This study aims to systematically investigate the combined effect of chemical activation of açaí seeds (Euterpe oleracea Mart.), with an aqueous sodium hydroxide (NaOH) solution at 2 mol·L⁻¹, and process temperature by pyrolysis of alkaline activated açaí seeds on the yield of reaction products (bio-oil, gas, H₂O, and biochar), physicochemical properties (acid value, density, and kinematic viscosity) and chemical composition (hydrocarbons and oxygenates) of bio-oil. Catalytic pyrolysis was carried out in a 143 L reactor at temperatures of 350 °C, 400 °C, and 450 °C, 1.0 atmosphere, operating in batch mode. The NaOH activation played a crucial role in modifying the thermal degradation pathway of the biomass, promoting the formation of specific chemical structures and altering the product yields. NaOH acted as a catalyst, enhancing the deoxygenation of the biomass and stimulating the formation of hydrocarbons. As a result, the yields of bio-oil, water, biochar, and gas varied from 5.77 to 7.20% (by mass), 14.90 to 19.77% (by mass), 41 to 54% (by mass), and 25.33 to 32.03%, respectively, influenced by the increase in temperature. FT-IR analyses indicated the presence of characteristic chemical functions of hydrocarbons (alkanes, alkenes, and aromatics) and oxygenated compounds (phenols, cresols, ketones, esters, carboxylic acids, aldehydes, and furans), with an intensification of hydrocarbon signals at higher temperatures. GC-MS analysis identified hydrocarbons and oxygenated compounds as the main chemical classes in the bio-oil, showing a strong dependence on pyrolysis temperature. It was observed that hydrocarbon concentration in bio-oil increased from 49.7% to 57.88% (area) with increasing temperature, while the concentration of oxygenated compounds decreased from 13.88% to 6.69% (area), demonstrating that NaOH activation, combined with temperature elevation, favors the formation of hydrocarbons and the reduction of oxygenated compounds, thereby improving the quality of the produced bio-oil.

In this study, the influence of chemical impregnation with an aqueous sodium hydroxide (NaOH) solution at 2 mol·L⁻¹, as well as process temperature, was systematically investigated at a pilot scale on the yield of pyrolysis products (bio-oil, gas, water, and biochar), as well as on the physi-cochemical properties (acid value, density, and kinematic viscosity) and chemical composition (hydrocarbons and oxygenated compounds) of the bio-oil obtained from açaí seeds (Euterpe oleracea Mart.). The pyrolysis reactions were carried out in a 143 L batch reactor at temperatures of 350 °C, 400 °C, and 450 °C under a pressure of 1.0 atmosphere. The NaOH impregnation played a crucial role in modifying the thermal degradation pathway of the biomass, promoting the formation of specific chemical structures and altering the product yields. NaOH acted as a catalyst, enhancing the deoxygenation of the biomass and stimulating the formation of hydrocarbons. As a result, the yields of bio-oil, water, biochar, and gas varied from 5.77 to 7.20% (by mass), 14.90 to 19.77% (by mass), 41 to 54% (by mass), and 25.33 to 32.03%, respectively, influenced by the increase in temperature. FT-IR analyses indicated the presence of characteristic chemical functions of hydrocarbons (alkanes, alkenes, and aromatics) and oxygenated compounds (phenols, cresols, ketones, esters, carboxylic acids, aldehydes, and furans), with an intensification of hydrocarbon signals at higher temperatures. GC-MS analysis confirmed hydrocarbons and oxygenated compounds as the main chemical classes in the bio-oil, showing a strong dependence on pyrolysis temperature. It was observed that the hydrocarbon concentration increased from 49.7% to 57.88% (area) with rising temperature, while the concentration of oxygenated compounds decreased from 13.88% to 6.69% (area), demonstrating that NaOH impregnation, combined with temperature elevation, favors the formation of hydrocarbons and the reduction of oxygenated compounds, thereby improving the quality of the produced bio-oil.

The performance of soils and granular materials must be considered in relation to the main deterioration mechanisms in pavement structure design. This study aims to evaluate the use of fine-grained soils as unbound materials in pavement applications. For this purpose, physical, chemical, and mechanical characterization tests were conducted. Repeated load triaxial tests were performed following current Brazilian standards and considering different soil saturation conditions. Five widely used mathematical models were employed to assess the resilient modulus under different moisture conditions, with the Compound and Universal models showing the best correlations. As moisture content increased, a reduction in resilient modulus was observed at higher stress levels. Regarding permanent deformation, the master curve approach was applied to obtain the parameters adopted as inputs for simulations within the mechanistic-empirical pavement design software, FlexPaveBR version 2.1.5. The model results adequately represented the plastic behavior of the analyzed conditions. The simulation results indicated differences between considering bonded and unbonded granular layers. The results also indicated that the use of fine-grained soils without stabilization can be considered for subbase layers, provided that triaxial testing is conducted and the materials demonstrate satisfactory performance under mechanistic-empirical evaluation.

RESUMO A deformação permanente nos revestimentos asfálticos constitui-se em um dos principais defeitos encontrados em pavimentos rodoviários e urbanos. Nesse contexto, estudos têm sido realizados sobre a contribuição da granulometria para minimizar esse tipo de problema. O trabalho em pauta avaliou a influência da estrutura mineral no desempenho mecânico, quanto: Índice de Densificação na Compactação, Índice de Densificação pelo Tráfego, Resistência à Tração por Compressão Diametral, Ensaio Uniaxial de Carga Repetida – Flow Number e Dano por Umidade Induzida. Pesquisaram-se duas misturas asfálticas. A primeira, composição referência, M0, habitualmente aplicada nos pavimentos manauaras e projetada segundo a metodologia Marshall. A segunda, a formulação proposta no presente estudo, M1, utilizou critérios mais atuais de dosagem, tais como: metodologia Superpave, Métodos Bailey e Faixa de Agregados Dominantes, fundamentada num forte esqueleto pétreo de graduação graúda, excluindo a areia natural presente na M0. Os resultados mostraram que a mistura asfáltica M1, relativa à composição asfáltica M0, alcançou melhor desempenho para vias com alto volume de tráfego e em condições severas, pois apresentaram deformações permanentes menores em relação a Mistura M0 comumente usadas nos pavimentos Urbanos.