Fibrocimento com modificação celulósica por baba de cupim sintética e aplicação de revestimento de etileno acetato de vinila

Abstract

The treatment of lignocellulosic fibers has been widely investigated as a strategy to improve durability and fiber–matrix interaction in cementitious composites. In this context, this study aimed to evaluate the effects of treating commercial eucalyptus fibers with synthetic termite saliva (STS), associated with an ethylene-vinyl acetate (EVA) coating, on the physical, mechanical, thermal, thermogravimetric (TG/DTG), and microstructural performance of extruded fiber-cement composites before and after accelerated aging. Reference composites (CR), EVA-coated composites (CRE), composites containing STS-treated fibers (CB), and composites containing STS-treated fibers associated with EVA coating (CBE) were produced. The comparison of the results obtained before and after accelerated aging revealed a reduction in water absorption and apparent porosity, as well as an increase in apparent density in all experimental groups, indicating greater densification of the cementitious matrix and reduced water accessibility within the composites. The CB group stood out, exhibiting an approximately 60.5% reduction in water absorption, a 23.1% increase in apparent density, a 4.3% increase in modulus of rupture, and a 7.0% reduction in thermal conductivity. The CBE group showed an approximately 52.6% increase in toughness, indicating greater energy dissipation capacity after aging. The CR and CRE groups also exhibited stability in their physical and mechanical properties after accelerated aging. TG/DTG analyses did not reveal significant changes in thermal stability or in the main degradation events of the composites, while microstructural analyses suggested greater continuity of the cementitious matrix and changes in the fiber–matrix interface after aging. All experimental groups met the requirements of ABNT NBR 15498 (2012), presenting water absorption values below 35% and modulus of rupture values above 4 MPa. It was concluded that the proposed treatments, especially in the CB and CBE groups, are promising for the development of more durable cementitious materials with improved thermal performance, demonstrating potential for applications in construction systems requiring enhanced thermal comfort and energy efficiency.