Effect of basalt fiber on metakaolin-based geopolymer mortars containing rilem, basalt and recycled waste concrete aggregates

Abstract With the development of technology, it is important to recommend new environmentally friendly materials instead of cement, which is the main binder of concrete. Recently, geopolymer mortars have been the focus of many researchers to achieve this goal. In this study, the effects of three different basalt fiber (BF) ratios on the metakaolin (MK)-based geopolymer mortars produced with three different aggregate types were investigated. By adding 0.0, 0.4, 0.8, and 1.2% BF for each group aggregate, a total of 12 different geopolymer mixtures were obtained. In the mixtures, metakaolin activated with sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) was used as the main binder. Rilem sand (RS), basalt Sand (BS), and recycled waste concrete (RWC) were used separately as filling materials. Mechanical strengths of 7, 28, and 56-day specimens obtained from all mixtures were tested. Ultrasonic pulse velocity (UPV), high-temperature, abrasion, freeze–thaw, and porosity tests were performed for the mortars produced. According to the results, positive effects were observed on all properties due to the more systematic performance of geopolymer samples with the addition of basalt fiber. According to the results, basalt fiber had positive effects, especially when 0.8–1.2% was used. When the results were examined, it was able to create an increase of up to 25% in the compressive strength results and 50% in the flexural strength results. Also, although the properties of geopolymers produced with recycled aggregate were inferior to the others, the results obtained were quite acceptable values for the application. With the basalt sand effect, higher results were obtained by obtaining a harder and more dense structure than others.