Abstract The study on the physical-mechanical properties of alkali-activated materials (AAM) produced by the ‘one-part’ method was carried out. For this, residues such as fly ash and rice husk ash (RHA) were used. The alkaline activator (NaOH) was calcined together with RHA for 2 h at 750 °C. Dry mixes were prepared by replacing fly ash with 10%, 20%, and 30% by weight of the calcined material. The samples produced were characterized after 7 and 28 days of curing. The results showed that the investigated variables (calcined material content and curing time at room temperature) were responsible for important variations: compressive strength from 2.40 to 24.92 MPa, modulus of elasticity from 0.90 to 12.32 GPa, water absorption from 2.92% to 13.64%, apparent porosity from 4.82% to 20.02%, and density from 1.48 to 1.71 g/cm3. It was concluded that these variations were due to the high concentration of Na2O and SiO2 in the dry mixtures.

Resumo Atualmente existe um interesse crescente no uso de resíduo industrial como matéria-prima na obtenção e desenvolvimento de novos produtos, a fim de atender as demandas tecnológicas e ambientais. As cinzas volantes, por exemplo, quando em contato com um meio alcalino formam polímeros inorgânicos ou geopolímeros, que possuem propriedades comparáveis com às do cimento Portland comum, mas são capazes de reduzir até 95% de emissão de CO2 na atmosfera. Neste trabalho, a resistência à corrosão de um geopolímero produzidos pela ativação alcalina de cinza volante tipo F foi avaliada em soluções de 3%, 6% e 9% de ácidos clorídrico e sulfúrico por até 28 dias. Os materiais apresentaram perda média total em termos de resistência à compressão de aproximadamente 29,8% e 39,5% após 28 dias de imersão em HCl e H2SO4, respectivamente. A imersão em HCl apresentou resultados divergentes devido à formação de cristais de NaCl em torno da microestrutura do material.

Abstract Currently, there is a growing interest in the use of industrial waste as a raw material in obtaining and developing new products in order to meet technological and environmental demands. Fly ash, for example, when in contact with an alkaline medium, forms inorganic polymers or geopolymers, which have properties comparable to ordinary Portland cement (OPC), but are capable of reducing up to 95% of CO2 emission into the atmosphere. In this study, the corrosion resistance of a geopolymer produced by the alkaline activation of fly ash type F was evaluated in 3%, 6%, and 9% hydrochloric and sulfuric acid solutions for up to 28 days. The materials showed an average loss in terms of compressive strength of approximately 29,8% and 39,5% after 28 days of immersion in HCl and H2SO4, respectively. The immersion in HCl showed divergent results due to the formation of NaCl crystals around the microstructure of the material.