Estudo das propriedades mecânicas e da durabilidade de biocompósito de adobe com inserção de micélio para aplicações sustentáveis

Abstract

The growing need to reduce the environmental impacts of construction has driven the development of sustainable materials aligned with the principles of the circular economy and the goals of the UN 2030 Agenda, especially SDG 9 (Industry, Innovation and Infrastructure), SDG 11 (Sustainable Cities and Communities) and SDG 12 (Responsible Consumption and Production). In this context, raw earth construction systems reappear as a promising alternative, as they use local resources, require low energy consumption and enable recycling at the end of their useful life. However, the limited mechanical resistance and high susceptibility to humidity still constitute important barriers to expanding its use. Faced with this problem, the research investigated the technical feasibility of incorporating microorganisms in the form of mycelium into adobe composites, configuring an innovative proposal for bioconsolidation of the material. The justification lies in the search for biotechnologies capable of improving the mechanical performance and durability of raw earth without compromising its environmental attributes, contributing to the transition to regenerative materials. Initially, the soil was characterized in terms of grain size, plasticity and mineralogy, obtaining an average composition of 62% sand, 13% silt and 25% clay. The limits of liquidity (29.45%), plasticity (20.92%) and contraction (17.32%) classified the soil as having low plasticity, suitable for molding adobes. Mineralogy revealed a predominance of kaolinite (71.4%), accompanied by gypsum, quartz, goethite and hematite. In the experimental phase, composites were produced subjected to four treatments, each with five replications: TC (control), TCB (potato broth), TM2 (2% mycelium) and TM5 (5% mycelium). In all modified treatments, 2% CH-I hydrated lime was added. The specimens maintained average dimensions close to 76.11 mm, with linear shrinkage varying between 4.21% (TM2) and 7.76% (TM5). Compressive strength presented average values of 0.97 MPa (TC), 0.29 MPa (TCB), 0.43 MPa (TM2) and 1.23 MPa for (TM5), the latter exceeding the value of the control treatment by 27%. The durability results were also more favorable to TM5, whose absorption by capillarity (180 min) was 7.58% and by immersion (24h) was 8.84%, in addition to the lower mass loss (3.80%). In general, it was found that the soil is technically suitable for the production of adobes and that the treatments did not compromise dimensional stability. The results highlight the potential of using mycelium as a modifying agent, especially in the composite with 5% incorporation, which presented the highest compressive strength value (1.23 MPa) and best overall performance, therefore being indicated for non-structural use. Thus, the research contributes to the advancement of knowledge about earth-based biocomposites, reinforcing the possibility of developing more sustainable construction materials, aligned with the circular economy and contemporary environmental objectives.