*Proceeding Paper* **A Study of Fly Ash-Based Geopolymers with Basalt Flour Addition †**

**Barbara Kozub \* , Krzysztof Miernik and Szymon G ˛adek**

Department of Materials Engineering, Faculty of Materials Engineering and Physics, Cracow University of Technology, Al. Jana Pawła II 37, 31-864 Cracow, Poland

**\*** Correspondence: barbara.kozub@pk.edu.pl

† Presented at the 10th MATBUD'2023 Scientific-Technical Conference "Building Materials Engineering and Innovative Sustainable Materials", Cracow, Poland, 19–21 April 2023.

**Abstract:** The purpose of this study is to evaluate the effect of basalt flour addition, replacing quartz sand, and its proportion on fly ash-based geopolymers' properties. As a base material, Fgrade fly ash was used. The activation process was carried out using a 10 mol solution of sodium hydroxide and an aqueous solution of sodium silicate. The tests included measurements of density, compressive and flexural strength, abrasion resistance, and observation of the microstructure of geopolymers. The results of the study showed that basalt flour significantly increases compressive strength and causes a slight increase in flexural strength—by about 106% and 11%, respectively—and it allows for the reduction of the size of voids and the share of porosity in the structure of the tested geopolymers. Basalt flour has an application potential in geopolymer materials to make them more useful in construction.

**Keywords:** fly ash; quartz sand; basalt flour; geopolymer; abrasion resistance; strength properties
