Investigation of some static and dynamic properties of a cohesive floor stabilized with geopolymer binder and fiber reinforcement mixtures

Following the determination that alkali-activated materials may be an alternative to conventional binders in concrete studies, the use of these materials as stabilization agents in soil improvement applications began to be investigated. The fact that the study is based on concrete technology has caused some applications to be reflected in the geotechnical field. Workability is one of the vital parameters affecting concrete properties, which is considered in the studies. However, the consistency of the mortar used in soil stabilization applications is much lower than concrete. Therefore, compaction is applied to the stabilized soils to reduce pore size. In this case, moisture content becomes prominent for soil stabilization application instead of workability. Most studies on soil stabilization using alkali-activated materials examined the effects of the molar ratio of Si/Al, Na/Al, Si/Ca, or SiO2/Na2O on workability. However, workability is not a parameter that can be considered for a mortar required to be placed by compaction. Using fiber inclusion is a common method to improve engineering properties of stabilized soil. The use of hybrid fiber, obtained by mixing more than one fiber into the material, leads to the positive aspects of each fiber in the matrix. In this way, multiple properties of the composite material can be improved simultaneously. However, use of hybrid fiber in soil stabilization applications is very rear. It is possible to use hybrid fiber mixtures in three different ways. These can be classified as using fibers with different structural properties, different functions, and different lengths. This study investigated the stabilization of silty soil with alkali-activated fly ash and fiber with 3 mm and 12 mm lengths. The objectives of this paper are (1) to examine the effect of activator content and fly ash content on the UCS, Al/Si ratio, and SiO2/Na2O ratio of the stabilized samples using a statistical approach, (2) to investigate the effect of hybrid fiber length on UCS, secant modulus, and stress-strain characteristics of the stabilized soil. A statistical approach was employed to investigate the relationship between fly ash content, alkali activator content, and UCS value. The fly ash content and alkali activator content were optimized considering the statistical model. The stabilized soil was characterized to examine geopolymer structures. The effects of fly ash and alkali activator content on UCS, Al/Si, and SiO2/Na2O ratios were determined considering the derived statistical model. The study showed that the activator content, which plays a crucial role in compaction, is a parameter that affects the UCS value at least as much as the Si/Al and SiO2/Na2O ratios. Additionally, using hybrid fiber length improved the multiple mechanic properties of the stabilized soil.