Shear strength and durability behavior of organic soils treated with recycled glass powder-based geopolymer

Organic soil has many construction problems due to its being weak in engineering properties, such as low shear strength and high deformation or compressibility. This study's primary goal was to determine whether employing recycled glass powder-based geopolymer can enhance the engineering properties of organic soil through tests of durability and unconfined compressive strength (UCS). The impact of an alkaline activator solution on UCS and durability, as well as the effects of recycled glass powder (RGP) contents on maximum dry unit (MDU) and optimum moisture content (OMC), were also examined in this study. RGP-based geopolymer was used with organic soil to improve durability and compensate for reduced shear strength. The RGP was added with different percentages (5, 10, 15, 20, and 25 %) by dry weight of soil. Sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) were used to prepare the geopolymer. First, sodium hydroxide with constant molarity (4M) was used with RGP to find the optimum mixture, then sodium hydroxide (SH) with sodium silicate (SS) (SH:SS = 72:28), and (SH:SS = 50:50) with the same molarity was used with the optimum mix only. According to the findings, maximum dry unit weight (MDU) increases as RGP content is added, but optimum moisture content (OMC) decreases. Additionally, as the RGP content increases up to 20 %, the results demonstrate that the unconfined compressive strength (UCS) increases. For the optimum mix (20 % RGP), the UCS increases by 29, 38, and 46 times, and the failure strain decreases by 31.4, 31, and 39.3 % with curing times of 7, 14, and 28 days at 65 °C, respectively, compared to the untreated soil. A durability test was conducted on compacted natural soil and stabilized organic soil with three different alkaline activator solutions (100:0), (72:28), and (50:50) for a curing time of 28 days at a curing temperature of 65 °C according to ASTM D559. Results showed that after 12 cycles of the wetting and drying cycles, UCS decreased by 20, 28.5, and 35.1 %, respectively.