Influence of storage conditions on geotechnical properties of Ariake clay and on its chemical stabilization is investigated to make use of the surplus clay as construction materials. The influence factors in lime and cement stabilization including salts, diatom and clay minerals were studied. The experiments were set up by mixing clays with various proportions of studied factors. As a result, for Bangkok clay, Kaolin and Bentonite, the factors improving the unconfined compressive strength of cement-stabilized clay are diatom content, cement content, CaCl2 and NaCl in descending order. Conversely, Kaolin and Bentonite are detrimental factors for Bangkok clay. For Ariake clay, the positive factors are only cement content and diatom content. In case of lime stabilization, for Ariake clay, the positive factors are only lime content and 5% of NaCl. The different characteristics between Ariake and Bangkok clays after treating with various admixtures may be due to the differences in chemical properties. Sometimes, due to soil containing high organic, the soil stabilized by lime cannot yield high strength enough for construction. Organic matters have the tendency to coat the soil particles, causing the obstruction or delay of the pozzolanic reaction when the lime is introduced. However, the test results indicated that when sodium salt (NaCl) or calcium salt (CaCl2) is added to the lime-organic clay mixture, the strength of mixture increases with increasing salt concentration. Finally, to investigate the effect of oxidation and drying on soil properties during storage, two series of laboratory testing on oxidation and drying effects were performed on Ariake clays that stored in the different conditions and periods. The results show that after storage, the properties of all samples were changed by oxidation or drying effect. Oxidation process usually produces acids causing the dissolution of calcium carbonate, which increases the concentration of divalent cation in clay. As a result, liquid limit of clay was changed. O
