Soil treatment is commonly resorted in order to improve the strength, stiffness properties of road foundations, and reduce the swelling potential of expansive soils. In Jordan, considerable amount of construction activity is carried out at relatively shallow depths where soil is likely to be unsaturated and subjected to low stresses level. Road damage is frequently observed when it is founded on weak sub-grade in Karak. Therefore, chemical stabilization of the base course, sub base course and sub-grade is essential. The soil will be treated by using sodium silicate and lime with different percentages. An experimental program was designed to study the behavior of soil as the percent of additive agent changes. The results showed that; the geotechnical properties have been improved when soil is treated by mixing lime and sodium silicate. The initial consumption of lime is of 4 and 2 % for sodium silicate. The reaction time is a significant parameter where strength improves as time increases.