High-temperature behavior and mechanical characteristics of boron waste additive metakaolin based geopolymer composites reinforced with synthetic fibers

Keywords: Geopolymer, metakaolin, boron waste, synthetic fibers, high temperature, abrasion resistance. This study aims to study some mechanical and microstructural properties and high temperature behavior of metakaolin based geopolymer mortar composites reinforced with boron waste using four different fibers. Synthetic fibers (polyolefin fiber, basalt fiber, modified polyamide fiber and polyvinyl alcohol fiber) were used to evaluate the behavioral effects of geopolymer composites. Some experimental tests have been carried out to determine the effect of fibers to be added on the properties of metakaolin-based geopolymer mortars, such as compressive strength, flexural strength, abrasion resistance, toughness and high temperature resistance. Geopolymer mixtures were prepared with a combination of metakaolin and boron waste activated by sodium hydroxide and sodium silicate solutions and then cured with heating. Experimental test results show that the addition of various fiber types improves the strength properties of geopolymer composites, for example, polyvinyl alcohol fiber samples provided a 415.58% flexural toughness improvement compared to the control sample. As regards abrasion resistance, all produced samples showed a length change less than 2 mm and a weight loss less than 15 g. Using synthetic fibers has a positive effect on the high temperature behavior of metakaolin based geopolymer composites due to loss of strength, loss of weight and loss of ultrapulse velocity. Microstructural analysis has shown that there is an acceptable degree of bonding between synthetic fibers and the geopolymer matrix.