การปรับปรุงสภาพดินบวมตัวด้วยการใช้สารละลายโพแทสเซียมในพื้นที่อำเภอแม่เมาะ

Abstract

This thesis aims to study the effects of four types of potassium solutions, namely Potassium Hydroxide (KOH), Potassium Chloride (KCl), Potassium Nitrate (KNO3) and Potassium Sulfate (K2SO4) on improving the quality of Mae Moh’s expansive soil for use as a guideline for studying the properties for designing subgrade soil with swelling characteristics. The initial test of free swell index on expansive soil mixed with those four K-solutions at variety of concentrations revealed that K2SO4 could not reduce the swell whilst KCl, KOH, and KNO3 at the concentrations of 10%, 20% and 20% respectively, reduced the swell significantly. Subsequently, the concentrations obtained from the initial test were used to test the percent free swell. It showed that the soil soaked in KCl solution demonstrated significant reduction of swelling, followed by KNO3 and KOH solutions. From the test results on swelling pressure, it was found that the soil soaked in KOH solution significantly increased the swelling pressure. Subsequently, laboratory tests were conducted by soaking the soil in KCl and KOH solutions, followed by drying and California Bearing Ratio (CBR) testing to simulate soil quality improvement in the field. It was found that both types of soaked soils showed increased CBR values. Ultimately, the results from the swelling tests indicated that both solutions could effectively reduce soil swelling. The soil treated with 20% KOH solution exhibit the improved CBR value from 1.42 to 17.80, and the decreased swelling from 6.08 to only 0.05 which ave acceptable for using as subgrade material.