Journal of the Faculty of Engineering and Architecture of Gazi University 34:3 (2019) 1253-1263 Synthesis of aerogel usage of sand by ultrasonically assisted sol-gel method, characterization and thermal insulation plaster application Nevin Karamahmut Mermer , Sabriye Pişkin * Department of Chemical Engineering, Yildiz Technical University, Istanbul, 34220, Turkey Highlights: Graphical/Tabular Abstract  Synthesis of silica-based aerogel from sand  Ultrasonic assisted sol- gel method  Thermal insulation plaster application Figure A. XRD pattern of the solid phase after thermally fusion reaction a) K, b) K-0.8, c) K-1, d) K-1.2, e) K-1.4, f) K-1.6, g) K-1.8, h) K-2 Purpose: This research aims to demonstrate the synthesis of silica based hydrophobic aerogel from sand by using of ultrasonic assisted sol-gel method. The modification process of aerogel was carried out during production and all drying processes were completed at ambient pressure without the use of supercritical pressure. Optimum sample was evaluated for the production of plaster with thermal insulation properties. Theory and Methods: The silica solutions were obtained from the sand, and the synthesis of materials was based on the base- catalyzed sol-gel process. Results: Hydrophobic silica based aerogels were synthesized by using a combination of the ultrasonic method and the one step sol-gel method, with the sand. Parameters that have an effect on the synthesis of hydrophobic silica aerogel as well as on the properties of synthesized samples, such as pH, silicon/total material mass ratio, reflux time, reflux temperature, aging time, aging temperature and drying method, were investigated. The physical properties of the produced material were determined by FT-IR, contact angle and density measurements. For the sample with the lowest density, XRD, TG / DTG, N2 adsorption / desorption and SEM analyzes were performed and evaluated in the production of thermal insulating plaster. Conclusion: As a result of the analyzes, optimum synthesis conditions were determined as pH 9, Si / total amount of 0.25, reflux temperature 100° C and 30 minutes, aging temperature 50° C, aging time 24 hours and fixed drying process. It was determined that the optimum sample was amorphous silicon, the surface area was 281.73 m 2 /g and the average pore width was 24.44 nm. The sample evaluated in the thermal insulation plaster production has been added to the mixture in various mass percentage ratios and it has been observed that the thermal conductivity coefficient decreases due to the increase in the amount of aerogel in the content until it reaches to 10%. Keywords:  Aerogel  Sand  Hydrophobicity  Thermal insulating plaster Article Info: Research Article Received: 13.12.2017 Accepted: 06.06.2018 DOI: 10.17341/gazimmfd.460521 Correspondence: Author: Sabriye Piskin e-mail: piskin@yildiz.edu.tr phone: +90 212 383 4729