The pulp and paper industry generates a significant volume of solid waste during its operations. In order to mitigate the environmental impact caused by this industry, one of its residues was applied in eco-friendly composites. Therefore, this research aims to use green liquor dregs as a partial replacement for lime in coating mortars. Hydrated lime was replaced by dregs in percentages of 10%, 15%, 20%, and 30%, and the manufactured mortar specimens were tested in terms of their flowability, air content, and specific gravity in the fresh state. In the hardened state, physical and chemical characterization was carried out to determine the influence of the introduction of the dregs on the properties of the different types of mortar. Mechanical testing of the mortar specimens’ compressive, flexural, and adhesive strengths was carried out, and scanning electron microscopy was performed to evaluate the microstructural features of the cement composites. In general, the types of mortar with dregs showed a high degree of similarity to conventional mortar in all studied aspects, including the 30% replacement group. The obtained SEM images indicated that the presence of dregs in the mortar did not change the formational mechanism of C-S-H crystals, maintaining the mechanical properties of the material even after the accelerated aging procedure was performed, reaching similar levels of flexural, compressive, and tensile bond strengths when compared to the neat mortar. Furthermore, tensile bond levels reached approximately 0.9 MPa for all the studied types of mortar, allowing the material to be used in external applications.

Natural tannin-based foams are three-dimensional porous materials. Many different formulations have been investigated in order to reach foams with improved performance and increased commercial attractiveness. In this sense, each different tannin pH may impart different physical and thermochemical properties to the foams, which has not yet been fully elucidated. In the present study, seven rigid tannin foams (formaldehyde/sulfur-free) were produced using tannin extracts with variable pH values ( c.a. from 2.3 to 12.2). The most acidic tannin extracts (below 4.8) yielded tannin foams with the most lightweight (apparent density below 0.077 g.cm−3), homogeneous, and hydrophobic (water solubility below 23.5%) cellular-network architectures. Also, in most cases, the smaller the tannin pH, the higher the thermal stability of the foam. Further studies may address other technological requirements needed for thermal insulation applications.