Soft Bangkok clay (SC) is recognized as a problematic soil in Thailand. This research investigates the possibility of using polyvinyl alcohol (PVA) and high calcium fly ash (FA) geopolymers to improve the strength of SC in deep soil mixing applications. The liquid alkaline activator (L) was composed of sodium silicate (Na₂SiO₃) and sodium hydroxide (NaOH). The studied influence factors included FA content, water content, L content, Na₂SiO₃/NaOH ratio, PVA concentration, PVA content, and curing time. Strength development and microstructure in the PVA-FA geopolymer stabilized SC were evaluated via the unconfined compressive strength (UCS) test and scanning electron microscope (SEM) test. The optimum ingredient considering workability and cost of FA geopolymer stabilized SC was found to be at a mix design of 1.0LL, Na₂SiO₃/NaOH = 1, FA = 40% and L/FA = 0.6, whereby a 28-day UCS of 1026 kPa was attained. The optimum PVA content and PVA concentrations were found at 15% and 4%. The 7-day and 28-day UCS values were improved by PVA up to 40% and 42% compared to those of the specimen without PVA, respectively. The outcome of this research will promote the usage of PVA-FA geopolymer as an alternative green soil stabilizer alternative to Portland cement for a DM improved soft Bangkok clay.

软曼谷粘土（SC）在泰国被认为是有问题的土壤。这项研究调查了在深层土壤搅拌应用中使用聚乙烯醇（PVA）和高钙粉煤灰（FA）地质聚合物来提高SC强度的可能性。液体碱性活化剂（L）由硅酸钠（Na ₂ SiO ₃）和氢氧化钠（NaOH）组成。研究的影响因素包括FA含量，水含量，L含量，Na ₂ SiO ₃/ NaOH比，PVA浓度，PVA含量和固化时间。通过无侧限抗压强度（UCS）测试和扫描电子显微镜（SEM）测试评估了PVA-FA地聚合物稳定的SC中的强度发展和微观结构。考虑到FA地聚合物稳定的SC的可加工性和成本，发现最佳成分为1.0LL，Na ₂ SiO ₃的混合设计/NaOH＝1，FA＝40％，L/FA＝0.6，由此获得1026kPa的28天UCS。发现最佳的PVA含量和PVA浓度为15％和4％。与不使用PVA的样品相比，PVA将7天和28天的UCS值分别提高了40％和42％。这项研究的结果将促进PVA-FA地聚合物作为DM改良软曼谷黏土的替代波特兰水泥的替代绿土稳定剂。