การลดศักยภาพการพองตัวของดินบวมตัวแม่เมาะด้วยการใช้สารละลายโพแทสเซียมไฮดรอกไซด์

Abstract

This thesis aims to assess the settlement of a factory building in Mae Mo, Lampang Province, Thailand, caused by the problem of expansive soil. The expansive soil has resulted in damage to the main structural of the building, including reinforced concrete columns, reinforced concrete slabs on the ground, and the foundation. The current elevation of the building, compared to the expected elevation based on the settlement assessment, indicates that the building has not yet reached the end of its uplift process. Therefore, the thesis proposes a method to improve the soil quality in the field using an experiment involving the use of a potassium hydroxide solution to help reducing soil heaving. This concept is based on the study of the structure of montmorillonite minerals, which causes soil expansion due to its interconnected silicate-gibbsite structure held together by water molecules.In contrast, another type of mineral, illite, has a similar structure to montmorillonite but does not expand and is linked by potassium ions. Therefore, the experiment was conducted by drilling deep holes of approximately 2 meters into the swelling soil layer in Mae Mo district and using a potassium hydroxide solution in both liquid and flakes. The solution was poured into the drilled holes and maintained at a consistent level throughout the duration of the experiment. After 30 and 90 days, additional holes were drilled beside the solution-filled holes to collect soil samples for laboratory analysis. The examination revealed that only the potassium hydroxide solution at a concentration of 20% was able to reduce soil heaving in the Mae Mo district. Furthermore, X-ray diffraction of the soil showed that within the first 30 days, montmorillonite transformed into illite, and after 90 days, it transformed into muscovite.