Multi-level assessment of TiO2/graphene-modified molybdenum slag/bauxite-based alkali-activated composites mechanical, microstructural, and self-cleaning performances

• Published in: Construction & building materials Vol. 417; p. 135256
• Main Authors: Rashidi, Soroush, Afzali, Seyed Ali Eftekhar, Mirhosseini, Ramin Tabatabaei, Foroughi, Mohammad Mehdi, Dai, Xiaodi
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 23.02.2024
• Subjects: Bauxite; BET test; Contact angle; Molybdenum slag; SHAP analysis; Titanium-graphene; Bauxite; Molybdenum slag; BET test; Contact angle; Titanium-graphene; SHAP analysis
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2024.135256

The objectives of this study were to understand the mechanical, microstructure, and self-cleaning performance of alkali-activated composites (AACs) based on molybdenum (Mo)-slag/bauxite (Ba)-powder containing 1.5% and 3% TiO2 and TiO2 coated with graphene oxide (GO) nanoparticles. Mechanical properties were assessed through compressive and flexural strength tests. The MIP to check porosity, XRD, FTIR, TGA/DTG to detect new and remnant phases, FESEM/EDS to check morphology and composition of the matrix and the self-cleaning performance was evaluated using methylene blue (MB) dye degradation and surface wettability assessments. Results showed that AACs with 15% bauxite performed best mechanically, while 35% bauxite composites were weaker. Nano-TiO2 marginally improved 7-day strength, whereas nano-TiO2-GO significantly increased strength at both 7 and 28 days. FESEM images revealed a distinctive wrinkled morphology in TiO2-GO composites, illustrating interlocking interactions between nano-TiO2-GO and the gel binding matrix. In the BET test results, the specific surface area of synthesized TiO2-GO was about 25% higher than TiO2. Also, MIP results demonstrated a significant refinement in AACs containing TiO2-GO, indicating increased polymerization products. According to TGA/DTG results, the highest weight loss in the first interval between 25–200 °C is related to the mixture containing 15% Ba-powder and 3% TiO2-GO. Additionally, the composition comprising 35% Ba and 3% TiO2-GO exhibited the highest level of MB dye degradation, reduced water contact angle following UV exposure, and superior self-cleaning performance. Finally, based on SHapley Additive exPlanation (SHAP) and P-value analyses, the specimen age, the nano-TiO2-GO dosage, and the Ba replacement ratio were recognized as the most crucial parameters affecting the mechanical performance of the synthesized AACs, respectively. [Display omitted] •Introducing the synthesis method of nano-TiO2 and modified TiO2 with GO nano-sheets (nano-TiO2-GO).•Investigation of the possibility of using Molybdenum (Mo) slag industrial waste as an alkali-activated precursor.•Determining the effect of nano-TiO2 coated with GO nano-sheets on the characteristics of nano-TiO2 and alkali-activated-nanocomposites.•Determine the most important factors affecting the mechanical properties of alkali-activated composites and conduct a parametric study according to the results of compressive and flexural strengths to determine the importance of the determined factors.