been carried out in order to reduce the emission of this gas, focusing on the analysis and evaluations of the production of the binders and their additions, as well as on the dimensioning with definitions of the most viable concrete characteristics. Therefore, this study aimed to search for subsidies that can be considered to obtain and minimize this environmental impact and, in parallel, the economic impact. In this way, four study scenarios were proposed, considering the phase from the cradle-to-gate, three of CO2 emissions and one of costs, taking into account concrete with different characteristic resistances, steel and wooden shapes. In the first scenario, CO2 emissions were quantified from the survey of the contribution of each raw material used in the study region, from its extraction to its use in the construction. For the second and third scenarios, the quantifications of raw material contributions in terms of CO2 emissions were generated from the 2018 Ecoinvent 3.5 database and the SimaPro software, version 9.0.0.48, differentiating a scenario from another through adjustments made to the global software database with regional data. In this sense, considerable differences in the values of CO2 emissions were verified, always having the binder with great influence and contribution. The fourth scenario focused on obtaining average material costs in the region. Therefore, evaluations based on the values obtained in the study scenarios were carried out, dimensioning wood beams in an optimized way with different spans, obtaining the best environmental results in the concretes of less resistance, and economic ones linked to the dimensions of the spans of the beams. When the wooden pillars were dimensioned in an optimized way, with different acting efforts, the best results in all scenarios were obtained for the higher characteristic resistances. A building was also evaluated, being considered more environmentally viable for all scenarios of study, the dimensioned structure with the smaller characteristic resistances. In addition, differentiated contributions to CO2 emissions from materials and similar structural elements were verified, when comparing these same scenarios. In relation to the economic scenario, the bigger resistance was more viable.