Abstract:
This thesis studies about the cement stabilization of peaty soil in order to investigate its physical, chemical and engineering properties in natural peaty soil from Phru Toe Daeng. Sample of peaty soil from Narathiwat-Takbi Road and Takbi-Sungaikolok Road at the depth of 3, 6 and 10 m. are tested to determine their properties and then mixed with cement at the proportions of 100, 125, 150, 200 and 250 kg./cu.m. of wet soil. After curing for 1, 3, 7, 14 and 28 days, the undrained shear strength (Su) and modulus of elasticity (E50) are determined from unconfined compression test. Test results show that the average Su values of raw soil at the depths of 3, 6 and 10 m. from Narathiwat-Tak Bai Road are 0.07, 0.04 and 0.03 kg./sq.cm. with the organic matter contents of 24.7, 15.8 and 12.9 percent ; and the ones from Takbi-Sungai Kolok Road are 0.11, 0.06 and 0.07 kg./sq.cm. with the organic matter contents of 7.9, 11.3 and 14.2 percent, respectively. The organic matter and acid content in peaty soil have an effect on the compressive strength of soil-cement. Peaty soil with high organic matter will require more cement than the one with low organic matter. According to the design criteria of the Department of Highways, the cement column under 28 days curing period should give Su value exceed than 3 kg./sq.cm. Thus the optimum cement content for improving the peaty soil for Narathiwat-Tak Bai Road should be equal to 250 kg./cu.m.