Economia circular na produção de concretos: avaliação das emissões de Gases de Efeito Estufa (GEE) de bioconcretos com casca de arroz

Abstract

abstract: Circular Economy (CE) is progressively attracting interest from construction sector stakeholders to support the development of products with higher amounts of recovered materials in order to decrease greenhouse gas (GHG) emissions. Concrete is one of the most used materials in the world and can be produced using waste as raw materials, including, bio-based sources, from both agricultural and forest activities. This research aims to assess the GHG emissions in the life cycle of innovative rice husk bio-concretes (RBC) in which rice husk (RH) and rice husk ash (RHA) are used as circular solutions. Four RBC, considering ordinary Portland cement replacement by 8% of RHA and, different contents of sand substitution by RH (0; 5 and 10%), were assessed. The Life Cycle Assessment (LCA) methodology was used, with a cradle-to-gate scope, using the GWPbio method, that contemplate the influence of biogenic carbon on the emissions reduction. Different transportation scenarios were evaluated considering the RBC production in different Brazilian regions. The service life of RBC in terms of carbon stock was also evaluated. Two carbon-performance indicators are also evaluated in terms of RBC compressive strength and thermal conductivity values. As the main conclusion, cement replacement by RHA alongside with sand replacement by RH are promising strategies to produce bio-concretes for specific applications, such as panels, partitions and façade elements, and to reduce its GHG emissions. However, this benefit varies according to RH availability, transport efficiency and RBC service life. The RBC can be considered a potential alternative for concrete industry, for specific applications, to reduce GHG emissions and can be developed where rice waste is an available source. This study contributes by presenting a new material and a methodology for the evaluation of life cycle GHG emissions of bio-concretes, which can help to promote a circular construction sector.